The effect of metallic composition of layered double hydroxide clay on the removal of phenol from aqueous solution

Abstract

The present study focused on the evaluation of Layered Double Hydroxide (LDH) clays containing various metallic compositions as adsorbents for phenol from wastewater. Neat clays were found to have low phenol adsorption efficiencies mainly due to poor mixing and incompatibility of the inorganic clays with phenolic water. Calcination of the clays at 500 °C produced amorphous mixed metal oxides which greatly increased the Brunauer Emmett Teller (BET) surface areas by more than 200 % from 8.71 to 29.73 m2 /g. The highest phenol adsorption removal (85 %) was observed within 24 h upon calcination of the clay. The presence of a substantial amount of zinc in hydrotalcite clay was found to be the main cause of a high phenol removal. Optimisation studies showed that higher adsorption efficiencies were attainable at pH 7 and the clay was reusable for up to 3 cycles.