Synergistic Effect of Zeolite on Removal of Chemical Oxygen Demand and Ammonia Nitrogen from the Shale Gas Distillate

Abstract

Ammonia nitrogen (NH₃-N) and chemical oxygen demand (COD) are two major pollutants in the first-effect distillate obtained from shale gas produced water after multiple-effect evaporation (MEE) treatment. Accordingly, an integrated adsorption–photocatalysis system with 4A zeolite was applied for the simultaneous removal of NH₃-N and COD from the shale gas first-effect distillate. Effects of temperature, light source, reaction time, light intensity, and solution pH of the integrated system were discussed and optimized for pollutants removal. After 60-min illumination (PL-XQ500W xenon lamp, AM1.5, 25 A), NH₃-N and COD removal rates were up to 88.9% and 59.0%, respectively. GC-MS analysis showed that long-chain organics in the shale gas distillate were oxidized and decomposed into short-chain organics mainly because of the effect of photocatalysis. The removal of NH₃-N was the synergistic effect of zeolite adsorption and photocatalysis based on nitrogen component analysis in water samples.

Introduction

In recent decades, the rapid development of shale gas industry has led to a huge increase in unconventional energy production. However, shale gas produced water, a mixture of fracturing fluid and formation water, contains high concentration of salt and complex organic compounds and could produce serious problems to environment if discharged inappropriately (Cho et al., 2018; Jang and Chung, 2019). As one kind of desalination processes, single-/multiple-effect evaporation (SEE/MEE) systems are widely applied for shale gas wastewater treatment (Onishi et al., 2017). The main pollutants in these distillates after SEE/MEE operation are ammonia nitrogen (NH₃-N) and chemical oxygen demand (COD). Therefore, the simultaneous removal of NH₃-N and COD from wastewater is necessary to the subsequent harmless treatment and recycling utilization of shale gas distillates. Aiming at the coexistence pollutants in wastewater, a combination of multiple treatment technologies can effectively and simultaneously remove complex pollutants (Chang et al., 2019; Moser et al., 2019).

Adsorption is applied to separate pollutants from aqueous system and is considered one of the most promising methods for water treatment. Zeolite is widely used in adsorption process because of its low cost, high efficiency, and simple operation (Zhou and Boyd, 2014; Lu et al., 2019). It is a kind of porous nonmetallic oxide adsorbent and a diverse group of alkaline and hydrated crystalline aluminum silicate mineral. The adsorption performance of zeolite is strongly related to its pore structures and chemical properties. The crystal structure of zeolite is generally considered to be a three-dimensional four-connected framework formed by TO₄ (T = Si, Al, P, etc.) tetrahedral, that is, connected by sharing vertex oxygen atoms (Li and Yu, 2014). Those interconnected channels are favorable for the high cation exchange capacity, which make zeolite a good NH₃-N adsorbent. Plenty of researches have confirmed the affinity of zeolites for NH₃-N (Huang et al., 2010; Yusof et al., 2010). One NaCl-modified zeolite had obtained a high NH₃-N removal of 81% for pretreated leachate treatment (Couto et al., 2017).

Adsorption of organic compounds on zeolite is significantly affected by organic properties including polarity, hydrophobicity, and alkalinity. Tsai et al. (2009) investigated the adsorption of methylene blue (MB) (cationic dye) and bisphenol-A from aqueous solutions onto a synthesized zeolite using hydrothermal method, and found that this novel zeolite exhibited much higher adsorption capacity on MB than bisphenol-A because of the difference in molecular hydrophilicity.

Photocatalysis is an advanced oxidation process. In recent years, photocatalytic degradation of various compounds in water and wastewater treatment has been deeply studied, especially in treatment of high organic concentration wastewaters (He et al., 2016; Nguyen et al., 2018; Wang et al., 2018). Threrujirapapong et al. (2017) investigated the efficiency of the photocatalysis process on an industrial wastewater containing high nonbiodegradable organic carbon, and the results showed that the highest COD removal efficiency (85%) was reached at 1 g/L titanium dioxide (TiO₂) loading in a laboratory scale reactor. Theoretically, when a photocatalyst excited under strong light, electrons (e⁻) migrate from the valence band to the conduction band, leaving a positive hole on the valence band. Hydroxyl radicals (•OH) and superoxide radicals ( $O_{2}^{-}$ ) with strong redox ability will generate when water takes place at the positive hole and oxygen reacts with the conduction band, and thus can effectively degrade pollutants under ambient temperature and pressure (Pelaez et al., 2012; Banerjee et al., 2014).

