Biosorption of lead (II) in aqueous solution with biomass of prickly pear cladodes (opuntia ficus indica)

The removal of lead from aqueous solutions by the biomass of prickly pear cladodes (BCT), a species found in abundance in the Sierra region in Peru, was investigated. The physical and chemical properties of BCT were determined by FTIR and SEM/EDX techniques. The FTIR analysis confirmed the presence of –OH, C–O–C, C=O and –NH₂ groups which would interact with the metal. The SEM micrograph revealed that the surface morphology of the BCT shows adequate porosity for biosorption. In a discontinuous system, the highest biosorption capacity (q_e ) was obtained with a BCT mass/volume ratio of 4 g/L, pH 4.5 and 1 h of contact time. Biosorption followed a pseudo-second order kinetic model and the intraparticle diffusion process was the main factor controlling speed. Data at equilibrium were correlated using five models (Langmuir, Freundlich, Temkin, DR, and Redlich-Peterson) and were better fitted to the Langmuir model, which would indicate that the process is carried out in energetically homogeneous active centers, the value of q_e maximum was 50.25 mg/g. The results obtained demonstrate that BCT can be used as an efficient biosorbent for the treatment of waters contaminated with Pb (II).