Phosphate Adsorption from Aqueous Solution Using Activated Carbon from Saba Banana Peels Impregnated with Ca2+

Abstract

Untreated municipal wastewater with elevated phosphate levels can trigger eutrophication and the flourishing of algal blooms in surface waters. Among various phosphate removal methods, adsorption, especially with surface modifications, demonstrated enhanced adsorption capacity. This study examined phosphate removal from aqueous solution using activated carbon (AC) derived from saba banana peels (ACB) and AC derived from banana peels impregnated with Ca²⁺ from eggshells (ACB-C). Scanning electron microscopy (SEM) was used to examine the surface morphology of the adsorbents before and after adsorption. Batch adsorption experiments were conducted to investigate the effect of adsorbent dosage and effect of pH on phosphate removal, and to compare the performance ACB and ACB-C. The findings indicate that 0.5 g of ACB demonstrated the highest phosphate removal efficiency of 41.58 % with an adsorption capacity of 1.17 mg/g at pH 6 while 0.5 g of ACB-C exhibited superior performance, with a remarkable 96.42 % phosphate removal efficiency and an adsorption capacity of 2.43 mg/g at pH 8. These results were consistent under specific conditions: contact time of 1 hand agitation speed of 300 rpm. Adsorption kinetics adhered well to pseudo-second-order kinetics for both ACB and ACB-C. Isotherm analysis revealed that phosphate adsorption on ACB followed the Langmuir isotherm model, indicative of monolayer adsorption. These findings affirm that Ca²⁺ impregnation enhances the efficiency of phosphate removal by the adsorbent.