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The ability of Natural Muscovite Clay (NMC) to adsorb Methylene Blue (MB) as a dye widely used in the industrial sector was investigated, and the adsorption process was interpreted at the molecular scale through computational modelling. After the characterisation of NMC, the effect of adsorbent mass (5–40 mg), contact time (1–60 min), solution pH (3.7-11.78), stirring speed (100–900 rpm), initial MB concentration (15–80 mg.L-1), and temperature (293.15-333.15 K) on the adsorption efficiency were inspected in the batch mode. The results showed that the basic pH, high stirring speed, and low temperature were the favourable conditions for the MB adsorption onto NMC. The adsorbed quantity Qe,exp of MB dye was found to be 59.828 mg.g-1 for the initial concentration of 80 mg.L-1 at 293.15 K using an NMC mass of 20 mg. The obtained values of thermodynamic parameters suggested that the removal of the MB dye was exothermic, and physical in nature. The adsorption isotherm of the MB/NMC system was analysed according to the statistical physics approach using the Levenberg-Marquardt iterating algorithm and showed a best fitting with the monolayer model with one energy. The analysis of kinetic data showed that the external diffusion and intra-particle diffusion steps have occurred simultaneously and contributed to the control of the adsorption rate of the MB dye onto NMC. The computational modelling of interactions between the MB molecule and the muscovite, kaolinite, and quartz minerals were examined according to the Monte Carlo simulation (MCS) and showed an ability of the dye molecule to be adsorbed onto the surface of these minerals. The calculated adsorption energies ranged between -2.23×104 and -1.10×104 Kcal.mol-1 reflected the stability and the spontaneity of the adsorption process. So, the surface of clay minerals (i.e. muscovite and kaolinite) was more favourable to the adsorption of the MB molecule. [ABSTRACT FROM AUTHOR]

Objective of this study is to develop a highly effective and durable phosphorus based epoxy resin as anticorrosive coating material for carbon steel in 3% NaCl medium. The hexaglycidyl N,N′,N″‐tris (4,4′‐ethylene dianiline) phosphoramide (HGTEDPA) was characterized using spectral methods. The anticorrosive formulation (HGTEDPA‐MDA) was synthesized using HGTEDPA curing with 4,4′‐methylenedianiline (MDA). The formulation (HGTEDPA‐MDA) coated steel specimens were exposed to UV radiation for a specific durable (189 days) and durability of the formulation was tested along with its inhibition effectiveness. The anticorrosive property of the formulation was evaluated using electrochemical (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP)) methods. Results showed that HGTEDPA‐MDA coating improved the corrosion resistance value even after exposing 180 days to the UV radiation. PDP study suggested that HGTEDPA‐MDA before and after UV radiations acted as mainly anodic and cathodic type of inhibitor, respectively. The EIS and PDP results were corroborated with density functional theory (DFT) and molecular dynamic simulations (MDS) methods and a reasonable good agreement was observed. DFT study revealed that HGTEDPA‐MDA interacts with the metallic surface using donor–acceptor interactions. MDS study revealed that HGTEDPA‐MDA spontaneously interacts with steel surface and adsorb using horizontal orientation. [ABSTRACT FROM AUTHOR]