Effective Removal of Malachite Green from Aqueous Solutions Using Magnetic Nanocomposite: Synthesis,Characterization,and Equilibrium Study

Abstract

In this work, magnetized activated Juniperus procera leaves (Fe₃O₄@AJPL) were successfully prepared via chemical activation of JPL and in situ coprecipitation with Fe₃O₄. A Fe₃O₄@AJPL nanocomposite was successfully applied for the elimination of malachite green (MG) dye from aqueous media. The prepared Fe₃O₄@AJPL adsorbent was characterized by SEM, EDX, TEM, XRD, FTIR, TGA, and BET surface area analyses. The BET surface area and pore size of the Fe₃O₄@AJPL nanocomposite were found to be 38.44 m²/g and 10.6 nm, respectively. The XRD and FTIR results indicated the formation of a Fe₃O₄@AJPL nanocomposite. Different parameters, such as pH of the solution (3–8), adsorbent dosage (10–100 mg), temperature (25–45°C), contact time (5-240 min), and initial MG concentrations (20–350 mg/L), for the elimination of the MG dye using Fe₃O₄@AJPL were optimized and found to be 7, 50 mg, 45°C, 120 min, and 150 mg/L, respectively. The nonlinear isotherm and kinetic studies exhibited a better fitting to second-order kinetic and Langmuir isotherm models, with a maximum monolayer adsorption capacity of 318.3 mg/g at 45°C, which was highly superior to the previously reported magnetic nanocomposite adsorbents. EDX analyses confirmed the presence of nitrogen on the Fe₃O₄@AJPL surface after MG adsorption. The calculated thermodynamic factors indicated endothermic and spontaneous processes. The desorption of MG dye from Fe₃O₄@AJPL was performed using a solution of 90% ethanol. Finally, it could be concluded that the designed Fe₃O₄@AJPL magnetic nanocomposite will be a cost-effective and promising adsorbent for the elimination of MG from aqueous media.

1. Introduction

Water pollution by organic wastes produced by human activities is considered as one of the most dangerous environmental problems which have threatened human health and other living organisms. Dyes are widely utilized in different industries such as pharmaceuticals, paper, plastics, leather, and textiles. Malachite green (MG) has been extensively used in various fields such as in food processing, textile, cosmetic, pharmaceutical, plastic, and paper industries [1]. MG is used in aquaculture industries due to its great fungicide and bactericidal efficacy. Thus, it is extremely toxic to humans, plants, and aquatic fauna [2, 3], and it can cause carcinogenesis damage to the kidney and liver [4, 5]. Due to the toxicity and carcinogenic effect of MG dye ions, their removal from the aqueous environment is highly demanded. Therefore, the removal of dyes such as MG from wastewaters or surface waters is mandatory for the protection of human health. Different techniques were developed by researchers for the dye removal from the wastewater including membrane [6], photodegradation [7, 8], oxidation [9], electrochemical [10] ion exchange [11], and adsorption methods [12–14]. Among these techniques, adsorption is a successful, effective, and economical technique that is used to eliminate dyes from the polluted water as compared to other techniques [15, 16].

Many adsorbent materials were obtained from natural materials such as chitosan [17] and alginate beads [18]; wastes of agricultural activities, for example, almond shell [19], garlic peel [20], coffee waste [21], sugarcane bagasse [22], orange peels [23], banana peels [24], and peanut hull; and industrial waste, i.e., fly ash [25] for the elimination of dyes from aqueous media. Among the tested natural materials, leaf-based materials have received great attention as they possess various characteristics such as their low cost, easy preparation, and availability in large quantities. Leaves are used as an adsorbent material for the elimination of MG dye from wastewater by reducing the amount of waste produced [26]. Gupta et al. [27] have prepared Ashoka (Saraca asoca) leaf powder and tested for the elimination of brilliant green (BG), malachite green (MG), rhodamine B (RB), and methylene blue (MB) from an aqueous solution with 125, 83.3, 66.6, and 90.9 mg/g, respectively, as the maximum adsorption capacity. The treatment of the raw leaf-based material with different chemical reagents such as acids and bases could improve their adsorption properties toward the removal of dyes [28, 29].

Recently, it has been reported that biosorbent treated with H₂O₂ improved the capacity of dye adsorption from the solution since the H₂O₂ could increase oxygen-containing functional groups on the surface of the adsorbent and thus augment its capability to remove dyes from aqueous media [30, 31]. As we know, nonmagnetic material adsorbents suffer from the difficulty of isolation of adsorbate-loaded absorbents from aqueous media after the adsorption process due to their small particle size. To overcome this problem, the use of magnetism has been proposed by several researchers. Magnetite nanoparticles (Fe₃O₄) attract significant attention due to their unique large surface area, and these possess high saturation magnetization and can easily isolate toxic pollutants from aqueous solutions by using a magnet without using centrifugation and filtration compared to conventional adsorbents [32]. New economical, highly effective, and locally available biosorbents are still under development. Juniperus procera leaves are the most abundant plant in Saudi Arabia and many countries such as Lebanon, Bosnia, and Turkey [33–36]. Magnetic modification of low-cost adsorbents such as Juniperus procera leaves (JPL) could lead to materials appropriate for environmental applications. After a thorough literature survey, we have concluded that there are no previous studies reporting the activation of Juniperus procera leaves with H₂O₂ to increase the oxygen-containing functional groups on its surface. To our best knowledge, this is the first work to report the synthesis of a Fe₃O₄@activated Juniperus procera leaf nanocomposite.

This study was aimed at synthesizing a new Fe₃O₄@activated Juniperus procera leaf nanocomposite (Fe₃O₄@AJPL) via chemical activation and in situ coprecipitation methods. The prepared adsorbent was applied for removal of dyes from aqueous media. The Fe₃O₄@AJPL adsorbent was characterized by SEM, EDX, TEM, XRD, TGA, FTIR, and BET surface area analysis. The impact of various parameters on the MG dye adsorption onto Fe₃O₄@AJPL adsorbent such as solution pH, adsorbent dosage, contact time, initial MG concentrations, and temperature was achieved. The isotherm and kinetic data were analyzed by applying nonlinear equation models. Thermodynamic factors were also calculated.

2. Experiments

2.1. Chemicals and Instrumentation

Malachite green (MG), hydrogen peroxide (H₂O₂, 30%), ferric chloride (FeCl₃·6H₂O, 97%), ethanol (C₂H₅OH, 99.8%), and ferrous chloride (FeCl₂·4H₂O, 98%) were procured from Sigma Aldrich. Nitric acid (HNO₃, 68.0-70.0%)_, sodium hydroxide (NaOH, ≥97%), and hydrochloric acid (HCl, 36%) were procured from BDH, England. Solutions were prepared using deionized water. The crystalline structures of AJPL, Fe₃O₄, and Fe₃O₄@AJPL were determined using an XRD-6000 (Shimadzu, Kyoto, Japan). The morphological properties of AJPL, Fe₃O₄, Fe₃O₄@AJPL, and Fe₃O₄@AJPL-MG were evaluated using a transmission electron microscope (TEM) and scanning electron microscope (SEM) (JEOL 200 kV, Tokyo, Japan). Fourier transform infrared spectra of activated Juniperus procera leaves (AJPL), Fe₃O₄@AJPL, and MG-saturated Fe₃O₄@AJPL (Fe₃O₄@AJPL-MG) were recorded using a Nicolet iS50, Thermo Scientific (Madison, WI, USA). The elemental composition of adsorbents was detected by energy-dispersive X-ray (EDX) (JEOL 7600F, Tokyo, Japan). The surface area of Fe₃O₄@AJPL was evaluated through the determination of N₂ adsorption-desorption isotherms at −196°C by Micromeritics (USA). The concentration of MG was determined using a UV-visible spectrophotometer (Shimadzu 2450) at 616 nm.

2.2. Chemical Treatment of Juniperus procera Leaves

Juniperus procera leaves (JPL) were collected from Al Baha Province, Saudi Arabia. The leaves were washed with distilled water and dried for 7 days at room temperature (22–27°C) and ground using an electrical grinder. To increase oxygen-containing functional groups on the JPL surface, the JPL was treated with H₂O₂ by using the reported methods [30, 31]. Briefly, 20 g of the obtained JPL powder was immersed in 200 mL of 10% H₂O₂ and stirred for 24 h. Then, the sample was filtered off and was washed several times with deionized water. Following, 20 g of the AJPL powder was added into 200 mL of 1 M NaOH for removal of the impurities from the surface of JPL powder, resulting in improvement of the surface roughness of particles, formation of a pore structure, and opening of more hydroxyl groups and other reactive functional groups on its surface. Therefore, the removal of surface impurities can improve the adsorption properties of the JPL powder [37, 38]. The JPL powder was stirred for 24 h at 25°C. The resulting AJPL powder was washed with D.I. water and dried at 25°C for 3 days. Finally, the AJPL-obtained material was ground again to obtain a uniform particle size (Figure 1).

