Determination Of Electrokinetic Potential Research Articles

КРИСТАЛЛОХИМИЧЕСКИЕ АСПЕКТЫ ОЦЕНКИ ЭНЕРГИИ ВЗАИМОДЕЙСТВИЯ ЧАСТИЦ ГЛИНИСТЫХ МИНЕРАЛОВ

The goal of the paper is to analyze the changes in mineral crystal lattice under acid activation. Methods. Clay from the Slyudyanka deposit is the material under investigation. The methods used in the study include x-ray phase analysis using Bruker D8 Advance diffractometer. The diffractogram is recorded using the EVA program installed on a PC in combination with the diffractometer. The quantitative composition is calculated using the Topas 3.0 program. The study also uses the methods of scanning microscopy of the oriented sample, titrimetric analysis methods (the methods of neutralization and complexometry 0; conductivity measurement (determination of solution electrical conductivity); potentiometric measurements (determination of electrokinetic potential at electrophoresis); sedimentation analysis in gravitational and centrifugal fields. Modern databases and Excel are used for thermodynamic calculations. Results. Crystallochemical analysis of mineral structure and thermodynamic assessment of process spontaneous flow conditions allowed to explain the nature of the potential curve after acid activation of the clay from the Slyudyanka deposit. The extreme nature of this dependence is associated with the changes in the field of force on the surface of particles as a result of the flow of the complex of physico-chemical interactions, the most important of which are interactions of backbone ions with the components of environment. In its turn, the changes in the interaction energy of clay particle weight calculated by the results of colloid-chemical studies allow to analyze the processes occurring in the crystal lattice of clay under acid activation. Experimental data confirm the similarity of some patterns of acid activation of clay minerals associated to the fact that the process is accompanied by the washout of ions from the crystal lattice skeleton and formation of structure defects. The defects of crystal lattice causing the disturbance of its regularity, the transition of surface silica in amorphous state provide the change in both system dispersion and porosity of clay samples. Conclusions. It is more preferable to use the acid activation for the production of mineral sorbents with developed porosity when minerals with an expanding structural cell are used as a source material.

Comparison of glow argon plasma-induced surface changes of thermoplastic polymers

Modification of high-density polyethylene (PE), polytetrafluoroethylene (PTFE), polystyrene (PS), polyethyleneterephthalate (PET) and polypropylene (PP) by Ar plasma was studied. The amount of the ablated material was determined by gravimetry. Wettability of polymers after the plasma treatment was determined from the contact angle measurement. The changes in the surface morphology of polymers were observed using atomic force microscopy (AFM). Chemical structure of modified polymers was characterized by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Surface changes were also studied by the determination of electrokinetic potential ( ζ-potential). It was found that under the plasma treatment the polymers are ablated and their surface morphology and roughness are changed dramatically. XPS measurements indicate an oxidation of the polymer surface. The plasma treatment results in a dramatic increase of the ζ-potential. EPR data show different radical amount present on the treated surface of all polymers. Most significant changes due to the degradation of polymer chains are observed on PTFE.

Determination of electrokinetic potential when coal is wetted by solutions

Determination of electrokinetic potential when coal is wetted by solutions

Stability of High Polymer Latexes and Their Electrokinetic Potentials

Abstract The stability of colloid systems is a central problem of colloid chemistry. Therefore, many papers have been devoted to studies of coagulation and to the development of criteria of stability for colloid systems. For a long time a prevalent opinion was that the stability of colloidal particles could be explained by the fact that like charge on the particles prevents agglomeration of particles which collide due to Brownian motion. This opinion was first expressed by Hardy and later developed by Powis, Ellis and a number of other scientists. According to this point of view, electrokinetic potential (ζ potential) is the measure of stability. However, after detailed investigation of coagulation phenomena and accumulation of experimental data the correctness of this point of view became less obvious, and the statement that the electrokinetic potential is a criterion of stability of colloidal systems underwent vigorous criticism. The reasons for the measured values of electrokinetic potentials not always corresponding to the stability of certain systems are as follows: firstly, the exact determination of electrokinetic potential is work of great experimental difficulty which seems to some investigators insuperable. Some of these difficulties are (1) the necessity of performing the mocroelectrophoresis in a medium which has the same characteristics as the colloidal system under investigation, (2) the influence on electrophoresis of the simultaneously occurring electrolysis (3) the wash out of the boundary line between the solution and the colloidal system, and a number of others. In the case of microelectrophoresis, these difficulties are replaced by others, which are not less difficult to overcome.