sio2

Nanocoating of biomedical materials has emerged as a crucial emerging discipline, to enhance tribological behaviors, durability, and performance of materials. This study aimed to investigate the tribological characteristics of substrates coated with Hydroxyapatite (HAp) and Silica glass (SiO2). In this experimental study, the substrates were Ti-6Al-4V, a widely used titanium alloy for osseointegration implants. The substrates were coated with 90% HAp and 10% SiO2 via the plasma cold spray technique. The friction examination was analyzed at room temperature and under the Simulated Body Fluid (SBF) condition using the pin-on-disc technique. The microstructural analysis confirmed the coated technique in producing a nano-sized layer. While the pin-on-disc test indicates that nanocoated Ti-6Al-4V specimens have a significantly higher average coefficient of friction than uncoated specimens, surface roughness is the primary contributor.  Through microstructure properties and tribological behavior, the coated alloy may provide a benefit in circumstances, in which lubrication availability is restricted or undesirable, such as when the implant comes into contact with the bone interface.

Water is essential for all life, but pollution, including heavy metals, poses severe health risks. The adsorption technology, known for being safe, cost-effective, and eco-friendly, uses silica to remove zinc ions from water. This paper detailed the kinetics, isotherms, and thermodynamics of this process. A stock solution of zinc sulfate in distilled water was prepared. Silica oxide, with its high surface area, was used to remove zinc ions from solutions of 5, 10, 15, and 20 mg/L concentrations. A double beam atomic absorption spectrophotometer (AAS) was used to obtain the calibration curve for the experiments. The study investigated the removal efficiency of Zn (II) using SiO₂ as an adsorbent. Factors such as initial concentration, contact time, adsorbent dose, pH, agitation speed, and temperature were examined in a batch process. Equilibrium was reached in 60 minutes for all concentrations. The highest Zn (II) adsorption (88%) was achieved with a 10 mg/L solution at pH 6, 180 rpm, and 303 K, using 1 g/L of silica. The adsorption kinetics followed a first-order rate mechanism with a rate constant of 3.91 × 10⁻² 1/min at 30 °C. Both Langmuir and Freundlich isotherms fit the data well, with rate constants of 0.089 and 0.248, respectively. The maximum adsorption capacity (qmax) from the Langmuir isotherm was 0.9416. The negative free energy change (ΔG° = -3938.21 kJ/mol at 298 K) indicated high capacity and affinity for Zn (II) removal, confirming the process’s feasibility and spontaneity.

Volatile organic compounds (VOCs) are one of the main group of air pollutants. Photocatalytic oxidation is one of the destructive methods for gaseous pollutants and has been received more attention in the past years. In this study investigated the comparison of the toluene removal efficiency by Photocatalytic Oxidation of Toluene by ZnO/SiO2 and TiO2/SiO2. In this study, the effect of parameters such as the amount of relative humidity, initial concentration of pollutant, the apparent speed of gas and the minimum speed of fluidizing of bed on the process of photocatalytic oxidation of Toluene is examined by comparison between TiO2/SiO2 and ZnO/SiO2 catalysts in a fluidized bed reactor. as it was explained, by absorption of water molecules on the surface of the catalyst and converting them to hydroxyl active radicals, these radicals act as a pushing factor in the reaction. The study also showed that an increase in the relative humidity in the 15–45% range would increase the efficacy of toluene oxidation. Conversion percentages between TiO2/SiO2 and ZnO/SiO2 catalysts were not significantly different (pv>0.05), while the reaction rate of ZnO/SiO2 catalyst was higher than TiO2/ SiO2 catalyst (pv<0.05). In the study of the interaction between the apparent velocity variables, initial concentration of toluene and loading of zinc oxide and titanium dioxide, only the interaction between two gas velocity variables and initial concentration of toluene was significant. The results showed that ZnO/SiO2 catalysts generally have a larger efficacy than TiO2/SiO2, presumably because ZnO/SiO2 has more active sites. Additionally, the ZnO/SiO2 catalysts offer better fluidity than TiO2/SiO2. The photo catalytic transformation rate of the pollutant is relatively low, as the optimum humidity level for appears to be 45%.

A surface molecularly imprinted dispersive solid phase extraction coupled with liquid chromatography–ultraviolet detection is proposed as a selective and fast clean-up technique for the determination of sertraline in biological sample. Surface sertraline-molecular imprinted polymer was grafted and synthesized on the SiO2/graphene oxide surface. Firstly SiO2 was coated on synthesized graphene oxide sheet using sol-gel technique. Prior to polymerization, the vinyl group was incorporated on to the surface of SiO2/graphene oxide to direct selective polymerization on the surface. Methacrylic acid, ethylene glycol dimethacrylate and ethanol were used as monomer, cross-linker and progen, respectively. Non-imprinted polymer was also prepared for comparing purposes. The properties of the molecular imprinted polymer were characterized using field emission-scanning electron microscopy and Fourier transform infrared spectroscopy methods. The surface molecular imprinted polymer was utilized as an adsorbent of dispersive solid phase extraction for separation and preconcentration of sertraline. The effects of the different parameters influencing the extraction efficiency, such as sample pH were investigated and optimized. The specificity of the molecular imprinted polymer over the non-imprinted polymer was examined in absence and presence of competitive drugs. Sertraline calibration curve showed linearity in the ranges 1–500 µg L-1. The limits of detection and quantification under optimized conditions were obtained 0.2 and 0.5 µg L-1. The within-day and between-day relative standard deviations (n=3) were 4.3 and 7.1%, respectively. Furthermore, the relative recoveries for spiked biological samples were above 92%.