ABSTRACT Magnesium doped titania (MDT) composites with varying magnesium weight percentages (1–5 wt. %) were synthesized through a very simple and economical route of sol-gel method. The reactants used for making alkoxide precursor were titanium tetrachloride whereas magnesium nitrate was used for doping magnesium into titania in a mixture of solvents i.e. ethyl alcohol and water. The optimum conditions maintained for preparing sol were pH 3 and 60°C temperature with constant stirring for 2 hours. The gel obtained after drying the sol for each sample was calcined at 500°C for two hours. The powdered composite samples thus prepared were characterized by X-ray diffraction analysis (XRD), differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The samples were evaluated for their photocatalytic activity against methyl red dye under UV light irradiation and the dye degradation was examined by UV-Vis spectrophotometer. The results confirmed the excellent photocatalytic activity of synthesized magnesium doped TiO2 for the degradation of methyl red dye where MDT-3 having 3% magnesium doping exhibited the maximum degradation i.e. 96.8%.

ABSTRACT Magnesium doped titania (MDT) composites with varying magnesium weight percentages (1-5 wt. %) were synthesized through a very simple and economical route of sol-gel method. The reactants used for making alkoxide precursor were titanium tetrachloride whereas magnesium nitrate was used for doping magnesium into titania in a mixture of solvents i.e. ethyl alcohol and water. The optimum conditions maintained for preparing sol were pH 3 and 60 ºC temperature with constant stirring for 2 hours. The gel obtained after drying the sol for each sample was calcined at 500 ºC for two hours. The powdered composite samples thus prepared were characterized by X-ray diffraction analysis (XRD), differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The samples were evaluated for their photocatalytic activity against methyl red dye under UV light irradiation and the dye degradation was examined by UV-Vis spectrophotometer. The results confirmed the excellent photocatalytic activity of synthesized magnesium doped TiO2 for the degradation of methyl red dye where MDT-3 having 3% magnesium doping exhibited the maximum degradation i.e. 96.8%.

Abstract Spinach is highly contaminated with different pesticide residues. This study was designed to evaluate organochlorine and pyrethroid pesticide residues present in various washing treatments (T0-T13) of fresh and chemically washed spinach with respect to maximum residues limits. Efficiency of washing solutions (citric acid, acetic acid, garlic extract and ginger extract) of different concentrations (w/v %) along with tap water in spinach was investigated for residues dissolution. Results showed that the highest reductions in endosulfan, deltamethrin and cypermethrin residues were 0.008 ± 0.008 mg.kg-1 (53%), 0.023 ± 0.024 mg.kg-1 (76%) and 0.017 ± 0.014 mgkg-1 (83%) in treatment of T5 (10% acetic acid) followed by 0.035 ± 0.029 mg.kg-1 (50%), 0.051 ± 0.029 mg.kg-1 (73%) and 0.037 ± 0.048 mg kg-1 (81%) in treatment T11 (10% ginger extract) while the lowest reductions in residues were 0.304 ± 0.004 mg.kg-1 (23%), 0.432 ± 0.030 mg.kg-1 (35%) and 0.468 ± 0.016 mg kg-1 (38%) in treatment T2 (5% citric acid), respectively. In conclusion, 10% acetic acid, ginger extract and mixture of acetic and citric acids can effectively minimize pesticide residues in treated spinach.

A discharge of nitrogen - hydrogen mixture by 50 Hz pulsed dc in the presence of active screen cage is investigated by optical emission spectroscopy (OES). The aim is to identify the parameters (mixture ratio, filling pressure and current density) that may lead to high concentration of active species (N2, N2+ and N). The maximum concentration in this experiment is found with 40% H2 - 60% N2, at filling pressure of 3 mbar with current density of 5 mAcm-2. High carbon steel samples are nitrided for 1 - 4 hours at 500ºC and the treated samples are characterized by X - ray diffraction (XRD), Raman spectroscopy and Vicker's micro - hardness testing. The XRD spectra show different phases of nitrides (Fe2 - 3N, FeN, CrN) along with iron oxides. The Raman spectra confirm the formation of α - β (C3N4). The surface hardness is found to increase up to six times for 2 hour treatment.