Wagih A. Sadik

Synthesis and characterization of core–shell–shell magnetic (CoFe2O4–SiO2–TiO2) nanocomposites and TiO2 nanoparticles for the evaluation of photocatalytic activity under UV and visible irradiation

Magnetic TiO2–SiO2–CoFe2O4 (TSC) composite photocatalytic particles with a core–shell structure and a high crystalline anatase TiO2 shell were synthesized via controlled hydrolysis and condensation of titanium isopropoxide. Nano-sized TiO2 powders were synthesized by a sol–gel/hydrothermal route. The prepared TiO2 and its composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and UV-Vis. The results show that the obtained TSC composite particles were composed of spherical nanoparticles, about 5–8 nm in diameter, with several CoFe2O4 fine particles as cores and silica as coatings and barrier layers between the magnetic cores and anatase titania shells. The average crystallite size of TiO2 nanoparticles with an anatase structure is 6 nm. The photocatalytic activities of the samples were evaluated by the photocatalytic degradation of dichlorophenol-indophenol (DCPIP) dye. The maximum level reached for the degradation of the dye molecule was 95.32 and 87.27% for 3 minutes under UV and visible light respectively for mesoporous TiO2 nanoparticles.

Photocatalytic parameters and kinetic study for degradation of dichlorophenol-indophenol (DCPIP) dye using highly active mesoporous TiO2 nanoparticles.

Highly active mesoporous TiO2 of about 6nm crystal size and 280.7m(2)/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared spectroscopy), TGA (thermogravimetric analysis), DSC (differential scanning calorimetry) and BET (Brunauer-Emmett-Teller) surface area. The degradation of dichlorophenol-indophenol (DCPIP) under ultraviolet (UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1g/L of catalyst, 10mg/L of DCPIP, pH of 3 and the temperature at 25±3°C after 3min under UV irradiation. Meanwhile, the Langmuir-Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model. The results proved that the prepared TiO2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.

Study on synthesis of superparamagnetic spinel cobalt ferrite nanoparticles as layered double hydroxides by co-precipitation method

Cobalt ferrite layered double hydroxide (LDH) nanoparticles with cubic structure were synthesized by the co-precipitation method: addition of NaOH solution to a solution of Co2+ and Fe3+. Formation of nanoparticles was confirmed by XRD, SEM, TEM, PSA, FT-IR, TGA, DSC, and magnetic characteristics were measured using VSM. Crystals produced by calcination at 900°C possessed high coercivity and pronounced physical and chemical stability. Nanoparticles of CoFe2O4 formed outer layers with poor crystallization on the surface of cobalt ferrite nanocrystals.

The effect of sugarcane bagasse fiber on the properties of recycled high density polyethylene

Recycled high density polyethylene/sugarcane bagasse fiber composites were prepared by melt mixing using a two-roll mill and compression molding. The effects of the sugarcane bagasse fibers content and the addition of compatibilizing agent maleated polyethylene on the composite properties were studied. The scanning electron micrographs of the compatibilized composites showed clear evidence of good interfacial adhesion between the fiber surface and the polymer matrix. The tensile tests revealed that the compatibilized composites provide better tensile strength and modules than the uncompatibilized composites. The elongation at break and the impact strength for all the composites decreased significantly compared to the recycled high density polyethylene. The composites had the same melting temperature and were thermally less stable than that of the recycled high density polyethylene. The presence of maleated polyethylene was found to decrease the water absorption and slightly increase the specific gravity of the composites.

UV-Induced Decolorization of Indophenol by Heterogeneous Advanced Oxidation Processes

Abstract The decolorization of 2,6-dichloroindophenol dye was investigated using a heterogeneous advanced oxidation processes which comprised irradiating aqueous solutions of the dye with UV light at a wavelength of 254 nm in the presence of ZnO at a pH of 6. Rate enhancement of dye decolorization has been observed by increasing ZnO concentration up to 1 g/L. Addition of small concentrations of inorganic oxidants (H2O2 and Na2S2O8) to ZnO slurry resulted in an enhancement in the rate of dye decolorization compared with ZnO only. First order kinetics adequately described the disappearance of the dye. Reaction rate orders with respect to oxidant species were 1.2, 1.8, and 0.8 for, respectively, ZnO, H2O2, and Na2S2O8. It was observed that UV/ZnO/ is the most effective catalytic system for dye decolorization and can be applied for a wide range of organic compounds.

Influence of calcination temperature on the physical properties of nano-titania prepared by sol-gel/hydrothermal method

Nano-sized TiO2 powders were synthesized by a modified hydrolysis reaction using titanium butoxide as a precursor, water as a solvent, acetylacetone to slowdown the hydrolysis and the condensation reactions and ammonia as a base catalyst. Phase transformation and particle size of the calcined powders were investigated as a function of the calcination temperature by room-temperature X-ray diffraction; scanning electron microscopy and Fourier transform infrared spectroscopy techniques. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO2 nanoparticles. The XRD showed that the uncalcined sample was mostly the anatase phase with some rutile content. It was indicated that the thermal annealing resulted in increasing the average crystallite size from 8.2 to 53.5 nm. As the calcination temperature increased, the particle size, the rutile phase, the crystallization of the anatase phase, and the agglomeration were increased. The increase in the rutile content and grain growth are caused by the calcination at higher temperatures even calcination at 800°C for 2 h.

A simple method to prepare superhydrophobic polypropylene coatings for biomedical applications

In this paper, a simple method of preparing superhydrophobic self-cleaning polypropylene coating for biomedical applications is reported. The effect of several factors on the preparation of superhydrophobic polypropylene (PP) surfaces has been studied. These factors include PP concentration, heating rate for PP dissolution, the solvent evaporation rate and the addition of different amounts of TiO2 nanoparticles. The prepared PP was studied by contact angle, SEM, FTIR, and DSC measurements. This study showed that the best suitable parameters for PP superhydrophobic surface formation were found to be 40 mg/ml of PP in xylene concentration, 3.5°C/min dissolution heating rate and 70°C curing temperature. Superhydrophobic polypropylene surfaces incorporating TiO2 nanoparticles have been successfully synthesised via the adopted method. Static contact angle of 165° was achieved. Also, preliminary biological studies, including bacteria antisticking effect and ISO cytotoxixcity, have been investigated. The antisti...

Effect of Durable Superhydrophobic FS/PS Using DCTES on Carbon Steel

Durable superhydrophobic surface on metal substrates was fabricated using very applicable method. The fabrication method aimed to decrease surface free energy and increase surface roughness at same time the process have been accomplished via the addition of silica nano particles with Dodecyltrimethoxysilane (DCTES) bonded to the surface of the silica particles. Adhesive polystyrene was added to improve bond between substrate and functionalized silica. The method is cheap, promising to be applied in factories heat exchangers to reduce fouling and corrosion on the large industrial scale. Scanning electron microscopy (SEM) was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88°) to superhydrophobicity (water contact angle 165.2°), while sliding contact angles dramatically decreased (<4°) by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS) and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution.