Low-cost biodiesel production using waste oil and catalyst.

With the production of renewable biofuels, concerns about the end of fossil fuels have been partially eliminated. On the other hand, the utilization of low-cost and waste materials to provide the raw essential substances to manufacture these fuels is of paramount importance. Biodiesel is one of these fuels and the required raw materials for the reaction are oil (triglycerides), alcohol and catalyst. In this work, travertine stone powder (as waste in the manufacture of building materials) was used as a catalyst and waste frying oil as a source of triglyceride for biodiesel production. Using thermogravimetric and X-ray diffraction analysis, optimum temperature for catalyst calcination was selected at 900°C. Furthermore, X-ray fluorescence, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, transmission electron microscopy and scanning electron microscopy analyses were performed. Using the design of experiments Response Surface Methodology, the optimum reaction conditions for biodiesel production yield of 97.74% were: reaction temperature 59.52°C (~60°C), time 3.8 h (228 min), catalyst concentration 1.36 wt.% and the methanol to oil molar ratio of 11:6. After reusing four times, the catalyst efficiency was reduced a little, and the biodiesel yield was 89.84%, indicating high strength and stability of the catalyst.

Sono-dispersion of TiO2 nanoparticles over clinoptilolite used in photocatalytic hydrogen production: Effect of ultrasound irradiation during conventional synthesis methods.

Hydrogen evolution via water splitting was investigated over the sonochemically synthesized TiO2-clinoptilolite photocomposites. To this aim, a series of photocatalysts containing 10wt% titania were prepared by impregnation and solid state dispersion (SSD) methods in the presence and absence of ultrasound irradiation. The samples were characterized by XRD, FESEM, EDX, BET, FTIR, PL and UV-vis techniques and tested for the water splitting. The characterization results indicated that ultrasound irradiation endowed the photocatalysts with uniform morphology, higher surface area and more homogenous dispersion. In addition, the analyses also exhibited less population of particle aggregates, a strong titania-support interaction and lower electron-hole pairs recombination rate. These features were more prominent when ultrasound was employed during SSD method. The TiO2/Clinoptilolite photocatalyst prepared by the ultrasound assisted SSD method (TiO2/CLT(US)), had more uniform active sites dispersion, high separation efficiency of electron-hole pairs and as a consequence, high surface density of active sites. The highest photocatalytic activity, 569.88 [Formula: see text] , was obtained for the TiO2/CLT(US) sample which was about 8 times more than that of P-25 as a reference sample. Furthermore, the TiO2/CLT(US) photocomposite as optimal photocatalyst showed sufficient reusability, making it a good choice for photocatalytic water splitting applications.