Potential of Agarose for Biosorption of Cu(II) In Aqueous System

The ability of agarose gel as an adsorbent for Cu(II) ions in aqueous solution was studied. The experiments were done as batch processes. Batch kinetics and isotherm studies were carried out under varying experimental conditions of contact time, Cu(II) ion concentration, adsorbent dose, temperature and pH. Adsorption equilibrium of agarose gel was reached within 4 h for agarose gel when initial metal ion concentration was 25 mg/l, while at higher concentration 175 mg/l equilibrium was achieved in 6 h. Kinetics of adsorption obeyed a pseudo second-order equation. The optimum sorbent loading was found to be 1% for Cu(II) removal. The biosorption of Cu(II) ions by agarose gel decreased as the initial concentration of metal ions increased in the medium. The maximum Cu(II) ions adsorbed was found to be 238 mg/g agarose gel. The maximum uptake of metal ions was obtained at pH 2.0. At temperature 35°C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. The suitability of the Langmuir and Freundlich adsorption models to the equilibrium data were investigated and it was found that the sorption data conformed well to Langmuir isotherm model. The studies showed that the agarose gel can be used as an efficient adsorbent biopolymer for removal of Cu(II) ions from water and wastewater.