TiO₂ is widely studied in the photocatalysis system because of its environmentally benign, chemical stable, strong oxidation and low cost advantages (Byrne et al., 2018). According to the determination and analysis of internal structures, zeolites with abundant holes displayed similar tetrahedral pore structures to TiO₂. It is highly possible that the internal electrons in zeolite might be also excited by the irradiation under strong light and generate charged electron holes and superoxide/hydroxyl radicals. Current researches have found that zeolites can exhibit excellent adsorption capacities and are also with high nonsemiconductor photocatalytic performance (Kato et al., 2002; Matsuoka and Anpo, 2003). The founding of Nassar and Abdelrahman (2017) showed that the prepared zeolite could be simultaneously used as adsorbents and photocatalysts for the removal of MB dye from aqueous solutions. However, simultaneous removal of NH₃-N and COD using zeolite as the adsorbent and photocatalyst was seldom reported. Thus, it is valuable to adopt zeolite in an adsorption–photocatalysis integrated system and explore its pollutants degradation ability.

According to our previous study (Wang et al., 2019a), 4A zeolites were used to effectively remove COD and NH₃-N from shale gas distillates through an integration system of adsorption and photocatalysis, and the treated wastewater could well meet the circulation cooling water (CCW) quality. The results proved that it was a feasible way to use zeolites for the simultaneous removal of COD and NH₃-N. The main objective of our research was to further discuss the impact of operational factors for removal of NH₃-N and COD from the shale gas distillate and also to discuss the degradation mechanism of NH₃-N and COD in this zeolite adsorption-photocatalytic system.

Materials and Methods

Materials and reagents

Typical wastewater used in this study was collected from a certain shale gas well located in Weiyuan, Sichuan Province, China. The raw wastewater was pretreated by alkali precipitation (Wang et al., 2019b), filtration, and MEE to get the target distillate (Wang et al., 2019a) for further research. Multiple-effect evaporation was carried out subsequently through three SEE units equipped with an externally heated evaporator to obtain different stage distillates. Table 1 provides the components of shale gas produced water and the first-effect distillate.

Table 1.

The Characteristics of Water Samples

	NH₃ (mg/L)	COD (mg/L)	Cl⁻ (mg/L)	pH
Shale gas produced water	75–95	550–1700	15,200–16,050	6.46–6.69
First-effect distillate	186–226	149–189	0–12	8.91–10.81

COD, chemical oxygen demand.

As given in Table 1, the distillate was alkaline with very little chloride ion, whereas it had an excess concentration of NH₃-N and COD that violated the CCW requirements (Q/SH 0104-2007, China).

A certain 4A zeolite (Na₂O·Al₂O₃·xSiO₂·yH₂O) was selected according to our previous research as the adsorbent and photocatalyst because of its good performance toward NH₃-N and organic compounds. All chemicals used in this study were analytical grade and provided by Kelong Chemical Reagent Co. Ltd.

Experiments

The aim of this study was to discuss the operation and mechanism of this integrated system (adsorption and photocatalysis) on the simultaneous removal of NH₃-N and COD from the first-effect distillate. Zeolite was used as the adsorbent and photocatalyst. A xenon lamp (luminous spectrum: 300–2500 nm, 25 A, Beijing Precise Technology Co. Ltd, China) was used as the light source. Zeolite (10 g/L) and wastewater (50 mL) were thoroughly mixed in a quartz beaker (100 mL) and put under the xenon lamp. The suspension was stirred at a rate of 150 rpm. The temperature of the suspension was kept constant by a cooling water system. After a period of reaction, the supernatant was filtered out (0.45 μm) and determined for COD and nitrogen fractions. Meanwhile, the residual gas was collected and its nitrogen components were determined.

All experiments and analysis were carried out twice under identical conditions, and all data were calculated as the average values.

Analytical methods

COD concentration was obtained according to the rapid-digestion method using a 5B-1 and 5B-3(C) COD rapid measurement instrument (Lian-hua Tech Co. Ltd, China). Ammonia nitrogen concentration (NH₃-N) was determined by spectrophotometry (Lian-hua Tech Co. Ltd, China). The measurement of COD and NH₃-N were in accordance with standard methods HJ/T 399-2007 and HJ 535-2009 (China), respectively. Chloride ion, total nitrogen (TN), nitrite nitrogen ( ${N O}_{2}^{-}$ ), nitrate nitrogen ( ${N O}_{3}^{-}$ ), and NH₃ were measured according to the standard methods (GB11896-89, GB11894-89, GB7493-87, GB7480-87, HJ535-2009, respectively). Organic nitrogen was calculated from the difference between TN and the sum of NH₃-N, ${N O}_{2}^{-}$ , and ${N O}_{3}^{-}$ components in solutions. PHS-3C pH meter (Shanghai Tec Front Electronics Co., Ltd, China) was used to determine pH values. Gas chromatograph mass spectrum (GCMS-QP2010 Plus; SHIMADZU Co. Ltd, Japan) was used to analyze the organic components of the distillate and water sample after adsorption–photocatalysis operation.