Figure 1

Synthesis of Fe₃O₄@AJPL nanocomposite and its mechanism of adsorption-desorption behavior for MG dye ions.

2.3. Magnetization of Juniperus procera Leaves (Fe₃O₄@AJPL)

The magnetization of AJPL powder was performed using the in situ coprecipitation method. Briefly, in a three-necked round bottom flask containing 90 mL D.I. water, 1.5 g of AJPL powder was suspended. To this mixture, 0.715 g of FeCl₂·4H₂O, and 2.15 g of FeCl₃·6H₂O (Fe²⁺ : Fe³⁺=1 : 2 molar ratio) were added and mechanically stirred for 20 min and heated to 80°C, and then, 10 mL of NH₄OH was added dropwise over a period of 2 hrs. The obtained black precipitate (termed Fe₃O₄@AJPL) was collected by external magnetic field and washed with ethanol and D.I. water. Finally, the Fe₃O₄@AJPL was dried at 60°C for 24 h. Figure 1 demonstrates the preparation scheme of the Fe₃O₄@AJPL nanocomposite.

2.4. Adsorption Studies

The batch experiment method was conducted to select the best parameters for the adsorption process. The impact of adsorption parameters on MG dye adsorption by Fe₃O₄@AJPL adsorbents including adsorbent dosage (10–100 mg), pH (3–8), temperature (25–45°C), contact time (5-240 min), and initial MG dye concentration (20–350 mg/L) was achieved. The general procedure was as follows: the desired quantity of Fe₃O₄@AJPL adsorbents was taken in a 250 mL Erlenmeyer flask containing a 50 mL solution of MG with a given concentration, and then, the sample solution pH was adjusted using a 0.1 M HCl or 0.1 M NaOH to the desired pH. Then, the sample solution was shaken at 100 rpm for a specific time. After that, the sample was separated using a magnet, and the residual MG concentration was measured using a UV/Vis spectrophotometer at 616 nm. The adsorption efficiency ( $R_{e}$ , %) and adsorbent capacity ( $q_{e}$ , mg/g) were determined according to the following equations, respectively: $\begin{matrix} (1) & R_{e} (%) = \frac{C_{o} - C_{e}}{C_{o}} \times 100, \\ (2) & q_{e} = (C_{o} - C_{e}) \frac{V}{m}, \end{matrix}$ where $C_{o}$ (mg/L) and $C_{e}$ (mg/L) represent the initial and equilibrium concentrations of MG, respectively; $m$ is the amount of Fe₃O₄@AJPL adsorbents (g); and $V$ (L) is the solution volume. For the desorption study, the separated adsorbent was placed into 50 mL of 90% ethanol or HCl (0.1 M) and HNO₃ (0.1 M) solution. Then, the sample solution was shaken at 100 rpm for 120 min. After that, the MG dye concentrations of the sample isolated with a magnet were determined using a UV/Vis spectrophotometer at 616 nm. The % desorption was calculated by using the following equation: $\begin{matrix} (3) & % desorption = \frac{Concentration of MG desorbed by the ethanol}{Initial concentration of MG adsorbed on {Fe}_{3} O_{4} @ AJPL} \times 100 . \end{matrix}$

3. Results and Discussion

3.1. Synthesis and Characterization of Fe₃O₄@AJPL

Juniperus procera leaves (JPL) were activated by using H₂O₂ and NaOH reagent. H₂O₂ is a strong oxidant, inexpensive, and clean. The use of H₂O₂ and NaOH is important to increase oxygen-containing functional groups on the JPL surface and improve the adsorption properties of JPL powder by removing the impurities from the surface of the JPL powder. AJPL carries hydroxyl, carboxyl, and carbonyl groups. Activated Juniperus procera leaves were successfully converted to the magnetized activated Juniperus procera leaves (Fe₃O₄@AJPL) via in situ coprecipitation. Fe₃O₄@AJPL has the ability to separate MG dye from aqueous solutions by using an external magnetic field, and it has a large surface area (116.9517 m²/g) and pore size (9.48 nm). It can easily separate the MG dye from aqueous solutions by using an external magnetic field. The Fe₃O₄@AJPL nanocomposite contains different functional groups (COOH, OH, C=O) which can adsorb MG ions by for π-π stacking, H-bonding, and electrostatic attraction (Figure 1).

Figure 2(a) displays the FTIR of AJPL, Fe₃O₄@AJPL before adsorption, and MG-saturated Fe₃O₄@AJPL (Fe₃O₄@AJPL-MG) adsorbent. In the spectrum of AJPL, the broad band centered at 3320 cm⁻¹ is attributed to the OH group, suggesting the presence of a phenolic group [39]. The bands at 1731 and 1606 cm⁻¹ ascribed to C=O and the one at 1026 cm⁻¹ corresponding to C-O-C groups indicate the existence of carboxylic acid derivatives. Furthermore, the observed band of C=C stretching vibration at 1549 cm⁻¹ as well as the C-H out-of-plane bending vibrations at 776 cm⁻¹ is possibly characterizing the aromatic rings. Additional peaks of CH modes were also identified, e.g., at about 2943 cm⁻¹. In the spectrum of Fe₃O₄@AJPL, a new band at 560 cm^-1 assigned to the distinctive band of Fe-O stretching vibration was observed, confirming the presence of Fe₃O₄ nanoparticles [40, 41]. Moreover, it is observed that the modification of AJPL with Fe₃O₄ nanoparticles has resulted in intensity reduction of some characteristic peaks including the OH and C-O-C peaks. The spectra of the MG-loaded Fe₃O₄@AJPL showed shifts in the bands of some functional groups such as C=O, OH, and C-O-C from 1731, 3320, and 1026 cm⁻¹ to 1721, 3329, and 1023 cm⁻¹, respectively, due to adsorptive interaction.

Figure 2

(a) FT-IR spectra, (b) XRD plot, (c) BET adsorption-desorption analysis, and (d) TGA analysis of adsorbents.

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(c)

(d)

Figure 2(b) shows the XRD pattern of AJPL, Fe₃O₄ nanoparticles, and Fe₃O₄@AJPL nanocomposite. As implied in Figure 2(b), the characteristic peaks of Fe₃O₄ nanoparticles and the Fe₃O₄@AJPL nanocomposite perfectly matched the face-centered cubic crystalline which was confirmed by 2θ values of 30.24°, 35.56°, 43.22°, 57.11°, and 62.76° to (220), (311), (400), (511), and (440) planes, respectively [42]. The diffraction peaks for AJPL are 13.45°, 14.83°, 21.2°, 24.29°, 30.02°, 35.8°, and 38.15°. After modification of magnetite nanoparticles with AJPL, new peaks appeared at $2 θ = {14.9}^{°}$ and 27.02° which matched to the strong peaks in the XRD pattern of leaves [43]. Therefore, these results indicated that the Fe₃O₄@AJPL nanocomposite was successfully synthesized.

Figure 2(c) displays the N₂ adsorption/desorption isotherms of Fe₃O₄ nanoparticles and the Fe₃O₄@AJPL nanocomposite. The surface area, pore volume, and pore size were found to be 116.9517 m²/g, 0.322 cm³/g, and 9.48 nm for Fe₃O₄ nanoparticles and 38.44 m²/g, 0.136 cm³/g, and 10.6 nm for the Fe₃O₄@AJPL nanocomposite. The N₂ adsorption-desorption curve of both adsorbents exhibited a type IV isotherm, suggesting the presence of mesopores in both adsorbents.

