Biosorptive removal of aluminum from aqueous solution using raw <i>Prosopis juliflora</i> biomass: biosorbent characterization, kinetic, and isotherm analysis

ABSTRACT In this study, Prosopis juliflora seed powder was used as a biosorbent for the removal of aluminum from aqueous solutions. Batch experiments were conducted to evaluate the efficiency of the powder for aluminum removal under various experimental parameters. The parameters were contact time, biosorbate initial concentration, solution pH, solid-to-liquid ratio, and particle size. Over 90% removal and 8.31 mg/g biosorption amount were achieved after 240-min agitation with very fine particles, at a low concentration, and at a pH range of 5–6. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller scientific techniques were used to characterize the biosorbent. The pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models were applied to determine the most suitable kinetic model. The pseudo-second-order model provided the most accurate description of the biosorption process with R2 = 0.99. The Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich isotherm models were used to find the most suitable isotherm model. Except for the Dubinin–Radushkevich model, three other models produced good results in the equilibrium data, but the Freundlich model provided a better fit. Desorption studies confirmed the biosorbent's regenerability, with an initial recovery rate of 80.6%. The result of this study suggested that P. juliflora is an efficient biosorbent to remove aluminum from aqueous solutions.