Removal of Hexavalent Chromium from Aqueous Solutions Using Magnetic Nanoparticles Coated with Alumina and Modified by Cetyl Trimethyl Ammonium Bromide

Introduction: The development of an effective method regarding chromium removal from the environment is of great importance. Therefore, the present study aimed to examiner magnetic nanoparticles coated with alumina modified by Cetyl Trimethyl Ammonium Bromide (CTAB) in the removal of Cr۶+ through magnetic solid phase extraction method. Materials & Methods: At first, iron oxide nanoparticles were synthesized, coated with alumina, modified with CTAB and characterized with suitable instruments. The factors affecting the process of chromium removal were investigated, including the concentration of CTAB, the pH, the amount of nanoparticles, the sample volume, a proper eluent, the adsorption and desorption time, and the effect of interfering ions. Moreover, the chromium concentration was determined by flame atomic absorption spectrometric (FAAS) technique. The adsorption isotherm, adsorption capacity, and recoverability of the adsorbent were further examined. Results: The modified magnetic nanoparticles were demonstrated to be homogeneous, spherical, with a size lower than ۲۰ nanometer having a magnetic property. The optimal conditions for chromium removal entailed ۷*۱۰-۶ mol/L concentration of CTAB, pH range of ۶-۸, ۰.۱ g of the nanoparticles, ۱۰ mL volume of the chromium sample (۵ &mug mL-۱), nitric acid ۲ M as a suitable eluent, ۱۵ minutes of adsorption and desorption, and no interference of interfering ions in the process of chromium separation. The process efficiency under optimal conditions was determined to be over ۹۵%, which this process followed the Langmuir adsorption isotherm. The adsorption capacity proved to be ۲۳.۸ mg/g. Reusing after four times of adsorbent recovering was effective in the chromium removal (۸۰%). The method accuracy for five measurement times was ۴.۱۵۵% and the method’s LOD was ۰.۰۸۱ mg/L. Conclusion: The method enjoys the benefits of convenient preparation of the adsorbent, high selectivity, high accuracy, short process time, and high-efficiency in chromium removal from aquatic environments, lending itself to be used in the real samples.

Keywords:

Hexavalent chromium , Magnetic solid phase extraction , Magnetic nanoparticles , Cationic surfactant , کروم شش ظرفیتی , استخراج فاز جامد مغناطیسی , نانوذرات مغناطیسی , سورفاکتانت کاتیونی