Figure 2(d) shows thermogravimetric analysis (TGA) of Fe₃O₄ and Fe₃O₄@AJPL. In the case of Fe₃O₄, about 10% is the total weight loss in the temperature range from 25°C to 1000°C due to the removal of the adsorbed water and conversion of hydroxide to oxide [44]. In the case of the Fe₃O₄@AJPL nanocomposite, it is a three-stage thermal degradation. The first stage from 25–180°C (3%) is related to the loss of moisture and adsorbed water. 7% and 50% weight loss were observed between the temperature ranges 180–320°C and 320–800°C in the second and third stages, respectively, due to decomposition of molecular organic compounds such as flavonoids of JPL in Fe₃O₄@AJPL [45]. The total weight losses of Fe₃O₄@AJPL and pure magnetite nanoparticles were 60% and 10%, respectively, which confirmed the formation of the Fe₃O₄@AJPL nanocomposite.

Figure 3 shows the SEM-EDX image results of the AJPL powder, Fe₃O₄, Fe₃O₄@AJPL, and MG dye-saturated Fe₃O₄@AJPL adsorbents. The surface structure of the AJPL powder is rough with the existence of some pore and crack sites (Figure 3(a)). After modifying the AJPL powder with magnetite nanoparticles, the magnetite nanoparticles are dispersed in the surface of AJPL (Figure 3(c)). The surface of Fe₃O₄ nanoparticles shows a spherical shape with diameters in the range of 12–25 nm (Figure 3(e)). The SEM image of the Fe₃O₄@AJPL loading MG showed a different morphology than before adsorption, which was well occupied with the MG dye as implied in Figure 3(g), indicating that the MG dye was successfully adsorbed on the Fe₃O₄@AJPL adsorbent. The EDX of the AJPL powder (Figure 3(b)) revealed the presence of mainly C (30.68%) and O (30.50%) and small amounts of Ca, Al, K, and Si. After modifying AJPL with magnetite nanoparticles, it was clearly observed that a new peak from iron (45.33%) appeared and increased in the intensity of oxygen (38.27%), confirming the synthesis of Fe₃O₄@AJPL successfully (Figure 3(d)). 65.32% of iron and 34.68% of oxygen were observed in the EDX spectrum of pure magnetite nanoparticles (Figure 3(e)). After MG dye was saturated on the Fe₃O₄@AJPL nanocomposite, a new peak of nitrogen was observed, indicating the successful adsorption of MG dye on the Fe₃O₄@AJPL adsorbent Figure 3(h). Figure 4(a) displays the TEM images of Fe₃O₄@AJPL nanocomposite. A small degree of agglomeration with a spherical shape was observed. The particle size was found to be 9 nm Figure 4(b). Figure 4(c) displays the lattice fringe spacing of the crystalline part (Fe₃O₄) of the Fe₃O₄@AJPL nanocomposite. The d spacing values were 0.291 nm and 0.252 nm, which are attributed to the (311) and (220) planes of Fe₃O₄ nanoparticles which were confirmed by the XRD results for the cubic structure of Fe₃O₄ nanoparticles. The selected area electron diffraction (SAED) analysis shows a ring pattern which confirms the presence of crystalline Fe₃O₄ nanoparticles in the nanocomposites (Fe₃O₄@AJPL) (Figure 4(c)).

Figure 3

(a) SEM image, (b) EDX analysis of activated Juniperus procera leaves (AJPL), (c) SEM image, (d) EDX analysis of Fe₃O₄@AJPL, (e) SEM images, (f) EDX analysis of magnetite nanoparticles, (g) SEM image, and (h) EDX analysis of MG adsorption onto Fe₃O₄@AJPL.

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(e)

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(g)

(h)

Figure 4

(a) TEM image, (b) size particles distribution, (c) SAED pattern, and (d) HRTEM image of Fe₃O₄@AJPAL adsorbent.

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3.2. Adsorption Studies

3.2.1. Adsorbate Selectivity

The prepared adsorbents AJPL and Fe₃O₄@AJPL nanocomposite were examined for elimination of different cationic dyes such as MG, CV, and MB from aqueous solutions as implied in Table 1. It was noticed that, at the adsorption conditions of adsorbent dose 50 mg, initial adsorbate concentration ( $C_{o}$ ) of 50 mg/L, and temperature of 25 C, the maximum removal efficiency of MG, CV, and MB dyes on both AJPL and Fe₃O₄@AJPL nanocomposite adsorbent were 98.76%, 94.81%, and 93.20% and 99.15%, 95.61%, and 73.11%, respectively. Accordingly, the removal of MG by the Fe₃O₄@AJPL adsorbent is considerably favored due to the high performance, easy separation, and recovery of the adsorbent using external magnetism. Thus, the adsorption parameters were further studied.

Table 1

Adsorption selectivity experiments with dye solutions (conditions: dye—20 mg/L, time—24 h, Fe₃O₄@AJPAL—50 mg, volume—0.05 L, temperature—25°C, and agitation—100 rpm).

Adsorbents	MG		CV		MB
Adsorbents	Adsorption capacity (mg/g)	Removal efficiency (%)	Adsorption capacity (mg/g)	Removal efficiency (%)	Adsorption capacity (mg/g)	Removal efficiency (%)
Activated Juniperus procera leaves (AJPL)	19.75	98.76	18.96	94.81	18.64	93.20
Fe₃O₄@AJPL	19.83	99.15	19.12	95.61	14.62	73.11

3.2.2. Effect of pH

The impact of the solution pH on MG adsorption onto Fe₃O₄@AJPL was tested over a range of pH values from 3 to 8 (MG: 20 mg/L, contact time: 24 h, adsorbent dose: 50 mg, temperature: 25°C, and agitation: 100 rpm) as shown in Figure 5(a). The results indicate an increase in the adsorption capacity and removal percentage with increase in pH up to pH 7. This increase in adsorption capacity was due to the surface charge of Fe₃O₄@AJPL nanocomposites becoming more negative and having strong electrostatic attraction with the cationic MG dye, resulting in higher adsorption efficiency. On the contrary, under an acidic medium, the excessive protonation of the Fe₃O₄@AJPL nanocomposite surface hindered the binding of cationic MG ions on the Fe₃O₄@AJPL nanocomposite surface, resulting in a lower adsorption efficiency [46]. Similar trends have been reported by Asfaram et al. for the removal of MG using biosorbent Yarrowia lipolytica ISF7 [47]. Compared with pH 7, an almost similar performance was observed at pH 8 above which the solution becomes colorless due to the reaction occurrence between the MG and OH. These results are inconsistent with the ones reported by Pan et al. [48] and De Marco et al. [49].

Figure 5

(a) Effect of pH value (conditions: MG—20 mg/L, time—24 h, Fe₃O₄@AJPAL—50 mg, temperature—25°C, and agitation—100 rpm), (b) contact time (conditions: MG—20 mg/L, pH—7, Fe₃O₄@AJPAL—50 mg, agitation—100 rpm, and temperature—25°C), (c) adsorbent dose (conditions: MG—20 mg/L, pH—7, time—120 min, temperature—25°C, and agitation—100 rpm), and (d) initial MG concentration (conditions: time—120, Fe₃O₄@AJPAL—50 mg, pH—7, temperature—25°C, and agitation—100 rpm) on the adsorption of MG on Fe₃O₄@AJPAL.

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3.2.3. Effect of Contact Time

The impact of the contact time on the MG adsorption by Fe₃O₄@AJPL was achieved over the time interval of 5–240 min under fixed conditions (MG: 20 mg/L, pH: 7, temperature: 25°C dose: 50 mg, and agitation: 100 rpm) (Figure 5(b)). At an initial period of 15 min, the adsorption rate was high with $R_{e}$ (%) and $q_{e}$ values of 85.7% and 17.14 mg/g, respectively. The initial rapid rate may indicate the existence of available active sites on the Fe₃O₄@AJPL surface. After 15 min, the adsorption was gradually increased with time, reaching the equilibrium, after 120 min, at which the $q_{e}$ and $R_{e}$ (%) were 18.32 mg/g and 91.6% at 120 min, respectively. Thus, the optimized equilibrium time for the work was 120 min. Compared with the literature, this equilibrium time is better than the ones previously reported by Pan et al. [48] and Gao et al. [50].

3.2.4. Effect of Dosage

The impact of the adsorbent dosage on the removal efficiency and adsorption capacity was tested in the range 10-100 mg under the following conditions: MG: 20 mg/L, pH: 7, contact time: 120 min, agitation: 100 rpm, and temperature: 25°C. As shown in Figure 5(c), the $R_{e}$ (%) value was slightly improved from 94.3% to 99.1% with the gradual rise in the amount of Fe₃O₄@AJPL adsorbent from 10 to 50 mg; however, the capacity ( $q_{e}$ ) was reduced. These results can be assigned to increased active sites at a high adsorbent dose [51, 52]. However, no significant increase in the adsorption efficiency above the 50 mg dose was observed. Moreover, the drop in the adsorption capacity is due to the aggregation events at a high dosage which lead to a decrease in the total surface area of the Fe₃O₄@JPL adsorbent. These outcomes are consistent with the results of the literature reported in [53]. As a result, under the examined condition, the optimal adsorbent dose was 50 mg.

