Optimizing sorbitol double dehydration: A Box-Behnken design approach with commercial sulfonic acid resin.

In this study, double dehydration of sorbitol into isosorbide using commercial sulfonic acid resin as a catalyst was carried out under vacuum conditions generated by water ejection. To improve the efficiency and selectivity of the process, optimum reaction conditions prescribed by temperature, catalyst loading, and reaction time were investigated using the Box-Behnken design (BBD) together with Response Surface Methodology (RSM). The results showed that using the water ejection system could increase reaction activity. Statistically, all the reaction parameters were found to significantly affect the double dehydration reaction response, including sorbitol conversion, 1,4-sorbitant yield, and isosorbide yield. Furthermore, accurate predictive equations for all the reaction responses displayed R2 > 95 %, with no significant errors observed. The optimized conditions resulted in the complete conversion of sorbitol with 6.42 % 1,4-sorbitant yield and 67.55 % isosorbide yield. The equations yielded predicted values of the responses with minor variances being lower than 1 % when compared with the experimental values. However, the efficiency of the catalyst decreased steadily over recycling cycle due to reduced active sites and textural properties, likely caused by structural collapse and by-product accumulation. This work contributes to biomass valorization by optimizing the effective process for the production of isosorbide via commercial catalysts under vacuum conditions.

Enhancing catalyst stability: Immobilization of Cu-Fe catalyst in sodium alginate matrix for methyl orange removal via Fenton-like reaction.

This study aims to enhance the stability and effectiveness of heterogeneous catalysts in Fenton-like reactions, explicitly addressing the acidity limitations inherent in traditional Fenton processes. Copper-iron was synthesized through co-precipitation, and a catalyst bead was produced from hydrogel formation. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirm phases in the bimetallic Copper-iron, aligning with the intended composition. Modification with alginate led to reduced metal leaching compared to the bare bimetallic counterpart, as confirmed by atomic absorption spectroscopy (AAS). Additionally, Fourier-transform infrared spectroscopy (FTIR) revealed the deactivation of alginate through the disappearance of carboxyl groups, indicating the depolymerization of the catalyst bead. Under the suggested conditions (Methyl Orange concentration of 25 mg/L, initial solution pH of 7, 2 g/L catalyst loading, concentration of hydrogen peroxide 100 mM in a 120-min reaction time), the catalyst demonstrated remarkable decolorization efficiency of Methyl Orange, achieving 97.67 %. Further highlighting its practicality, the catalyst exhibited outstanding reusability over four cycles under identical conditions, showcasing robust immobilization capabilities and sustained performance. Notably, the catalyst's magnetic properties facilitated easy separation using an external magnet. In conclusion, the developed catalyst beads offer a solution with high reusability, magnetic separability, and reduced iron leaching. The advantageous characteristics underscore its potential as a heterogeneous catalyst for wastewater treatment applications, warranting further exploration under practical conditions.

Degradation of formaldehyde by photo-Fenton process over n-ZVI/TiO2 catalyst.

The degradation of formaldehyde in a photo-Fenton reaction was studied using n-ZVI/TiO2 as the catalyst. The effects of %n-ZVI loading, catalyst dosage, H2O2, and pH on formaldehyde degradation were studied. The n-ZVI/TiO2 catalysts were prepared by impregnation with chemical reduction, and their catalytic activity was evaluated in a batch reactor under UVC light. Transmission electron microscopy (TEM) was used to determine that the n-ZVI nanoparticle size was 39.41 nm. X-ray photoelectron spectroscopy (XPS) was used to study the oxidation states of 2%n­ZVI/TiO2, and the Fe 2p spectrum of 2%n-ZVI/TiO2 indicated the presence of Fe0. The optimal conditions for the complete removal of formaldehyde within 30 min were an n-ZVI loading of 2 wt.%, a catalyst dosage of 0.5 g/L, 30 mM H2O2, and an initial pH of 3. After the reaction, the C-H functional group of formaldehyde was not observed due to the •OH radicals generated by Fe0 and H2O2 attacking the formaldehyde molecule. Moreover, no Fe leaching was observed, presenting an advantage compared with homogeneous Fe catalysts. Therefore, 2%n­ZVI/TiO2 shows excellent potential as a photo-Fenton catalyst for the environmentally friendly degradation of formaldehyde.