铜精矿选择性浸出降铋研究

钢精矿超铋使其冶炼受到极大限制,针对这一问题,研究了超铋铜精矿选择性浸出降铋的作用机理及效果,影响浸铋的因素与技术参数,寻求最佳工艺条件。

Polyoxometalates‐doped Bi_(2)O_(3–x)/Bi photocatalyst for highly efficient visible‐light photodegradation of tetrabromobisphenol A and removal of NO

Bismuth‐based photocatalysts are a class of excellent visible‐light photocatalysts;however,their redox activity is relatively poor and the efficiency of photogenerated carrier separation is low,limiting their development and application in the field of photocatalysis.To address these issues,a series of polyoxometalate PW_(12)O_(40)^(3–)‐doped Bi_(2)O_(3–x)/Bi Schottky photocatalysts PW_(12)@Bi_(2)O_(3–x)/Bi‐n(PBOB‐n,where n is the amount of NaBH4,i.e.,6,12,18,24,and 48 mg)were prepared by a simple electrospinning/calcination/in‐situ NaBH4 reduction method.In this composite photocatalyst,the doping of PW_(12) could effectively adjust the electronic structure of Bi_(2)O_(3–x) and improve its redox properties.As a shallow electron trap,PW_(12) promoted the separation of the photogenerated carriers.Furthermore,desirable Schottky junction between the metal Bi nanoparticles and PW_(12)@Bi_(2)O_(3–x) further accelerated the separation of the photogenerated carriers.The synergistic effect of the aforementioned factors endowed PBOB‐n with excellent photocatalytic activity.Among the samples,PBOB‐18 exhibited superior photocatalytic activity.Under visible‐light irradiation,93.7%(20 mg catalyst)of 20 ppm tetrabromobisphenol A(TBBPA,20 mL)was degraded in 60 min.Its activity was 4.4 times higher than that of Bi_(2)O_(3).PBOB‐18 also exhibited an ultrahigh photocatalytic performance for the removal of NO.Its removal rate(600 ppb)reached 83.3%in 30 min,making it one of the most active Bi‐based photocatalysts.Furthermore,the photocatalytic mechanisms of PBOB‐18 for TBBPA and NO have been proposed.This work provides a new direction and reference for the design of low‐cost,efficient,stable,and versatile photocatalysts.

Pt/Bi_(24)O_(31)Cl_(10) composite nanosheets with significantly enhanced photocatalytic activity under visible light irradiation

Efficient composite semiconductor photocatalysts are highly desirable for the visible-light-driven degradation of organic pollutants. In this study, Bi24O31Cl10 photocatalyst was prepared via a hydrothermal method and modified with Pt nanoparticles (NPs) through a facile deposition procedure. The composite photocatalyst was characterized by X-ray diffraction, transmission electronic microscopy, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, photoluminescence spectroscopy, and electron spin resonance. The 1.0 wt% Pt/Bi24O31Cl10 photocatalyst showed the highest activity for the degradation of methyl orange under visible light (source: 300 W Xe lamp coupled with a UV-cutoff filter), and the photocatalytic degradation efficiency improved about 2.2 times compared to that of pure Bi24O31Cl10. The composite photocatalyst could maintain most of its activity after four runs of the photocatalytic experimental cycle. This study could provide a novel insight for the modification of other desirable semiconductor materials to achieve high photocatalytic activities.

Synthesis of Bi_2S_3 microsphere and its efficient photocatalytic activity under visible-light irradiation

A novel Bi2S3 microsphere was fabricated through one-pot urea-assisted solvothermal method.The synthesized Bi2S3 microsphere was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transformed infrared spectroscopy(FT-IR)and thermal gravimetric analysis and differential thermal analysis(DTA-TG).Subsequently,the photocatalytic performances of Bi2S3 microsphere were evaluated by photocatalytic degradation of methyl orange(MO)simulation solution under visible-light irradiation.The results show that,Bi2S3 microsphere could be used as a potential cost-efficient catalysis for eliminating of methyl orange from aqueous solutions,whose degradation rate could reach 91.07%within 180 min.Besides,a tentative photocatalytic reaction mechanism was discussed according to the energy band position.Therefore,this work indicated a simplistic approach for the fabrication of visible-light responsive Bi2S3 microsphere photocatalyst,which can be used as a valuable candidate in solar energy conversion and environment pollution treatment.