3.2.5. Effect of Initial Concentration and Temperatures

The adsorption capacities of the Fe₃O₄@AJPL adsorbent at different initial MG concentrations (20–350 mg/L) and temperatures (25, 35, and 45°C) were also studied, keeping other factors (time: 120 min, pH: 7, dose: 50 mg, and agitation: 100 rpm) as given in Figure 5(d). The outcomes show that the adsorbed amount of MG dye by Fe₃O₄@AJPL was linearly increased while the initial MG concentration increased, e.g., as $C_{o}$ was augmented from 20 to 350 mg/L, the adsorption capacity improved from 18.5 to 201.2 mg/g at 25°C. Such results can be ascribed to the increment in the driving force of the adsorbate concentration, resulting in a high diffusion rate of the MG dye from the liquid phase to the solid phase. At the higher $C_{o}$ and at 45°C, the archived $q_{e}$ value was 258.6 mg/g. Also, the adsorption capacity was increased from 18.5 to 20 mg/g with increasing temperature from 25°C to 45°C at 20 mg/L. This increase in adsorption capacity is possibly due to diffusion enhancement of MG molecules to the surface and pores of Fe₃O₄@AJPL which is driven by elevated kinetic energy at higher temperature, thus suggesting an endothermic adsorption process. These outcomes are consistent with other studies for the removal of MG ions by organically modified clay [54] and Fe-Mg BACs [55].

3.3. Adsorption Modeling

3.3.1. Adsorption Isotherm

The adsorption isotherm studies were accomplished over a range of MG initial concentrations of 20–350 mg/L and at temperatures of 25, 35, and 45°C, keeping the other factors constants (i.e., adsorbent dose: 50 mg, pH: 7, contact time: 120 min, and agitation speed: 100 rpm). Nonlinear isotherm adsorption models such as Langmuir (Equation (4)) [56] and Freundlich (Equation (5)) [57] were applied to describe the behavior of the MG adsorption onto Fe₃O₄@AJPL. $\begin{matrix} (4) & q_{e} = \frac{q_{m} K_{L} C_{e}}{1 + K_{L} C_{e}}, \\ (5) & q_{e} = K_{F} {C_{e}}^{1 / n}, \end{matrix}$ where $q_{m}$ is the maximum adsorption capacity (mg/g), $n$ is the adsorption intensity, $K_{F}$ is the Freundlich isotherm constants, and $K_{L}$ is the Langmuir constant. According to the isotherm data shown in Figure 6(a) and Table 2, it is clear that the Langmuir model ( $R^{2} = 0.989$ ) provided a better fit than the Freundlich one ( $R^{2} = 0.929$ ), suggesting monolayer coverage. The adsorbent capacity corresponding to the maximum monolayer coverage ( $q_{m}$ , mg/g) was 318.3 mg/g at 45°C. The separation factor ( $R_{L}$ ) values during the work were found in favorable adsorption (<1) (i.e., 0.026, 0.040, and 0.052 at 298, 308, and 318 K). Moreover, the increase in the values of the $K_{F}$ and $K_{L}$ constants with temperature confirmed endothermic adsorption [58, 59].

Figure 6

(a) Nonlinear adsorption isotherm at different temperature (conditions: MG—20-350 mg/L, time—120 min, Fe₃O₄@AJPAL—50 mg, pH—7, and agitation—100 rpm) and (b) nonlinear kinetic models for MG adsorption by Fe₃O₄@AJPAL (conditions: MG—20 mg/L, time—120 min, Fe₃O₄@AJPAL—50 mg, pH—7, temperature—25°C, and agitation—100 rpm).

(b)

Table 2

Langmuir and Freundlich isotherm models for MG adsorption on Fe₃O₄@AJPL nanocomposite (conditions: MG—20-350 mg/L, time—120 min, Fe₃O₄@AJPAL—50 mg, volume—0.05 L, and agitation—100 rpm).

Model	MG dye
Model	298 K	308 K	318 K
Langmuir
$q_{m}$ (mg/g)	260.8	302.7	318.3
$K_{L}$ (L/mg)	0.026	0.040	0.052
$R_{L}$	0.657	0.551	0.485
$R^{2}$	0.989	0.980	0.980
Freundlich
$K_{f}$ (mg/g) (L/mg)^1/n	21.67	31.65	39.91
$R^{2}$	0.929	0.894	0.925

3.3.2. Kinetic Adsorption

The adsorption mechanism was achieved using the nonlinear kinetic models and pseudo-first-order (PFO) and pseudo-second-order models described by the following equations: $\begin{matrix} (6) & q_{t} = q_{e} (1 - e^{- k_{1} t}), \\ (7) & q_{t} = \frac{q_{e}^{2} k_{2} t}{1 + q_{e} k_{2} t}, \end{matrix}$ where $q_{t}$ (mg/g) is the adsorption capacity at time $t$ (min) and $k_{1}$ and $k_{2}$ are the rate constants of PFO and PSO, respectively. Figure 6(b) displays the kinetic plots for the MG adsorption onto Fe₃O₄@AJPL. It was observed that adsorption was fast in the first stage of the adsorption period (20 min), then slowly developed until equilibrium (120 min). The calculated kinetic parameters are given in Table 3. On the basis of $R^{2}$ values, the adsorption kinetics fit PSO ( $R^{2} = 0.998$ ) better than the PFO ( $R^{2} = 0.991$ ), suggesting that the adsorption of MG onto Fe₃O₄@AJPL occurred by the chemisorption mechanism. Moreover, the $q_{e}$ , calculated according to the PSO kinetic model ( $q_{e},_{cal} = 18.36 mg / g$ ), was closer to the experimental value ( $q_{e},_{\exp} = 18.35 mg / g$ ), supporting the PSO model. Similar trends have been reported by other adsorbents [60, 61].

Table 3

Kinetic model parameters for MG adsorption on Fe₃O₄@AJPL (conditions: MG—20 mg/L, time—120 min, Fe₃O₄@AJPAL—50 mg, volume—0.05 L, temperature—25°C, and agitation—100 rpm).

$C_{o}$ (mg/L)	$q_{e, \exp}$ (mg/g)	Pseudo-first-order			Pseudo-second-order
$C_{o}$ (mg/L)	$q_{e, \exp}$ (mg/g)	$q_{e 1, cal}$ (mg/g)	$K_{1}$ (1/min)	$R^{2}$	$q_{e 2, cal}$ (mg/g)	$K_{2}$ (g/mg-min)	$R^{2}$
20	18.35	17.80	0.308	0.991	18.36	0.040	0.998

3.3.3. Adsorption Thermodynamics

The adsorption thermodynamic factors such as the Gibbs free energy ( $Δ G^{°}$ ), entropy ( $Δ S^{°}$ ), and enthalpy ( $Δ H^{°}$ ) for the removal of the MG dye onto the Fe₃O₄@AJPL nanocomposite were calculated using Equation (8) and the van’t Hoff equation (Equation (9)) [62]: $\begin{matrix} (8) & ∆ G^{°} = - R T \ln K_{c}, \\ (9) & \ln K_{c} = - \frac{∆ H^{0}}{R T} + \frac{∆ S^{0}}{R}, \end{matrix}$ where $R$ is gas constant (8.314 J/mol·K) and $K_{c}$ represents the equilibrium constant and its equal $q_{e} / c_{e}$ [63]; the other notations have the same meaning as above.

Figure 7(a) and Table 4 summarize the data obtained. The value of $Δ G^{°}$ obtained was negative, indicating that the adsorption of MG onto Fe₃O₄@AJPL is spontaneous. The positive values of $Δ H^{°}$ and $Δ S^{°}$ indicate the endothermic process and increase in randomness during the adsorption process, respectively. The temperature-dependent $Δ G^{°}$ revealed favorable adsorption at higher temperature; however, the effect of the initial concentration of MG suggests better adsorption at a lower concentration. Additionally, the value of $Δ H^{°} > 40 kJ mo l^{- 1}$ at a low concentration means that the mechanism of MG adsorption is chemisorption. Therefore, at the examined adsorption conditions, the obtained $Δ G^{°}$ and $Δ H^{°}$ values suggest physical and chemical adsorption mechanisms, respectively [64]. Similar trends have been reported by Arabkhani et al. for the removal of MG using the GO/MMT polymer nanocomposite [65].