Results and Discussion

Integration of adsorption and photocatalysis

Adsorption, illumination, photocatalysis after adsorption equilibrium, and integration of adsorption–photocatalysis were carried out for comparison. Fifty milliliter distillate was stirred (150 rpm) and illuminated under the xenon lamp (25 A) for 60-min photolysis, whereas 50 mL distillate with 10 g/L zeolite was stirred (150 rpm) for 4-h adsorption. After 4-h equilibrium adsorption, the mixture was illuminated under the xenon lamp (25 A) for 60-min photocatalysis. The integration of adsorption–photocatalysis experiment was carried out using 50 mL distillate mixed with 10 g/L zeolite and stirred (150 rpm) under the xenon lamp (25 A) for 60-min reaction.

As given in Fig. 1, there was little elimination of COD under 4-h adsorption or 1-h illumination. However, photocatalysis after 4-h adsorption equilibrium improved COD removal to 63.4% degradation, whereas in the 1-h adsorption–photocatalysis system, the removal rate of COD could obviously increase from none to 59.0%. Thus it indicated that the removal mechanism of COD in this system was mainly because of zeolite photocatalytic degradation. The NH₃-N removal rates were 24.5%, 56.7%, 96.7%, and 88.9% for illumination, adsorption, photocatalysis after adsorption, and adsorption–photocatalysis treatment, respectively. It showed that zeolites' adsorption played an important role in NH₃-N removal, whereas photocatalysis had a good synergistic effect on NH₃-N degradation and encouraged the treatment process. It should be noted that the adsorption–photocatalysis method was more efficient owing to its time-saving and easy operation. Detailed discussion on these four systems was elaborated in our previous research (Wang et al., 2019a).

FIG. 1.

COD and NH₃-N removal in the shale gas distillate by illumination, adsorption, and photocatalysis after adsorption, and adsorption–photocatalysis. COD, chemical oxygen demand; NH₃-N, ammonia nitrogen.

Adsorption-photocatalysis studies

Reaction temperature

PL-XQ500W xenon lamp was used as the excited light source and brought excess energy to the reaction system. Directly exposing under the light would lead to a temperature increment of water samples in the system. To study the influence of temperature change in the integrated system, two reaction systems were studied and discussed. One group used a water cooling system (Fig. 2) to keep the whole reactor under a steady temperature (25°C), and the other was without cooling apparatus as a control group. All experiments were carried out under xenon lamp irradiation and with a light intensity of 25 A.

FIG. 2.

The impact of temperature on NH₃-N and COD removal in the shale gas distillate by adsorption–photocatalysis integrated treatment.

After 30, 45, and 60 min, the temperature differences of the two groups were 5.5°C, 7.5°C, and 7.5°C, respectively. In Fig. 2, the removal rates for both contaminants increased with reaction time. For 30 or 45 min, the degradation rates of the two systems were almost the same. After 60 min, NH₃-N and COD removal without special cooling was only 4.6% and 2.0% higher than the ones with condensation. Meng et al. (2018) applied g-C₃N₄ for the photocatalytic degradation on Congo Red, and found the fluctuation of removal rate was <10% within temperature range of 20°C. Above all, the efficiencies for both NH₃-N and COD were insignificantly affected by temperature changing in a small range (5.5–7.5°C).

Light source

The wavelength and energy are much different among ultraviolet light, visible light, and sunlight, and thus have important roles on the photocatalytic reaction. Three kinds of filter (AM1.5, UV cut-400 nm, UV) to get different wavelength conditions were installed on the xenon lamp to simulate sunlight (0–2500 nm), visible light (400–760 nm), and ultraviolet light (250–400 nm) individually. All experiments were carried out with a light intensity at 25 A.

