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In this work, an effective adsorbent-catalyst coupling (ACC) process is proposed and investigated to treat the wastewater polluted with triazole fungicides. In this regard, PEG-CuO as well as Ag pa...

The rapid advances in biodiesel technologies in recent years and the generation of huge amounts of glycerol as a by-product have led to a glycerol glut in the market and a significant drop in its price. The development of suitable techniques for glycerol valorization has recently attracted considerable attention and the photocatalytic process emerged as a forefront technology that integrates solar energy with glycerol conversion at ambient temperature and atmospheric pressure. The present review focusses on the analysis of this photocatalytic process to address the challenges and opportunities for its implementation. In this regard, the mechanisms of glycerol photoreforming and photo-oxidation as well as their gaseous (like hydrogen) and value-added liquid products are first analyzed. The developed kinetic and empirical models are then discussed to evaluate the prospects in the analysis of this process through a modeling approach. Finally, a thorough critical assessment is performed on the research related to synthesis parameters like cocatalyst percentage and calcination conditions, as well as the most critical operating parameters such as the hydrogen source, reaction time, glycerol concentration, solution pH, photocatalyst loading, photocatalyst stability, source and intensity of light, and reaction temperature.

Glycerol is a significant byproduct of biomass conversion into biodiesel, and numerous studies have been focused on its valorization technologies in recent years. Photocatalytic glycerol valorizati...

Solution pH is an important parameter in photocatalytic reactions that substantially affects the process by changing photocatalyst agglomeration and substrate adsorption on photocatalyst surface. In this work, a kinetic study was performed on photocatalytic hydrogen production from alcohols and an intrinsic kinetic model was developed to predict the rate of hydrogen production from different alcohols as a function of pH. Glycerol, ethanol, and methanol were selected as representative substrates and tested in a pH range of 2–12. The very good agreement between model predictions and experimental data was confirmed by statistical analyses (R2, R2adj, RMS, AAD, and MAE). The results revealed that for all substrates investigated, the maximum hydrogen rate was obtained at a pH~8. A local minimum for hydrogen production was observed around pHzpc, as a result of catalyst agglomeration. The results of this study can be very useful in future investigations of the effects of pH on other aqueous phase photocatalytic processes.

The spent bleaching clay (SBC) from the edible oil refining industries contains different types of contaminants, including fatty acids and trace amounts of heavy metals and hazardous materials. Therefore, the conventional procedure of landfilling of SBC is not safe for the environment. Because of this, researchers have been trying to find alternative routes, such as novel processes to regenerate the clay and reuse it. The large amounts of oil remaining in SBC justifies the investigation of in-situ transesterification of the oil to biodiesel. In this study, clays that have been de-oiled by in-situ transesterification at various operating conditions are investigated for their final regenerated bleaching capacity. The different in-situ operating parameters considered are: the choice between two different alkali catalysts, catalyst/SBC ratio, ethanol/SBC ratio, temperature, and reaction time. With 60 different experiments and using the method of experimental design, the optimum operating parameters were determined and presented for achieving maximum bleaching capacity of the regenerated clay. The suggested conditions were then confirmed experimentally. Results showed that the maximum bleaching capacity at these optimum conditions was 17.03%.

The spent bleaching clays (SBC) of vegetable oil refining plants have residual vegetable oil contents ranging from 17 to 40 wt%. The common worldwide practice of landfilling such spent clays imposes inevitable environmental hazards. The extraction of oil from a spent clay will not only alleviate this problem, but can also provide an oil source for processes, such as transesterification for the production of alcohol-esters. In-situ transesterification of the residual oil within SBC is an even more attractive idea, as it can eliminate the extraction step from the process. In this study, in-situ transesterification on the spent bleaching clay of a local vegetable oil plant was investigated experimentally. Furthermore, optimum operating conditions were determined for a number of parameters influencing the conversions, including reaction temperature, ethanol-to-SBC ratio, alkali catalyst type, and catalyst-to-SBC mass ratio. The experiments were designed by the response surface method based on the central composite approach (RSM-CCD model). The results were analyzed using the analysis of variance method (ANOVA) to investigate the effect of the parameters on the efficiencies of the biodiesel produced and the oil removed from the initial SBC. Within the ranges investigated, the maximum conversion to ethyl-ester was 72.90% at the optimum conditions of a reaction temperature of 73.2 °C, reaction time of 4.5 h, ethanol/SBC ratio of 4.2 ml/g, while using NaOH alkali catalyst with a catalyst-to-SBC mass ratio of 4.33%.