Phenol removal from aqueous media using BEA zeolite: A molecular simulation study on the effect of zeolite mobile cations

Abstract

Phenol removal from wastewater is crucial due to its high toxicity at low concentrations. In this study, the effectiveness of BEA zeolites (All-Si-BEA, H-BEA, Ca-BEA, and Na-BEA) for phenol removal was investigated using GCMC and MD simulations. The surface area and pore volume of the BEA structures were analyzed. The results showed that All-Si-BEA and H-BEA zeolites had slightly larger pore volumes (less than 2 %) compared to cationic BEA zeolites, indicating minimal impact of cations on pore volume. Efficient phenol adsorption was observed on all zeolite structures, even at low concentrations. All-Si-BEA and H-BEA exhibited high selectivity (105-106) and phenol adsorption capacity (1.86 mmol/g) at low phenol concentrations. Water adsorption was lower on All-Si-BEA and H-BEA, while cationic zeolites had higher water adsorption. The simulations showed that water molecules gather around mobile cations in the pores, causing variation in water adsorption in All-Si-BEA, H-BEA compared to cationic BEAs. The energy examination confirmed this observation. The diffusion coefficients of phenol in BEA (All-Si-BEA, H-BEA, Na-BEA, and Ca-BEA) were 5.34 × 10−5, 3.49 × 10−5, 5.32 × 10−6, and 1.02 × 10−6 (cm2/s), respectively, indicating higher mobility in All-Si-BEA and H-BEA compared to cationic BEA zeolites. Increasing the number of water molecules in the zeolite structures resulted in a decrease in the diffusion coefficient of phenol due to the hindrance caused by water molecules. Overall, All-Si-BEA and H-BEA showed higher potential for phenol separation from water compared to cationic BEA zeolites.