Figure 7

(a) Adsorption thermodynamics, (b) adsorption/desorption plot of MG dye from Fe₃O₄@AJPAL, and (c) recycling study (conditions: MG—20 mg/L, time—120 min, Fe₃O₄@AJPAL—50 mg, pH—7, temperature—25°C, and agitation—100 rpm).

(b)

(c)

Table 4

Thermodynamic factors for adsorption of MG on Fe₃O₄@AJPL (conditions: time—120 min, Fe₃O₄@AJPAL—50 mg, volume—0.05 L, pH—7, and agitation—100 rpm).

Concentration MG dye	$Δ H^{°}$ (kJ/mol)	$Δ S^{°}$ (J/mol·K)	$(-) Δ G^{°}$ (kJ/mol)
Concentration MG dye	$Δ H^{°}$ (kJ/mol)	$Δ S^{°}$ (J/mol·K)	298 K	308 K	318 K
20	40.12	151.2	5.095	6.192	8.139
50	50.10	180.7	3.998	5.065	7.646
100	27.69	106.0	3.716	5.342	5.811

3.4. Adsorption Mechanism

Figure 1 shows the stepwise preparation of the adsorbent Fe₃O₄@AJPL and the proposed adsorption mechanism. According to the FTIR spectrum, after MG dye adsorption on the Fe₃O₄@AJPL nanocomposite, there was a decrease and shift in the peak intensities of the functional groups. it was observed that the peaks at 3320 cm⁻¹, 1731 cm⁻¹, and 1026 cm⁻¹ decrease and shift to 3329 cm⁻¹, 1721 cm⁻¹, and 1023 cm⁻¹, respectively, due to adsorptive interaction between the MG dye and the COOH, OH, and C-O-C groups on the Fe₃O₄@AJPL surface by different mechanisms such as hydrogen bonding, π-π stacking, and electrostatic interaction. The nonlinear isotherm and kinetic adsorption studies exhibited a better fit to PSO kinetic and Langmuir isotherm models, indicating chemisorption adsorption. Additionally, the weak desorption efficiency of MG from the Fe₃O₄@AJPL surface confirms the chemisorption mechanism. It was observed that adsorption of MG onto Fe₃O₄@AJPL was fast in the first stage of the adsorption period (15 min) then slowly developed until equilibrium (120 min). The initial rapid rate may indicate existence of available active sites on the Fe₃O₄@AJPL surface. Furthermore, the data indicate that more than 85.7% of MG molecules were adsorbed in the first stage, supporting the chemical adsorption mechanism. However, the first stage cannot be recognized, and the slow rate in the second adsorption phase suggests a physical mechanism, which is possibly controlled by the diffusion process. On the other hand, the thermodynamic data support the physisorption mechanism. Therefore, it could be concluded that the MG adsorption on Fe₃O₄@AJPL occurred by physical adsorption together with the chemisorption process. The EDX analysis clearly shows a new peak of nitrogen along with the peaks of elements of the Fe₃O₄@AJPL nanocomposite, indicating MG adsorption onto the whole surface of the Fe₃O₄@AJPL adsorbent.

3.5. Comparative Performance of Fe₃O₄@AJPL with Other Adsorbents

For comparative purposes, the maximum adsorption capacity, $q_{m}$ , of some other adsorbents reported in the literature for the MG uptake are given in Table 5 [49, 66–70]; the adsorption conditions are also tabulated for easy comparison. Obviously, the $q_{m}$ value of Fe₃O₄@AJPL (318.3 mg/g) for MG adsorption is greater than the other listed magnetic nanocomposite adsorbents. The difference in the efficiencies of various adsorbents is due to the diversity in the adsorbent’s structures and morphologies. Hence, the characteristics and performance of the investigated adsorbent, Fe₃O₄@AJPL, support its being appropriate as a potential adsorbent for the removal of cationic pollutants such as MG from polluted aqueous systems.

Table 5

Comparison of the MG adsorption capacity of Fe₃O₄@AJPL nanocomposite with other magnetic adsorbents.

Adsorbent	Conditions	$q_{m}$ (mg/g)	Ref.
HNT-Fe₃O₄	$C_{o}$ : 40-120 mg/L; $T$ : 298 K; pH: 8; time: 240 min; dose: 150 mg	44.25	[49]
A litchi peel-based magnetic	$C_{o}$ : 150 mg/L; pH: 6; $T$ : 298 K; dose: 5.14 g/L; time: 66.69 min	70.42	[66]
PDA/CS/Fe₃O₄	$C_{o}$ : 5-200 mg/L; $T$ : 303 K; pH: 8; time: 40 min; dose: 100 mg	60.97	[67]
Magnetic pectin-Chlorella vulgaris	$C_{o}$ : 5-100 mg/L; $T$ : 303 K; dose: 50 mg; time: 30 min	247.2	[68]
3-MPA@PMNPs	$C_{o}$ : 25 mg/L; $T$ : 298 K; pH: 6; time: 120 min; dose: 500 mg	81.2	[69]
Fe₃O₄@AMCA-MIL-53 (Al)	$C_{o}$ : 25-400 mg/L; $T$ : 298 K; pH: 6.8; time: 210 min; dose: 20 mg	262.52	[70]
Fe₃O₄@AJPL	$C_{o}$ : 25-350 mg/L; $T$ : 318 K; pH: 7; time: 120 min; dose: 50 mg	318.3	This study

3.6. Desorption and Reusability Studies

To recover the MG dye from the Fe₃O₄@AJPL nanocomposite, three eluents, 0.1 M HCl, 0.1 M HNO₃, and ethanol (90%), were used (Figure 7(b)). From the results, it was observed that the recovery performance of ethanol was the highest (50.77%), while the acidic eluents (HCl and HNO₃) used showed only negligible efficiencies toward MG elution. The low recovery efficiency of MG from the Fe₃O₄@AJPL nanocomposite surface using ethanol indicates that most of the MG adsorption was probably by chemisorption. The outcomes of the kinetic and isotherm adsorption confirm the chemical adsorption mechanisms. The regeneration efficiency after two cycles was also examined. The result revealed that the adsorption efficiency of the MG dye on Fe₃O₄@AJPL was decreased from 89.5% to 58.2% as well as in the recovery percentage mostly due to incomplete desorption in the first cycle of the adsorption-desorption process as well as possible destruction of some active sites on the Fe₃O₄@AJPL surface.

4. Conclusion

In summary, a new magnetic nanocomposite (Fe₃O₄@AJPL) adsorbent was successfully synthesized via chemical activation of JPL and in situ coprecipitation with Fe₃O₄. The Fe₃O₄@AJPL nanocomposite was applied for the removal of the MG dye from aqueous solutions. The Fe₃O₄@AJPL nanocomposite was analyzed using different analytical techniques, and the results confirmed that the Fe₃O₄@AJPL nanocomposite was successfully synthesized. The surface area of the Fe₃O₄@AJPL nanocomposite was identified via BET analysis, and it is found to be 38.44 m²/g. The Fe₃O₄@AJPL nanocomposite was tested to thoroughly clarify the influences of the factors on the adsorption of MG onto Fe₃O₄@AJPL. The optimized adsorption factors were found to be pH: 7, contact time: 120 min, adsorbent dose: 50 mg, temperature: 45°C, and initial MG concentration: 150 mg/L. The adsorption kinetic and isotherm were revealed to be a better fit to the PSO kinetic and Langmuir isotherm models. The maximum monolayer adsorption capacity was 318.3 mg/g at 45°C, which was greater than magnetic nanocomposite adsorbents reported previously. The thermodynamic studies indicated that the adsorption of MG onto Fe₃O₄@AJPL is a spontaneous and endothermic process. The interaction between the Fe₃O₄@AJPL nanocomposite and the MG dye occurred by chemisorption and physisorption that can be achieved by H-bonding, π–π interactions, and electrostatic attractions. The recovery results indicated that ethanol was the best eluent among the all the tested eluents. Overall, it could be concluded that the prepared Fe₃O₄@AJPL adsorbent will be a promising adsorbent for the elimination of MG dye from aqueous solutions

Footnotes

Data Availability

Anyone who wants to request research article data can contact me directly via the following email: aalorabi@bu.edu.sa, Chemistry Department, College of Science, Al Baha University.

