Effects of calcination and acid treatment on improving benzene adsorption performance of halloysite

Abstract

Abstract In this paper, calcination and subsequent acid treatment were performed on halloysite to investigate their effects on dynamic benzene adsorption performance. Calcination at 800\u202f°C had little effect on halloysite s tubular morphology, but it caused dehydroxylation and phase separation of amorphous SiO2 and Al2O3. The occurrence of dehydroxylation resulted in removal of hydroxyl groups, which reduced halloysite s hydrophilicity, leading to an improvement in the halloysite s affinity for hydrophobic benzene molecules. The dynamic benzene adsorption capacity increased from 68.1\u202fmg/g in the original halloysite to 103.6\u202fmg/g in the calcined halloysite. The acid treatment after pre-calcination preserved the halloysite s tubular morphology and introduced massive micropores as a result of the rapid dissolution of Al2O3 layers. The emergence of these massive micropores substantially improved the specific surface area and dynamic benzene adsorption capacity of the acid-treated calcined halloysite, which reached 472.3\u202fm2/g and 204.2\u202fmg/g, respectively. In addition, the recycling efficiency of the acid-treated calcined halloysite for benzene adsorption reached 92.5%, thus displaying good regeneration performance. These results demonstrate that calcination and subsequent acid treatment play important roles in promoting the halloysite s benzene adsorption performance, which makes the resulting halloysite a promising adsorbent for the treatment of volatile organic compounds.