Comparison of the efficiencies of modified clay with polyethylene glycol and tetradecyl trimethyl ammonium bromide for BTEX removal

Abstract

Aims: In this study, the effectiveness of modified clay [montmorillonite (Mt)] with polyethylene glycol (PWG) and tetradecyl trimethyl ammonium bromide (TTAB) on the benzene, toluene, ethylbenzene and xylene (BTEX) removal from aqueous solution was investigated.Materials and Methods: The batch adsorption experiments including surfactant loading rates (0.2-4 cation exchange capacity [CEC] of the clay), contact time (0-24 h), pH (4-12) and adsorbate concentration (10-200 mg/L) were conducted at room temperature (25°C) with 100 mL of BTEX solution into a 200-mL conical flask and mixed by an orbital shaker (250 rpm for 24 h). Results: It was found that the optimum adsorption condition obtains for the surfactant loading rate of 200% clay CEC for both the adsorbents at the contact time of 24 h. The sorption capacity of BTEX by both the adsorbents was in order of benzene toluene ethylbenzene xylene. The results of both the adsorbents also showed that the pseudo-second-order kinetic model and Freundlich isotherm model fitted the experimental data better than of other kinetic and isotherm models, respectively.Conclusion: The adsorption capacity of TTAB-Mt (22.11 mg/g) was slightly higher than PEG-Mt (18.77 mg/g). With regard to lower toxic effects and lower cost of nonionic surfactants than the cationic type, using the nonionic modified Mt is preferred than cationic modified Mt for the removal of BTEX from aqueous solution.