Influence of pH on Initial Concentration Effect of Arsenate Adsorption on TiO2 Surfaces: Thermodynamic, DFT, and EXAFS Interpretations | Zendy

Guangzhi He | Zendy; Meiyi Zhang | Zendy; Gang Pan | Zendy

Open Access

Influence of pH on Initial Concentration Effect of Arsenate Adsorption on TiO₂ Surfaces: Thermodynamic, DFT, and EXAFS Interpretations

Author(s) -

Guangzhi He,

Meiyi Zhang,

Gang Pan

Publication year - 2009

Publication title -

the journal of physical chemistry c

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.401

H-Index - 289

eISSN - 1932-7455

pISSN - 1932-7447

DOI - 10.1021/jp906019e

Subject(s) - adsorption , arsenate , chemistry , outer sphere electron transfer , extended x ray absorption fine structure , inner sphere electron transfer , absorption (acoustics) , gibbs free energy , denticity , density functional theory , inorganic chemistry , thermodynamics , crystallography , arsenic , crystal structure , computational chemistry , absorption spectroscopy , organic chemistry , materials science , ion , composite material , physics , quantum mechanics

Under the same thermodynamic condition where the total mass of arsenate was fixed, when the initial arsenate was added to TiO2 suspension by multiple batches, adsorption isotherms declined as the multi-batch increased, which was termed initial concentration (C0) effect. The extent of C0 effect decreased gradually as pH decreased from 7.0 to 5.5. Extended X-ray absorption fine structure analysis of 1-batch and 3-batch isotherm samples showed that the relative proportion of bidentate binuclear (BB) and monodentate mononuclear (MM) complex was rarely affected by pH change from 5.5 to 7.0, indicating that the dependence of C0 effect on pH was not due to inner-sphere chemiadsorption. The influence of pH on adsorption was simulated by density functional theory through changing the number of H+ in model clusters. Calculation of adsorption energy showed that BB surface complex was the most thermodynamically favorable mode (−244.5 kJ mol−1) at low pH, but MM surface complex was the most thermodynamically favorable...

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