Preparation and characterization of electrolytic alumina deposit on austenitic stainless steel

Conversion coating modified by alumina has been studied as a way for improving the resistance to thermal oxidation of an austenitic stainless steel. Conversion coating, characterized by a particular morphology and strong interfacial adhesion with the substrate, facilitate the electrochemical deposition of ceramic layers and enhance their adhesion to the substrate. The influence of the current density and treatment time on alumina deposit was studied using statistical experimental designs like Doehlert uniform shell design. After heating, coatings present a continuous composition gradient with refractory compounds at the surface. The behavior at high temperature (1000 8C) of the alumina coating was investigated. The presence of alumina increases the oxidation resistance of an austenitic stainless steel at 1000 8C. The morphology and the chemical composition of the deposit are analyzed. Results on the thermal stability of coating on austenitic stainless steel are presented

Adsorption and mobility of veterinary compounds on Moroccan soil; Case of Ivermectin

Ivermectin (IVR) is an antihelmitic and anti-parasitic substance used mainly in veterinary medicine worldwide. Its release in the environment could have a negative effect on living organisms and generate soil and groundwater pollution. The main objective of this work aimed at the study of the adsorption of IVR on soil from Gharb region in Morocco. Sorption tests were carried out according to conventional guideline by varying the mass of the adsorbate and the pH of the solution. Analysis was made by UV-visible spectrophotometer. Adsorption kinetics of IVR was rapid and equilibrium was reached within 20 minutes. The Freundlich and Langmuir isotherms models were compared and adsorption constants were calculated. Comparison between the two models showed that Freundlich model fitted best data while kinetic data fitted pseudo-second order. Thermodynamically, sorption process of IVR on the examined soils would be exothermic and controlled by physisorption Tests of mobility have shown strong adsorption of IVR in the soils tested After 7 batches of water percolated, less than 2% of the applied quantity has been detected

Supported TiO2 on Borosilicate Glass Plates for Efficient Photocatalytic Degradation of Fenamiphos

Supported titanium dioxide (TiO2) was investigated for the photodegradation of the insecticide fenamiphos in water. The photocatalyst was immobilised on borosilicate glass plates and the kinetics of degradation were studied in a stirred tank reactor under UV irradiation. Two types of TiO2, for example, Millennium PC500 (100% anatase) and Degussa P25 (80% anatase, 20% rutile), were used. Their activities have been based on the rates of insecticide disappearance. Experiments were investigated to evaluate the effect of pH and initial concentrations of fenamiphos as well as catalyst doses on the photocatalytic degradation of fenamiphos. Kinetic parameters were experimentally determined and an apparent first-order kinetic was observed. For photolysis process of fenamiphos, two photoproducts were identified and characterized using high performance liquid chromatography/mass spectrometry (HPLC/MS). The plausible mechanism of photolysis involved is the oxidation of sulfonamide group. In presence of photocatalyst TiO2, photodegradation was observed. Under identical conditions, Degussa P25 shows higher photocatalytic activity in regard to PC500 Millennium and complete degradation was observed after 180 min

DFT and Molecular docking study of natural molecules proposed for COVID-19 treatment

AbstractEmergence and spread of corona virus disease 2019 (COVID-19), caused by severe respiratory syndrome coronavirus, is considered a public health emergency threatening global health systems, as of June, 2020, It caused a cumulative total of 9,033,423 confirmed cases and more than 469,539 deaths across 215 countries, person to-person transmission has being identified as the route for spreading. So far, the lack of effective vaccines for the treatment or prevention of Covid-19 has further worsened the situation. In this context, the present study aims to assess whether naturally occurring components have an antiviral effect via a computational modeling approach. Density Functional theory (DFT) was performed to estimate the kinetic parameters, frontier molecular orbitals, molecular electrostatic potential as well as chemical reactivity descriptors of various ligands. The results revealed that Crocin and Digitoxigenin exhibited a potential applicant with the lowest resistance to electronic charge transfer with a chemical hardness of 2.19eV and 2.96eV respectively, as well as the lowest HOMO-LUMO difference. In addition to the DFT calculation, a docking simulation study was conducted on the SARS-CoV-2 base protease (PDB: 6LU7) to determine the binding affinity of ligands. The findings show that Crocin exhibits the lowest binding energy of -8.1 Kcal/mol and may be a good inhibitor of CoV-2-SARS compared to hydroxychloroquine and chloroquine, which have a binding affinity of -5.4 and -4.9 Kcal/mol, respectively. The high binding affinity of L3 was assigned to the existence of 14 hydrogen bonds connecting the ligand to the critical amino acid residues of the receptor

