Optimization and Isothermal Studies of Antibiotics Mixture Biosorption From Wastewater Using Palm Kernel, Chrysophyllum albidum, and Coconut Shells Biocomposite

The presence of persistent pharmaceutical products in water bodies is a significant problem that obstructs wastewater reuse. This study investigated the adsorption process for removing the recalcitrant antibiotics, including tetracycline (TC), ampicillin (AMP), and amoxicillin (AMOX) from an aqueous solution using a composite biosorbent made from a mixture of palm kernel shell (PKS), Chrysophyllum albidum (CAS), and coconut shell (CS). Simplex centroid design in the Design of Expert (12.0.1.0) was applied to optimize the percentage composition (20-55%) of the composite biosorbent precursor and to remove TC-AMP-AMOX mixtures from the aqueous solution in a batch study. The equilibrium data were fitted to 12 isotherm models and analyzed statistically. The maximum adsorption capacity of 9.12 mg/g, 8.66 mg/g, and 7.11 mg/g was achieved for TC, AMP, and AMOX, respectively, using the biocomposite biosorbent with an optimal mixture of 55% PKS, 20% CAS, and 25% CS. The adsorption behavior of TC, AMP, and AMOX was well-described by the Langmuir/Elovich isotherm (R2=1.000), Hill-DeBoer (R2=0.9953), and Freundlich/ Halsey (R2=0.9898) models, respectively. The obtained results showed that the biocomposite PKS-CAS-CS leverages the individual adsorptive capacity of each constituent to enhance the adsorption process. Moreover, the composite biosorbent demonstrated excellent potential for removing recalcitrant pharmaceuticals from wastewater effectively.