As given in Fig. 3, there was no obvious difference in degradation of NH₃-N under three different light sources. After 60 min, NH₃-N removal rate under sunlight was high up to 80.3%, and 4.2% and 2.8% higher than that under visible light and ultraviolet light, respectively. For COD, the removal rates under visible and ultraviolet light were nearly identical, and only ∼5% lower than the one under sunlight illumination. Either visible light or ultraviolet light had certain impact on degradation of NH₃-N and COD in the adsorption–photocatalysis integrated system. Sunlight, combining both energy of visible light and ultraviolet light, had a better performance on COD and NH₃-N removal. Hong et al. (2019) found that the photocatalysis rate constant of glutaraldehyde removal with Ag/AgCl/BiOCl under natural light was 0.0336 min⁻¹, suggesting the potential of sunlight photocatalysis. It is favorable to apply nature light source and complete a better degradation efficiency on simultaneous removal of COD and NH₃-N from shale gas distillate.

FIG. 3.

The impact of light source on NH₃-N and COD removal in the shale gas distillate by adsorption–photocatalysis integrated treatment.

Reaction time

A series of experiments were studied from 0 to 60 min to determine the impact of illumination time on the degradation of NH₃-N and COD. All experiments were carried out under xenon lamp (AM1.5) with the light intensity 25 A. As given in Fig. 4, NH₃-N and COD removal exhibited a similar trend. The degradation was fast in the first 30 min, then became unchanged after 45 min. Within the first 10 min, NH₃-N removal rate reached 61.8% quickly. The degradation of COD mainly occurred in the first half hour and was up to 51.0%. The removal rates of NH₃-N and COD were finally stabilized at 88.9% and 59.0% after 1 h.

FIG. 4.

The impact of reaction time on NH₃-N and COD removal in the shale gas distillate by adsorption–photocatalysis integrated treatment.

Intensity

The rate of photocatalysis activation and electron-hole formation are highly related to the light intensity. Working current of the xenon lamp (AM1.5) was adjusted within 15–25 A (500–2000 W). In Fig. 5, NH₃-N removal rate slightly increased with the increasing light intensity. After 60 min, NH₃-N removal rates under light intensity of 15, 20, and 25 A were 74.4%, 76.6%, and 80.3%, respectively. However, COD removal rates were substantially changed with the increasing light intensity. After 60 min, COD removal rate under 25 A was 17.9% higher than the one under 15 A. Generally, larger light intensity is helpful for higher degradation efficiency by generating more incident photons and more active substances. Bendjabeur et al. (2018) found that the degradation rate of gentian violet increased from 23% to 51% with light intensity increasing from 2 to 6 mW/cm².

FIG. 5.

The impact of light intensity on NH₃-N and COD removal in the shale gas distillate by adsorption–photocatalysis integrated treatment.

The increasing light intensity did not significantly improve the degradation of NH₃-N. It could be deduced that NH₃-N removal in this system was mainly controlled by zeolite adsorption rather than photocatalytic effect. Meanwhile, COD removal under the photocatalytic process was much sensitive with light intensity changes.

pH

pH is an important factor in the integration system of adsorption–photocatalysis. It relates to the surface charge properties of the adsorbent/photocatalyst and the existence form of contaminants. Under acidic or alkaline condition, zeolite surface could be protonated or deprotonated; thus it was positively charged in acidic conditions and negatively charged in alkaline conditions. In our study, the original pH of the target distillate was basic (between 9 and 11). The solution's pH was adjusted from 2 to 12 by NaOH and HCl solution. Experiments were operated under xenon lamp (AM1.5) with the light intensity 25 A for 1 h (Fig. 6).

FIG. 6.

The impact of solution pH on NH₃-N and COD removal in the shale gas distillate by adsorption–photocatalysis integrated treatment.

For NH₃-N, the removal rate increased from 31.6% to 98.9% with pH changing from 2 to 11 and then slightly decreased at pH 12. Similar trends were also found in other NH₃-N photolysis studies (Wang et al., 2017; Liu et al., 2019; Tu et al., 2019). As pH increased, H⁺ ion concentration was gradually decreased, which abated the competition with ${N H}_{4}^{+}$ for ion exchange sites on zeolite. As a consequence, the removal rate of NH₃-N was increased with the increase in pH. Moreover, under high pH values (pH = 11–12), almost all NH₃-N escaped from the solutions as free NH₃. The COD degradation did not present obvious change in a wide pH range. Under alkaline conditions, COD removal efficiency was more stable. In this study, original pH of shale gas distillate was between 9 and 11, which had a positive effect on both contaminants' removal.

