Removal of Bromophenol Blue from Aqueous Solution Using Bentonite, Zeolite and Graphene Oxide

Abstract

In this study, an anionic dyestuff bromophenol blue (BrPB) from the aqueous solution was removed by adsorption in the presence of bentonite (B), zeolite (Z) and graphene oxide (GO). The effects of pH, adsorbent amount, initial concentration of BrPB, temperature and time on adsorption were investigated. After the adsorption process, ultraviolet-visible region spectrophotometer (UV-VIS) was used to measure the amount of dyestuff remaining in the solution which is not adsorbed. It’s found that; the optimum values obtained for the adsorption process; the optimum pH value 5 for B and Z, 4 for GO; 0.03 g amount of adsorbent and 60 minutes for the equilibrium time. The compatibility of Langmiur and Freundlich isotherm models was found as Z> GO> B and GO> B> Z respectively. In terms of kinetics aspect, it was observed that all adsorbents were comply with pseudo-second order reaction kinetics. To be positive of ΔG° value for B and Z is of physical nature of adsorption, to be negative of ΔG° value for GO requires to be chemical nature of adsorption. When the obtained ΔH° values were examined, it was observed that the reaction was endothermic for B and Z and exothermic for GO. The negative value of ΔS° for B and Z adsorbent species indicates that the randomness between solid and liquid decreases, whereas the positive ΔS° value for GO indicates that the randomness between solid and liquid increases. The highest adsorption capacity value obtained after the measurements made under optimum conditions is 589 mg g-1 for GO and 15.7 and 19.8 mg g-1 for B and Z, respectively.