Conflicts of Interest

There are no conflicts to declare.

Acknowledgments

We gratefully acknowledge the financial support by Albaha University (Project No. 1441/3) and are grateful to the Scientific Research Deanship.

References

Bagheri

Ghaedi

Asfaram

Alipanahpour Dil

Javadian

RSM-CCD design of malachite green adsorption onto activated carbon with multimodal pore size distribution prepared from Amygdalus scoparia: Kinetic and isotherm studies

Polyhedron 2019 171

2359110

464 472

10.1016/j.poly.2019.07.037

2-s2.0-85070860726

Sun

Huang

Chen

Ruan

Zhao

Electrospun reduced graphene oxide/TiO₂/poly(acrylonitrile- co -maleic acid) composite nanofibers for efficient adsorption and photocatalytic removal of malachite green and leucomalachite green

Chemosphere 2020 239, article 124764

2359110

10.1016/j.chemosphere.2019.124764

Gopinathan

Kanhere

Banerjee

Effect of malachite green toxicity on non target soil organisms

Chemosphere 2015 120

2359110

637 644

10.1016/j.chemosphere.2014.09.043

2-s2.0-84912060873

25462308

Ahmad

A. A.

Ahmad

M. A.

Yahaya

N. K. E. M.

Karim

Adsorption of malachite green by activated carbon derived from gasified Hevea brasiliensis root

Arabian Journal of Chemistry 2021 14

2359110

4, article 103104

10.1016/j.arabjc.2021.103104

Zhang

Huang

Highly effective removal of malachite green from aqueous solution by hydrochar derived from phycocyanin-extracted algal bloom residues through hydrothermal carbonization

RSC Advances 2017 7

2359110

10 5790 5799

10.1039/C6RA27782A

2-s2.0-85010669658

Reza Shirzad Kebria

Rahimpour

Membrane distillation: basics, advances, and applications

Advances in Membrane Technologies 2020 67

2359110

10.5772/intechopen.86952

Vinay

S. P.

Alharthi

F. A.

Udayabhanu Alsalme

Nagaraju

Hydrothermal synthesis of Ag/rGO@CTFE nanocomposite as a promising photocatalyst for degradation action

Journal of Molecular Structure 2021 1228, article 129722

2359110

10.1016/j.molstruc.2020.129722

Krishnakumar

Alsalme

Alharthi

F. A.

Mani

Anandan

Amutha

Sobral

A. J. F. N.

Synthesis, characterization of gelatin assisted ZnO and its effective utilization of toxic azo dye degradation under direct sunlight

Optical Materials 2021 113, article 110854

2359110

10.1016/j.optmat.2021.110854

Oller

Malato

Sánchez-Pérez

J. A.

Combination of Advanced Oxidation Processes and biological treatments for wastewater decontamination--A review

Science of the Total Environment 2011 409

2359110

20 4141 4166

10.1016/j.scitotenv.2010.08.061

2-s2.0-78651399964

10.

Martínez-Huitle

C. A.

Brillas

Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods: a general review

Applied Catalysis B: Environmental 2009 87

2359110

3-4 105 145

10.1016/j.apcatb.2008.09.017

2-s2.0-61649087870

11.

Labanda

Sabaté

Llorens

Modeling of the dynamic adsorption of an anionic dye through ion-exchange membrane adsorber

Journal of Membrane Science 2009 340

2359110

1-2 234 240

10.1016/j.memsci.2009.05.036

2-s2.0-67649365432

12.

Alqadami

A. A.

Khan

M. A.

Siddiqui

M. R.

Alothman

Z. A.

Development of citric anhydride anchored mesoporous MOF through post synthesis modification to sequester potentially toxic lead (II) from water

Microporous and Mesoporous Materials 2018 261

2359110

198 206

10.1016/j.micromeso.2017.11.016

2-s2.0-85034110337

13.

Alqadami

A. A.

Khan

M. A.

Siddiqui

M. R.

Alothman

Z. A.

Sumbul

A facile approach to develop industrial waste encapsulated cryogenic alginate beads to sequester toxic bivalent heavy metals

Journal of King Saud University - Science 2020 32

2359110

2 1444 1450

10.1016/j.jksus.2019.11.040

14.

Alsuhybani

Alshahrani

Algamdi

Al-Kahtani

A. A.

Alqadami

A. A.

Highly efficient removal of Pb(II) from aqueous systems using a new nanocomposite: adsorption, isotherm, kinetic and mechanism studies

Journal of Molecular Liquids 2019 301, article 112393

2359110

10.1016/j.molliq.2019.112393

15.

Alorabi

A. Q.

Shamshi Hassan

Azizi

Fe₃O₄-CuO-activated carbon composite as an efficient adsorbent for bromophenol blue dye removal from aqueous solutions

Arabian Journal of Chemistry 2020 13

2359110

11 8080 8091

10.1016/j.arabjc.2020.09.039

16.

Amer

W. A.

Omran

M. M.

Rehab

A. F.

Ayad

M. M.

Acid green crystal-based in situ synthesis of polyaniline hollow nanotubes for the adsorption of anionic and cationic dyes

RSC Advances 2018 8

2359110

40 22536 22545

10.1039/C8RA02236D

2-s2.0-85049019268

17.

Crini

Torri

Lichtfouse

Kyzas

G. Z.

Wilson

L. D.

Morin-Crini

Dye removal by biosorption using cross-linked chitosan-based hydrogels

Environmental Chemistry Letters 2019 17

2359110

4 1645 1666

10.1007/s10311-019-00903-y

18.

Parlayici

Ş.

Alginate-coated perlite beads for the efficient removal of methylene blue, malachite green, and methyl violet from aqueous solutions: kinetic, thermodynamic, and equilibrium studies

Journal of Analytical Science and Technology 2019 10

2359110

1 4

10.1186/s40543-019-0165-5

2-s2.0-85071242205

19.

Ben Arfi

Karoui

Mougin

Ghorbal

Adsorptive removal of cationic and anionic dyes from aqueous solution by utilizing almond shell as bioadsorbent

Euro-Mediterranean Journal for Environmental Integration 2017 2

2359110

1 1 13

10.1007/s41207-017-0032-y

20.

Hameed

B. H.

Ahmad

A. A.

Batch adsorption of methylene blue from aqueous solution by garlic peel, an agricultural waste biomass

Journal of Hazardous Materials 2009 164

2359110

2-3 870 875

10.1016/j.jhazmat.2008.08.084

2-s2.0-62649144672

18838221

21.

Oliveira

L. S.

Franca

A. S.

Alves

T. M.

Rocha

S. D. F.

Evaluation of untreated coffee husks as potential biosorbents for treatment of dye contaminated waters

Journal of Hazardous Materials 2008 155

2359110

3 507 512

10.1016/j.jhazmat.2007.11.093

2-s2.0-44449157690

22.

Tahir

Sultan

Akhtar

Hameed

Abid

Application of natural and modified sugar cane bagasse for the removal of dye from aqueous solution

Journal of Saudi Chemical Society 2016 20

2359110

S115 S121

10.1016/j.jscs.2012.09.007

2-s2.0-84868262439

23.

Oyekanmi

A. A.

Ahmad

Hossain

Rafatullah

Statistical optimization for adsorption of rhodamine B dye from aqueous solutions

Journal of Molecular Liquids 2019 281

2359110

48 58

10.1016/j.molliq.2019.02.057

2-s2.0-85061715571

24.

Munagapati

V. S.

Yarramuthi

Kim

Lee

K. M.

Kim

D.-S.

Removal of anionic dyes (reactive black 5 and Congo red) from aqueous solutions using banana peel powder as an adsorbent

Ecotoxicology and Environmental Safety 2018 148

2359110

601 607

10.1016/j.ecoenv.2017.10.075

2-s2.0-85032890905

29127823

25.

Janoš

Buchtová

Rýznarová

Sorption of dyes from aqueous solutions onto fly ash

Water Research 2003 37

2359110

20 4938 4944

10.1016/j.watres.2003.08.011

2-s2.0-0242329777

14604640

26.

Hamdaoui

Saoudi

Chiha

Naffrechoux

Sorption of malachite green by a novel sorbent, dead leaves of plane tree: equilibrium and kinetic modeling

Chemical Engineering Journal 2008 143

2359110

1-3 73 84

10.1016/j.cej.2007.12.018

2-s2.0-50649110733

27.