Removal mechanism of COD

To study the removal mechanism of COD in the integrated system, GC-MS analysis was performed on the distillate and water sample after 1 h of adsorption–photocatalysis treatment. In Table 2, the organic contents in the distillate were mainly C₈H₈O and C₁₄H₁₈N₂Si, which accounted for 77.24% and 8.85%, respectively. After degradation, the main components were 44.48% C₅H₈O and 26.78% CH₂Cl₂, respectively. Long-chain organic matters, that is, C₁₄H₁₈N₂Si, C₁₃H₁₈O₂, C₁₁H₁₆O, and C₈H₁₆O were not detected after treatment, which indicated that those organic matters were completely degraded. Meanwhile, nonexistent matters in the distillate including CH₂Cl₂, C₅H₈O, C₈H₉NO₂, and C₁₃H₂₂O were presented in the treated water.

Table 2.

GC-MS Analysis of Distillate and Water Sample After Adsorption-Photocatalysis

Constituent	TIC peak area percentage (%)
Constituent	Distillate	After treatment
CH₂Cl₂	N.D.	26.78
C₅H₈O	N.D.	44.48
C₆H₁₂O	0.86	1.5
C₆H₁₆N₂	0.27	1.37
C₇H₉N	1.51	0.39
C₈H₉NO₂	N.D.	1.16
C₈H₁₆O	1.51	N.D.
C₈H₁₈O	77.24	14.25
C₉H₁₈O	0.09	2.13
C₁₁H₁₆O	1.26	N.D.
C₁₃H₂₂O	N.D.	3.16
C₁₃H₁₈O₂	1.36	N.D.
C₁₄H₁₈N₂Si	8.85	N.D.

N.D., not detected.

When exposed to strong light, the generation of $O_{2}^{-}$ and •OH could oxidize and break down organic matters into intermediates, and then eventually convert them to carbon dioxide and water (Sheng et al., 2019; Yuan et al., 2019). As given in Table 2, the proportion of organic compounds with more than eight carbon atoms was decreased from 90.2% to 20.7%. This change might be caused mainly by the conversion of C8 alcohols to C5 aldehydes. Similar change can also be found in researches on selective oxidation of alcohols into aldehydes (Unsworth et al., 2017; Marcì et al., 2018). Li et al. (2018) used dye-sensitized TiO₂ to directly regulate the photocatalytic selective oxidation of alcohols to produce aldehydes. In our integrated system, long-chain organics were oxidized and decomposed to short-chain molecules, which were further favored to be absorbed on zeolite or completely degraded into carbon dioxide and thus easily removed from the system.

Removal mechanism of NH₃-N

The removal mechanism of NH₃-N was studied by nitrogen component analysis in water samples. TN, NH₃-N, ${N O}_{2}^{-}$ , ${N O}_{3}^{-}$ , and NH₃ in the system were collected and analyzed. The comparison groups were shale gas distillate (I), water sample after 4-h adsorption (II), water sample with subsequent 1-h photocatalysis after 4-h adsorption (III), and water sample under 1-h adsorption–photocatalysis integrated treatment (IV).

As given in Table 3, the nitrogenous components for the target distillate were mainly NH₃-N and organic nitrogen and their proportions were 83.5% and 16.5%, respectively (sample I). After 4-h adsorption to get equilibrium, the remaining nitrogen in the water was still NH₃-N and organic nitrogen in sample II. Compared with sample I, 52.7% nitrogen components were adsorbed by zeolite. Moreover, organic nitrogen content was almost unchanged in sample II. Then, 1-h additional photocatalytic operation was conducted in sample III. The TN removal was further increased to 64.1% compared with sample II (52.7%). Concentrations of ${N O}_{2}^{-}$ , ${N O}_{3}^{-}$ , and organic nitrogen in sample III were similar to those in sample II. Because a saturated adsorptive capacity on zeolite was achieved after 4-h adsorption (II), it could be inferred that 31.79 mg/L nitrogenous components (mainly NH₃-N) were converted into gaseous nitrogen and escaped from the system during the additional photocatalysis process. After 1-h adsorption–photocatalysis operation, the TN removal efficiency was 59.3% (sample IV). Under the synchronous action of adsorption and photocatalysis, NH₃-N in sample IV was effectively removed and the organic nitrogen content that remained in sample IV was almost unchanged as that in samples II and III.

Table 3.