Construction of Z-scheme Ag_3PO_4/Bi_2WO_6 composite with excellent visible-light photodegradation activity for removal of organic contaminants

Ag3PO4has good potential for use in photocatalytic degradation of organic contaminants.However,the activity and stability of Ag3PO4is hard to sustain because of photocorrosion and the positive potential of the conduction band of Ag3PO4.In this study,A composite consisting of Bi2WO6nanosheets and Ag3PO4was developed to curb recombination of charge carriers and enhance the activity and stability of the catalyst.Formation of a Ag3PO4/Bi2WO6composite was confirmed using X‐ray diffraction,energy‐dispersive X‐ray spectroscopy,and X‐ray photoelectron spectroscopy.Photoluminescence spectroscopy provided convincing evidence that compositing Bi2WO6with Ag3PO4effectively reduced photocorrosion of Ag3PO4.The Ag3PO4/Bi2WO6composite gave a high photocatalytic performance in photodegradation of methylene blue.A degradation rate of0.61min?1was achieved;this is1.3and6.0times higher than those achieved using Ag3PO4(0.47min?1)and Bi2WO6(0.10min?1),respectively.Reactive species trapping experiments using the Ag3PO4/Bi2WO6composite showed that holes,?OH,and?O2?all played specific roles in the photodegradation process.The photocatalytic mechanism was investigated and a Z‐scheme was proposed as a plausible mechanism.

Preparation of a p-n heterojunction BiFeO_3@TiO_2 photocatalyst with a core–shell structure for visible-light photocatalytic degradation

Magnetically separable bismuth ferrite(BiFeO3)nanoparticles were fabricated by a citrate self‐combustion method and coated with titanium dioxide(TiO2)by hydrolysis of titanium butoxide(Ti(OBu)4)to form BiFeO3@TiO2core-shell nanocomposites with different mass ratios of TiO2to BiFeO3.The photocatalytic performance of the catalysts was comprehensively investigated via photocatalytic oxidation of methyl violet(MV)under both ultraviolet and visible‐light irradiation.The BiFeO3@TiO2samples exhibited better photocatalytic performance than either BiFeO3or TiO2alone,and a BiFeO3@TiO2sample with a mass ratio of1:1and TiO2shell thickness of50-100nm showed the highest photo‐oxidation activity of the catalysts.The enhanced photocatalytic activity was ascribed to the formation of a p‐n junction of BiFeO3and TiO2with high charge separation efficiency as well as strong light absorption ability.Photoelectrochemical Mott-Schottky(MS)measurements revealed that both the charge carrier transportation and donor density of BiFeO3were markedly enhanced after introduction of TiO2.The mechanism of MV degradation is mainly attributed to hydroxyl radicals and photogenerated electrons based on energy band theory and the formation of an internal electrostatic field.In addition,the unique core-shell structure of BiFeO3@TiO2also promotes charge transfer at the BiFeO3/TiO2interface by increasing the contact area between BiFeO3and TiO2.Finally,the photocatalytic activity of BiFeO3@TiO2was further confirmed by degradation of other industrial dyes under visible‐light irradiation.

Fabrication of Z-scheme MoO3/Bi2O4 heterojunction photocatalyst with enhanced photocatalytic performance under visible light irradiation

Constructing Z-scheme heterojunction to improve the separation efficiency of photogenerated carriers of photocatalysts has gained extensive attention.In this work,we fabricated a novel Z-scheme MoO3/Bi2O4 heterojunction photocatalyst by a hydrothermal method.XPS analysis results indicated that strong interaction between MoO3 and Bi2O4 is generated,which contributes to charge transfer and separation of the photogenerated carriers.This was confirmed by photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)tests.The photocatalytic performance of the as-synthesized photocatalysts was evaluated by degrading rhodamine B(RhB)in aqueous solution under visible light irradiation,showing that 15%MoO3/Bi2O4(15-MB)composite exhibited the highest photocatalytic activity,which is 2 times higher than that of Bi2O4.Besides,the heterojunction photocatalyst can keep good photocatalytic activity and stability after five recycles.Trapping experiments demonstrated that the dominant active radicals in photocatalytic reactions are superoxide radical( O2-)and holes(h+),indicating that the 15-MB composite is a Z-scheme photocatalyst.Finally,the mechanism of the Z-scheme MoO3/Bi2O4 composite for photo-degrading RhB in aqueous solution is proposed.This work provides a promising strategy for designing Bi-based Z-scheme heterojunction photocatalysts for highly efficient removal of environmental pollutants.