Adsorption of Pb2+, Cd2+, Cu2+, and Zn2+ from aqueous solution by modified sugarcane bagasse

Adsorption performances of pyromellitic dianhydride modified sugarcane bagasse (SCB) for Pb2+, Cd2+, Cu2+, and Zn2+ were investigated. According to the Langmuir equation, the adsorption capacities of the modified SCB for Pb2+, Cd2+, Cu2+, and Zn2+ were 1.06, 0.93, 1.21, and 1.00 mmol g(-1), respectively, while those for the unmodified SCB were 0.04, 0.13, 0.10, and 0.07 mmol g(-1), respectively. Adsorption rates were rapid for the four metal ions, and both pseudo-first-order and pseudo-second-order models could predict the kinetic process. Removal percentages of the four metal ions all increased with increasing the solution pH and dosage in our investigated range. The main adsorption mechanism for the metal ions was investigated by FTIR and EDX. Competitive adsorption in the quaternary system showed that adsorption on the modified SCB followed the affinity order: Pb2+ > Cu2+ > Cd2+ > Zn2+. This performance made it possible to separate and enrich the four metal ions in the mixture solutions in the dynamic adsorption experiment.