title: Adsorptive selenite removal from water using a nano-hydrated ferric oxides (HFOs)/polymer hybrid adsorbent.
abstract: Selenite (SeO(3)(2-)) is an oxyanion of environmental significance due to its toxicity when taken in excess. In the present study, a hybrid adsorbent (HFO-201) was prepared by irreversibly impregnating hydrated ferric oxide (HFO) nanoparticles within a commercial available anion-exchange resin (D-201), and its adsorption towards selenite from water was investigated in batch and column tests. HFO-201 exhibited improved sorption selectivity toward selenite as compared to the polymeric anion exchanger D-201. Two possible adsorption interactions were responsible for selenite removal by HFO-201, the electrostatic interaction from the ammonium groups bound to the D-201 matrix, and the formation of inner-sphere complexes between the loaded HFO nanoparticles and selenite. In a wide pH range (i.e., 3-8), increasing solution pH was found to result in a decrease of selenite removal on HFO-201. Adsorption isotherms fit the Freundlich model well, and selenite adsorption increased with increasing ambient temperature, indicating its endothermic nature. Column adsorption tests suggested that satisfactory removal of selenite from 2 mg/L to less than 0.01 mg/L could be achieved by HFO-201 even in the presence of the commonly encountered anionic competition at greater concentration, with the treatment capacity of approximately 1200 bed volume (BV) per run, while that for D-201 was only less than 30 BV under otherwise identical conditions. Furthermore, the exhausted HFO-201 was amenable to efficient in situ regeneration with a binary NaOH-NaCl solution.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing, 210093, PR China.
authors.forename: Bingjun
authors.initials: B
authors.lastname: Pan
authors.forename: Lili
authors.initials: L
authors.lastname: Xiao
authors.forename: Guangze
authors.initials: G
authors.lastname: Nie
authors.forename: Bingcai
authors.initials: B
authors.lastname: Pan
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.forename: Lu
authors.initials: L
authors.lastname: Lv
authors.forename: Weiming
authors.initials: W
authors.lastname: Zhang
authors.forename: Shourong
authors.initials: S
authors.lastname: Zheng
mesh_terms: D000327:Adsorption; D000641:Ammonia / Q000737:chemistry; D000837:Anion Exchange Resins; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D018038:Sodium Selenite / Q000737:chemistry / Q000302:isolation & purification*; D055672:Static Electricity; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D000837:Anion Exchange Resins; D005290:Ferric Compounds; D011108:Polymers; D014874:Water Pollutants, Chemical; C000499:ferric oxide; D012965:Sodium Chloride; D012972:Sodium Hydroxide; D000641:Ammonia; D018038:Sodium Selenite