Adsorptive selenite removal from water using a nano-hydrated ferric oxides (HFOs)/polymer hybrid adsorbent

J Environ Monit. 2010 Jan;12(1):305-10. doi: 10.1039/b913827g. Epub 2009 Sep 25.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Ammonia / chemistry
  • Anion Exchange Resins
  • Ferric Compounds / chemistry*
  • Hydrogen-Ion Concentration
  • Kinetics
  • Microscopy, Electron, Scanning
  • Nanoparticles / chemistry
  • Particle Size
  • Polymers / chemistry*
  • Sodium Chloride / chemistry
  • Sodium Hydroxide / chemistry
  • Sodium Selenite / chemistry
  • Sodium Selenite / isolation & purification*
  • Static Electricity
  • Thermodynamics
  • Water Pollutants, Chemical / chemistry
  • Water Pollutants, Chemical / isolation & purification*
  • Water Purification / instrumentation
  • Water Purification / methods*

Substances

  • Anion Exchange Resins
  • Ferric Compounds
  • Polymers
  • Water Pollutants, Chemical
  • ferric oxide
  • Sodium Chloride
  • Sodium Hydroxide
  • Ammonia
  • Sodium Selenite