Biosorption of Copper(II) from Aqueous Solutions by Brown Macroalga Cystoseira myrica Biomass

Abstract

Nowadays, heavy metals pollution of water resources represents an important environmental problem due to thier toxic and carcinogenic effects and accumulation throughout the food chain. In this research, biosorption of copper(II) from aqueous solutions was studied in a batch system by using two types of biosorbent: original and protonated Cystoseira myrica biomass. Kinetic experiments indicated that copper (Cu²⁺) uptake, especially by the protonated Cystoseira myrica, was rapid. Pseudosecond-order equation described the kinetic of Cu²⁺ biosorption onto both the original and protonated biomass (R² > 0.999 and ɛ% < 5%). Optimized condition of pH value for Cu²⁺ biosorption was obtained to be 5.5 in the pH range of 2–5.5. Isotherm experiments were conducted in initial ion concentrations from 0.05 to 5 mM. Isotherm data of Cu²⁺ biosorption by the original biomass were found to be in the best fitness with the Langmuir equation (R² > 0.999 and ɛ% < 17%), while the Redlich-Peterson equation described the isotherm of Cu²⁺ biosorption by the protonated biomass (R² > 0.997 and ɛ% < 5%). According to the Langmuir model, the maximum uptake capacities (q_m) of Cu²⁺ by the original and protonated Cystoseira myrica were determined to be 1.54 and 1.21 mmol/g, respectively. Therefore, however, pretreatment of the biomass by protonation increased the biosorption rate, but because of reducing its uptake capacity could be considered as an inefficient pretreatment method.