Removal of gas condensate from industrial wastewater using low‐cost adsorbents: Optimization by Box–Behnken design method

Abstract

AbstractIn this study, three effective adsorbents such as Padina sanctae cruces algae (PSC), activated carbon (AC), and bentonite clay were used to remove gas condensates from industrial wastewater generated in the fourth refinery of South Pars Gas Complex in Iran. Physical and surface properties of the adsorbents were characterized using Brunauer–Emmett–Teller (BET), field‐emission scanning electron microscope, Fourier transform‐infrared spectroscopy, and energy dispersive X‐ray spectroscopy (EDAX) analyses. Also, droplet size distribution analysis was used to determine the size distribution of gas condensate droplets in the emulsion and to evaluate the emulsion stability. According to the BET analysis, the specific surface area of AC, PSC, and bentonite were obtained as 900.93, 0.0463, and 40.70 m2/g, respectively. To check the effect of different parameters on the removal efficiency of gas condensates, the Box–Behnken design method was used. Moreover, the optimal conditions for the removal of gas condensates included pH 9, temperature of 65°C, contact time of 120 min, and an adsorbent dosage of 5 g/L. Under such optimal conditions, the adsorption efficiencies using AC, PSC, and bentonite were obtained as 98.90%, 96.35%, and 97.24%, respectively. Furthermore, the maximum adsorption capacities of 1250, 54.95, and 99.01 mg/g were achieved using AC, PSC, and bentonite, respectively, in which AC showed the highest adsorption capacity ever achieved for the removal of gas condensate from wastewater. Besides, the thermodynamic study indicated that the sorption process was exothermic and spontaneous.