Physico-Chemical Characterization of Water and Soil of the M’nasra region in the Gharb plain (Northwest Morocco)

The aim of this work is to carry out an evaluation of the quality of agricultural soils and water in the irrigated area of the M’nsara region in the Gharb plain (Northwest Morocco) with the goal of describing the degree of degradation of natural resources and improve the sustainability of the environment and irrigated farming systems of the region through optimal management of these resources. Eighteen water and nineteen soil samples were collected based on existing soil and piezometric maps of the irrigated areas, distributed into 3 different zones: A, B, and C. Characterizations of the main parameters of soil and irrigation water quality were made. Irrigation water salinity varies between 0.5 and 1.3 dS/m. The irrigated soils from the groundwater have shown a secondary salinization superior to that of irrigated soils by the waters of the dam. Cultivated soils present a salinity that reaches 1.90 dS/m in some areas. The results show that 68.4% of the soil samples are poor to moderately poor in organic matter. The sodium adsorption ratio (SAR) shows a minimal risk to accumulate sodium in the soil with 16.7% is slightly alkaline. The soils are weakly to moderately basic and represent respectively 73.7 and 10.5 % of the study area. Potassium and available phosphorus have very low values in the majority of soils which will have a negative impact on the environment. The spatialization of these parameters was performed by the determinsitc method of inverse distance weighted (IDW). In order to delineate areas that are a priori subject to environmental degradation in order to understand the effect of agricultural intensification on the sustainability of natural resources, taking into account the type of management water irrigation in the arid region

Study of dependence between two types of most abundant natural clays in Bejaad province (Central Morocco) using a statistical approach

This work proposes the studying of characterization analysis of two natural Moroccan clays (RC and GC) in the same location from Bejaad (Province of Khouribga, Morocco) and to know the relationship dependence between them. The values obtained during the determination of a few parameters (density, pH, conductivity, dry matter - moisture content, organic matter-mineral matter) show that the two materials RC and GC studied have the same physical-chemical properties. The all characterization of the two clays was carried out by XRD, XRF, FTIR, SEM/EDX and TGA. The results obtained show that the two materials have very irregular and microporous structures, a heterogeneity of the pore forms and they are contain a mixture of Kaolinite, Illite, Quartz, Calcite, and Dolomite, with the presence of Hematite only in clay RC. On the other hand, The statistical approach applied to determine the dependence relationship between the two clays was based on two tests: Student's t-test (Comparison of two means for physical-chemical parameters) and Pearson's test (contingency table for XRF analysis) in order to prove that the two materials studied are the same chemical and physical-chemical characteristics

Adsorptive removal of Methylene Blue, from aqueous solution using Tea Waste as a Low-Cost indigenous biosorbent: Mechanism of Adsorption, Equilibrium Study, Kinetics and Isotherms

For the current investigation, extracted Tea-Waste has been employed without activation for Methylene Blue removing in aqueous media. The experiment has been operated under batch conditions. The impact of a variety of significant factors affecting adsorption process, of which, adsorbent particle size, adsorbent/adsorbate shaking time, adsorbent dose, pH medium as well as the adsorbate initial concentration on Methylene Blue removing were investigated for optimization of the process according to the One Factor At a Time approach. The laboratory results revealing that this process is both spontaneously occurring and feasible. It has been demonstrated that maximal removing percentage (R) of 78.92% was obtained at a maximal experimental adsorption capacity (Qm,exp) of 7.892 mg.g-1. Methylene Blue adsorptive to Tea-Waste was according to the (S-class) isotherm. The Pseudo-Second-Order Kinetic Model agrees perfectly with results, with an adsorption capacity calculated (Qe,cal) of 7.194 mg.g-1. Also, we can affirm a best fitting adsorptive process through Langmuir's isothermal model, this confirms an adsorptive effect occurring in homogeneous area of Tea-Waste. Maximum calculated adsorption capacity (Qm,cal) defined by using Langmuir's has proven up to 14.085 mg.g-1. Consequently, the research suggests that Tea-Waste is a highly interesting option for efficiently treating real wastewater polluted by Methylene Blue