Theoretical study of phosphate adsorption from wastewater using Al-(hydr)oxide

The overabundance of phosphorus in water causes eutrophication of aquatic environments. As a consequence, developing an adsorbent and understanding the adsorption process to remove phosphate is vital for the prevention of eutrophication in lakes. In this study, quantum chemical calculations were use...

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Autores:
Tipo de recurso:
Fecha de publicación:
2017
Institución:
Universidad de Medellín
Repositorio:
Repositorio UDEM
Idioma:
eng
OAI Identifier:
oai:repository.udem.edu.co:11407/4380
Acceso en línea:
http://hdl.handle.net/11407/4380
Palabra clave:
Adsorption
Al-(hydr)oxide
DFT
Gibbs free energy
IR
PH
Phosphate
Wastewater
Rights
License
http://purl.org/coar/access_right/c_16ec
Description
Summary:The overabundance of phosphorus in water causes eutrophication of aquatic environments. As a consequence, developing an adsorbent and understanding the adsorption process to remove phosphate is vital for the prevention of eutrophication in lakes. In this study, quantum chemical calculations were used to simulate the adsorption of phosphate on variably charged Al-(hydr)oxide, taking into account both explicit and implicit solvation. The corresponding adsorption reactions were modeled via ligand exchange between phosphate species and surface functional groups (-H2O/-OH-). Gibbs free energies of phosphate adsorption, for inner and outer sphere complexes, using three different simulated pH conditions (acidic, intermediate, and basic) were estimated. The theoretical results indicate that the thermodynamic favorability of phosphate adsorption on Al-(hydr)oxide is directly related to pH. At intermediate pH condition, H-bonded and MM1 complexes present the most thermodynamically favorable mode of adsorption with -126.2 kJ/mol and -107.8 kJ/mol, respectively. At high pH, simulated IR spectra show that the values of P-O and P-OH stretching modes shifted to higher frequencies with respect to those at low pH. © 2017 Desalination Publications. All rights reserved.