Textile effluent contains different organic and inorganic pollutants, among these are COD and heavy metals such as lead (Pb), chromium (Cr), cadium (Cd), and copper (Cu) used for the production of color pigments. In this study the adsorption capacity of chitosan produced from snail shells as an adsorbent for the treatment of textile effluent and for the removal of lead (Pb2+) from waste water carried out. Batch experiments were performed to study the treatment of textile waste water and the adsorption of lead Pb2+ion unto chitosan. The effect of various experimental parameters (adsorbent dose, contact time and temperature) was studied, and optimal conditions were determined. Batch adsorption study on textile waste water showed 96.9 % COD removal was achieved for carbon dosage of 15mg carbon/100ml of textile wastewater solution. The equilibrium data were analyzed with Langmuir, Freundlich, Temkin, Elovich, Florry Huggins, Jovanovic, Harkin Jura and Dubinin–Radushkevich (DRK) adsorption models. Freundlich isotherm yielded the best fit to the experimental equilibrium adsorption data with a correlation coefficient (R2 ) of 0.991. The adsorption intensity is 1.68. This was closely followed by Langmuir Isotherm with a correlation coefficient (R2 ) of is 0.943. The maximum monolayer coverage (Qo) from Langmuir isotherm model was determined to be 50.51mg/g, KL (Langmuir isotherm constant) is 0.00374L/mg, RL (the separation factor) is 0.217 indicating that the equilibrium sorption was favorable. Adsorption kinetics data for sorption of Pb2+ion unto chitosan were analyzed using the pseudo first order, pseudo second order and intra particle diffusion models. The results indicated that the adsorption kinetic data were best described by pseudo secondorder model. For the thermodynamic studies, the enthalpy change, ΔH°, and the entropy change, ΔS°, for the adsorption processes are -18.10 kJ/mol and -0.0652KJ/mol K respectively. The free energy, ΔG° for the process are 2186.39 J/mol, 3071.761 J/mol, 3689.615J/mol and 4153.032 J/mol at 303K, 313K, 323 K and 333K respectively. The results of thermodynamic parameters evaluated showed that the process was non spontaneous and exothermic in nature. The results show that chitosan can be used as an alternative low-cost adsorbent for treatment of textile effluent and the removal of COD and lead from wastewater.
Agriculture waste from banana peel as low cost adsorbent in treating methylene blue from batik textile waste water effluents
