Neural Network Modelling for Prediction of Zeta Potential

The study is focused on monitoring the influence of selected parameters on the zeta potential values of titanium dioxide nanoparticles. The influence of pH, temperature, ionic strength, and mass content of titanium dioxide in the suspension was assessed. More than a thousand samples were measured by combining these variables. On the basis of results, the model of artificial neural network was proposed and tested. The authors have rich experiences with neural networks applications and this case shows that the neural network model works with a very high prediction success rate of zeta potential. Clearly, pH has the greatest effect on zeta potential values. The influence of other variables is not so significant. However, it can be said that increasing temperature results in an increase in the value of the zeta potential of titanium dioxide nanoparticles. The ionic force affects the zeta potential depending on the pH; in the vicinity of the isoelectric point, its effect is negligible. The effect of the mass content of titanium dioxide in the suspension is absolutely minor.

Kinetic pathways of water exchange in the first hydration shell of magnesium: Influence of water model and ionic force field

Water exchange between the first and second hydration shell is essential for the role of Mg2+ in biochemical processes. In order to provide microscopic insights into the exchange mechanism, we resolve the exchange pathways by all-atom molecular dynamics simulations and transition path sampling. Since the exchange kinetics relies on the choice of the water model and the ionic force field, we systematically investigate the influence of seven different polarizable and non-polarizable water and three different Mg2+ models. In all cases, water exchange can occur either via an indirect or direct mechanism (exchanging molecules occupy different/same position on water octahedron). In addition, the results reveal a crossover from an interchange dissociative (Id) to an associative (Ia) reaction mechanism dependent on the range of the Mg2+-water interaction potential of the respective force field. Standard non-polarizable force fields follow the Id mechanism in agreement with experimental results. By contrast, polarizable and long-ranged non-polarizable force fields follow the Ia mechanism. Our results provide a comprehensive view on the influence of the water model and ionic force field on the exchange dynamics and the foundation to assess the choice of the force field in biomolecular simulations.

Theoretical Description for Sunset Yellow Electrochemical Determination in Food, Assisted by Poly(3,4-ethylenedioxypyrrole) – VO(OH) Composite

In this work, the possibility for sunset yellow electrochemical determination, assisted by the composite of VO(OH) with conducting polymer, has been evaluated theoretically. The correspondent balance equation model of three variables has been developed and analyzed by means of linear stability theory and bifurcation analysis. The oscillatory and monotonic instabilities are shown to be manifested more probably than for the simplest case. The double electric layer (DEL) is influenced by the cyclic changes of ionic force observed during ionic forms' chemical transformation. Nevertheless, the CP – VO(OH) composite may be considered an efficient electrode modifier for yellow sunset determination.

Low salinity effects on oil recovery performance: underlying physical mechanisms and practical assessment

This paper is a tentative synthesis of the main knowledge and experience gained from recent studies and application of Low Salinity Water Injection (LSWI) in carbonate and clayey silico-clastic rocks. A physical model based on ionic force is presented to explain the so-called Dual Layer Expansion (DLE) mechanism often invoked to account for the Low Salinity Effects (LSE) on rock wettability and oil recovery. The role played by the Multi Ion Exchange (MIE) mechanism is clarified, at least for clayey rocks. Eventually, the proposed physical analysis shows the complementary roles that injected brine concentration and composition can play on waterflood recovery efficiency depending on the Crude Oil Brine Rock (COBR) system under consideration. To account for the diversity of COBR systems, a straightforward modelling methodology is then proposed to simulate laboratory LSWI tests on a case-by-case basis and infer the actual evolution of residual oil saturation with brine concentration and/or composition. The simulation involves a wettability driver that may be either the global salinity or the square root of ionic force. The analysis of published results actually shows that the latter predicts low salinity effects on residual oil saturation better than the former. Hopefully, this paper contributes to the understanding of the DLE and MIE mechanisms induced by a smart water injection and provides a simple and robust methodology to simulate the reference coreflood experiments that remain necessary to assess and optimize LSWI.

APPLICATION OF THE FLOCCULATION PROCESS FOR THE MUNICIPAL SEWAGE SLUDGE TREATMENT

<p>All municipal sewage treatments using classic treatment chain create an amount of organic sludge. The stabilization/neutralization of them is essential before any conditioning or reuse. For agronomical recycling or energy-giving optimization, the sludge needs to correspond to some standards. That's why, it exist several treatment of stabilization, packaging and water extraction of sludge. This study deals with sludge chemical conditioning by flocculation process. In the first hand, the flocculation process allows to break up colloidal aversion between particles in sludge. This process is possible by charge neutralization thanks to synthetic or natural organic flocculation which is often cationic since the ionic force of sludge particle usually is negative and the flocculants can be used with lowest dose than common coagulant like aluminum sulfate or ferric chloride. Thanks to laboratory experiments by analysis of several doses of synthesis cationic flocculants, it has been possible to get performance on total suspended solids (TSS), by spectrophotometry measurement and consistency of sludge cake. Graphical analyses allow making comparison between some organic cationic flocculants and select the best one for this type of sludge and the kind of treatment used. The aim is to improve quality of sludge, quantity of filtrated volume, and quality of water.</p>

Sorption of Richlokain on Polycarboxylic Acid Gels

The sorption immobilization of richlokain on gels of polyacrylic acid (PAAG) or polymethacrylic acid (PMAAG) has been studied. By a number of methods – equilibrium swelling, potentiometry, IR-spectroscopy, and sorption it has been shown that binding of richlokain with these gels leads to the complex formation owing to the electrostatic interaction, which is stabilised by the hydrophobic and hydrogen bonds. Effect of an ionic force, reagent concentration, cross-link degree, hydrophobic nature of gels, and pH of solutions on the sorption process has been studied.

Ion-Exchange Separation and Concentration of Ions of Rare-Earth Elements on Fibrous Sorbents

Acid-base properties and selectivity of absorption such ions as REE (Eu3+, Gd3+, Nd3+, Yb3+) from solutions with various ionic force by the fibrous ampholytes PAN-FOSPAN and PAN-IDUC are investigated. PAN-FOSPAN shows the greatest selectivity to ions of REE. This fact can be used for division and the subsequent definition of ions. PAN-IDUC as a high selective fibrous sorbent after alkaline treatment is perspective one for absorption of the REE sum.