Caesalpinia bonducella Leaf Powder as Biosorbent for Cu(II) Removal from Aqueous Environment: Kinetics and Isotherms

The ability of Caesalpinia bonducella leaf powder has been utilized as an inexpensive biosorbent for the removal of Cu(II) from aqueous media. Optimum biosorption conditions were found to be pH 5.0, adsorbent dosage 0.07 g/L, agitation speed 180 rpm, and equilibrium time 120 min. Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction were used to characterize the surface functional groups, structure, compositional analysis, and crystallinity of the biosorbent. FT-IR analysis shows the involvement of various functional groups such as hydroxyl, amide, carboxyl, and carbonyl groups in the removal of Cu(II) from aqueous environment. Kinetic data were fitted well to a pseudo-second-order kinetic model compared to pseudo-first-order and intraparticle diffusion kinetic models. The equilibrium data were well fitted by the Langmuir isotherm model by revealing the maximum sorption capacity of 76.92 mg/g.