scholarly journals Influence of organic cations sorption on the point of zero charge of natural zeolite

2009 ◽  
Vol 63 (4) ◽  
pp. 325-330 ◽  
Author(s):  
Milan Kragovic ◽  
Aleksandra Dakovic ◽  
Sonja Milicevic ◽  
Zivko Sekulic ◽  
Slobodan Milonjic
Keyword(s):  
Ion Exchange ◽  
Natural Zeolite ◽  
Point Of Zero Charge ◽  
Organic Cations ◽  
Ammonium Ions ◽  
Inorganic Cations ◽  
Ph Values ◽  
Zero Charge ◽  
Basic Characteristics

In this paper, the results of the surface modification of natural zeolite with different amounts (2, 5 and 10 mmol M+/100g) of octadecyldimethylbenzyl ammonium ions (ODMBA) are presented. The obtained organozeolites were denoted as OZ-2, OZ-5 and OZ-10. The degree of ion exchange was followed by determination of amounts of inorganic cations released from zeolite. Results confirmed that reaction between ODMBA and starting zeolite has occurred via ion exchange mechanism. The obtained value for point of zero charge, pHpzc, of natural zeolite was 6.8?0.1, while for OZ-2, OZ-5 and OZ-10 pHpzc was 7.0?0.1. Below the pHpzc, the surfaces of materials are positive while at pH values higher than pHpzc their surfaces are negative. Compared to the pHpzc of natural zeolite, no significant differences in pHpzc was observed for all three organozeolites indicating that obtained products have similar functional groups with similar acid and basic characteristics as starting zeolite. The pHpzc was not dependent on the amount of ODMBA ions at the zeolitic surface and the value of pHpzc for all investigated sorbents is the same for all three electrolyte concentrations indicating that the pHpzc of each material is independent of the ionic strength of KNO3.

scholarly journals Determination of Point of Zero Charge (PZC) of Concrete Particles Adsorbents

2021 ◽  
Vol 1184 (1) ◽  
pp. 012004
Author(s):  
Ebtehal A. Al-Maliky ◽  
Hatem A. Gzar ◽  
Mohammed G. Al-Azawy
Keyword(s):  
Point Of Zero Charge ◽  
Zero Charge

scholarly journals Adsorption studies of Mo and Vonto ferrihydrite

2008 ◽  
Vol 72 (1) ◽  
pp. 385-388 ◽  
Author(s):  
L. Brinza ◽  
L. G. Benning ◽  
P. J. Statham
Keyword(s):  
Binary System ◽  
Binding Sites ◽  
Point Of Zero Charge ◽  
High Uptake ◽  
Adsorption Efficiency ◽  
Adsorption Studies ◽  
Ph Values ◽  
Zero Charge ◽  
Kinetics Of

AbstractIn this paper, the kinetics of Mo and V (100 μM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 μM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V showed high uptake efficiencies even at pH 9 (60% efficiency). The results from the bi-sorbate experiments (Mo-P and V-P) showed that at pH 7, P out-competed (97%) Mo for binding sites on FHY, while in the V-P binary system only ∼44% of the binding sites are occupied by P with the remaining sites being occupied by V.

scholarly journals Determination of the Point of Zero Charge pH of Borosilicate Glass Surface Using Capillary Imbibition Method

2017 ◽  
Vol 9 (3) ◽  
pp. 67 ◽  
Author(s):  
Mumuni Amadu ◽  
Adango Miadonye
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Borosilicate Glass ◽  
Present Method ◽  
Interfacial Free Energy ◽  
Point Of Zero Charge ◽  
Oxide Surface ◽  
Colloid Chemistry ◽  
Zero Charge

The point of zero charge pH of an oxide surface is a fundamental surface chemistry property or solids or metal oxides that determine the nature of interaction at the solid-aqueous solution interface. In colloid chemistry this physical parameter controls the evolution of the electric double layer as well as adsorption and desorption processes.In colloid chemistry a number of methods have been used for the determination of the point of zero charge pH of an oxide surface. This ranges from titrimetric to radiation chemistry approach that deals with scanning electron microscopy.In this study, the direct effect of aqueous solution acidity on the solid-liquid interfacial free energy and the consequence of this effect on spontaneous imbibition of aqueous solution into borosilicate glass have been exploited for the determination of the point of zero charge pH of this type of glass. What is new in this method is that while the traditional titration method relies on neutralization of surface charges, the present method relies on interfacial free energy changes due to aqueous solution pH changes and the effect of this on the wettability of borosilcate glass surface. Result of point of zero charge pH obtained from the present method has been compared with those obtained using traditional methods. The comparison shows close agreements and this proves the technique used in the present work as a novel method for the determination of the point of zero charge pH of oxide surfaces.

