Defluoridation of water using activated alumina in presence of natural organic matter via response surface methodology

• Published in: Environmental science and pollution research international 2016-01, Vol.23 (1), p.887-897
• Main Authors: Samarghandi, Mohammad Reza, Khiadani, Mehdi, Foroughi, Maryam, Zolghadr Nasab, Hasan
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; adverse effects; Alumina; Aluminum; aluminum oxide; Aluminum Oxide - chemistry; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Carbon; defluoridation; Disinfection & disinfectants; Drinking water; Earth and Environmental Science; Ecotoxicology; Efficiency; Environment; Environmental Chemistry; Environmental Health; Environmental science; Experiments; fluorescence; Fluoridation; Fluorides; Fluorides - chemistry; Fourier transform infrared spectroscopy; Fourier transforms; Fresh water; freshwater; guidelines; Infrared spectroscopy; Kinetics; mathematical models; Medical research; Membrane separation; Methods; Organic chemicals; Organic matter; Research Article; response surface methodology; scanning electron microscopes; scanning electron microscopy; Spectroscopy, Fourier Transform Infrared; Studies; Variables; Waste Water Technology; Water Management; Water Pollution Control; Water Purification - methods; Water treatment; X-radiation; X-ray diffraction; X-ray fluorescence
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-015-5293-x

Adsorption by activated alumina is considered to be one of the most practiced methods for defluoridation of freshwater. This study was conducted, therefore, to investigate the effect of natural organic matters (NOMs) on the removal of fluoride by activated alumina using response surface methodology. To the authors’ knowledge, this has not been previously investigated. Physico-chemical characterization of the alumina was determined by scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and X-ray diffractometer (XRD). Response surface methodology (RSM) was applied to evaluate the effect of single and combined parameters on the independent variables such as the initial concentration of fluoride, NOMs, and pH on the process. The results revealed that while presence of NOM and increase of pH enhance fluoride adsorption on the activated alumina, initial concentration of fluoride has an adverse effect on the efficiency. The experimental data were analyzed and found to be accurately and reliably fitted to a second-order polynomial model. Under optimum removal condition (fluoride concentration 20 mg/L, NOM concentration 20 mg/L, and pH 7) with a desirability value of 0.93 and fluoride removal efficiency of 80.6 %, no significant difference was noticed with the previously reported sequence of the co-exiting ion affinity to activated alumina for fluoride removal. Moreover, aluminum residual was found to be below the recommended value by the guideline for drinking water. Also, the increase of fluoride adsorption on the activated alumina, as NOM concentrations increase, could be due to the complexation between fluoride and adsorbed NOM.