Персона: Маслов, Михаил Михайлович
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Preparation of Eco-Friendly Composite Material for Mercury (II) Adsorption Including Non-Wood Content From Walnut Green Husk (Juglon Regia L.): Experimental and Theoretical Studies
Abstract In this study, the adsorption properties of a composite material consisting of polyacrylamide, an inert polymer, and an extract obtained from the water-soluble part of a green walnut shell were investigated for Hg(II) ions. SEM, EDX, FTIR, and PZC analyses were performed to characterize the newly synthesized material. SEM and EDX analyses confirmed that the surface of the synthesized adsorbent became softer and smoother after adsorption, indicating the presence of Hg in its elemental composition. FTIR analysis showed that mercury enters the structure through chemical interactions, and there are changes in bond vibration frequencies in the presence of Hg(II). According to the PZC point analysis, the point at which the surface charge was zero was found to be pH 4. The Langmuir model was used to calculate the adsorption capacity after investigating the effect of concentration on adsorption. The adsorption capacity was found to be 1.808 molkg ў??1 (362,67 mgg ў??1 ) from the Langmuir model, which is very high compared to similar adsorbents. PFO model was used to explain the adsorption kinetics and very fast adsorption kinetics were observed. The adsorption entropy increased, free enthalpy of adsorption was negative, and heat of adsorption was in the energy-consuming direction.
Removal of lead ions (Pb2+) from aqueous solution using chitosan/starch composite material: Experimental and density functional theory findings
Abstract Treatment of wastewater has become vital to prevent environmental pollution in recent years. Adsorption is an easily applicable, low-cost and efficient method and is the subject of this study. In this study, an adsorbent was synthesized to be used in heavy metal removal using chitosan and starch. The composite was characterized by Fourier transform infrared (FTIR) spectrophotometry, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis. It was determined that the composite had an amorphous and compact structure. Adsorption experiments were carried out under the optimized parameters such as solution pH, concentration, adsorbent amount, equilibrium time, and temperature. It shows that during adsorption, with the increase in pH, the adsorption efficiency and adsorption capacity first increase and then a fluctuation occurs. The highest adsorption efficiency and Q value were reached at pH 3.46 as 78% and 0.038 mol/kg, respectively. Moreover, the adsorption capacity (Q) reached its highest value with a value of 0.067 mol/kg in the presence of 30 mg adsorbent. Equilibrium experiments were validated by the Langmuir, Freundlich, Temkin and Dubininў??Radushkevich isotherm models. To investigate the adsorption mechanism, pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models were used. It was determined that the adsorption process followed the D-R isotherm (R 2 = 0.99) and PSO (R 2 = 0.99). Therefore, the existence of chemical adsorption can be mentioned. Thermodynamic parameters enthalpy (ў??H), Gibbs free energy (ў??G) and entropy change (ў??S) were investigated. The adsorbate-adsorbent interactions were studied by density functional theory (DFT).