title: Equilibrium, kinetic and thermodynamic studies on the removal of U(VI) by low cost agricultural waste.
abstract: In this research, biosorption efficiency of different agro-wastes was evaluated with rice husk showing maximum biosorption capacity among the selected biosorbents. Optimization of native, SDS-treated and immobilized rice husk adsorption parameters including pH, biosorbent amount, contact time, initial U(VI) concentration and temperature for maximum U(VI) removal was investigated. Maximum biosorption capacity for native (29.56 mg g(-1)) and immobilized biomass (17.59 mg g(-1)) was observed at pH 4 while SDS-treated biomass showed maximum removal (28.08 mg g(-1)) at pH 5. The Langmuir sorption isotherm model correlated best with the U(IV) biosorption equilibrium data for the 10-100 mg L(-1) concentration range. The kinetics of the reaction followed pseudo-second order kinetic model. Thermodynamic parameters like free energy (ΔG(0)) and enthalpy (ΔH°) confirmed the spontaneous and exothermic nature of the process. Experiments to determine the regeneration capacity of the selected biosorbents and the effect of competing metal ions on biosorption capacity were also conducted. The biomass was characterized using scanning electron microscopy, surface area analysis, Fourier transformed infra-red spectroscopy and thermal gravimetric analysis. The study proved that rice husk has potential to treat uranium in wastewater.
authors.affiliation: Department of Chemistry & Biochemistry, University of Agriculture, Faisalabad 38040, Pakistan. Electronic address: abida.kausar@hotmail.com.
authors.forename: Abida
authors.initials: A
authors.lastname: Kausar
authors.affiliation: Department of Chemistry & Biochemistry, University of Agriculture, Faisalabad 38040, Pakistan. Electronic address: haq_nawaz@uaf.edu.pk.
authors.forename: Haq Nawaz
authors.initials: HN
authors.lastname: Bhatti
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, Scotland, UK. Electronic address: Gillian.MacKinnon@glasgow.ac.uk.
authors.forename: Gillian
authors.initials: G
authors.lastname: MacKinnon
mesh_terms: D000327:Adsorption; D000383:Agriculture; D000838:Anions; D001673:Biodegradation, Environmental; D002412:Cations; D003365:Costs and Cost Analysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008962:Models, Theoretical; D012275:Oryza / Q000737:chemistry / Q000648:ultrastructure; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013816:Thermodynamics; D013818:Thermogravimetry; D013997:Time Factors; D014501:Uranium / Q000302:isolation & purification*; D014866:Waste Products / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000191:economics*
chemical_list: D000838:Anions; D002412:Cations; D014866:Waste Products; D014874:Water Pollutants, Chemical; D014501:Uranium
keywords: Agro-wastes; Biosorption; Desorption; Immobilization; Kinetics; Uranium