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.

Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

1992 ◽  
Vol 57 (9) ◽  
pp. 1905-1914
Author(s):  
Miroslav Bleha ◽  
Věra Šumberová
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Total Content ◽  
Distribution Coefficients ◽  
Exchange Capacity ◽  
Ion Exchange Membranes ◽  
Ion Exchange Capacity ◽  
Equilibrium Sorption ◽  
Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

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

Determination of the ion-exchange capacity of anion-selective membranes

2014 ◽  
Vol 39 (10) ◽  
pp. 5054-5062 ◽  
Author(s):  
F. Karas ◽  
J. Hnát ◽  
M. Paidar ◽  
J. Schauer ◽  
K. Bouzek
Keyword(s):  
Ion Exchange ◽  
Exchange Capacity ◽  
Ion Exchange Capacity ◽  
Selective Membranes

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.

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.

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