title: Removal of uranium(VI) from aqueous solutions and nuclear industry effluents using humic acid-immobilized zirconium-pillared clay.
abstract: Removal of uranium [U(VI)] from aqueous solutions with humic acid-immobilized zirconium-pillared clay (HA-Zr-PILC) was investigated using a batch adsorption technique. The adsorbent was characterized using XRD, FTIR, SEM, TG/DTG, surface area analyzer and potentiometric titration. The effects of pH, contact time, initial concentration, adsorbent dose, and adsorption isotherm on the removal process were evaluated. A maximum removal of 97.6+/-2.1 and 94.7+/-3.3% was observed for an initial concentration of 50 and 100 mg L(-1), respectively at pH 6.0 and an adsorbent dose of 2.0 g L(-1). Equilibrium was achieved in approximately 180 min. The mechanism for the removal of U(VI) ions by HA-Zr-PILC was based on an ion exchange reaction. The experimental kinetic and isotherm data were analyzed using a second-order kinetic equation and Langmuir isotherm model, respectively. The monolayer adsorption capacity for U(VI) removal was found to be 132.68+/-5.04 mg g(-1). An increase of temperature of the medium caused an increase in metal adsorption. Complete removal (approximately = 100%) of U(VI) from 1.0 L of a simulated nuclear industry effluent sample containing 10.0 mg U(VI) ions was possible with 1.5 g of HA-Zr-PILC. The adsorbent was suitable for repeated use (over 4 cycles) without any noticeable loss of capacity.
authors.affiliation: Department of Chemistry, University of Kerala, Kariavattom, Trivandrum-695581, India. tsani@rediffmail.com
authors.forename: T S
authors.initials: TS
authors.lastname: Anirudhan
authors.forename: C D
authors.initials: CD
authors.lastname: Bringle
authors.forename: S
authors.initials: S
authors.lastname: Rijith
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D000077215:Clay; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D014501:Uranium / Q000302:isolation & purification*; D017974:Uranium Compounds / Q000302:isolation & purification; D014865:Waste Disposal, Fluid / Q000379:methods; D014875:Water Pollutants, Radioactive / Q000737:chemistry* / Q000302:isolation & purification; D015040:Zirconium
chemical_list: D000538:Aluminum Silicates; D006812:Humic Substances; D012996:Solutions; D017974:Uranium Compounds; D014875:Water Pollutants, Radioactive; D014501:Uranium; D015040:Zirconium; C047385:uranium oxide; D000077215:Clay