Elimination of bisphenol A with visible light-enhanced peroxydisulfate activation process mediated by Fe3+-nitrilotriacetic acid complex

Interfacial complexation between Fe3+ and Bi2MoO6 promote efficient persulfate activation via Fe3+/Fe2+ cycle for organic contaminates degradation upon visible light irradiation

To address the observed decrease in efficiency during Fe2+-mediated persulfate (PDS) activation caused by slow electron transfer rates and challenges in cycling between Fe3+/Fe2+ states, we devised a strategy to establish interfacial complexation between Fe3+ and Bi2MoO6 in the presence of PDS. The proposed approach facilitates more efficient capture of photogenerated electrons, thereby accelerating the rate-limiting reduction process of the Fe3+/Fe2+ cycle under visible light irradiation and promoting PDS activation. The Bi2MoO6/Fe3+/PDS/Vis system demonstrates complete degradation of organic pollutants, including Atrazine (ATZ), carbamazepine (CBZ), bisphenol A (BPA), and 2,4-dichlorophenol (DCP) at a concentration of 10 mg/L within a rapid reaction time of 30 min. Radical scavenging experiments and electron paramagnetic resonance spectra (EPR) confirm that the sulfate radical (•SO4-) is the dominant species responsible for organic contaminant degradation. The real-time conversion process between Fe3+ and Fe2+ was monitored by observing changes in iron species forms and concentrations within the reaction system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy verify the formation of a complexation between Fe3+ and Bi2MoO6, facilitating anchoring of Fe3+ onto material surface. Based on these findings, we propose a reliable mechanism for the activation reaction. This work presents a promising heterogeneous PDS activation method based on Fe3+/Fe2+ cycle for water treatment.

Multi-level FeCo/N-doped carbon nanosheet for peroxymonosulfate oxidation and sterilization inactivation

Magnetic carbon-based catalysts with environmental friendliness have exhibited prominent effects on advanced oxidation processes. Herein, a multi-level FeCo/N-doped carbon nanosheet (FeCo/CNS) was synthesized by facile impregnation iron-cobalt salt onto cotton and followed by confined pyrolysis. We identified excellent advantages of the modified FeCo/CNS materials: (i) The convenience of the synthesis method and (ii) The dual effect of sterilization and contaminant degradation achieved through the FeCo/CNS-activated Peroxymonosulfate (PMS). The comparative experimental showed that FeCo/CNS could provide favorable catalytic performance, completely removing bisphenol A (BPA) and tetracycline (TC) within 5 min. Moreover, the potent sterilization properties against Staphylococcus aureus and Escherichia coli were also verified. Analysis of the degradation pathway confirmed the existence of intermediates, and toxicological research demonstrated that the toxicity of the degradation intermediates of BPA gradually decreased over time. Our research provided an excellent application of FeCo/CNS in PMS oxidation and sterilization inactivation.

Organic cocatalysts improved Fenton and Fenton-like processes for water pollution control: A review

In recent times, organic compounds have been extensively utilized to mitigate the limitations associated with Fe(Ⅲ) reduction and the narrow pH range in Fenton and Fenton-like processes, which have garnered considerable attention in relevant studies. This review presents the latest advancements in the comprehensive analysis and applications of organic agents as assistant/cocatalysts during Fenton/Fenton-like reactions for water pollution control. The primary focus includes the following: Firstly, the mechanism of organic co-catalytic reactions is introduced, encompassing both complexation and reduction aspects. Secondly, these organic compounds are classified into distinct categories based on their functional group structures and applications, namely polycarboxylates, aminopolycarboxylic acids, quinones, phenolic acids, humic substances, and sulfhydryl compounds, and their co-catalytic functions and mechanisms of each category are discussed in meticulous detail. Thirdly, a comprehensive comparison is conducted among various types of organic cocatalysts, considering their relative merits, cost implications, toxicity, and other pertinent factors. Finally, the review concludes by addressing the universal challenges and development prospects associated with organic co-catalytic systems. The overarching objective of this review is to provide insights into potential avenues for the future advancement of organic co-catalytic Fenton/Fenton-like reactions in the context of water purification.

Flotation Separation of Fluorite from Calcite using an Efficient Depressant Nitrilotriacetic Acid in the NaOL System

Fluorite and calcite were separated with nitrilotriacetic acid (NTA) as a depressant. The single mineral flotation experiment confirmed that with 40 mg/L NaOL and 80 mg/L NTA, the fluorite recovery and calcite recovery were 24.37 and 94.13%, respectively, at pH 9. Meanwhile, in the fluorite-calcite binary mixed ore flotation experiment, the calcite recovery and fluorite recovery were 75.50 and 26.84%, respectively, and the CaCO3 and CaF2 grade in concentrate was 74.32 and 25.61%, respectively. The results confirmed that NTA could be used as a depressant to selectively inhibit fluorite flotation. The mechanism study illustrated that NTA was selectively reacted with fluorite by chemical interaction between O of NTA and Ca of fluorite. The adsorption of NTA on fluorite will impede the interaction between fluorite and NaOL. NTA could adsorb on fluorite in three ways, while the dominant two ways were the complex between double O of NTA and Ca of fluorite in a vertical model and the complex between double O of NTA and Ca of fluorite in a horizontal model.