The static anion exchange method for generation of high purity aluminium polyoxocations and monodisperse aluminium hydroxide nanoparticles

Shafran, Kirill L.; Deschaume, Olivier; Perry, Carole C.

doi:10.1039/b505466d

Cited by 27 publications

(35 citation statements)

References 41 publications

(78 reference statements)

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“…Al 30 species was more thermal resistant and more stable in low pH solution than Al 13 species (Chen, 2006;Chen et al, 2007). It became a dominant polymeric Al species in highly concentrated polyaluminum solutions (Shafran et al, 2005b;Chen et al, 2005). Our recent research results indicated that Al 30 species was more effective for turbidity removal than Al 13 species.…”

Section: Introductionmentioning

confidence: 92%

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

Chen

Luan

Jia

et al. 2009

Journal of Environmental Management

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a b s t r a c tThe hydrolysis/precipitation behaviors of Al 3þ , Al 13 and Al 30 under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl 3 , PAC Al13 and PAC Al30 were 6.5-7.5, 8.5-9.5, and 7.5-9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl 3 [ PAC Al30 > PAC Al13 . The precipitates' size increased when the dosage increased from 50 mM to 200 mM, but it decreased when the dosage increased to 800 mM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The isoelectric points of the freshly formed precipitates for AlCl 3 , PAC Al13 and PAC Al30 were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl 3 hydrolysis precipitates were lower than those of PAC Al13 and PAC Al30 when pH > 5.0. The Zeta potential of PAC Al30 hydrolysis precipitates was higher than that of PAC Al13 at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al-Ferron research indicated that the hydrolysis precipitates of AlCl 3 were composed of amorphous Al(OH) 3 precipitates, but those of PAC Al13 and PAC Al30 were composed of aggregates of Al 13 and Al 30 , respectively. Al 3þ was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al 13 and Al 30 species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al-Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al-Ferron method. The chemical composition of Al a , Al b and Al c depended on coagulant and solution pH. The Al b measured in the current case was different from Keggin Al 13 , and the high Al b content in the AlCl 3 hydrolysis precipitates could not used as testimony that most of the Al 3þ was converted to highly charged Al 13 species during AlCl 3 coagulation.

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Section: Introductionmentioning

confidence: 92%

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

Chen

Luan

Jia

et al. 2009

Journal of Environmental Management

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“…For the preparation of the Al 13 -mers the formal hydrolysis ratio of the solution (the formal hydrolysis ratio is the ratio of the concentration of added alkali and total Al concentration h = C(OH − ) added /C(Al) total ) was adjusted to h ∼ 2.46, close to the theoretical hydrolysis ratio h = 2.462 of these species [18]. For preparation of a model Al 30 -mer solution, the Al 13 -mer solution prepared at room temperature at h ∼ 2.40 was thermally aged at 85 • C for 48 h as described previously [26,27]. The sol of aluminium hydroxide was prepared at room temperature by adjusting the hydrolysis ratio of the stock solution of AlCl 3 to h ∼ 2.85 also using the static anion exchange method [26] followed by ageing the resulting sol for 2 months which led to mean particle size of 55 ± 6 nm, as measured by dynamic light scattering (DLS).…”

Section: Sample Preparationmentioning

confidence: 99%

“…For preparation of a model Al 30 -mer solution, the Al 13 -mer solution prepared at room temperature at h ∼ 2.40 was thermally aged at 85 • C for 48 h as described previously [26,27]. The sol of aluminium hydroxide was prepared at room temperature by adjusting the hydrolysis ratio of the stock solution of AlCl 3 to h ∼ 2.85 also using the static anion exchange method [26] followed by ageing the resulting sol for 2 months which led to mean particle size of 55 ± 6 nm, as measured by dynamic light scattering (DLS). Summary of the data on the model solutions containing four distinct Al species is given in Table 1.…”

Section: Sample Preparationmentioning

confidence: 99%

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A multi-technique study of the effect of aqueous aluminium speciation on hydrolytic gelation of aluminium (oxy)hydroxide

Fournier

Shafran

Perry

2009

Journal of Colloid and Interface Science

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“…The research contents concerned on the preparing methods and mechanism, structural characteristics, chemical property, etc. [23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

On the acid–base stability of Keggin Al13 and Al30 polymers in polyaluminum coagulants

et al. 2009

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The acid-base stabilities of Al 13 and Al 30 in polyaluminum coagulants during aging and after dosing into water were studied systematically using batch and flowthrough acid-base titration experiments. The acid decomposition rates of both Al 13 and Al 30 increase rapidly with the decrease in solution pH. The acid decompositions of Al 13 and Al 30 with respect to H ? concentration are composed of two parallel first-order and second-order reactions, and the reaction orders are 1.169 and 1.005, respectively. The acid decomposition rates of Al 13 and Al 30 increase slightly when the temperature increases from 20 to ca. 35°C, but decrease when the temperature increases further. Al 30 is more stable than Al 13 in acidic solution, and the stability difference increases as the pH decreases. Al 30 is more possible to become the dominant species in polyaluminum coagulants than Al 13 . The acid catalyzed decomposition and followed by recrystallization to form bayerite is one of the main processes that are responsible for the decrease of Al 13

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The static anion exchange method for generation of high purity aluminium polyoxocations and monodisperse aluminium hydroxide nanoparticles

Cited by 27 publications

References 41 publications

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

A multi-technique study of the effect of aqueous aluminium speciation on hydrolytic gelation of aluminium (oxy)hydroxide

On the acid–base stability of Keggin Al13 and Al30 polymers in polyaluminum coagulants

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