Optimization Study on the Biosorption of Toxic Metals from Mining Wastewater Using Carica Papaya Stem Activated Carbons

Abstract

Optimization studies enhanced the effectiveness of two Carica Papaya Stem Activated Carbons (CPSAC) in removing chosen harmful metals from mining wastewater and the associated problem of multivariate parameters in the process. Adsorbent dosage, stirring speed, contact time, particle size, pH, and temperature were used as independent variables in the experimental design. Batch adsorption experiments were carried out using the experimental design result, after which the collected experimental data was optimized with the Design-Expert program and the results were validated. CPSAC–NaOH had an adsorption optimization solution of 0.204 g adsorbent dosage, 149.887 rpm stirring speed, 52.79 min contact time, 1.999 mm particle size, pH 7, and 29.599 °C temperature, while CPSAC–H3PO4 had an adsorption optimization solution of 0.584 g adsorbent dosage, 147.426 rpm stirring speed, 53.303 min contact time, 2 mm particle size, pH 7, and 30 °C temperature, which results in 100% removal efficiencies for all selected toxic metals with a standard error of no more than 2.518%. Consequently, in adsorption investigations, the optimization method is a very valuable tool. It is strongly suggested for the biosorption of hazardous metals from mine wastewater with the adsorbent manufactured from the Carica papaya stem because it is cost-effective, energy-efficient, and time-saving.