Photoelectrocatalytic oxidation of ascorbate promoted by glucose and tris-(hydroxylmethyl)-amino methane on cadmium sulfide/titanium dioxide electrodes for efficient visible light-enhanced fuel cells

Donor-Acceptor Compensated ZnO Semiconductor for Photoelectrochemical Biosensors

Hindering the recombination of a photogenerated carrier is a crucial method to enhance the photoelectrochemical performance of ZnO due to its high exciton binding energy. Herein, the intramolecular donor-acceptor compensated semiconductor ZnO (I-D/A ZnO), introducing C dopants and oxygen vacancies, was prepared with the assistance of ascorbic acid (AA). According to the DFT calculations, the asymmetry DOS could lead to the longer carrier lifetime and the smaller electron transfer resistance. Then, the photoelectrochemical biosensor toward glucose was regarded as a model to discuss the application of ZnO in biosensors. As a result, the biosensor based on I-D/A ZnO showed good performance with high sensitivity, low limit of detection, and fine anti-interference, meaning that I-D/A ZnO is a promising semiconductor for photoelectrochemical biosensors.

Photoelectrocatalytic reactor improvement towards oil-in-water emulsion degradation

Oil-in-water (O/W) emulsion is critical wastewater that is challenging to eliminate and requires a long treatment process, and it is necessary to develop highly effective removal methods before releasing it into natural water sources. This research has selected the photoelectrocatalytic (PEC) technique to solve this problem by developing a PEC reactor for high efficiency in O/W degradation and understanding the essential factors related to the PEC reactor's efficiency improvement. The PEC reactor has been designed on a large scale with suitable positioning of an electrode that is, designing a light source near the anode electrode to enhance light irradiation efficiency and including a circulating pump to provide continuous flow to the solution through the electrode surface. We studied the main factors of supporting the electrolyte, electrode characteristics, and catalytic process. We investigated the O/W-degradation efficiency using a UV/Vis spectrophotometer, chemical oxygen demand (COD) measurement, and GC-MS analysis. We optimized the PEC reactor using the developed BiVO₄ photoanodes and placed them parallel with the zinc plates. Then, we controlled the applied potential at 1.0 V in 0.1 M Na₂SO₄ supporting an electrolyte under visible light irradiation. The developed PEC reactor can be degraded in the O/W emulsion up to 76% and decreased the COD value up to 78% for 7h. This PEC cell can be completely decomposed of many functional groups, such as carbonyl, ester, nitrile, amine, phosphate, chloro group, and nitro group, that were contained in the O/W substance. The highlight of this research is the designed light source and circulating pump inside of the PEC reactor to enhance the light irradiation, refresh the anode electrode, and understand the critical factor for the improvement of O/W-degradation efficiency. This PEC reactor presents a high-efficiency O/W degradation with practical use and a fast process suitable for further application in high turbidity of wastewater treatment from the oil industry.

Hazardous waste treatment technologies

This is a review of the literature published in 2018 on topics related to hazardous waste management in water, soils, sediments, and air. The review covers treatment technologies applying physical, chemical, and biological principles for contaminated water, soils, sediments, and air. PRACTITIONER POINTS: The management of waters, wastewaters, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) was reviewed according to the technology applied, namely, physical, chemical and biological methods. Physical methods for the management of hazardous wastes including adsorption, coagulation (conventional and electrochemical), sand filtration, electrosorption (or CDI), electrodialysis, electrokinetics, membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non-thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed. Chemical methods including ozone-based, hydrogen peroxide-based, persulfate-based, Fenton and Fenton-like, and potassium permanganate processes for the management of hazardous were reviewed. Biological methods such as aerobic, anaerobic, bioreactor, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed.