The zero point of charge of silica—alumina oxide suspensions

Schwarz, John H.; Driscoll, Charles T.; Bhanot, A.K

doi:10.1016/0021-9797(84)90274-1

Cited by 211 publications

(113 citation statements)

References 4 publications

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“…There was a decrease in the PZSE of the allophanes with decreasing A1/Si ratio. The decrease was not linear with respect to A1/Si ratio, as predicted by Parks (1967) for mixed oxide systems and as found by Schwarz et al (1984) for heat-treated silica-alumina oxide suspensions.…”

Section: Resultsmentioning

confidence: 49%

Adsorption of Cations on Imogolite and their Effect on Surface Charge Characteristics

Harsh

Traina

Boyle

et al. 1992

Clays and clay miner.

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Abstract--Noncrystalline aluminosilicates termed allophane and imogolite are common constituents of spodosols, soils derived from volcanic ash, and many inceptisols. The surface charge characteristics of their synthetic analogues may be used to better understand their ion retention properties. In this study, we determined the point of zero salt effect (PZSE) by potentiometric titration of allophanes with A1/Si ratios of 1.12, 1.52, and 2.04 and of imogolite with an A1/Si ratio of 2.02. We also used microelectrophoresis to determine the point of zero charge (PZC) at the particle shear plane for the same materials in C1 solutions of Li, Na, Cs, and tetramethyl ammonium. The PZSE decreased with decreasing A1/Si ratio for the allophanes, but the imogolite PZSE was much lower than that of the allophane with 2.04 A1/Si. The PZC was always higher than the PZSE of the same material, especially for imogolite. The results are best explained if cations reside within the hollow tubes ofimogolite. This conclusion is supported by a fluorescence study that showed that only quenchers smaller than the inner diameter of the imogolite tube could fully quench Ce-imogolite.

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Section: Resultsmentioning

confidence: 49%

Adsorption of Cations on Imogolite and their Effect on Surface Charge Characteristics

Harsh

Traina

Boyle

et al. 1992

Clays and clay miner.

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“…To determine the pH zpc , the potentiometric titration method was used. 9 The cation exchange capacity (CEC) of the Na-Mte and PILC was measured by MgCl 2 saturation and subsequent displacement by CaCl 2 .…”

Section: ±6mentioning

confidence: 99%

Sorption of tannic acid on zirconium pillared clay

Vinod

Anirudhan

2001

J of Chemical Tech & Biotech

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Zirconium pillared clay (PILC) was prepared using montmorillonite as the base clay. Adsorption of tannic acid (tannin) was studied by a batch equilibrium technique, as a function of adsorbate concentration, temperature, pH, agitation speed, particle size of the adsorbent and ionic strength. The process of uptake is governed by diffusion controlled ®rst-order reversible rate kinetics. The higher uptake for the pH range 4.0±6.0 was attributed to external hydrogen bonding between phenolic-OH groups of tannin molecules and the hydrogen bonding sites on the clay. The removal of tannin by adsorption was found to be >99.0% depending on the initial concentration in the pH range of 4.0±6.0. The process involves both ®lm and pore diffusion to different extents. The effects of solute concentration, temperature, agitation speed and particle size on the diffusion rate were investigated. Tannin uptake was found to increase with ionic strength due to the compression of diffuse double layers. The applicability of Langmuir and Freundlich isotherm models has been tested. The maximum adsorption capacity of PILC was found to be 45.8 mmol g À1 of clay and the af®nity constant is 2.9 Â 10 À2 dm 3 mmol À1 at 30°C. Thermodynamic parameters such as DG°,DH°and DS°were calculated to predict the nature of adsorption. The isosteric enthalpies of adsorption were also determined and found to decrease with increasing surface coverage. Regeneration with hot water (60°C) has been investigated for several cycles with a view to recovering the adsorbed tannin and also restoring the sorbent to its original state.

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“…The specific surface area of CP and PGCP-COOH was measured by BET N 2 adsorption using Quantasorb surface area analyzer (Qs/7). A potentiometric 17 method was used to determine the point of zero charge (pH pzc ). The cation exchange capacity (CEC) of the adsorbents was determined by NaNO 3 saturation method using a column operation.…”

Section: Equipment and Methods Of Characterizationmentioning

confidence: 99%

“…The surface charge density s o was determined by potentiometric method 17 using the following equation…”

Section: Sorbent Characterizationmentioning

confidence: 99%

Synthesis and characterization of polyacrylamide‐grafted coconut coir pith having carboxylate functional group and adsorption ability for heavy metal ions

Anirudhan

Unnithan

Divya

et al. 2007

J of Applied Polymer Sci

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The present investigation was undertaken to evaluate the effectiveness of a new adsorbent prepared from coconut coir pith (CP), a coir industry-based lignocellulosic residue in removing metal ions from aqueous solutions. The adsorbent (PGCP-COOH) having a carboxylate functional group at the chain end was prepared by grafting polyacrylamide onto CP using potassium peroxydisulphate as an initiator and in the presence of N,N 0 -methylenebisacrylamide as a crosslinking agent. The adsorbent was characterized by infrared (IR) spectroscopy, thermogravimetry (TG), X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and potentiometric titration. The adsorbent exhibits very high adsorption potential for the removal of Pb(II), Hg(II), and Cd(II) ions from aqueous solutions. The optimum pH range for metal ion removal was found to be 6.0-8.0. The adsorption process follows a pseudo-second-order kinetic model. The adsorption capacities for Hg(II), Pb(II), and Cd(II) calculated using the Langmuir isotherm equation were 254.52, 189.49, and 63.72 mg g À1 , respectively. Adsorption isotherm experiments were also conducted for comparison with a commercial carboxylate form cation exchanger. Different industry wastewater samples were treated by the PGCP-COOH to demonstrate its efficiency in removing heavy metals from wastewater. The reusability of the PGCP-COOH was also demonstrated using 0.2M HCl.

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The zero point of charge of silica—alumina oxide suspensions

Cited by 211 publications

References 4 publications

Adsorption of Cations on Imogolite and their Effect on Surface Charge Characteristics

Adsorption of Cations on Imogolite and their Effect on Surface Charge Characteristics

Sorption of tannic acid on zirconium pillared clay

Synthesis and characterization of polyacrylamide‐grafted coconut coir pith having carboxylate functional group and adsorption ability for heavy metal ions

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