Amalgamation of g-C3N4 with KNbO3 for enhanced removal of Bisphenol A under sunlight irradiation

Bisphenol A (BPA) is a pollutant exits in an enormous amount in wastewater effluent resulted from the rapid industrialization. Advanced oxidation technology (AOP) based on solar photocatalysis can be employed to solve this issue. This study will focus on adopting photocatalyst graphitic carbon nitride (g-C3N4) with potassium niobate (KNbO3) via a simple sol-gel synthesis method. The different weight percentages 0.5, 1.0 and 1.5 wt% g-C3N4, were adopted to formed KNbO3/g-C3N4composites. The physicochemical properties of the created KNbO3/g-C3N4composites were characterized with advanced analysis methods to unveil this composite’s ability to enhance the photodegradation of BPA under sunlight irradiation. It was found that 1.0 wt% KNbO3/g-C3N4composites exhibited the highest photocatalytic degradation of 69.39% in 5 h. This superior photodegradation of BPA was achieved resulted from the presence of g-C3N4that enhances light-harvesting, especially in the visible light spectrum. The increase of light-harvesting enables the composite to excite more electrons and holes leading to the massive formation of active radicals. These massive active radicals will then enhance the redox reaction and further improve the efficacy of the photodegradation of BPA. Hence, the outcome of this study path an alternative solution for eliminating complex organic pollutants in wastewater treatment.

A Review of Activation Persulfate by Iron-Based Catalysts for Degrading Wastewater

Advanced oxidation technology of persulfate is a new method to degrade wastewater. As the economy progresses and technology develops, increasingly more pollutants produced by the paper industry, printing and dyeing, and the chemical industry are discharged into water, causing irreversible damage to water. Methods and research directions of activation persulfate for wastewater degradation by a variety of iron-based catalysts are reviewed. This review describes the merits and demerits of advanced oxidation techniques for activated persulfate by iron-based catalysts. In order to promote the development of related research work, the problems existing in the current application are analyzed.

Detoxification of Arsenic-Containing Copper Smelting Dust by Electrochemical Advanced Oxidation Technology

A large amount of arsenic-containing solid waste is produced in the metallurgical process of heavy nonferrous metals (copper, lead, and zinc). The landfill disposal of these arsenic-containing solid waste will cause serious environmental problems and endanger people’s health. An electrochemical advanced oxidation experiment was carried out with the cathode modified by adding carbon black and polytetrafluoroethylene (PTFE) emulsion. The removal rate of arsenic using advanced electrochemical oxidation with the modified cathode in 75 g/L NaOH at 25 °C for 90 min reached 98.4%, which was significantly higher than 80.69% of the alkaline leaching arsenic removal process. The use of electrochemical advanced oxidation technology can efficiently deal with the problem of arsenic-containing toxic solid waste, considered as a cleaner and efficient method.

Study on the Electrochemical Technology and Nanotechnology of Composite Electrode Used as An Alternative to Ultraviolet Light

Advanced oxidation technology has the advantage of being able to efficiently degrade refractory organics, and plays an important role in the treatment of industrial organic wastewater. The article analyses its role in the purification of organic wastewater by the electrochemical method of polymer composite nano-titanium dioxide. The oxygen evolution potential of the nano titanium dioxide electrode is up to 2.8V, showing excellent electrochemical performance. Didache, Si/BDD, Nb/BDD, It/BDD electrodes and surface-modified BDD electrodes can generate strong oxidizing hydroxyl radicals on the surface of the electrodes, which are organic to phenols, dyes, pesticides, and surfactants. The degradability of wastewater is strong. Nano-titanium dioxide electrodes can degrade a variety of organic matter, with a current efficiency of >90%, and can completely mineralize organic matter. Nano-titanium dioxide electrodes have good application prospects in organic wastewater treatment.

Degradation Mechanism of Methyl Orange by Pyrite-Activated Persulfate

This paper took methyl orange (MO), a typical azo dye, as the target substance to explore the degradation mechanism of pyrite (FeS2)-activated persulfate (PS) by advanced oxidation technology, and response surface methodology was used to determine the optimal dosage of FeS2 and PS. The related experiments were conducted focused on different factors and degradation mechanisms. The results showed that when the initial concentration of MO was 0.1 mM, the pyrite was 1.6 g/L and PS was 1.0 mM, the degradation rate of MO could reach 92.94% in 150 min. In the FeS2/PS system, the main free radical was sulfate radical, which contributed about 22.43% to the degradation of MO, but the hydroxyl radical contributed little. Both pH ≤ 2 and pH ≥ 10 would have an inhibitory effect on the system, and the removal effect of MO was the best at initial pH of 4. The Cl−, HCO3− and H2PO4− might play an important role in the treatment of actual wastewater. This study had shown that HCO3− in a low concentration and Cl− had little effect on the system; H2PO4− and high concentration of HCO3− could inhibit the reaction of the system. By exploring the influence of different water matrices such as tap water, river water, and distilled water, it was found that HCO3− would have a negative impact on the experiment, and the degradation effect was obviously observed when the pH was adjusted to 4. The results can provide technical support for the degradation of pyrite-activated persulfate system in printing and dyeing wastewater.