The Nitrogen Component of Distillate and Treated Water

	Samples	TN (mg/L)	Nitrogen in solutions (mg/L)				NH₃ (mg/L)	N₂ (mg/L)	Zeolite adsorption (mg/L)
	Samples	TN (mg/L)	NH₃-N	$N O_{2}^{-}$	$N O_{3}^{-}$	Organic-N	NH₃ (mg/L)	N₂ (mg/L)	Zeolite adsorption (mg/L)
I	First-effect distillate	280.85	234.45	0.0046	N.D.	46.40	N.D.	—	—
II	Adsorption equilibrium	132.71	91.94	0.0060	N.D.	40.76	N.D.	—	148.14
III	Photocatalysis after adsorption equilibrium	100.92	56.34	0.0159	N.D.	44.56	0.74	31.79	—
IV	Adsorption-photocatalysis integrated treatment	114.37	68.9	0.0093	N.D.	45.46	0.74	166.48

NH₃-N, ammonia nitrogen; ${N O}_{2}^{-}$ , nitrite nitrogen; ${N O}_{3}^{-}$ , nitrate nitrogen; TN, total nitrogen.

The produced water was collected from a working shale gas well, and the organic components in samples were relatively complicated and difficult to eliminate. NH₃-N in the solutions was the target nitrogenous part to be treated in our adsorption–photocatalysis system. Referring to the nitrogen concentrations in samples II and III, photocatalysis efficiently improved NH₃-N removal rate (up to 18%) in sample III with the subsequent illumination compared with the one in sample II with simple adsorption. It proved that zeolite could additionally exert a photocatalytic oxidation under illumination and promote the conversion/degradation of NH₃-N.

Overall, NH₃-N in the target distillate was mainly adsorbed by high cation exchange capacity of zeolite (Wang and Peng, 2010; Markou et al., 2014). A part of NH₃-N in the integrated system was converted into nitrogen by active radicals like hydroxyl radicals (•OH) or superoxide radical ( $O_{2}^{-}$ ) generated during zeolite photocatalysis process and escaped from the system, which exhibited an enhanced synergistic effect on NH₃-N removal.

Conclusions

Aiming at the coexistence of NH₃-N and COD in the shale gas first-effect distillate, the integrated adsorption–photocatalysis system with 4A zeolites was adopted and could efficiently remove these pollutants simultaneously. Effects of system temperature, light source, reaction time, light intensity, and solution pH of the integrated system were studied and optimized for pollutants removal. After 60 min, the removal rates of NH₃-N and COD with 10 g/L zeolite under a xenon light (AM1.5, 25 A) were 88.9% and 59.0%, respectively. Compared with visible light or ultraviolet light, sunlight was more favorable for simultaneous removal of COD and NH₃-N from shale gas distillate. Compared with NH₃-N, COD removal was substantially enhanced by increasing light intensity, and the removal rate under 25 A was 17.9% higher than that under 15 A. Alkaline conditions were beneficial to degrade both COD and NH₃-N in the system. In the integrated system, COD removal from the distillate was mainly dependent on photocatalysis, and long-chain organics in solution was reduced from 90.2% to 20.7% after treatment. For NH₃-N, zeolite adsorption was much crucial on NH₃-N removal, whereas photocatalysis excited by zeolite had a good synergistic effect (18%) to improve the elimination.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

Funding Information

This study was supported by the National Science and Technology Major Project in the 13th Five-Year Plan “High-efficiency development of ultra-deep bioherm gas reservoirs with bottom water” (No. 2016ZX05017-005).

References

Banerjee

, Pillai

S.C.

, Falaras

, O'Shea

K.E.

, Byrne

J.A.

, and Dionysiou

D.D.

(2014). New insights into the mechanism of visible light photocatalysis. J. Phys. Chem. Lett. 5, 2543.

Bendjabeur

, Zouaghi

, Zouchoune

, and Sehili

(2018). DFT and TD-DFT insights, photolysis and photocatalysis investigation of three dyes with similar structure under UV irradiation with and without TiO₂ as a catalyst: Effect of adsorption, pH and light intensity. Spectrochim. Acta. A Mol. Biomol. Spectrosc. 190, 494.

Byrne

, Subramanian

, and Pillai

S.C.

(2018). Recent advances in photocatalysis for environmental applications. J. Environ. Chem. Eng. 6, 3531.

Chang

, Liu

, Yang

, Guo

, He

, Liang

, Chen

, and Yang

(2019). An integrated coagulation-ultrafiltration-nanofiltration process for internal reuse of shale gas flowback and produced water. Sep. Purif. Technol. 211, 310.

