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In this report, TiO2-SiO2 composite nanoparticles were prepared by the thermal hydrolysis method using titanium tetrachloride and tetraethylorthosilicate as TiO2 and SiO2 precursors, respectively. The prepared nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption/desorption and UV-Vis diffuse reflectance spectroscopy (DRS). The results indicated that, in comparison with pure TiO2, TiO2-SiO2 composite nanoparticles had a higher thermal stability, which prevents phase transformation from anatase to rutile. In addition, the TiO2-SiO2 nanoparticles had a higher specific surface area, larger pore volume, greater band gap energy and smaller crystallite size. Thus, the surface area of TiO2-40% SiO2 composite nanoparticles was about 17 times higher than that of pure TiO2 nanoparticles. The photocatalytic activity of TiO2-SiO2 composite nanoparticles in the photodegradation of C.I. Basic Violet 2 was investigated. The photodegradation rate of Basic Violet 2 using TiO2-40% SiO2 nanoparticles calcined at 600°C was much faster than that using pure TiO2 and Degussa P25 TiO2 by 10.9 and 4.3 times, respectively. The higher photoactivity of the TiO2-SiO2 composite nanoparticles was attributed to their higher surface area, larger pore volume, greater band-gap energy and smaller crystallite size compared with pure TiO2. [ABSTRACT FROM AUTHOR]

Essential oils with antimicrobial or antioxidant activities have received extensive attention among customers, manufacturers, and food scientists, especially with rising worries about the safety of synthetic food preservatives. However, like other functional lipid compounds their incorporation into aqueous systems is challenging, due to their less water solubility. Furthermore, their susceptibility to light, moisture, heat, and oxygen origins their less chemical and structural stabilities. Consequently, the present research was aimed to encapsulate the thyme essential oil into nanoliposomes, using a thin layer hydration-sonication technique, which can be a proficient solution for revealed problems. The effects of phospholipid and stabilizing agents' concentrations, namely, lecithin, cholesterol, and glycerol, as main formulation parameters were investigated on characteristics of gained nanoliposomes, using a response surface method. Various empirical models were also developed to predict product characteristics by changing the formulation parameters. According to the numerical multiple optimizations, the best thyme oil nanoliposomes can be gained using equal concentrations of all three components as 1% with a mean particle size of 189.6 nm, PDI of 0.3487, the net zeta-potential of 42.48 mV, and DPPH radical scavenging of 12.72%. The prepared nanoliposomes had acceptable physical but limited chemical stabilities. The antibacterial action of manufactured essential oil nanoliposomes against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus has made them efficient candidates as natural food preservatives. [ABSTRACT FROM AUTHOR]

Abstract: The construction, performance characteristics, and application of a novel iron(III) membrane sensor based on a new bis-benzilthiocarbohydrazide (BBTC) are reported in this paper. The sensor is prepared by incorporating of BBTC, nitrobenzene (NB), and sodium tetraphenyl borate (NaTPB) into a plasticized poly(vinyl chloride) membrane. The electrode reveals a Nernstian behavior over a wide iron ion concentration range (1.0×10−2–1.0×10−7 mol L−1), and relatively low detection limit (8.6×10−8 mol L−1). The potentiometric response is independent on the pH of the solution in the range of 1.6–4.3. The electrode shows a very short response time (<10 s). The proposed electrode can be used for at least nine weeks without any considerable divergence in potentials. It exhibits very good selectivity relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions. In fact, the selectivity of the proposed sensor shows great improvements compared to the previously reported electrodes for the iron ion. Also, the sensors accuracy was investigated in two ways: (i) with the potentiometric titration of a Fe(III) solution with EDTA and (ii) with the Fe(III) monitoring in river and wastewater samples. [Copyright &y& Elsevier]

The decolorization and mineralization of Acid Red 27 (AR27), an anionic monoazo dye of acid class, were studied by UV/H2O2 process in laboratory and real samples. Effects of different process parameters such as initial H2O2 and AR27 concentrations, pH and EtOH as an electron scavenger have been studied. H2O2 and UV light have a negligible effect when they were used on their own. The decolorization rate follows pseudo-first order kinetic with respect to the dye concentration. The rate constant of the attack of •OH radicals to the AR27 has been estimated through the adoption of a simplified kinetic model (1.03 × 108 M−1 s−1). This model allows predicting the pseudo-first order rate constant and concentration of AR27 in different illumination times for different initial concentrations of H2O2. Mineralization studies showed, the formation of sulfate ions, the decrease of pH and 85% of COD reduction occur in less than 60 min. In the real wastewater color removal could be achieved after only 75 min, whereas 45% of COD reduction occurs after 105 min of illumination. [ABSTRACT FROM AUTHOR]