Adsorption behavior of cationic surfactant onto aluminum hydroxide nanoparticles and application in lindane removal

The present study investigates adsorption behavior of cationic surfactant, cetyltrimethylammonium bromide (CTAB) on synthesized alpha aluminum hydroxide nanomaterials, alpha-Al(OH)3 and application in removal of a micropollutant pesticide lindane. The alpha-Al(OH)3 with high purity was confirmed by XRD, TEM, EDX, FT-IR, zeta potential and BET methods. Adsorption of CTAB increased with increasing pH from 3 to 10 due to the enhancement of electrostatic attraction between cationic CTAB ions and negatively charged alpha-Al(OH)3 surface. Ionic strengths effect demonstrated that electrostatic interaction was the main driving force contribute to CTAB adsorption onto alpha-Al(OH)3 while two-step model could fit adsorption isotherms at three ionic strengths well due to the presence of hemi-micelles. The removal of lindane using CTAB modified aluminum hydroxide nano -particles (CMAH) achieved to 95 % under optimum conditions of pH 6, contact time 60 min, CMAH dosage 10 mg/mL, and ionic strength 1 mM NaCl. Maximum adsorption capacity of lindane on CMAH was found to be 230 mu g/g. After three times regenerations, the lindane removal using CMAH was still higher than 70 %. Adsorption isotherms of lindane on CMAH can be reasonable represented by a two-step model. We demonstrate that CMAH is an excellent adsorbent for lindane removal in water environment.