Equilibrium and kinetics studies for the adsorption of aqueous Cu (II) ions onto mangroves biomass

Abstract

In this study, adsorption of copper from aqueous solutions was investigated using mangrove biomass from the Kenyan Coast. The efficacy of mangrove biomass on the removal of copper (II) ions from aqueous solutions was investigated in single state in batch mode with respect to effects of initial pH, temperature, initial concentration of the metal ion, adsorbent dosage and contact time on metal ions adsorption. The roots showed highest ability for the uptake of the metal ions from aqueous solutions, therefore were used for all subsequent sorption studies in this research. The adsorption of the copper metal ions increased with increase in the ratio of the sample dose of the adsorbent and decreased with increasing adsorbent particle size. Increase in shaking speed was observed to increase the amount of ions that adsorbed on the adsorbent. However, agitation rate beyond 500 rpm led to a decrease in percentage adsorption. Langmuir and Freundlich adsorption models were used for mathematical description of adsorption equilibrium and after evaluating the correlation coefficients, Langmuir isotherm described the data appropriable (R2=0.989) with the adsorption capacity (Qmax) of 11.36mg/g than Freundlich isotherm (R2=0.928).The data was also subjected to kinetic models and pseudo second order model was more suitable than the pseudo first order model. These results indicated that mangrove roots can be used as low cost adsorbent for the removal of heavy metals from aqueous solutions.