Recent advances in the application of metal organic frameworks using in advanced oxidation progresses for pollutants degradation

Metal-organic frameworks(MOFs)materials with highly ordered and porous crystalline structure,have excellent performance in advanced oxidation progresses(AOPs)for organic contaminants degradation in water treatment.This review intends to summarize the timely references and insights for the recent advances in MOFs that are used in AOPs.Starting with the preparation methodologies,including conventional hydrothermal method,electrochemical method,sol-gel method,and emerging microwave and ultrasound assisted synthesis methods.Application and mechanism for MOFs using in various AOPs of Fenton-like,photocatalysis,catalytic ozonation,persulfate catalysis and other emerging oxidation methods are emphatically discussed.We hope this review can comprehensively summarize the research and application progress of MOFs in AOPs,deepen the understanding of the catalytic mechanisms.

Peroxymonosulfate enhanced photoelectrocatalytic oxidation of organic contaminants and simultaneously cathodic recycling of silver

Degradation of organic contaminants with simultaneous recycling of Ag+from silvercontaining organic wastewater such as photographic effluents is desired. Although photoelectrocatalysis(PEC) technology is a good candidate for this type of wastewater, its reaction kinetics still needs to be improved. Herein, peroxymonosulfate(PMS) was employed to enhance the PEC kinetics for oxidation of phenol(PhOH) at the anode and reduction of Ag^(+) at the cathode. The degradation efficiency of phenol(PhOH, 0.1 mmol/L) was increased from 42.8% to 96.9% by adding 5 mmol/L PMS at a potential of 0.25 V. Meanwhile, the Ag(by wt%)deposited on the cathode was 28.1%(Ag_(2)O) in PEC process, while that of Ag(by wt%) was 69.7%(Ag^(0)) by adding PMS. According to the electrochemistry analysis, PMS, as photoelectrons acceptor, enhances the separation efficiency of charges and the direct hoxidation of Ph OH at the photoanode. Meantime, the increasing cathode potential avoided Hevolution and strongly alkaline at the surface of cathode, thus enabling the deposition of Ag+in the form of metallic silver with the help of PMS. In addition, PMS combined with PEC process was effective in treating photographic effluents.

Phenotype and metabolism alterations in PCB-degrading Rhodococcus biphenylivorans TG9^(T) under acid stress

Environmental acidification impairs microorganism diversity and their functions on substance transformation.Rhodococcus is a ubiquitously distributed genus for contaminant detoxification in the environment,and it can also adapt a certain range of pH.This work interpreted the acid responses from both phenotype and metabolism in strain Rhodococcus biphenylivorans TG9^(T)(TG9)induced at pH 3.The phenotype alterations were described with the number of culturable and viable cells,intracellular ATP concentrations,cell shape and entocyte,degradation efficiency of polychlorinated biphenyl(PCB)31 and biphenyl.The number of culturable cells maintained rather stable within the first 10 days,even though the other phenotypes had noticeable alterations,indicating that TG9 possesses certain capacities to survive under acid stress.The metabolism responses were interpreted based on transcription analyses with four treatments including log phase(LP),acid-induced(PER),early recovery after removing acid(RE)and later recovery(REL).With the overview on the expression regulations among the 4 treatments,the RE sample presented more upregulated and less downregulated genes,suggesting that its metabolism was somehow more active after recovering from acid stress.In addition,the response mechanism was interpreted on 10 individual metabolism pathways mainly covering protein modification,antioxidation,antipermeability,H+consumption,neutralization and extrusion.Furthermore,the transcription variations were verified with RT-qPCR on 8 genes with 24-hr,48-hr and 72-hr acid treatment.Taken together,TG9 possesses comprehensive metabolism strategies defending against acid stress.Consequently,a model was built to provide an integrate insight to understand the acid resistance/tolerance metabolisms in microorganisms.

Self-powered electrochemical system by combining Fenton reaction and active chlorine geheration for organic contaminant treatment

Environmental deterioration,especially water pollution,is widely dispersed and could affect the quality of people's life at large.Though the sewage treatment plants are constructed to meet the demands of cities,distributed treatment units are still in request for the supplementary of centralized purification beyond the range of plants.Electrochemical degradation can reduce organic pollution to some degree,but it has to be powered.Triboelectric nanogenerator(TENG)is a newly-invented technology for low-frequency mechanical energy harvesting.Here,by integrating a rotary TENG(R-TENG)as electric power source with an electrochemical cell containing a modified graphite felt cathode for hydrogen peroxide(H2O2)along with hydroxyl radical(·OH)generation by Fenton reaction and a platinum sheet anode for active chlorine generation,a self-powered electrochemical system(SPECS)was constructed.Under the driven of mechanical energy or wind flow,such SPECS can efficiently degrade dyes after power management in neutral condition without any O2 aeration.This work not only provides a guideline for optimizing self-powered electrochemical reaction,but also displays a strategy based on the conversion from distributed mechanical energy to chemical energy for environmental remediation.