Gupta

Kushwaha

A. K.

Chattopadhyaya

M. C.

Adsorption studies of cationic dyes onto Ashoka (Saraca asoca) leaf powder

Journal of the Taiwan Institute of Chemical Engineers 2012 43

2359110

4 604 613

10.1016/j.jtice.2012.01.008

2-s2.0-84862536176

28.

Bulgariu

Escudero

L. B.

Bello

O. S.

Iqbal

Nisar

Adegoke

K. A.

Alakhras

Kornaros

Anastopoulos

The utilization of leaf-based adsorbents for dyes removal: a review

Journal of Molecular Liquids 2019 276

2359110

728 747

10.1016/j.molliq.2018.12.001

2-s2.0-85058400950

29.

al-Shehri

H. S.

Almudaifer

Alorabi

A. Q.

Alanazi

H. S.

Alkorbi

A. S.

Alharthi

F. A.

Effective adsorption of crystal violet from aqueous solutions with effective adsorbent: equilibrium, mechanism studies and modeling analysis

Environmental Pollutants and Bioavailability 2021 33

2359110

1 214 226

10.1080/26395940.2021.1960199

30.

Huff

M. D.

Lee

J. W.

Biochar-surface oxygenation with hydrogen peroxide

Journal of Environmental Management 2016 165

2359110

17 21

10.1016/j.jenvman.2015.08.046

2-s2.0-84942163260

26402867

31.

Xue

Gao

Yao

Inyang

Zhang

Zimmerman

A. R.

K. S.

Hydrogen peroxide modification enhances the ability of biochar (hydrochar) produced from hydrothermal carbonization of peanut hull to remove aqueous heavy metals: batch and column tests

Chemical Engineering Journal 2012 200-202

2359110

673 680

10.1016/j.cej.2012.06.116

2-s2.0-84865553099

32.

Alqadami

A. A.

Naushad

Abdalla

M. A.

Khan

M. R.

Alothman

Z. A.

Adsorptive removal of toxic dye using Fe₃O₄−TSC nanocomposite: equilibrium, kinetic, and thermodynamic studies

Journal of Chemical & Engineering Data 2016 61

2359110

11 3806 3813

10.1021/acs.jced.6b00446

2-s2.0-84998888228

33.

Burits

Asres

Bucar

The antioxidant activity of the essential oils of Artemisia afra, Artemisia abyssinica and Juniperus procera

Phytotherapy Research 2001 15

2359110

2 103 108

10.1002/ptr.691

2-s2.0-0035070986

11268106

34.

Loizzo

Tundis

Conforti

Saab

Statti

Menichini

Comparative chemical composition, antioxidant and hypoglycaemic activities of Juniperus oxycedrus ssp. oxycedrus L. berry and wood oils from Lebanon

Food Chemistry 2007 105

2359110

2 572 578

10.1016/j.foodchem.2007.04.015

2-s2.0-34447261425

35.

Šarić-Kundalić

Dobeš

Klatte-Asselmeyer

Saukel

Ethnobotanical survey of traditionally used plants in human therapy of east, north and north-east Bosnia and Herzegovina

Journal of Ethnopharmacology 2011 133

2359110

3 1051 1076

10.1016/j.jep.2010.11.033

2-s2.0-79551571080

21094241

36.

Öztürk

Tümen

İ.

Uǧur

Aydoǧmuş-Öztürk

Topçu

Evaluation of fruit extracts of six Turkish Juniperus species for their antioxidant, anticholinesterase and antimicrobial activities

Journal of the Science of Food and Agriculture 2011 91

2359110

5 867 876

10.1002/jsfa.4258

2-s2.0-79952321157

21384354

37.

Ndazi

B. S.

Karlsson

Tesha

J. V.

Nyahumwa

C. W.

Chemical and physical modifications of rice husks for use as composite panels

Composites Part A: applied science and manufacturing 2007 38

2359110

3 925 935

10.1016/j.compositesa.2006.07.004

2-s2.0-33845417889

38.

Le Van

Luong Thi

T. T.

Activated carbon derived from rice husk by NaOH activation and its application in supercapacitor

Progress in Natural Science: Materials International 2014 24

2359110

3 191 198

10.1016/j.pnsc.2014.05.012

2-s2.0-84926408143

39.

Ibrahim

E. H.

Kilany

Ghramh

H. A.

Khan

K. A.

ul Islam

Cellular proliferation/cytotoxicity and antimicrobial potentials of green synthesized silver nanoparticles (AgNPs) using Juniperus procera

Saudi Journal of Biological Sciences 2019 26

2359110

7 1689 1694

10.1016/j.sjbs.2018.08.014

2-s2.0-85051752831

31762645

40.

Alqadami

A. A.

Khan

M. A.

Otero

Siddiqui

M. R.

Jeon

B.-H.

Batoo

K. M.

A magnetic nanocomposite produced from camel bones for an efficient adsorption of toxic metals from water

Journal of Cleaner Production 2018 178

2359110

293 304

10.1016/j.jclepro.2018.01.023

2-s2.0-85041840080

41.

Khan

M. A.

Alqadami

A. A.

Otero

Siddiqui

M. R.

Alothman

Z. A.

Alsohaimi

Rafatullah

Hamedelniel

A. E.

Heteroatom-doped magnetic hydrochar to remove post-transition and transition metals from water: synthesis, characterization, and adsorption studies

Chemosphere 2019 218

2359110

1089 1099

10.1016/j.chemosphere.2018.11.210

2-s2.0-85057890170

30609488

42.

Allafchian

Mousavi

Z. S.

Hosseini

S. S.

Application of cress seed musilage magnetic nanocomposites for removal of methylene blue dye from water

International Journal of Biological Macromolecules 2019 136

2359110

199 208

10.1016/j.ijbiomac.2019.06.083

2-s2.0-85067287094

31201917

43.

Tang

Wang

Zhang

Chen

Zn(II) removal with Activated Firmiana Simplex Leaf: kinetics and equilibrium studies

Journal of Environmental Engineering 2012 138

2359110

2 190 199

10.1061/(ASCE)EE.1943-7870.0000471

2-s2.0-84863390692

44.

Alqadami

Naushad

Abdalla

M. A.

Ahamad

Abdullah Alothman

Alshehri

S. M.

Synthesis and characterization of Fe₃O₄@TSC nanocomposite: highly efficient removal of toxic metal ions from aqueous medium

RSC advances 2016 6

2359110

27 22679 22689

10.1039/C5RA27525C

2-s2.0-84960158622

45.

Karthivashan

Masarudin

M. J.

Umar Kura

Abas

Fakurazi

Optimization, formulation, and characterization of multiflavonoids-loaded flavanosome by bulk or sequential technique

International Journal of Nanomedicine 2016 11

2359110

3417 3434

10.2147/IJN.S112045

2-s2.0-84982719829

27555765

46.

Ekmen

Bilici

Turan

Tamer

Zengin

Surface molecularly-imprinted magnetic nanoparticles coupled with SERS sensing platform for selective detection of malachite green

Sensors and Actuators B: Chemical 2020 325, article 128787

2359110

10.1016/j.snb.2020.128787

47.

Asfaram

Ghaedi

Ghezelbash

G. R.

Dil

E. A.

Tyagi

Agarwal

Gupta

V. K.

Biosorption of malachite green by novel biosorbent Yarrowia lipolytica isf7: Application of response surface methodology

Journal of Molecular Liquids 2016 214

2359110

249 258

10.1016/j.molliq.2015.12.075

2-s2.0-84958115620

48.

Pan

Zuo

Cheng

Dong

Polycarboxylic magnetic polydopamine sub-microspheres for effective adsorption of malachite green

Colloids and Surfaces A: Physicochemical and Engineering Aspects 2019 560

2359110

106 113

10.1016/j.colsurfa.2018.10.014

2-s2.0-85054469357

49.

De Marco

Mauler

R. S.

Daitx

T. S.

Krindges

Cemin

Bonetto

L. R.

Crespo

J. S.

Guégan

Carli

L. N.

Giovanela

Removal of malachite green dye from aqueous solutions by a magnetic adsorbent

Separation Science and Technology 2020 55

2359110

6 1089 1101

10.1080/01496395.2019.1585455

2-s2.0-85062452698

50.

