Modelling and Optimizing the Removal of Methylene Blue by a Mixture of Titaniferous Sand and Attapulgite Using Complete Factorial Design

This paper focuses on the removal of methylene blue by adsorption using a mixture of titaniferous sand and attapulgite. The different adsorbents were characterized by X-ray fluorescence spectroscopy and their different parameters such as pH, zero charge potential, and specific surface area were determined. The experiments performed were optimized and modeled by a full 2-level and 4-factor design. The four factors are the ratio of titaniferous sand and attapulgite, the concentration of methylene blue, pH, and time. These vary from 4 to 19, 20 to 100 mg/L, 2 to 9, and 30 to 150 min respectively. The study of the effects of the different factors showed that the effect of methylene blue concentration and pH significantly influence the adsorption capacity and removal efficiency of the dye. The optimum parameters (adsorbent ratio, adsorbate concentration, pH and time) obtained for the adsorption capacity through the desirability function are: 19, 100mg/L, 9 and 150min. Those obtained for the yield are: 4, 100mg/L, 9, 150min. The pseudo second order adsorption kinetics gave an equilibrium adsorption capacity qe (calculated) = 7.6863 mg/g which is almost equal to that obtained experimentally qe (exp) = 7.3562 mg/g. This shows that the pseudo second order kinetic model is the adequate mathematical model to describe the methylene blue adsorption phenomenon on the mixture of titaniferous sand and attapulgite. The thermodynamic study showed that the methylene blue adsorption reaction is exothermic, non-spontaneous, and the degree of disorder of the particles at the adsorbing surface decreases.

Development and Characterization of Activated Carbon from Olive Pomace: Experimental Design, Kinetic and Equilibrium Studies in Nimesulide Adsorption

The lack of adequate treatment for the removal of pollutants from domestic, hospital and industrial effluents has caused great environmental concern. Therefore, there is a need to develop materials that have the capacity to treat these effluents. This work aims to develop and characterize an activated charcoal from olive pomace, which is an agro-industrial residue, for adsorption of Nimesulide in liquid effluent and to evaluate the adsorption kinetics and equilibrium using experimental design. The raw material was oven dried at 105 °C for 24 h, ground, chemically activated in a ratio of 1:0.8:0.2 of olive pomace, zinc chloride and calcium hydroxide and thermally activated by pyrolysis in a reactor of stainless steel at 550 °C for 30 min. The activated carbon was characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) method, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), density and zero charge potential analysis. The surface area obtained was 650.9 m2 g−1. The kinetic and isothermal mathematical models that best described the adsorption were PSO and Freundlich and the highest adsorption capacity obtained was 353.27 mg g−1. The results obtained showed the good performance of activated carbon produced from olive pomace as an adsorbent material and demonstrated great potential for removing emerging contaminants such as Nimesulide.

Grain Boundary Conductance Mechanisms of Ultra-fine Grained CeO2/BaCeO3 Based Electrolytes Fabricated by a Two-step Sintering Process

Aiming to clarify the grain boundary conductance mechanism of CeO2/BaCeO3 based electrolytes suitable for solid oxide fuel cells (SOFCs), Sm, Bi co-doping CeO2/BaCeO3 (80 wt.% Ce0.8Sm0.1Bi0.1O2-δ - 20 wt.% BaCe0.8Sm0.1Bi0.1O3-δ, BiSDC-BCSBi) electrolytes with ultra-fine grained (110-220 nm) and micron (1-1.8 μm) structures were prepared by the two step sintering and conventional sintering method, respectively. Both electrolytes have pure phases corresponding to CeO2 and BaCeO3 without other purities. In the ultra-fine grained structure, apparent grain boundary conductivities measured at 350 oC and 400 oC are 1-2 orders of magnitude higher than micron structures, thus resulting in dramatically enhanced electrical performances. This grain boundary effect can be attributed to two aspects. One is the decrease of space charge potential Δφ(0) (0.165 V for ultrafine-fine grained ones, 0.396 V for micron ones). The other is the dilution of impurities (the impurity blocking term ω/dg is 0.94 for ultrafine-fine grained ones, and 0.53 for micron ones). In the ultra-fine grained electrolytes, no extra electronic conduction is introduced, and the ion migration number of O2- is higher than that of H+. Finally, the ultra-fine grained BiSDC-BCSBi electrolytes maintain a good long-term stability in the operating condition of SOFCs at 600 oC for 100 h.

Effect on Current Density on Zero Charge Corrosion Protection of Pure Mg in 3.5% NaCl Solution

The cathodic protection uses two-electrode polarization, which requires large currents and substantial voltages. Efforts are being made to identify possibilities for improvements by developing zero-charge corrosion protection techniques. Studies were performed to determine the zero-charges potential effect by analyzing corrosion signs on reactive metal samples such as pure Mg. Mg samples were fed by current/ voltage pulses for 120 hours, with specified pulse parameters and varied Ecorr- offsets, ranging from +2 to -218 mV. The volumetric hydrogen gas collection technique is used to determine the hydrogen evolution rate. Surface observation is carried out by stereomicroscope to determine the presence of corrosion signs on the sample surface. Overall, all current densities and hydrogen evolution rates had very low readings on the studied Ecor offset parameters. Mg samples fed with pulses at -1800 and -1900 mV vs SCE revealed zero charge potential effects since their surface was clean and showed no indications of corrosion even after being exposed to the corrosive solution for 120 hours. Thus, corrosion protection is successfully done and meets the Epzc condition.

