Complexation at the edges of hydrotalcite: The cases of arsenate and chromate
Sorption of CrO42- and HAsO42- by hydrotalcite, in its chloride form, was studied as a function of anion concentration. In both cases, the shape of the isotherms is langmuirian. The maximum uptake of CrO42- equals the ion-exchange capacity of the solid, whereas sorption of HAsO42- saturates at a hig...
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2013
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paper:paper_00219797_v393_n1_p314_Jobbagy2023-06-08T14:44:57Z Complexation at the edges of hydrotalcite: The cases of arsenate and chromate Jobbagy, Matias Adsorption Arsenate Chromate Hydrotalcite Layered double hydroxides Surface complexation Anion concentrations Arsenate Arsenate uptake Charge reversal Chloride concentrations Chloride ions Electrophoretic behavior Equilibrium concentration Hydrotalcite surfaces Hydrotalcites Ion exchange capacity Layered double hydroxides Particle charge Surface complex Surface complexation Adsorption Chromates Dyes Negative ions Chlorine compounds arsenic acid chloride ion chromic acid hydrotalcite article complex formation crystal structure electrophoresis ion exchange isotherm pH priority journal Adsorption Aluminum Hydroxide Arsenates Chromates Hydrogen-Ion Concentration Magnesium Hydroxide Surface Properties Sorption of CrO42- and HAsO42- by hydrotalcite, in its chloride form, was studied as a function of anion concentration. In both cases, the shape of the isotherms is langmuirian. The maximum uptake of CrO42- equals the ion-exchange capacity of the solid, whereas sorption of HAsO42- saturates at a higher value. Chloride ions inhibit the uptake of both anions, the amount of sorbed CrO42- declining rapidly to zero. The uptake of HAsO42-, however, attains a constant value at high chloride concentrations. The excess of arsenate uptake follows, at constant pH, a langmuirian dependence with equilibrium concentration and decreases with increasing pH, depicting a marked change in slope at pHpQa3. CrO42- and HAsO42- have notable, albeit different, effects on the electrophoretic behavior of hydrotalcite; the positive particle charge is screened almost completely by CrO42-, whereas sorption of HAsO42- produces charge reversal. These results reflect the formation of inner-sphere arsenate surface complexes at the edges of hydrotalcite particles. The underlying rationale is discussed in terms of the crystal structure of hydrotalcite surfaces. © 2012 Elsevier Inc. Fil:Jobbágy, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2013 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219797_v393_n1_p314_Jobbagy http://hdl.handle.net/20.500.12110/paper_00219797_v393_n1_p314_Jobbagy |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Adsorption Arsenate Chromate Hydrotalcite Layered double hydroxides Surface complexation Anion concentrations Arsenate Arsenate uptake Charge reversal Chloride concentrations Chloride ions Electrophoretic behavior Equilibrium concentration Hydrotalcite surfaces Hydrotalcites Ion exchange capacity Layered double hydroxides Particle charge Surface complex Surface complexation Adsorption Chromates Dyes Negative ions Chlorine compounds arsenic acid chloride ion chromic acid hydrotalcite article complex formation crystal structure electrophoresis ion exchange isotherm pH priority journal Adsorption Aluminum Hydroxide Arsenates Chromates Hydrogen-Ion Concentration Magnesium Hydroxide Surface Properties |
| spellingShingle |
Adsorption Arsenate Chromate Hydrotalcite Layered double hydroxides Surface complexation Anion concentrations Arsenate Arsenate uptake Charge reversal Chloride concentrations Chloride ions Electrophoretic behavior Equilibrium concentration Hydrotalcite surfaces Hydrotalcites Ion exchange capacity Layered double hydroxides Particle charge Surface complex Surface complexation Adsorption Chromates Dyes Negative ions Chlorine compounds arsenic acid chloride ion chromic acid hydrotalcite article complex formation crystal structure electrophoresis ion exchange isotherm pH priority journal Adsorption Aluminum Hydroxide Arsenates Chromates Hydrogen-Ion Concentration Magnesium Hydroxide Surface Properties Jobbagy, Matias Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| topic_facet |
Adsorption Arsenate Chromate Hydrotalcite Layered double hydroxides Surface complexation Anion concentrations Arsenate Arsenate uptake Charge reversal Chloride concentrations Chloride ions Electrophoretic behavior Equilibrium concentration Hydrotalcite surfaces Hydrotalcites Ion exchange capacity Layered double hydroxides Particle charge Surface complex Surface complexation Adsorption Chromates Dyes Negative ions Chlorine compounds arsenic acid chloride ion chromic acid hydrotalcite article complex formation crystal structure electrophoresis ion exchange isotherm pH priority journal Adsorption Aluminum Hydroxide Arsenates Chromates Hydrogen-Ion Concentration Magnesium Hydroxide Surface Properties |
| description |
Sorption of CrO42- and HAsO42- by hydrotalcite, in its chloride form, was studied as a function of anion concentration. In both cases, the shape of the isotherms is langmuirian. The maximum uptake of CrO42- equals the ion-exchange capacity of the solid, whereas sorption of HAsO42- saturates at a higher value. Chloride ions inhibit the uptake of both anions, the amount of sorbed CrO42- declining rapidly to zero. The uptake of HAsO42-, however, attains a constant value at high chloride concentrations. The excess of arsenate uptake follows, at constant pH, a langmuirian dependence with equilibrium concentration and decreases with increasing pH, depicting a marked change in slope at pHpQa3. CrO42- and HAsO42- have notable, albeit different, effects on the electrophoretic behavior of hydrotalcite; the positive particle charge is screened almost completely by CrO42-, whereas sorption of HAsO42- produces charge reversal. These results reflect the formation of inner-sphere arsenate surface complexes at the edges of hydrotalcite particles. The underlying rationale is discussed in terms of the crystal structure of hydrotalcite surfaces. © 2012 Elsevier Inc. |
| author |
Jobbagy, Matias |
| author_facet |
Jobbagy, Matias |
| author_sort |
Jobbagy, Matias |
| title |
Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| title_short |
Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| title_full |
Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| title_fullStr |
Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| title_full_unstemmed |
Complexation at the edges of hydrotalcite: The cases of arsenate and chromate |
| title_sort |
complexation at the edges of hydrotalcite: the cases of arsenate and chromate |
| publishDate |
2013 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219797_v393_n1_p314_Jobbagy http://hdl.handle.net/20.500.12110/paper_00219797_v393_n1_p314_Jobbagy |
| work_keys_str_mv |
AT jobbagymatias complexationattheedgesofhydrotalcitethecasesofarsenateandchromate |
| _version_ |
1768542395077492736 |