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- Title
Kinetic, equilibrium and thermodynamic modelling of the sorption of metals from aqueous solution by a silica polyamine composite.
- Authors
Tutu, H.; Bakatula, E.; Dlamini, S.; Rosenberg, E.; Kailasam, V.; Cukrowska, E. M.
- Abstract
Batch sorption studies were conducted to assess the potential of a phosphonated silica polyamine composite (BPAP) to remove metals (Co, Cu, Fe, Mg, Mn, Ni, U and Zn) from mine waters. The metal adsorption showed a good Langmuir isotherm fit. Ni and Mn fitted both the Freundlich and Langmuir isotherms. The activation energies (Ea) of Co, Mg and Ni ranged between 5 and 40 kJ·mol-1, signifying physisorption while U showed a chemisorption type of adsorption (with Ea > 50 kJ·mol-1). Cu and Fe on the other hand gave negative Ea values, indicating their preference to bind to low-energy sites. The pseudo-second-order kinetic model provided the best correlation of the experimental data, except for Mg and Ni for which the pseudo-first-order model and the Elovich model gave a better fit, respectively. Adsorption was almost constant over a wide pH regime and increased with time. Adsorption increased with concentration of the metals with the exception of Co, Fe and Ni which displayed about a 40% drop at a concentration of 200 mg·l-1. Desorption experimental data gave poor results except for U which showed 99.9% desorption
- Subjects
POLYAMINES; SILICON compounds; ATMOSPHERIC temperature; HYDROGEN-ion concentration; PHYSISORPTION; SURFACE chemistry
- Publication
Water SA, 2013, Vol 39, Issue 4, p437
- ISSN
0378-4738
- Publication type
Article
- DOI
10.4314/wsa.v39i4.1