نشریه شیمی کاربردی روز
پیاپی 57 (زمستان 1399)

Er2Ti2O7 pyrochlore structure was successfully prepared by solid-state method. The prepared microstructure mixed-metal oxide was characterized by XRD, SEM, EDX, FT-IR and BET. X-ray powder diffraction revealed a Cubic crystal system with Fd-3m space group for Er2Ti2O7. The morphology and mean particle size of the sample was characterized by the scanning electron microscope. The elemental analysis or chemical characterization of the sample was determined by Energy Dispersive X-ray microanalysis. The absorption bands between the A and B sites in the pyrochlore structure were confirmed by Fourier transmission infrared spectra in (400–4000 cm-1) range. The specific surface area and the pore size distributions of the sample were calculated using Brunauer–Emmett–Teller (BET) method and Barrett–Joyner–Halenda (BJH) method respectively. The complex has been used as a catalyst for epoxidation of cyclooctene with TBHP (tert-butyl hydroperoxide). Various parameters including catalyst amount, solvent type and amount, oxidant/substrate ratio and time have been optimized and almost. Considerable catalytic activity and high epoxide selectivity has been found.

Currently, the need for more efficient materials that work in the visible light spectrum for water treatment has been increasing. A CoFe2O4/CuO nanocomposite was successfully synthesized by co-precipitation method. The obtained nanocomposite was characterized by XRD, DRS, FT-IR and FESEM. X-ray diffraction data showed that the obtained nanoparticle was composed of CoFe2O4 and CuO with average crystal size of 36nm. The optical absorption spectrum of the CuO/CoFe2O4 nanocomposite displayed a band gap of 2.75 eV. The materials showed photocatalytic activity due to the presence of Cu, associated with the magnetic activity of CoFe2O4, which is useful for the separation and recovery of the photocatalyst after use in an oxidative process. Photocatalytic activity was studied by degradation of methylene blue under visible light. Compared with pure CuO, the CoFe2O4/CuO nanocomposite exhibited improved photodegradation performance (about five more time). To optimize process and obtain a mathematical model, CCD (with three factors at five levels) was used. The optimal conditions were determined where the amount of photocatalyst= 1 g/L, irradiation time= 140 min and the concentration of MB= 15 ppm with optimum degradation efficiency as 84.98%. The synthesized CoFe2O4/CuO nanocomposite can be potentially used as a visible-light responsive magnetically separable photocatalyst.

In this work, a series of binary oxides with 0:1, 1:10, 1:7, 1:5, and 1:0 Cu:Fe molar ratios were synthesized by a simple, low cost and effective procedure. The anionic dyes namely, Acid Red 14 (AR14) and Methyl Orange (MO) and Malachite Green (MG) as a cationic dye removal and adsorption onto these materials was investigated. The effects of Cu:Fe molar ratio, pH, and sorbent dosage were investigated at 25±1 °C. The synthesized adsorbent compound containing 1:7 molar ratio of Cu:Fe verified to possess an uppermost dye adsorption capacity. Subsequently, this new sorbent was characterized using different techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy(TEM), and Energy-dispersive X-ray spectroscopy (EDX). The new nanostructure was confirmed for dye adsorption in the presence of UV irradiation. Selected Fe-Cu binary oxide exposed the highest adsorption capacities of MG regarding the other dyes. It would be a practical process of removing MG from aqueous solution by increasing adsorption efficacy during wastewater treatment. The photocatalytic performance of as-fabricated binary oxides was surveyed with the destruction of dye.

Textile wastewater is one of the most important environmental pollutants. These wastewaters are containing different kinds of dyes, chemicals and salts. Therefore, it is essential to remove these dyes and chemicals from wastewaters before discharging them into the environment. One of the best methods to remove these dyes and chemicals from wastewater is using oxidation agents such as H2O2, O3 and etc. Ozone is an important oxidizing agent which is widely used in the purification of water, wastewater treatment, water disinfection and decomposition of organic materials. The main aim of this study is the investigation of the removal of C. I. Reactive Blue RB 203 as a textile dye from aqueous solutions by using electrochemical ozone generation with a titanium anode electrode modified with a mixture of nickel, antimony and tin oxides. Some parameters such as the pH of the solution, current density and ozonation time were optimized. The textile dye concentration during the degradation process was estimated from the calibration curve (the UV-Vis absorption values versus the dye concentration) and also the kinetic order of the removal of RB 203 was investigated. The results showed that removal of the dye (100 ppm) from the solution increased by increasing ozonation time at a constant current density of 20 mA/cm2 for 40 min electrolysis and also it was removed from solutions with an efficiency of 99%.

The study of surfactant properties are significant for the production of pharmaceutical and anti-corrosion products, detergents and enhanced oil recovery. In the present work, the formation of micelles in different types of surfactants, i) cationic (cetyl pyridinium chloride, CPC, and cetyl trimethylammonium bromide, CTAB) and ii) non-ionic (Brij-C2, Brij-C12, Brij-C15 and Brij-C20) has been investigated in aqueous medium by tensiometric technique at 298.15 K. These surfactants (CPC, CTAB, Brij-C2, Brij-C12, Brij-C15 and Brij-C20) have the same hydrophobic chain length (C16H33) and different polar head groups. The major focus in this research is on the effect of polar head groups on critical micelle concentration (CMC), the standard free energy of micellization ( ), Gibbs adsorption energy ( ) and some interfacial parameters, for example, surface excess concentration (max), minimum surface area per surfactant molecule (Amin), surface pressure at CMC (CMC) and pC20(= −log(C20). The results obtained show that the micellization properties of surfactants has more spontaneous and favorable conditions in nonionic structures. In Brij family surfactants, values of and πcmc at CMC point decreased with increasing the number of oxyethylene groups (or hydrophilic section) from Brij-C2 to Brij- C20. Also, increase in hydrophilicity of head groups of Brij series surfactants by more incorporation of oxyethylene groups enhanced their solubilization capacity in bulk solution.

Potassium superoxide-fiberglass nanocomposite is as chemical oxygen sources and carbon dioxide removal that can be used in human air revitalization systems. The potassium superoxide (KO2) nanoparticles as a part of nanocomposite was synthesized by electrohydrodynamic (EHD) method and coated on the fiberglass support as the second part of the nanocomposite. To investigate morphology of synthesized nanocomposite (KO2-fiberglass), field emission scanning electron microscopy (FESEM) was employed. The results showed that KO2-fiberglass nanocomposite obtained by EHD has uniform structure in nanometer dimension. To simulate oxygen generation and carbon dioxide removal of nanocomposite, a human like lung simulated (HLLS) set up was designed and made. Experimental studies in the HLLS set up was performed under different humidity and effect of humidity was investigated to the changes of oxygen and carbon dioxide concentration. Consequently, studying of data showed that KO2-fiberglass nanocomposite has suitable performance as air revitalization because increases oxygen amounts up to 29.4 percentage. Also, it decreases carbon dioxide amount to the half, twice faster than of commercial KO2 samples (in 60min). Moreover, higher amount of humidity (85%), as catalyst, causes increasing rate of CO2 removal and O2 generation