Cho

, Choi

, and Lee

(2018). Effect of pretreatment and operating conditions on the performance of membrane distillation for the treatment of shale gas wastewater. Desalination, 437, 195.

Couto

R.S.

, Oliveira

A.F.

, Guarino

A.W.

, Perez

D.V.

, and Marques

M.R.

(2017). Removal of ammonia nitrogen from distilled old landfill leachate by adsorption on raw and modified aluminosilicate. Environ. Technol. 38, 816.

, Sutton

N.B.

, Rijnaarts

H.H.H.

, and Langenhoff

A.A.M.

(2016). Degradation of pharmaceuticals in wastewater using immobilized TiO₂ photocatalysis under simulated solar irradiation. Appl. Catal. B Environ. 182, 132.

Hong

, Ratpukdi

, Sungthong

, Sivaguru

, and Khan

(2019). A sustainable solution for removal of glutaraldehyde in saline water with visible light photocatalysis. Chemosphere, 220, 1083.

Huang

, Xiao

, Yan

, and Yang

(2010). Ammonium removal from aqueous solutions by using natural Chinese (Chende) zeolite as adsorbent. J. Hazard. Mater. 175, 247.

10.

Jang

, and Chung

(2019). Lithium adsorptive properties of H₂TiO₃ adsorbent from shale gas produced water containing organic compounds. Chemosphere, 221, 75.

11.

Kato

, Yoshida

, Satsuma

, and Hattori

(2002). Photoinduced non-oxidative coupling of methane over H-zeolites around room temperature. Micropor. Mesopor. Mat. 51, 223.

12.

, Shi

J.-L.

, Hao

, and Lang

(2018). Visible light-induced selective oxidation of alcohols with air by dye-sensitized TiO₂ photocatalysis. Appl. Catal. B Environ. 232, 260.

13.

, and Yu

(2014). New stories of zeolite structures: Their descriptions, determinations, predictions, and evaluations. Chem. Rev. 114, 7268.

14.

Liu

, Zhou

, Chen

, Wang

, and Chen

(2019). Application of magnetic ferrite nanoparticles for removal of Cu(II) from copper-ammonia wastewater. J. Alloys Compd. 773, 140.

15.

, Han

, Chen

, Liu

, Li

, Leng

, Li

, and Zhou

(2019). A novel approach of using zeolite for ammonium toxicity mitigation and value-added Spirulina cultivation in wastewater. Bioresour. Technol. 280, 127.

16.

Marcì

, García-López

E.I.

, and Palmisano

(2018). Polymeric carbon nitride (C₃N₄) as heterogeneous photocatalyst for selective oxidation of alcohols to aldehydes. Catal. Today, 315, 126.

17.

Markou

, Vandamme

, and Muylaert

(2014). Using natural zeolite for ammonia sorption from wastewater and as nitrogen releaser for the cultivation of Arthrospira platensis. Bioresour. Technol. 155, 373.

18.

Matsuoka

, and Anpo

(2003). Local structures, excited states, and photocatalytic reactivities of highly dispersed catalysts constructed within zeolites. J. Photochem. Photobiol. C, 3, 225.

19.

Meng

, Liu

, Wang

, Tan

, Sun

, Liu

, and Wang

(2018). Temperature dependent photocatalysis of g-C₃N₄, TiO₂ and ZnO: Differences in photoactive mechanism. J. Colloid Interface Sci. 532, 321.

20.

Moser

P.B.

, Bretas

, Paula

E.C.

, Faria

, Ricci

B.C.

, Cerqueira

A.C.F

.P., and Amaral

M.C.S.

(2019). Comparison of hybrid ultrafiltration-osmotic membrane bioreactor and conventional membrane bioreactor for oil refinery effluent treatment. Chem. Eng. J. 378, 121952.

21.

Nassar

M.Y.

, and Abdelrahman

E.A.

(2017). Hydrothermal tuning of the morphology and crystallite size of zeolite nanostructures for simultaneous adsorption and photocatalytic degradation of methylene blue dye. J. Mol. Liq. 242, 364.

22.

Nguyen

C.H.

, Fu

C.-C.

, and Juang

R.-S.

(2018). Degradation of methylene blue and methyl orange by palladium-doped TiO₂ photocatalysis for water reuse: Efficiency and degradation pathways. J. Clean. Prod. 202, 413.

23.

Onishi

V.C.

, Carrero-Parreño

, Reyes-Labarta

J.A.

, Fraga

E.S.

, and Caballero

J.A.

(2017). Desalination of shale gas produced water: A rigorous design approach for zero-liquid discharge evaporation systems. J. Clean. Prod. 140, 1399.

