The influence of surface functionalization of activated carbon on dyes and metal ion removal from aqueous media

Abstract

Enhancement of the adsorptive properties of commercial activated carbons by simple surface modifications using chemical agents and their application to methylene blue, bemacid blue N-TF dyes, and nickel(II) ion removal from their aqueous solutions was the aim of this study. Impregnations in 10% KOH (MAC-K) for 24 h and concentrated H 2 SO 4 (MAC-S) for 2 h, applied to Merck activated carbon, and NaOH (RHAC-N) with different strength applied to Riedel- de Haen activated carbon in order to functionalize and to mod- ify their surfaces were investigated. These treatments were found to increase the adsorption capacity of the considered pollutants significantly relative to their untreated state of up to 250.00 mg/g for methylene blue, 11.47 mg/g for nickel(II) ions, and 312.00 mg/g for bemacid blue ET-L by MAC-K, MAC-S, and RHAC-N, respectively. Three well-known model equations namely Langmuir, Freundlich, and Temkin were used to analyze the adsorption equilibrium data. Parameters influencing adsorption capacity such as contact time, adsorbent dosage, pH, and temperature were studied. FT-IR and DRX analysis were performed for chemical functionalities; pH zpc , methylene blue accessible area, iodine number, and morphological analysis by scanning electron microscopy determination were also performed to characterize the prepared adsorbents. Adsorption kinetics was found to comply with the pseudo-second-order with a good correlation factor ( R 2 = 0.99) and with intra-particle diffusion as the rate-determining steps. This study showed that surface functionalization of activated carbon could prove to be a very useful method in removing toxic substances from wastewater and the environment.