Study on Fenton-like degradation of bisphenol A by α-MnO2 and α-MnO2/AC (1:1, w/w)

Bisphenol A is used in various industrial productions and large amounts of industrial wastewater containing bisphenol A is produced. Heterogeneous Fenton-like process in advanced oxidation technology can oxidize and degrade most organic compounds non-selectively, and it has become an effective method to treat bisphenol A. The aim is to overcome the shortcomings of the traditional Fenton method and synthesize catalysts by a simple method, which can help to degrade bisphenol A effectively under neutral conditions, with less catalyst and less H2O2 consumption. In this experiment, α-MnO2 and α-MnO2/AC (1:1, w/w) were synthesized by a simple method, and the degradation rate of bisphenol A by α-MnO2 and α-MnO2/AC (1:1, w/w) under different conditions were studied. The optimal conditions for the degradation of bisphenol A by the two materials were determined by single factor and orthogonal experiments. When the dosage of α-MnO2 catalyst is 6.5g/L and the concentration of H2O2 is 200 mg/L with pH = 4.5 at 328K, the degradation rate of 50mg/L bisphenol A can reach 91.02% within 70 minutes. When α-MnO2/AC (1:1, w/w) has a catalyst dosage of 1.5g/L, at 298K with no pH adjustment, the degradation rate of 50 mg/L of bisphenol A within 70 minutes can be reached 94.17%.

Removal of Pharmaceutical Residues from Water and Wastewater Using Dielectric Barrier Discharge Methods—A Review

Persistent pharmaceutical pollutants (PPPs) have been identified as potential endocrine disruptors that mimic growth hormones when consumed at nanogram per litre to microgram per litre concentrations. Their occurrence in potable water remains a great threat to human health. Different conventional technologies developed for their removal from wastewater have failed to achieve complete mineralisation. Advanced oxidation technologies such as dielectric barrier discharges (DBDs) based on free radical mechanisms have been identified to completely decompose PPPs. Due to the existence of pharmaceuticals as mixtures in wastewater and the recalcitrance of their degradation intermediate by-products, no single advanced oxidation technology has been able to eliminate pharmaceutical xenobiotics. This review paper provides an update on the sources, occurrence, and types of pharmaceuticals in wastewater by emphasising different DBD configurations previously and currently utilised for pharmaceuticals degradation under different experimental conditions. The performance of the DBD geometries was evaluated considering various factors including treatment time, initial concentration, half-life time, degradation efficiency and the energy yield (G50) required to degrade half of the pollutant concentration. The review showed that the efficacy of the DBD systems on the removal of pharmaceutical compounds depends not only on these parameters but also on the nature/type of the pollutant.

Research Status and Countermeasures of photocatalyst in Water Pollution Treatment

With economic development and population growth, the demand for fresh water resources is also increasing. However, affected by sewage discharge from industry, agriculture, mining and domestic, not only the ecological environment and natural resources are seriously damaged, but also the water resources available for people to drink are decreasing day by day. How to improve the water pollution treatment technology has become an urgent task. Because of the high cost and great limitation, the traditional treatment method has no significant effect in water pollution control. As an advanced oxidation technology, photocatalyst can effectively degrade pollutants in water pollution, and has a positive effect on improving water quality, protecting natural resources and maintaining ecological balance.

Research Progress of Advanced Oxidation Technology for Drinking Water Treatment

Advanced oxidation technology is attracting attention as an effective method of water treatment that can degrade various organic pollutants. The combination of photocatalysis (UV) and ozone (O3) and titanium dioxide (TiO2) is a promising advanced oxidation technology. The combination of ozone, hydrogen peroxide, ultraviolet light and other oxidants for catalytic oxidation is also the current mainstream advanced oxidation technology. They can effectively degrade emerging water pollutants and alleviate water pollution problems. Titanium dioxide, hydrogen peroxide, and ozone are all popular catalysts because of their low cost, non-toxicity, strong oxidizing ability, and easy contact with various surfaces.