Gao

Wang

Yang

Ning

Zhou

Novel magnetic graphene oxide decorated with persimmon tannins for efficient adsorption of malachite green from aqueous solutions

Colloids and Surfaces A: Physicochemical and Engineering Aspects 2019 566

2359110

48 57

10.1016/j.colsurfa.2019.01.016

2-s2.0-85059853671

51.

Amer

W. A.

Omran

M. M.

Ayad

M. M.

Acid-free synthesis of polyaniline nanotubes for dual removal of organic dyes from aqueous solutions

Colloids and Surfaces A: Physicochemical and Engineering Aspects 2019 562

2359110

203 212

10.1016/j.colsurfa.2018.10.081

2-s2.0-85056903223

52.

Ghaedi

Rozkhoosh

Asfaram

Mirtamizdoust

Mahmoudi

Bazrafshan

A. A.

Comparative studies on removal of erythrosine using ZnS and AgOH nanoparticles loaded on activated carbon as adsorbents: kinetic and isotherm studies of adsorption

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2015 138

2359110

176 186

10.1016/j.saa.2014.10.046

2-s2.0-84915748505

53.

Aldawsari

A. M.

Alsohaimi

I. H.

Al-Kahtani

A. A.

Alqadami

A. A.

Ali Abdalla

Z. E.

Saleh

E. A. M.

Adsorptive performance of aminoterephthalic acid modified oxidized activated carbon for malachite green dye: mechanism, kinetic and thermodynamic studies

Separation Science and Technology 2021 56

2359110

5 835 846

10.1080/01496395.2020.1737121

54.

Arellano-Cárdenas

López-Cortez

Cornejo-Mazón

Mares-Gutiérrez

J. C.

Study of malachite green adsorption by organically modified clay using a batch method

Applied Surface Science 2013 280

2359110

74 78

10.1016/j.apsusc.2013.04.097

2-s2.0-84879695004

55.

Guo

Jiang

Jia

Liang

Qian

Synthesis of MgO/Fe₃O₄ nanoparticles embedded activated carbon from biomass for high-efficient adsorption of malachite green

Materials Chemistry and Physics 2020 240, article 122240

2359110

10.1016/j.matchemphys.2019.122240

56.

Wallis

Dollard

M. F.

Local and global factors in work stress - the Australian dairy farming examplar

Scandinavian Journal of Work, Environment and Health 2008 34

2359110

6 66 74

57.

Freundlich

Über die adsorption in lösungen 1907 57

2359110

Zeitschrift Für Physikalische Chemie

58.

Agarwal

Tyagi

Gupta

V. K.

Mashhadi

Ghasemi

Kinetics and thermodynamics of malachite green dye removal from aqueous phase using iron nanoparticles loaded on ash

Journal of Molecular Liquids 2016 223

2359110

1340 1347

10.1016/j.molliq.2016.04.039

2-s2.0-84964287489

59.

Jain

S. N.

Shaikh

Mane

V. S.

Vishnoi

Mawal

V. N.

Patel

O. R.

Bhandari

P. S.

Gaikwad

M. S.

Nonlinear regression approach for acid dye remediation using activated adsorbent: kinetic, isotherm, thermodynamic and reusability studies

Microchemical Journal 2019 148

2359110

605 615

10.1016/j.microc.2019.05.024

2-s2.0-85065912826

60.

Jayasantha Kumari

Krishnamoorthy

Arumugam

T. K.

Radhakrishnan

Vasudevan

An efficient removal of crystal violet dye from waste water by adsorption onto TLAC/chitosan composite: a novel low cost adsorbent

International Journal of Biological Macromolecules 2017 96

2359110

324 333

10.1016/j.ijbiomac.2016.11.077

2-s2.0-85007189465

27889343

61.

Arabkhani

Javadian

Asfaram

Ateia

Decorating graphene oxide with zeolitic imidazolate framework (ZIF-8) and pseudo-boehmite offers ultra-high adsorption capacity of diclofenac in hospital effluents

Chemosphere 2021 271, article 129610

2359110

10.1016/j.chemosphere.2021.129610

62.

Alghamdi

A. A.

Al-Odayni

A.-B.

Saeed

W. S.

Almutairi

M. S.

Alharthi

F. A.

Aouak

Al-Kahtani

Adsorption of azo dye methyl orange from aqueous solutions using alkali-activated polypyrrole-based graphene oxide

Molecules 2019 24

2359110

20 3685

10.3390/molecules24203685

2-s2.0-85073440202

31614943

63.

Ayad

M. M.

Amer

W. A.

Zaghlol

Minisy

I. M.

Bober

Stejskal

Polypyrrole-coated cotton textile as adsorbent of methylene blue dye

Chemical Papers 2018 72

2359110

7 1605 1618

10.1007/s11696-018-0442-6

2-s2.0-85048875343

64.

Alghamdi

A. A.

Al-Odayni

A.-B.

Abduh

N. A. Y.

Alramadhan

S. A.

Aljboar

M. T.

Saeed

W. S.

Adsorptive performance of polypyrrole-based KOH-activated carbon for the cationic dye crystal violet: kinetic and equilibrium studies

Adsorption Science and Technology 2021 2021, article 5527594

2359110

1 11

10.1155/2021/5527594

65.

Arabkhani

Asfaram

Ateia

Easy-to-prepare graphene oxide/sodium montmorillonite polymer nanocomposite with enhanced adsorption performance

Journal of Water Process Engineering 2020 38, article 101651

2359110

10.1016/j.jwpe.2020.101651

66.

Zheng

Jiang

Gao

Adsorption of malachite green by magnetic litchi pericarps: a response surface methodology investigation

Journal of Environmental Management 2015 162

2359110

232 239

10.1016/j.jenvman.2015.07.057

2-s2.0-84939136456

26254991

67.

Wang

Zhang

Hou

Liu

Mussel-inspired synthesis of magnetic polydopamine-chitosan nanoparticles as biosorbent for dyes and metals removal

Journal of the Taiwan Institute of Chemical Engineers 2016 61

2359110

292 298

10.1016/j.jtice.2016.01.008

2-s2.0-84956868154

68.

Khorasani

A. C.

Shojaosadati

S. A.

Magnetic pectin-Chlorella vulgaris biosorbent for the adsorption of dyes

Journal of Environmental Chemical Engineering 2019 7

2359110

3, article 103062

10.1016/j.jece.2019.103062

2-s2.0-85064210035

69.

Ali

Peng

Naz

Sorption of cationic malachite green dye on phytogenic magnetic nanoparticles functionalized by 3-marcaptopropanic acid

RSC Advances 2018 8

2359110

16 8878 8897

10.1039/C8RA00245B

2-s2.0-85042715968

70.

Alqadami

A. A.

Naushad

Alothman

Z. A.

Ahamad

Adsorptive performance of MOF nanocomposite for methylene blue and malachite green dyes: kinetics, isotherm and mechanism

Journal of Environmental Management 2018 223

2359110

29 36

10.1016/j.jenvman.2018.05.090

2-s2.0-85048157607

29885562

Effective Removal of Malachite Green from Aqueous Solutions Using Magnetic Nanocomposite: Synthesis,Characterization,and Equilibrium Study

Abstract

1. Introduction

2. Experiments

2.1. Chemicals and Instrumentation

2.2. Chemical Treatment of Juniperus procera Leaves

2.3. Magnetization of Juniperus procera Leaves (Fe3O4@AJPL)

2.4. Adsorption Studies

3. Results and Discussion

3.1. Synthesis and Characterization of Fe3O4@AJPL

3.2. Adsorption Studies

3.2.1. Adsorbate Selectivity

3.2.2. Effect of pH

3.2.3. Effect of Contact Time

3.2.4. Effect of Dosage

3.2.5. Effect of Initial Concentration and Temperatures

3.3. Adsorption Modeling

3.3.1. Adsorption Isotherm

3.3.2. Kinetic Adsorption

3.3.3. Adsorption Thermodynamics

3.4. Adsorption Mechanism

3.5. Comparative Performance of Fe3O4@AJPL with Other Adsorbents

3.6. Desorption and Reusability Studies

4. Conclusion

Footnotes

Data Availability

Conflicts of Interest

Acknowledgments

References

2.3. Magnetization of Juniperus procera Leaves (Fe₃O₄@AJPL)

3.1. Synthesis and Characterization of Fe₃O₄@AJPL

3.5. Comparative Performance of Fe₃O₄@AJPL with Other Adsorbents