LAUSR

Abstract The effectiveness of ammonium (NH4+) adsorption was investigated, using spray-dried, pH-treated bentonite, and kaolin as adsorbents. Each powder's adsorption capacity towards NH4+ was examined after up to 120 min of sample exposure, and results were compared. The zeta potential values for bentonite samples were between −1.1 and −19.4 mV, while for kaolin samples, they were between −35.7 and −40.9 mV (pH range examined was 2–10). The adsorption isotherm for bentonite showed a fit with the Langmuir model. The pH 10-treated bentonite and as-received bentonite (dispersed as pH 10 in distilled water) showed the highest adsorption capacity towards NH4+. Meanwhile, for kaolin, the adsorption capacity was low and observed only at low NH4+ concentration (100 mg/L and 200 mg/L), with pH 10-treated kaolin showed the highest adsorption capacity.