title: Hexavalent chromium removal from wastewater using aniline formaldehyde condensate coated silica gel.
abstract: A resinous polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent in batch system for removal of hexavalent chromium from aqueous solution by considering the effects of various parameters like reaction pH, dose of AFC coated silica gel, initial Cr(VI) concentration and aniline to formaldehyde ratio in AFC synthesis. The optimum pH for total chromium [Cr(VI) and Cr(III)] adsorption was observed as 3. Total chromium adsorption was second order and equilibrium was achieved within 90-120 min. Aniline to formaldehyde ratio of 1.6:1 during AFC synthesis was ideal for chromium removal. Total chromium adsorption followed Freundlich's isotherm with adsorption capacity of 65 mg/g at initial Cr(VI) 200mg/L. Total chromium removal was explained as combinations of electrostatic attraction of acid chromate ion by protonated AFC, reduction of Cr(VI) to Cr(III) and bond formation of Cr(III) with nitrogen atom of AFC. Almost 40-84% of adsorbed chromium was recovered during desorption by NaOH, EDTA and mineral acids. AFC coated silica gel can be effectively used for treatment of chromium containing wastewaters as an alternative.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039, India.
authors.forename: P Albino
authors.initials: PA
authors.lastname: Kumar
authors.forename: Manabendra
authors.initials: M
authors.lastname: Ray
authors.forename: Saswati
authors.initials: S
authors.lastname: Chakraborty
mesh_terms: D000327:Adsorption; D000814:Aniline Compounds / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D005557:Formaldehyde / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000814:Aniline Compounds; D002857:Chromium; C074702:chromium hexavalent ion; D005557:Formaldehyde; D058428:Silica Gel; D012822:Silicon Dioxide; C023650:aniline