title: Competitive adsorption of fluoride and natural organic matter onto activated alumina.
abstract: Natural organic matter (NOM) is a major water constituent that affects the performance of water treatment processes. Several studies have shown that NOM can be adsorbed on the surface of oxides and may compete with other ions. The overall goal of this study was essentially to investigate the competitive adsorption between fluoride and NOM on activated alumina (AA). For this purpose, a humic acid (HA) was used as a model compound for NOM. The interaction of NOM with fluoride, the simultaneous competitive adsorption, and the effect of preloading AA with NOM were investigated. The specific absorbance of HA was determined at 254 nm. Size-exclusion chromatography measurements confirmed the adsorption of aromatic fractions of NOM onto AA. The presence of HA in the system inhibited fluoride sorption onto AA and the removal yield using fresh AA decreased from 70.4 % to 51.0 % in the presence of HA. The decrease was more pronounced using AA preloaded with HA, reaching 37.7 %. The interference of coexisting ions and their effect on fluoride removal capacity were evaluated, showing a severe impact of the presence of phosphate on the removal capacity unlike nitrates and sulfates, which slightly improved the fluoride sorption.
authors: a Desalination and Water Treatment Research Unit, Faculty of Sciences of Tunis , University of Tunis El Manar , Tunis , Tunisia.
authors: Meral
authors: M
authors: Mouelhi
authors: b Ecole Nationale Supérieure de Chimie de Rennes, CNRS , Rennes , France.
authors: Sylvain
authors: S
authors: Giraudet
authors: b Ecole Nationale Supérieure de Chimie de Rennes, CNRS , Rennes , France.
authors: Abdeltif
authors: A
authors: Amrane
authors: a Desalination and Water Treatment Research Unit, Faculty of Sciences of Tunis , University of Tunis El Manar , Tunis , Tunisia.
authors: Béchir
authors: B
authors: Hamrouni
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical; D000537:Aluminum Oxide; D005459:Fluorides
keywords: Competitive adsorption; alumina; defluoridation; fluoride; natural organic matter