Boost activation of peroxymonosulfate by iron doped K_(2-x)Mn_(8)O_(16):Mechanism and properties

Among the numerous transition metal catalysts,manganese-based compounds are considered as promising peroxymonosulfate(PMS)catalysts due to their low cost and environmental friendliness,such as cryptomelane manganese oxide(K_(2-x)Mn_(8)O_(16):abbreviation KMnO).However,the limited catalytic performance of KMnO limits its practical application.In this work,iron-doped KMnO(Fe-KMnO)was prepared by one-step hydrothermal method to optimize its catalytic performance.Compared with KMnO/PMS system,Fe-KMnO/PMS system possessed more excellent removal efficiency of tetracycline(TC).Meanwhile,the Fe-KMnO/PMS system also exhibited good practical application potential and excellent stability.The mechanism of Fe-KMnO activation of PMS was further analyzed in detail.It was found that Fe participated in the redox of high-valent Mn,which promoted the activation of PMS.Moreover,The Fe site as an adsorption site enhanced the TC enrichment ability of the catalyst,reducing the mass transfer resistance and further enhancing the TC removal ability of Fe-KMnO/PMS system.This work not only provides an excellent PMS catalyst,but also offers new insights into the mechanism of PMS activation by bimetallic manganese-based catalysts.

Insights into moisture content in coals of different ranks by low field nuclear resonance

The moisture occurrence in coal reservoirs has important significance in the evaluation of gas-bearing properties and production of coalbed methane(CBM).In order to investigate the occurrence mechanism of moisture content of coals,a series of experiments including mercury intrusion porosimetry(MIP),low temperature nitrogen gas absorption/desorption(N_(2)GA)and nuclear magnetic resonance(NMR)are conducted in this study to characterize and quantify pore structure properties.The nature of occurrence of moisture content in coal reservoir pores is then divided into four categories by NMR saturation and centrifugation experiments.The bound water content in the adsorption pore accounts for the highest proportion.Based on the relevance of bound water content and its influencing factors,moisture occurrence in coal reservoirs of different ranks is revealed by SPSS statistical methods.The moisture content of low-rank coal is mainly controlled by elemental oxygen and specific surface area,whereas for medium-and high-rank coals,this is controlled mainly by minerals.Our study finds application in CBM evaluation and development.

Characteristics and formation mechanism of siltstone-mudstone rhythmic sedimentary sections in the Lower Silurian Longmaxi Formation in the Changning area,South Sichuan Basin,southwest China

The Lower Member of the Longrnaxi Forma-tion is generally dominated by siliceous shale,but recently we found some siltstone-mudstone rhythm sections developed in the Lower Member of the Longmaxi Formation.The study of formation mechanism of siltstone-mudstone rhythmic sedimentary sections may provide new insights into the shale sedimentary environ-ment.Therefore,we studied the characteristics and formation mechanism of siltstone-mudstone rhythmic sedimentary sections in the Lower Member of the Long-maxi Formation in the Changning area based on core observation,thin section identification,major elements and trace elements analysis.The results show the following:1)Two siltstone-mudstone rhythmic sedimentary sections are characterized by frequent interbed between black or gray-black shale and light gray siltstone,abundant argillaceous laminas and silty laminas,with obvious lithological boundaries having developed.Horizontal laminas and rhythmic laminas are well-developed in the shale layer,while the wavy laminas are well-developed in the siltstone layer.2)The major compositional elements are SiO2,Al2O3 and CaO,followed by Fe_(2)O_(3),MgO,K_(2)O and Na_(2)O.3)Compared with the world average shale,these siltstone-mudstone rhythmic sedimentary sections are rich in Mo,U and Ba,but less in V,Co,Ni,Cu.Compared with the shale layer,the siltstone layer has lower contents of V,Co and Ni.4).The geochemical redox indices,Mo-U and CIA values suggest the formation of the siltstone-mudstone rhythmic sedimentary sections are related to influences from bottom currents in an oxic condition with a warm and humid paleoclimate.