Exploring the Feasibility of Adsorptive Removal of ZnO Nanoparticles from Wastewater

This study tested the feasibility of adsorptive removal of ZnO nanoparticles using activated carbon from wastewater. The effects of pH (5, 6, 7, 8, and 9) and nanoparticle/activated carbon concentration ratios (10, 1, 0.1, 0.01, and 0.001) on the removal were studied in batch kinetic studies in both deionized water and wastewater. The adsorption capacity of activated carbon for ZnO nanoparticles were found to be 9.3 +/- 0.8 mg/g (93% removal) and 8.2 +/- 3.7 mg/g (85% removal) at 640 and 780 min in deionized and wastewater respectively at optimum conditions (pH 8; 10g/L activated carbon concentration, 100mg/L ZnO nanoparticle concentration). The rate constant was lowest at ratio 0.01 and pH 8, and highest at ratio 10 and 1 and pH 5 and 6. Pseudo-second-order and the Weber-Morris model best described the adsorption process. Characterization analysis also confirmed the deposition of ZnO nanoparticles onto activated carbon. Overall activated carbon successfully removed ZnO nanoparticles using the adsorptive process.