Biosorption of nickel and cadmium using Pachira aquatica Aubl. peel Biochar

Abstract

Chemical contamination of the environment by heavy metals is becoming a serious problem in the worldwide due to increased human activities and industrial development. Therefore, researchers have been looking for alternatives to remediate these contaminants with economical and efficient technologies. This work aimed to value Pachira aquatica Aubl. fruit peels through the applicability of this material in the biosorption process for removal of Ni(II) and Cd(II) metal ions. Characterization of Pachira aquatica Aubl. fruit peel biochar (PAB) was performed through the proximate analysis, helium pycnometry, XRD, SEM, point of zero charges, zeta potential, and Boehm titration method. Design of experiment (DOE) was carried out, as well as kinetic, isotherm, and thermodynamic batch biosorption, and finally, column biosorption tests were performed. The PAB presents potential as a biosorbent due to its low amount of moisture, density similar to that of commercial activated carbons, neutral point of zero charges, porous, irregular, heterogeneous, and negative surface within the presence of functional groups capable of efficiently connecting with heavy metal. The biosorption equilibrium time was obtained at 300 min for both ions, following a pseudo second-order kinetic model and Langmuir isotherm model. The column tests presented an exhaust volume of 40.2 mg/L and 29.2 mg/L for Ni(II) and Cd(II), respectively. Thus, it is concluded that the PAB has the potential as a biosorbent for the removal of heavy, it leads to the valorization of this co-product and the reduction of environmental pollution.