24.

Pelaez

, Nolan

N.T.

, Pillai

S.C.

, Seery

M.K.

, Falaras

, Kontos

A.G.

, Dunlop

P.S.M.

, Hamilton

J.W.J.

, Byrne

J.A.

, O'Shea

, Entezari

M.H.

, and Dionysiou

D.D.

(2012). A review on the visible light active titanium dioxide photocatalysts for environmental applications. Appl. Catal. B Environ. 125, 331.

25.

Sheng

, Wei

, Miao

, Yao

, Li

, and Zhu

(2019). Enhanced organic pollutant photodegradation via adsorption/photocatalysis synergy using a 3D g-C₃N₄/TiO₂ free-separation photocatalyst. Chem. Eng. J. 370, 287.

26.

Threrujirapapong

, Khanitchaidecha

, and Nakaruk

(2017). Treatment of high organic carbon industrial wastewater using photocatalysis process. Environ Nanotechnol Monit Manag. 8, 163.

27.

Tsai

W.T.

, Hsien

K.J.

, and Hsu

H.C.

(2009). Adsorption of organic compounds from aqueous solution onto the synthesized zeolite. J. Hazard. Mater. 166, 635.

28.

, Feng

, Ren

, Cao

, Wang

, and Xu

(2019). Adsorption of ammonia nitrogen on lignite and its influence on coal water slurry preparation. Fuel, 238, 34.

29.

Unsworth

C.A.

, Coulson

, Chechik

, and Douthwaite

R.E.

(2017). Aerobic oxidation of benzyl alcohols to benzaldehydes using monoclinic bismuth vanadate nanoparticles under visible light irradiation: Photocatalysis selectivity and inhibition. J. Catal. 354, 152.

30.

Wang

, Song

, Chen

, Wang

, and Zhu

(2017). Effects of pH and H₂O₂ on ammonia, nitrite, and nitrate transformations during UV_254nm irradiation: Implications to nitrogen removal and analysis. Chemosphere, 184, 1003.

31.

Wang

, He

, Wang

, Chen

, Yao

, Jiang

, and Chen

(2019a). Simultaneous removal of NH₃-N and COD from shale gas distillate via an integration of adsorption and photo-catalysis: A hybrid approach. J. Environ. Manage. 249, 109342.

32.

Wang

, Wang

, Chen

, Gong

, Yao

, Jiang

, and Chen

(2019b). Evaluation of pre-treatment techniques for shale gas produced water to facilitate subsequent treatment stages. J. Environ. Chem. Eng. 7, 102878.

33.

Wang

, and Peng

(2010). Natural zeolites as effective adsorbents in water and wastewater treatment. Chem. Eng. J. 156, 11.

34.

Wang

, Zhou

, Zhao

, Chen

, and Yu

(2018). Synergistic effect of adsorption and visible-light photocatalysis for organic pollutant removal over BiVO₄/carbon sphere nanocomposites. Appl. Surf. Sci. 453, 394.

35.

Yuan

, Floresyona

, Aubert

P.-H.

, Bui

T.-T.

, Remita

, Ghosh

, Brisset

, Goubard

, and Remita

(2019). Photocatalytic degradation of organic pollutant with polypyrrole nanostructures under UV and visible light. Appl. Catal. B Environ. 242, 284.

36.

Yusof

A.M.

, Keat

L.K.

, Ibrahim

, Majid

Z.A.

, and Nizam

N.A.

(2010). Kinetic and equilibrium studies of the removal of ammonium ions from aqueous solution by rice husk ash-synthesized zeolite Y and powdered and granulated forms of mordenite. J. Hazard. Mater. 174, 380.

37.

Zhou

, and Boyd

C.E.

(2014). Total ammonia nitrogen removal from aqueous solutions by the natural zeolite, mordenite: A laboratory test and experimental study. Aquaculture, 432, 252.

Synergistic Effect of Zeolite on Removal of Chemical Oxygen Demand and Ammonia Nitrogen from the Shale Gas Distillate

Abstract

Introduction

Materials and Methods

Materials and reagents

Experiments

Analytical methods

Results and Discussion

Integration of adsorption and photocatalysis

Adsorption-photocatalysis studies

Reaction temperature

Light source

Reaction time

Intensity

pH

Removal mechanism of COD

Removal mechanism of NH3-N

Conclusions

Footnotes

Author Disclosure Statement

Funding Information

References

Removal mechanism of NH₃-N