Progress and prospects of Mg-based amorphous alloys in azo dye wastewater treatment

Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater degradation.However,the problems like difficulty in preparation and poor cycling stability need to be solved.At present,Mg-based amorphous alloys applied in wastewater degradation are available in powder and ribbon.The amorphous alloy powder fabricated by ball milling has a high specific surface area,and its reactivity is thousands of times better than that of gas atomized alloy powder.But the development is limited due to the high energy consumption,difficult and costly process of powder recycling.The single roller melt-spinning method is a new manufacturing process of amorphous alloy ribbon.Compared to amorphous powder,the specific surface area of amorphous ribbon is relatively lower,therefore,it is necessary to carry out surface modification to enhance it.Dealloying is a way that can form a pore structure on the surface of the amorphous alloys,increasing the specific surface area and providing more reactive sites,which all contribute to the catalytic performance.Exploring the optimal conditions for Mg-based amorphous alloys in wastewater degradation by adjusting amorphous alloy composition,choosing suitable method to preparation and surface modification,reducing cost,expanding the pH range will advance the steps to put Mg-based amorphous alloys in industrial environments into practice.

Dual-functional MnS_(2)/MnO_(2) heterostructure catalyst for efficient acidic hydrogen evolution reaction and assisted degradation of organic wastewater

The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy.Herein,MnS_(2)/MnO_(2)-CC heterostructure dual-functional catalysts with ultrathin nanosheets were prepared by a twostep electrodeposition method for efficient acidic hydrogen evolution reaction(HER) and degradation of organic wastewater(such as methylene blue(MB)).The electronic structure of Mn atoms at the MnS_(2)/MnO_(2)-CC heterostructure interface is reconfigured under the joint action of S and O atoms.Theoretical calculations show that the Mn d-band electron distribution in MnS_(2)/MnO_(2)-CC catalyst has higher occupied states near the Fermi level compared to the MnO_(2) and MnS_(2) catalysts,which indicates that MnS_(2)/MnO_(2)-CC catalyst has better electron transfer capability and catalytic activity.The MnS_(2)/MnO_(2)-CC catalysts require overpotential of only 66 and 116 mV to reach current density of 10 and 100 mA cm^(-2)in MB/H_(2)SO_(4) media.The MnS_(2)/MnO_(2)-CC catalyst also has a low Tafel slope(26.72 mV dec^(-1)) and excellent stability(the performance does not decay after 20 h of testing).In addition,the MB removal efficiency of the MnS_(2)/MnO_(2)-CC catalyst with a better kinetic rate(0.0226) can reach 97.76%,which is much higher than that of the MnO_(x)-CC catalyst(72.10%).This strategy provides a new way to develop efficient and stable non-precious metal dual-functional electrocatalysts for HER and organic wastewater degradation.

The degradation of oxadiazon by nonthermal plasma with a dielectric barrier configuration

To explore the feasibility of a degradation approach by non-thermal plasma and the corresponding degradation pathways,studies on the oxadiazon removal in synthetic wastewater by a dielectric barrier discharge plasma reactor were investigated.The loss of the nitro group,dechlorination and ring cleavage is mainly involved in the non-thermal plasma degradation pathways of oxadiazon in a solution based on the OES and LC-MS analysis.Detection of EC25 and the production of the chlorine ion and nitrate ion further demonstrate the feasibility and validity of the approach.The conditions with a proper applied voltage,solution flow rate,oxygen flow rate,and solution pH contribute to the plasma degradation processes with a degradation ratio of over 94%.

Application of Microbial Fuel Cells in Wastewater Treatment

Traditional wastewater treatment is an industry with high energy consumption. Under the dual pressures of environmental pollution and energy shortage,microbial fuel cells（ MFCs） have been paid more attention to due to their unique advantages of high efficiency,high cleanliness,and environmental protection,and have become a research hotspot in the current environmental field. In this study,advances in the application of MFCs in wastewater treatment were summarized,and main problems were analyzed.

Screening of an Effective Degrading Strain for Treatment of Antibiotic Pharmaceutical Wastewater and Determination of Its Biological Properties

In this study,an effective antibiotic-degrading strain NG3 was isolated from activated sludge of antibiotic wastewater treatment.According to the results of morphological,physiological and biochemical identification and phylogenetical analysis of 16S r DNA sequence,the isolated strain belonged to Acinetobacter sp.,which was named Acinetobacter sp.NG3.Moreover,biological properties of the isolated strain were analyzed preliminarily,which provided a basis for the application of Acinetobacter sp.NG3 strain in efficient treatment of antibiotic industrial wastewater.

