Fabrication, activity and mechanism studies of transition metal molybdate/molybdenum trioxide hybrids as novel CWAO catalysts

Critical review of advanced oxidation processes in organic wastewater treatment

With the development of industrial society, organic wastewater produced by industrial manufacturing has caused many environmental problems. The vast majority of organic pollutants in water bodies are persistent in the environment, posing a threat to human and animal health. Therefore, efficient treatment methods for highly concentrated organic wastewater are urgently needed. Advanced oxidation processes (AOPs) are widely noticed in the area of treating organic wastewater. Compared with other chemical methods, AOPs have the characteristics of high oxidation efficiency and no secondary pollution. In this paper, the mechanisms, advantages, and limitations of AOPs are comprehensively reviewed. Besides, the basic principles of combining different AOPs to enhance the treatment efficiency are described. Furthermore, the applications of AOPs in various wastewater treatments, such as oily wastewater, dyeing wastewater, pharmaceutical wastewater, and landfill leachate, are also presented. Finally, we conclude that the main direction in the future of AOPs are the modification of catalysts and the optimization of operating parameters, with the challenges focusing on industrial applications.

A novel hybrid construction of MnMoO4 nanorods anchored graphene nanosheets; an efficient electrocatalyst for the picomolar detection of ecological pollutant ornidazole in water and urine samples

Nitroimidazole compounds are widely used antibiotics to encounter anaerobic bacterial and parasitic infections. The wide usage of antibiotic drugs became an ecological contaminant which in turn into potential monitoring. In this regards, we have designed and developed a new electrochemical sensing probe to monitor an antiprotozoal drug, ornidazole (ODZ), with the aid of a glassy carbon electrode (GCE) integrated with manganese molybdate nanorods (MnMoO4) decorated graphene nanosheets (GNS) hybrid materials that prepared by feasible probe sonochemical method (parameters: 2-4 W, 5 mV amp, 20 kHz). The electrochemical investigations of the developed probe were performed by using rapid scan electrochemical workstations namely cyclic voltammetry (CV) and amperometric (i-t) techniques. The as-prepared MnMoO4/GNS nanocomposite was characterized and its purity of nanocomposite formation was confirmed by various analytical techniques like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. In addition to that, the textural morphology of the MnMoO4/GNS nanocomposite was examined with the aid of field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). The MnMoO4/GNS nanocomposite rotating disk glassy carbon electrode (RDGCE) plays a crucial role in electrochemical detection of ODZ, which results in excellent anti-interference ability, a lower detection limit of 845 pM, massive linear ranges from 10 to 770 nM, and good sensitivity of about 104.62 μA μM-1 cm-2. From the acquired electrochemical studies, we have developed a disposable electrochemical sensor probe using a low-cost screen-printed carbon electrode (SPCE) with MnMoO4/GNS nanocomposite. The MnMoO4/GNS/SPCE are capably employed in real-time sensing of ODZ in water and urine samples. These electrochemical studies revealed the integral new vision on the electrocatalytic performance of the modified SPCE and also shown excellent amplification results in ultra-trace levels.

Performance of various catalysts on treatment of refractory pollutants in industrial wastewater by catalytic wet air oxidation: A review

The tremendous increase of industrialization and urbanization worldwide causes the depletion of natural resources such as water and air which urges the necessity to follow the environmental sustainability across the globe. This requires eco-friendly and economical technologies for depollution of wastewater and gases or zero emission approach. Therefore, in this context the treatment and reuse of wastewater is an environmental friendly approach due to shortage of fresh water. Catalytic wet air oxidation (CWAO) is a promising technology for the treatment of toxic and non-biodegradable organic pollutants in the wastewater generated from various industries. Various heterogeneous catalysts have been extensively used for treatment of various model pollutants such as phenols, carboxylic acids, nitrogenous compounds and different types of industrial effluents. The present review focuses on the literature published on the performances of various noble and non-noble metal catalysts for the treatment of various pollutants by CWAO. Reports on biodegradability enhancement of industrial wastewater containing toxic contaminants by CWAO are reviewed. Detailed discussion is made on catalyst deactivation and their mitigation study and also on the various factors which affects the CWAO reaction.