Effect of Reduction Method of Reduced Graphene Oxide for Phenol Adsorption from Aqueous Solutions

Phenol can easily enter groundwater supplies and have an adverse impact on human health. There is great concern about the need to remove phenol from water, and this study presents reduction methods for reduced graphene oxide as a material to remove phenol from contaminated water. Here the reduction of GO was carried out in two methods such as chemical and thermal reduction and compared their surface and phenol adsorption removal capacity. The characteristics of the rGO were characterized using nitrogen adsorption and desorption isotherms. The resultant BET surface areas of of thermal reduced GO shows high surface area (872.67 m²/g) and pore diameter (872.67 m²/g) than the chemical reduced GO (C-rGO) (411.91 m²/g, 3.693 nm). The adsorption mechanism and its efficiency were investigated in terms of the non-linear adsorption kinetics and isotherms using phenol adsorption data. The results of the non-linear modeling indicate that phenol adsorption was determined by rate-limiting monolayer adsorption on the homogeneous T-rGO surface and multilayer adsorption on the C-rGO surface. Also found that the maximum removal capacity of C-rGO (65.321 mg/g) is higher than that T-rGO (53.899 mg/g), which suggests that the chemical adsorption is more influenced for phenol removal than the physical adsorption. The overall results indicate that rGO is an efficient adsorbent that effectively removes the phenol from water, thereby reducing the risk to humans and the aqueous environment.