Wastewater Fines Influence the Adsorption Behavior of Pollutants onto Microplastics

Millions of tons of microplastics (MPs) enter the wastewater collection systems every day and interact with raw sewage. In addition to MPs, varieties of organic and inorganic fines from urban effluents release into the sewer system and provide suitable surfaces for adsorption. To better understand the quantitative assessment of MPs sorption in wastewater and the role of fines, batch reactor experiments were performed using synthetic wastewater solutions containing organic, inorganic, and mixed organic–inorganic fines, and the results compared to a solution without fines. The MPs were two types of clean polypropylene (PP) particles, isotactic (iPP) and atactic (aPP). The results showed in all applied solutions the adsorption of pollutants was higher for the aPP averaging 1.3 mg/g compared with 0.5 mg/g for iPP, indicating that the adsorption varies with the type of polymer and surface properties. Further experiments also revealed a decrease in the sorption values of MPs for solutions containing inorganic fines, measured as the partition coefficient (Kd) and adsorbed concentration at equilibrium (qe). The result of the measured reference conductivity (к25) of the solutions for the same tests showed similar trends indicating that the magnitude of pollution adsorption onto MPs surfaces is controlled by the surface charge potential of the fine particles. The relationship between the qualitative assessments of ion removal, measured in terms of к25, and their quantitative assessment of adsorption values in terms of Kd in several identical tests, verifying that the conductivity of the solution was modified after adsorption of wastewater constituents onto the MPs.

Improvement of Foaming Characteristics and Stability of Sterilized Liquid Egg with Egg White Hydrolysate (EWH)

A pasteurized liquid egg leads to protein denaturation and degradation of processing properties, whereas non-pasteurized eggs may have food safety risks. If the negative impact of the pasteurization process on liquid eggs can be reduced, for example, the loss of stability and foamability, companies will be willing to purchase pasteurized eggs, thereby reducing food safety risks. Therefore, in this study, specific hydrolyzation conditions were used to produce egg white hydrolysate (EWH) with a lower molecular mass of amino acid and peptide fragments, and the effects of various concentration of EWH refilling on pasteurized liquid egg properties were investigated. The results showed that up to 30.1% of EWH was hydrolyzed by protease A and papain. Adding 1% (w/w) EWH can improve the negative charge potential value, surface tension, viscosity, and weight loss analysis of the sample. In addition, the cake structure and the appearance was acceptable to consumers. Therefore, to ensure its efficient use in the baking industry and considering the cost and stability, 1% (w/w) EWH was chosen as the best concentration.

KARPOVSKY PERIOD” THE SCIENTIFIC ACTIVITY OF ACADEMICIAN A. N. FRUMKIN ( BASED ON THE MATERIALS OF THE R-16 FUND OF THE RUSSIAN STATE ARCHIVE IN SAMARA)

This article attempts to reveal, based on archival materials, the main directions of research activities of the outstanding scientist A. N. Frumkin (1895-1976) during His work at the L. ya.Karpov research Institute. It was at this time, from 1992 to 1946, that A. N. Frumkin worked his way up from the head of the Department of surface phenomena to the Deputy Director of the Institute for scientific work. The main directions of his research interests in the field of physical chemistry are shown. He paid special attention to the study of the surface properties of metals. In the circle of his interests included the study of adsorption phenomena. The "Frumkin isotherm" was developed, and the fundamental position about the zero charge potential was proved. A. N. Frumkin has repeatedly made scientific reports in leading scientific institutions in Germany, the USA, the Netherlands, and others. A. N. Frumkin's contribution to the development of electrochemistry, which is of great importance for both science and practice, was appreciated. His scientific work was highly appreciated by the government. Thus, it was during the "Karpov period" of A. N. Frumkin's scientific activity that the most important fundamental research was carried out, which for many years determined the directions of development of physical and chemical science, and an authoritative scientific school of electrochemistry was formed.

Plasma Diagnostic Methods: Test Charge Response in Lorentzian Dusty Plasmas

Different plasma diagnostic methods are briefly discussed, and the framework of a test charge technique is effectively used as diagnostic tool for investigating interaction potentials in Lorentzian plasma, whose constituents are the superthermal electrons and ions with negatively charged dust grains. Applying the space-time Fourier transformations to the linearized coupled Vlasov-Poisson equations, a test charge potential is derived with a modified response function due to energetic ions and electrons. For a test charge moving much slower than the dust-thermal speed, there appears a short-range Debye-Hückel (DH) potential decaying exponentially with distance and a long-range far-field (FF) potential as the inverse cube of the distance from test charge. The FF potentials exhibit more localized shielding curves for low-Kappas, and smaller effective shielding length is observed in dusty plasma compared to electron-ion plasma. However, a wakefield (WF) potential is formed behind the test charge when it resonates with dust-acoustic oscillations, whereas a fast moving test charge leads to the Coulomb potential having no shielding around. It is revealed that superthermality and plasma parameters significantly alter the DH, FF, and WF potentials in space plasmas of Saturn’s E-ring, where power-law distributions can be used for energetic electrons and ions in contrast to Maxwellian dust grains.