Comparison of kinetic study of the adsorption of bromothymol blue on activated Attapulgite clay and commercial activated carbon

Abstract

This work is included studying the removal efficiency method of bromothymole blue (BTB) from industrial waste water by using thermally activated Attapulgite clay (ATC) and by activated carbon (AC) as adsorbent when applying adsorption technology. The most efficient dose obtained for the removal of BTB by AC and ATC is then using 20 mL of dye solution with 3*10^-4 M concentration are 0.03 and 0.1 g respectively. The use of AC required 0.03g of AC to give % ads 95.97 while the use of o.1 g of ATC gave % ads. 91.71, The results gave a preference of the clay ATC to be used as a cheap and efficient adsorbent. Comparison of the adsorption efficiency of the Attapulgite clay with commercial activated carbon where carried out. The optimal conditions of the adsorption systems under study such as effect of dose, initial concentration, and temperature were investigated. Two isotherm models, Langmuir and Freundlich were fitted to the experimental data of adsorption. The thermodynamic Functions of the studied systems (∆H^o, ∆G°, ∆S°) were estimated. The results of the thermodynamic study showed that the forces controlling the adsorption process of the systems under consideration are physical in nature. The adsorption process is exothermic, occur spontaneously in the direction of connecting the dye to the clay surface, and forming less random system. The research also included achieving kinetic study by application of the pseudo first-order and pseudo second-order reaction models on the experimental data of the studied system, this indicted by the value of R² (0.999) and the agreement between the experimental and calculated ( q_e ) . The second order equation were better fitted to the experimental data of the system under consideration. In addition, the matching of the calculated q_e value (34.843 mg/g) with the practical (33.821 mg/g) one sustain this results. The application of the intra-particle diffusion method showed that, the diffusion process of the adsorbed molecules into the pores present on the adsorbent surface is not the only mechanism driving the adsorption process in the studied reaction K_diff.(mg.g‾¹.min‾½) = 0.893, R² = 0.943.