Equilibrium and kinetic modelling of cadmium(II) biosorption by nonliving algal biomass Oedogonium sp. from aqueous phase

• Published in: Journal of hazardous materials 2008-05, Vol.153 (1), p.759-766
• Main Authors: Gupta, V.K., Rastogi, A.
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Biological and medical sciences; Biomass; Biosorption; Biotechnology; Cadmium; Cadmium - chemistry; Chemical engineering; Chlorophyta - chemistry; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Kinetics; Langmuir model; Methods. Procedures. Technologies; Models, Chemical; Oedogonium; Oedogonium sp; Others; Pollution; Sorption/desorption; Temperature; Thermodynamics; Various methods and equipments; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - chemistry; Water Purification - methods
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2007.09.021

The biosorption of cadmium(II) ions on Oedogonium sp. is studied in a batch system with respect to initial pH, algal dose, contact time and the temperature. The algal biomass exhibited the highest cadmium(II) uptake capacity at 25 °C, at the initial pH value of 5.0 in 55 min and at the initial cadmium(II) ion concentration of 200 mg L −1. Biosorption capacity decreased from 88.9 to 80.4 mg g −1 with an increase in temperature from 25 to 45 °C at this initial cadmium(II) concentration. Uptake kinetics follows the pseudo-second-order model and equilibrium is well described by Langmuir isotherm. Isotherms have been used to determine thermodynamic parameters of the process, viz., free energy change, enthalpy change and entropy change. FTIR analysis of algal biomass revealed the presence of amino, carboxyl, hydroxyl and carbonyl groups, which are responsible for biosorption of metal ions. Acid pretreatments did not substantially increase metal sorption capacity but alkali like NaOH pretreatment slightly enhanced the metal removal ability of the biomass. During repeated sorption/desorption cycles at the end of fifth cycle, Cd(II) sorption decreased by 18%, with 15–20% loss of biomass. Nevertheless, Oedogonium sp. appears to be a good sorbent for removing metal Cd(II) from aqueous phase.