title: Kinetic study of time-dependent fixation of UVIon biochar.
abstract: Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of UVIfrom aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20°C, including pH, initial concentration of UVIand contact time. Uranium (UVI) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH>7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of UVIwithin the biochar structure. Desorption experiments showed that UVIwas only sparingly desorbable from the biochar with time and isotopic dilution with233UVIconfirmed the low, or time-dependent, lability of adsorbed238UVI. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5-9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5.
authors: Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, United Kingdom; Radiation Protection Department, Nuclear Research Centre, Egyptian Atomic Energy Authority, Cairo, Egypt.
authors: A
authors: A
authors: Ashry
authors: Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, United Kingdom. Electronic address: liz.bailey@nottingham.ac.uk.
authors: E H
authors: EH
authors: Bailey
authors: British Geological Survey, Nicker Hill, Keyworth, Nottingham NG12 5GG, United Kingdom.
authors: S R N
authors: SRN
authors: Chenery
authors: Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, United Kingdom.
authors: S D
authors: SD
authors: Young
keywords: Adsorption; Biochar; Isotherm; Kinetics; Uranium; pH