Influence of Pulp pH on Flotation of Fluorite and Calcite

2012 ◽  
Vol 616-618 ◽  
pp. 614-618
Author(s):  
Wen Juan Zhao ◽  
Dian Wen Liu ◽  
Hong Shuai Li ◽  
Qi Cheng Feng ◽  
Guo Yin Xu ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Fatty Acid ◽  
Significant Role ◽  
Ph Value ◽  
Froth Flotation ◽  
Point Of Zero Charge ◽  
Zeta Potentials ◽  
Ph Values ◽  
Zero Charge ◽  
Optimum Ph

Pulp pH value plays a significant role in the froth flotation. Especially in the flotation of fluorite, the performance of flotation will be affected greatly by pulp pH. MO, a new kind of modified fatty acid was used as collector, and H2SO4 and Na2CO3 were used to regulate pulp pH in the experiment. The mechanism of influence of pulp pH on flotation of fluorite and calcite was investigated by such parameters as fluorite recovery, zeta potentials and the infrared spectroscopy about minerals at different pulp pH values. As is shown in the results, the point of zero charge(PZC) of fluorite is pH=9.5 and the PZC of calcite is pH=8.5. The optimum pulp pH of the flotation of fluorite and calcite is determined as 9.5~10 and 8~9 respectively. pH value should be controlled above 9 to depress calcite. Finally, 9.5~10 was determined as the optimum pH to float the fluorite from the calcium-containing fluorite ores.

Synthesis of Polyvanadates from Solutions

1996 ◽  
Vol 457 ◽  
Author(s):  
J. Livage ◽  
L. Bouhedja ◽  
C. Bonhomme ◽  
M. Henry
Keyword(s):  
Vanadium Oxide ◽  
Weak Interactions ◽  
Hollow Spheres ◽  
Hybrid Nanocomposites ◽  
Point Of Zero Charge ◽  
Organic Cations ◽  
Zero Charge ◽  
Counter Ions ◽  
Wide Range ◽  
Vanadium Oxide Gels

ABSTRACTA wide range of polyvanadates can be synthesized from aqueous solutions. Vanadium oxide gels V2O5nH2O are formed around the point of zero charge (pH≈2). They exhibit a ribbon-like structure. Weak interactions between these ribbons lead to the formation of mesophases in which vanadium oxide gels or sols behave as nematic liquid crystals. Organic species can be easily intercalated between these oxide ribbons leading to the formation of hybrid nanocomposites made of alternative layers of organic and inorganic components. Hybrid nanophases can also be formed above the point of zero charge, in the presence of large organic ions such as [N(CH3)4]+. They often exhibit layered structures in which organic cations lie between the polyvanadate planes. Cluster shell polyvanadates have been obtained in the presence of anions such as Cl− or I−. They are made of negatively charged polyvanadate hollow spheres in which the anion is encapsulated. Organic cations then behave as counter ions for the formation of the crystal network.

DETERMINATION OF POINTS OF ZERO CHARGE OF NATURAL AND TREATED ADSORBENTS

2007 ◽  
Vol 14 (03) ◽  
pp. 461-469 ◽  
Author(s):  
M. NASIRUDDIN KHAN ◽  
ANILA SARWAR
Keyword(s):  
Particle Size ◽  
Ph Dependence ◽  
Exchange Capacity ◽  
Point Of Zero Charge ◽  
Surface Charges ◽  
Ion Exchange Capacity ◽  
Zero Charge ◽  
Wide Range ◽  
Acid And Base

Although particle size and its measurement are intuitively familiar to particle technologists, the concept of point of zero charge (pzc) is less widely understood and applied. This is unfortunate since it is at least as fundamentally important as particle size in determining the behavior of particulate materials, especially those with sizes in the colloidal range below a micrometer. pzc is related to the charge on the surface of the particle and strongly depends on the pH of the material; so it influences a wide range of properties of colloidal materials, such as their stability, interaction with electrolytes, suspension rheology, and ion exchange capacity. The pH dependence of surface charges was quantified for four different adsorbent–aqueous solution interfaces. The points of zero charge were determined for activated charcoal, granite sand, lakhra coal, and ground corn cob materials using three methods: (1) the pH drift method, measuring pH where the adsorbent behaves as a neutral specie; (2) potentiometric titration, measuring the adsorption of H + and OH - on surfaces in solutions of varying ionic strengths; (3) direct assessment of the surface charge via nonspecific ion adsorption as a function of pH. The intrinsic acidity constants for acid and base equilibria, [Formula: see text] and [Formula: see text], were also calculated. Lakhra coal was found to have the lowest pzc value among all other adsorbents studied owing to the presence of a large amount of humus material. The results were used to explain general connections among points of zero charges, cation exchange capacity, and base saturation % of adsorbents.

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