title: Manganese-oxide-coated alumina: a promising sorbent for defluoridation of water.
abstract: In this study, adsorption potential of a new sorbent manganese-oxide-coated alumina (MOCA) was investigated for defluoridation of drinking water using batch and continuous mode experiments. The effects of different parameters such as pH, initial fluoride concentration and co-existing ions (usually present in groundwater sample) were studied to understand the adsorption behavior of the sorbent under various conditions. Optimum removal of fluoride ions occurred in a pH range of 4-7. Results of the present study indicate that fluoride adsorption rate and adsorption capacity of MOCA are far superior to that of activated alumina (AA), which was used as the base material for MOCA preparation. The MOCA can be effectively regenerated using 2.5% NaOH as eluent. The Langmuir equilibrium model was found to be suitable for describing the fluoride sorption on AA and MOCA. The maximum fluoride uptake capacity for MOCA and AA was found to be 2.85 and 1.08 mg g(-1), respectively. The kinetic results showed that the fluoride sorption to MOCA followed pseudo--second-order kinetics with a correlation coefficient greater than 0.98. The fluoride sorption capacity at breakthrough point for both the adsorbents was greatly influenced by bed depth. A bed depth service time (BDST) approach was adopted to describe the continuous flow system. The batch and column studies demonstrated the superiority of MOCA over AA in removing fluoride from the drinking water system.
authors.affiliation: Department of Civil Engineering, EWRE Division, Indian Institute of Technology-Madras, Chennai 600036, India. shihab@iitm.ac.in
authors.forename: Shihabudheen M
authors.initials: SM
authors.lastname: Maliyekkal
authors.forename: Atul Kumar
authors.initials: AK
authors.lastname: Sharma
authors.forename: Ligy
authors.initials: L
authors.lastname: Philip
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D005457:Fluoridation; D005459:Fluorides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D018508:Water Purification / Q000379:methods*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D000537:Aluminum Oxide; D005459:Fluorides