Engineering FeS_(2) nanoparticles on tubular g-C_(3)N_(4) for photo-Fenton treatment of paint wastewater

An efficient photo-Fenton catalyst(Fe S_(2)@HTCN)was designed by maximizing the synergistic effect of Fe S_(2)nanoparticles and hollow tubular g-C_(3)N_(4)(HTCN).Molecule self-assembly and molten salts-assisted calcination were used to engineering the hollow structured g-C_(3)N_(4)before anchoring Fe S_(2)nanoparticles on the walls of HTCN via reflux method.Compared to bulk g-C_(3)N_(4),the unique structure of HTCN and heterojunction in the composite endowed FeS_(2)@HTCN with more active sites and abundant channels for electron transfer and charge separation.The enriched electrons can improve the Fe^(3+) recycling and boost Fe^(2+) catalyzed ^(·)OH production via H_(2)O_(2).As-prepared photo-Fenton catalyst was successfully applied to the treatment of industrial paint wastewater.The paint wastewater with its COD as high as 8200 mg/L can be effectively degraded with 0.2 mol/L H_(2)O_(2)in 90 min under visible light irradiation.The photoFenton system was further evaluated according to the process stability and economic benefit,proving that the strategy presented in this work would be applicable to the treatment of real wastewater.

Co_(78)Si_(8)B_(14)metallic glass:A highly efficient and ultra-sustainable Fenton-like catalyst in degrading wastewater under universal pH conditions

Overcoming the pH limitation and increasing the catalyst reusability remain pressing demands for metal-lic glass(MG)in wastewater remediation.Herein,Co_(78)Si_(8)B_(14)MG ribbons are used to degrade dye wastew-ater by activating hydrogen peroxide(H_(2)O_(2))as Fenton-like catalysts.The Co-based MG catalysts exhibit high degradation efficiency under both acidic and alkaline conditions,and the kinetic reaction rate at pH 10(0.176 min^(−1)) and pH 4(0.089 min^(−1)) is 5.9 and 1.2 times higher than that of the extensively studied Fe-based MG catalysts,respectively.Impressively,the Co-based MG catalysts can be reused up to 20-60 times at universal pH conditions,demonstrating fairly good reusability.The newly discovered Co-based MG catalysts do not follow the classical Fenton reactions with H_(2)O^(2) the way Fe-based MGs do.In an acid environment,hydroxyl radicals play a dominant role in the degradation,while in an alkaline environ-ment,the effect of hydroxyl radicals is weakened,and Co^(3+) ions exert a relatively major function on the degradation.The excellent performance in catalytic activity and reusability at universal pH conditions of the Co-based MGs will inspire the development of MGs in wastewater treatment.

Synthesis,characterization and application of ZnO-Ag as a nanophotocatalyst for organic compounds degradation,mechanism and economic study

The current work deals with ZnO-Ag nanocomposites（in the wide range of x in the Zn1-x O-Ag x chemical composition） synthesized using microwave assisted solution combustion method.The structural, morphological and optical properties of the samples were characterized by XRD（X-ray diffraction）, FTIR（Fourier transform infrared spectrometry）, SEM（scanning electron microscopy technique）, EDX（energy dispersive X-ray spectrum）, ICP（inductively coupled plasma technique）, TEM（transmission electron microscopy）, BET（Brunauer–Emmett–Teller method）, UV–Vis（ultraviolet–visible spectrophotometer） and photoluminescence spectrophotometer. The photocatalytic activity of the ZnO-Ag was investigated by photo-degradation of Acid Blue 113（AB 113） under UV illumination in a semi-batch reactor. This experiment showed that ZnO-Ag has much more excellent photocatalytic properties than ZnO synthesized by the same method. The enhanced photocatalytic activity was due to the decrease in recombination of photogenerated electron-holes. The results showed the improvement of ZnO photocatalytic activity and there is an optimum amount of Ag（3.5 mol%） that needs to be doped with ZnO.The effect of operating parameters such as p H, catalyst dose and dye concentration were investigated. The reaction byproducts were identified by LC/MS（liquid chromatography/mass spectrometry） analysis and a pathway was proposed as well. Kinetic studies indicated that the decolorization process follows the first order kinetics. Also, the degradation percentage of AB113 was determined using a total organic carbon（TOC） analyzer. Additionally, cost analysis of the process, the mechanism and the role of Ag were discussed.

Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7

Fe（III） immobilized fire clay （Fe-FC） was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7 （AV 7） under natural sunlight. The 26% ferric nitrate loaded fire clay was found to be most efficient. The experimental conditions such as solution pH, H2O2 concentration for efficient degradation of AV 7 have been determined. Unlike Fenton catalyst, Fe-FC is photoactive over a wide pH range of 3-7. This catalyst was found to be stable and reusable. The GC-MS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6- triol, 8-aminonaphthalene-1,2,3,6-tetrol, 2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/ 2-aminobenzene-1,4-diol as intermediates. The 26% ferric nitrate loaded fire clay was characterized by XRD, ICP-AES, BET surface area, FT-IR, SEM-EDS and UV-DRS studies.