Optimization of As(V) adsorption on Fe-RH-MCM-41-immobilized GAC using Box–Behnken Design: Effects of pH, loadings, and initial concentrations

This work focused on the removal from water of arsenate in the 100 to 500 μg/L range using Fe-RH-MCM-41 immobilized on GAC by a colloidal impregnation method. A Response Surface Method (RSM) based on the Box–Behnken Design (BBD) was used to evaluate the effects of pH, adsorbent loading, and initial arsenate concentrations. The thermal stability of Fe-RH-MCM-41/GAC was greater than 460 °C because Fe-RH-MCM-41 and epoxy resin covered the GAC, preventing GAC weight loss. The rate and capacity for arsenate adsorption on Fe-RH-MCM-41/GAC were higher than for GAC. The effects of pH, adsorbent loading, and initial arsenate concentration showed significant effects on efficiency, in terms of percent arsenate removal. Significant interaction occurred as positive effects between arsenate and arsenate concentrations, and pH and arsenate concentrations, and as negative effects between pH and pH, adsorbent loading and adsorbent loading, and adsorbent loading and arsenate concentrations.