Amino-functionalized mesoporous MCM-41 silica as an efficient adsorbent for water treatment: batch and fixed-bed column adsorption of the nitrate anion

• Published in: Applied water science 2017-07, Vol.7 (4), p.1887-1901
• Main Authors: Ebrahimi-Gatkash, Mehdi, Younesi, Habibollah, Shahbazi, Afsaneh, Heidari, Ava
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Analytical methods; Anions; Aquatic Pollution; Aqueous solutions; Capacity; Coefficients; Comparative Law; Composite materials; Constants; Desorption; Earth and Environmental Science; Earth Sciences; Electron microscopy; Experimental data; Flow rates; Fourier transforms; Grafting; Hydrogeology; Industrial and Production Engineering; Infrared spectroscopy; International & Foreign Law; Kinetics; Mathematical models; Nanotechnology; Nitrate removal; Nitrates; Nitrogen; Nutrient removal; Original Article; Powder; Private International Law; Removal; Scanning electron microscopy; Silica; Silicon dioxide; Spectroscopic analysis; Spectroscopy; Thermogravimetric analysis; Waste Water Technology; Water Industry/Water Technologies; Water Management; Water Pollution Control; Water pollution treatment; Water treatment; X-ray diffraction
• ISSN: 2190-5487; 2190-5495
• DOI: 10.1007/s13201-015-0364-1

In the present study, amino-functionalized Mobil Composite Material No. 41 (MCM-41) was used as an adsorbent to remove nitrate anions from aqueous solutions. Mono-, di- and tri-amino functioned silicas (N-MCM-41, NN-MCM-41 and NNN-MCM-41) were prepared by post-synthesis grafting method. The samples were characterized by means of X-ray powder diffraction, FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy and nitrogen adsorption–desorption. The effects of pH, initial concentration of anions, and adsorbent loading were examined in batch adsorption system. Results of adsorption experiments showed that the adsorption capacity increased with increasing adsorbent loading and initial anion concentration. It was found that the Langmuir mathematical model indicated better fit to the experimental data than the Freundlich. According to the constants of the Langmuir equation, the maximum adsorption capacity for nitrate anion by N-MCM-41, NN-MCM-41 and NNN-MCM-41 was found to be 31.68, 38.58 and 36.81 mg/g, respectively. The adsorption kinetics were investigated with pseudo-first-order and pseudo-second-order model. Adsorption followed the pseudo-second-order rate kinetics. The coefficients of determination for pseudo-second-order kinetic model are >0.99. For continuous adsorption experiments, NNN-MCM-41 adsorbent was used for the removal of nitrate anion from solutions. Breakthrough curves were investigated at different bed heights, flow rates and initial nitrate anion concentrations. The Thomas and Yan models were utilized to calculate the kinetic parameters and to predict the breakthrough curves of different bed height. Results from this study illustrated the potential utility of these adsorbents for nitrate removal from water solution.