title: Sorption-desorption of carbamazepine by palygorskite-montmorillonite (PM) filter medium.
abstract: Palygorskite-montmorillonite (PM) was studied as a potential sewage treatment effluent filter material for carbamazepine. Batch sorption experiments were conducted as a function of granule size (0.3-0.6, 1.7-2.0 and 2.8mm) and different sewage effluent conditions (pH, ionic strength and temperature). Results showed PM had a mix of fibrous and plate-like morphologies. Sorption and desorption isotherms were fitted to the Freundlich model. Sorption is granule size-dependent and the medium granule size would be an appropriate size for optimizing both flow and carbamazepine retention. Highest and lowest sorption capacities corresponded to the smallest and the largest granule sizes, respectively. The lowest and the highest equilibrium aqueous (Ce) and sorbed (qe) carbamazepine concentrations were 0.4 mg L(-1) and 4.5 mg L(-1), and 0.6 mg kg(-1) and 411.8 mg kg(-1), respectively. Observed higher relative sorption at elevated concentrations with a Freundlich exponent greater than one, indicated cooperative sorption. The sorption-desorption hysteresis (isotherm non-singularity) indicated irreversible sorption. Higher sorption observed at higher rather than at lower ionic strength conditions is likely due to a salting-out effect. Negative free energy and the inverse sorption capacity-temperature relationship indicated the carbamazepine sorption process was favorable or spontaneous. Solution pH had little effect on sorption.
authors.affiliation: Department of Geology and Environmental Earth Science, Miami University, 250 South Patterson Avenue, Shideler Hall, Oxford, OH 45056, USA. Electronic address: tedros.berhane@gmail.com.
authors.forename: Tedros M
authors.initials: TM
authors.lastname: Berhane
authors.affiliation: Department of Geology and Environmental Earth Science, Miami University, 250 South Patterson Avenue, Shideler Hall, Oxford, OH 45056, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Levy
authors.affiliation: Department of Geology and Environmental Earth Science, Miami University-Hamilton, 1601, University Boulevard, Hamilton, OH 45011, USA.
authors.forename: Mark P S
authors.initials: MP
authors.lastname: Krekeler
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, 360C Hughes Hall, 701 East High Street, Oxford, OH 45056, USA.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Danielson
authors.affiliation: Department of Chemical Sciences, Dublin City University, Ireland.
authors.forename: Apryll
authors.initials: A
authors.lastname: Stalcup
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D002220:Carbamazepine / Q000737:chemistry*; D005374:Filtration; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D017616:Magnesium Compounds / Q000737:chemistry*; D009994:Osmolar Concentration; D010316:Particle Size; D016062:Porosity; D017655:Silicon Compounds / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D017655:Silicon Compounds; D014874:Water Pollutants, Chemical; D001546:Bentonite; D002220:Carbamazepine; C026325:attapulgite
keywords: Carbamazepine; Desorption; Montmorillonite; Palygorskite; Sorption