Use of Ricinus communis leaves as a low-cost adsorbent for removal of Cu(II) ions from aqueous solution

The study was conducted to compare removal of Cu(II) from aqueous solutions by water-washed raw leaves of Ricinus communis (RLRC) and by activated carbon prepared, with microwave assistance, from zinc chloride-treated leaves of R. communis (ZLRC). The ZLRC preparation conditions were: radiation power 100 W, radiation time 8 min, were mixed with the ZnCl2 concentration of 30 % by volume, and impregnation time 24 h. The RLRC and ZLRC were characterized by FTIR, SEM-EDAX, and XRD analysis. The effects of different conditions, for example solution pH, initial metal ion concentration, contact time, adsorbent dose, and presence of other ions were studied by use of batch-mode experiments. Maximum adsorption of Cu(II) was observed at pH 5.4 for RLRC (50 %) and at pH 6.3 for ZLRC (64.25 %). The Langmuir, Freundlich, Temkin, and Dubin-Radushkevich isotherm models were used to analyze the equilibrium data. The data were also fitted to the pseudo-first order, pseudo-second order, intra particle, and Elovich kinetic models. The adsorption equilibrium data were well fitted by the Langmuir model. Kinetic studies showed that adsorption followed pseudo-second order and intra particle diffusion models. The adsorption capacity of ZLRC was greater than that of RLRC. According to the experimental results, the adsorbent derived from this material is expected to be an economical product for metal ion remediation of water and waste water.