Preparation of heterogeneous Fenton catalyst γ-Cu-Ce-Al2O3 and the evaluation on degradation of phenol

The Effect of Magnetic Composites (γ-Al2O3/TiO2/γ-Fe2O3) as Ozone Catalysts in Wastewater Treatment

Using municipal sewage as a source of reclaimed water is an important way to alleviate the shortage of water resources. At present, advanced oxidation technology (AOPs), represented by ozone oxidation, is widely used in wastewater treatment. In this study, γ-Al₂O₃, a low-cost traditional ozone catalyst, was selected as the matrix. By modifying magnetic γ-Fe₂O₃ with a titanate coupling agent, in situ deposition, and calcination, the final formation of a γ-Al₂O₃/TiO₂/γ-Fe₂O₃ micrometer ozone catalyst was achieved. A variety of material characterization methods were used to demonstrate that the required material was successfully prepared. The catalyst powder particles have strong magnetic properties, form aggregates easily, and have good precipitation and separation properties. Subsequently, ibuprofen was used as the degradation substrate to investigate the ozone catalytic performance of the prepared catalyst, and this proved that it had good ozone catalytic activity. The degradation process was also analyzed. The results showed that in the ozone system, some of the ibuprofen molecules will be oxidized to form 1,4-propanal phenylacetic acid, which is then further oxidized to form 1,4-acetaldehyde benzoic acid and p-phenylacetaldehyde. Finally, the prepared catalyst was applied to the actual wastewater treatment process, and it also had good catalytic performance in this context. GC-MS detection of the water samples after treatment showed that the types of organic matter in the water were significantly reduced, among which nine pollutants with high content, such as bisphenol A and sulfamethoxazole, were not detected after treatment.

Simple preparation of a CuO@γ-Al2O3 Fenton-like catalyst and its photocatalytic degradation function

We designed a photocatalyst and developed sustainable wastewater purification technology, which have significant advantages in effectively solving the global problem of drinking water shortage. In this study, a new nanocomposite was reported and shown to be a catalyst with excellent performance; CuO was coated successively onto functionalized nano γ-Al₂O₃, and this novel structure could provide abundant active sites. We evaluated the performance of the CuO@γ-Al₂O₃ nanocomposite catalyst for polyvinyl alcohol (PVA) degradation under visible light irradiation. Under optimized conditions (calcination temperature, 450 °C; mass ratio of γ-Al₂O₃:Cu(NO₃)₂·3H₂O, 1:15; pH value, 7; catalyst dosage, 2.6 g/L; reaction temperature, 20 °C; and H₂O₂ dosage, 0.2 g/mL), the CuO@γ-Al₂O₃ nanocomposite catalyst presented an excellent PVA removal rate of 99.21%. After ten consecutive degradation experiments, the catalyst could still maintain a PVA removal rate of 97.58%, thus demonstrating excellent reusability. This study provides an efficient and easy-to-prepare photocatalyst and proposes a mechanism for the synergistic effect of the photocatalytic reaction and the Fenton-like reaction.

Binary electrochemical mineralization of heterocyclic nitrogenous compounds: parametric optimization using Taguchi method and mineralization mechanism

The main objective of the present work was to understand the interactive behaviour of various operating parameters including concentration of pollutants during binary electrochemical mineralization of the two nitrogenous heterocyclic pollutants in the aqueous solution. Indole and pyrrole were selected as pollutants, whereas Pt/Ti was selected as anode and cathode. The effects of different operating parameters like current density, solution conductivity, initial concentration of the pollutants and time were studied. Taguchi method was used to optimize these operating parameters for obtaining the ultimate rate of degradation for the nitrogenous compounds. There were basically two responses, i.e. chemical oxygen demand (COD) degradation and specific energy consumption. These responses were maximized and minimized, respectively. At the optimum condition, removal efficiencies of pyrrole, indole and COD were found to be 46.1%, 62.4% and 61.4%, respectively. The optimum value of specific energy consumption was found to be 159.5 kWh per kg COD removed. Possible mineralization pathways are also proposed on the basis of the identified intermediates by gas chromatography coupled with mass spectroscopy. The operating cost was also calculated for the binary lab-scale treatment of the indole and pyrrole and compared with reported cost analysis for the electrochemical treatment.