Hydrogen generation by photocatalytic reforming of potential biofuels: polyols, cyclic alcohols and saccharides

We have studied hydrogen gas production using photocatalysis from C2-C5 carbon chain polyols, cyclic alcohols and mono and di-saccharides using palladium nanoparticles supported on a TiO2 catalyst. For many of the polyols the hydrogen evolution rate is found to be dictated by the number of hydroxyl groups and available α-hydrogens in the structure. However the rule only applies to polyols and cyclic alcohols, while the sugar activity is limited by the bulky structure of those molecules. There was also evidence of ring opening in photocatalytic reforming of cyclic alcohols that involved dehydrogenation and decarbonylation of α Csingle bondC bond

Experimental investigation on biodiesel production through simultaneous esterification and transesterification using mixed rare earth catalysts

In this study, biodiesel production through simultaneous esterification and transesterification of palm oil with 10 wt% of oleic acid using the mixed rare earth catalyst was investigated. The mixed rare earth catalysts were prepared via the co-precipitation method. The effects of the precipitating parameters such as temperature, stirring speed and pH on the physicochemical and morphology of the catalysts were studied. All catalysts were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), fourier transform-infrared spectroscopy (FTIR), N2adsorption/desorption, CO2 temperature programmed desorption (CO2-TPD) and NH3 temperature programmed desorption. (NH3-TPD). The results indicated that the mixed rare earth catalyst prepared under the precipitation conditions: at pH 9, a stirring of 400 rpm and temperature of 30 °C showed the highest catalytic of 90% FAME content. High surface area of the catalyst, a significant larger amount of Ce and La contents in the catalyst and an appropriate amount of acid and basic sites on the catalyst led to the high catalytic activity. The catalyst could also accelerate the initial reaction rate to achieve the high FAME content of 50% within 30 min

Preparation of CaO@CeO₂ Solid Base Catalysts Used for Biodiesel Production

The study investigated the use of CeO2 extracted from monazite with calcium oxide (CaO) as a solid catalyst for biodiesel production. The wet impregnation method was used to produce CaO@CeO2 mixed-oxide catalysts with 0–50 wt.% CaO. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and a Fourier transform infrared spectrometer (FTIR) was used to characterize the catalysts. In order to determine the optimal preparation conditions, the effect of different CaO compositions on the performance of CaO@CeO2 mixed-oxide catalysts was examined. The catalytic activity of the CaO@CeO2 catalyst for the transesterification reaction of palm oil to produce biodiesel was studied. The results show that the optimum yield of biodiesel can reach 97% fatty acid methyl ester over the 30CaO@CeO2 catalyst at the reaction conditions of 5 wt.% catalysts, methanol-to-oil molar ratio of 9:1, with a reaction temperature of 65 °C within 30 min. The results show that the high catalytic activity and stability of the CaO@CeO2 catalyst make it a promising candidate for industrial-scale biodiesel production. Further study is needed to improve the stability and efficiency of catalysts in transesterification reactions to achieve a high FAME yield using long-life-span catalysts. Moreover, it is necessary to investigate the economic feasibility of this process for application in large-scale biodiesel production

Management of 137Cs in electric arc furnace dust by solid-liquid extraction and treatment of contaminated wastewater using co-precipitation

Efficient decontamination of 137Cs in electric arc furnace dust (EAFD) was carried out using a solid-liquid extraction method and then the obtained wastewater contaminated with 137Cs was treated by a co-precipitation. The influences of pH, stirring time, settling time, and different radioactivity on removal efficiency were assessed. Depended on the initial concentration and the solid-liquid ratio, it is possible to reduce around 93–96% radioactivity from EAFD, meanwhile the removal efficiency of 137Cs from wastewater exhibits in excess of 99%. After treatment, the final solution was certified safe from 137Cs, while the radioactive sludge could be stored safely

Removal efficiency of 137Cs from radioactively contaminated electric arc furnace dust using different solvents

An advertent meltdown of radioactive source during steel smelting generates electric arc furnace dust (EAFD) polluted with 137Cs. The removal efficiency of 137Cs from EAFD was assessed by the lixiviation method using different solvents and at various radioactivity levels. More than 90% of 137Cs was removed from EAFD by rinsing with 0.5 M HNO3 and H2SO4, while removal efficiencies of deionized water, tap water, CsCl and Ca(OH)2 ranged from 84 to 89%. Mass loss and composition of the EAFD samples were investigated and compared. Results can assist in the decision-making of different solvents for large-scale removal of 137Cs from EAFD

Determination of X-ray and gamma-ray shielding capabilities of recycled glass derived from deteriorated silica gel

We determined the radiation shielding properties for 10CaO–xPbO–(90-x) deteriorated silica gel (DSG) glass system (x = 20, 25, 30, 35, 40, and 45 mol.%). The mass attenuation coefficient (MAC) has been estimated at photon energies of 74.23, 97.12, 122, 662, 1173, and 1332 keV using a narrow beam X-ray attenuation and transmission experiment, the XCOM program, and a PHITS simulation. The obtained MAC values were applied to estimate the half value layer (HVL), mean free path (MFP), effective atomic number, and effective electron density. Results show that the MAC value of the studied glasses ranges between 0.0549 and 1.4415 cm2/g, increases with the amount of PbO, and decreases with increasing photon energy. The HVL and MFP values decrease with increasing PbO content and increase with increasing photon energy. The recycled glass, with the addition of PbO content (20–45 mol.%), exhibited excellent radiation shielding capabilities compared to standard barite and ferrite concretes and some glass systems. Moreover, the experimental radiation shielding parameters agree with the XCOM and PHITS values. This study suggests that this new waste-recycled glass is an effective and cost-saving candidate for X-ray and gamma-ray shielding applications