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Enhanced visible-light photocatalytic activity of multi-elements-doped ZrO_2 for degradation of indigo carmine

Journal of Rare Earths 2015年第5期33卷 498-506页

作者： E.S.Agorku A.T.Kuvarega b.b.mamba A.C.Pandey A.K.Mishra Department of Applied Chemistry University of Johannesburg University of South Africa College of Engineering Science and Technology Nanotechnology & Water Sustainability Research Unit Florida Campus Nanotechnology and Application Centre University of Allahabad

In this study, C,N,S-doped ZrO2 and a series of Eu doped C,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of C, N and S and Eu（NO3）·6H2O as source of Eu. The materials were characterized by X-ray dif-fraction （XRD）, Raman spectroscopy, Fourier transform infrared spectroscopy （FTIR）, UV-visible diffuse reflectance spectroscopy, scanning electron microscopy （SEM）/energy dispersive X-ray spectroscopy （EDX）, and transmission electron microscopy （TEM）. Indigo carmine （IC） was chosen as a model for organic pollutants and used to evaluate the photocatalytic performance of the photo-catalysts under simulated solar light. Commercial ZrO2 was used as a reference material. XRD and Raman results indicated the for-mation of both tetragonal and monoclinic phase ZrO2 with particle size ranging from 8–30 nm. Multi-element doping had a great in-fluence on the optical responses manifested as red shift in the absorption edge. The highest photocatalytic activity towards IC was observed for the Eu,C,N,S-doped ZrO2 （0.6 mol.%Eu） sample （k=1.09×10–2 min–1）. The commercial ZrO2 showed the lowest photo-degradation activity （k=5.83×10–4 min–1）. The results showed that the control of Eu doping in the C,N,S-ZrO2 was very important in reducing electron-hole recombination. The synergistic effect of Eu, C, N, and S in the ZrO2 matrix led to enhanced utilization of simulated solar energy for the degradation of IC through narrowing of bandgaps.

关键词： photocatalysis indigo carmine multi-elements-doped ZrO2 rare earths

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UV/visible spectroscopic analysis of CO^(3+) and CO^(2+) during the dissolution of cobalt from mixed Co-Cu oxidized ores

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 260-269页

作者： J. Ndalamo A.F. Mulaba-bafubiandi b.b. mamba Department of Chemical Technology University of Johannesburg Department of Extraction Metallurgy University of Johannesburg

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H2SO4 and SO2 as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solu-tions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO2. Fur-thermore, UV/visible spectroscopy confirmed that as SO2 was flushed into the acidified leaching solution, Co3＋ bearing minerals were re-duced to the readily soluble Co2＋ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co3＋ to Co2＋ bearing minerals when SO2 is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co3＋, Co2＋, and Cu2＋ complexes, as shown by their UV/visible spectra, are also discussed.

关键词： cobalt metallurgy dissolution leaching reaction kinetics spectroscopic analysis

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Rational design of efficient visible-light photocatalysts(1D@2D/0D)ZnO@Ni-doped biObr/bi heterojunction:Considerations on hierarchical structures,doping and SPR effect

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Journal of Materials Science & Technology 2022年第30期125卷 38-50页

作者： Zhouzheng Jin Jingru Li Yiming Zhang Dan Liu Hui Ding bhekie b.mamba Alex T.Kuvarega Jianzhou Gui State Key Laboratory of Separation Membranes and Membrane Processes Tianjin Key Laboratory of Green Chemical Technology and Process Engineeringand School of Material Science and EngineeringTiangong UniversityTianjin 300387China School of Chemical Engineering and Technology Tiangong UniversityTianjin 300387China School of Chemistry Tiangong UniversityTianjin 300387China School of Environmental Science and Engineering Tianjin UniversityTianjin300072China University of South Africa College of ScienceEngineering and TechnologyNanotechnology and Water Sustainability Research UnitFlorida Science Campus 1710South Africa

Simultaneously integrating heterogeneous interface,element doping,and metal decorating was a promising strategy to promote the visible-light-driven photocatalytic ***,we demonstrated a facile solvothermal route for Ni-doped biObr/bi^(0) with ZnO 3D hierarchical heterojunction(denoted as Z@b/biNi).The optimal photocatalysts of Z@b/bi-Ni sample presented a remarkable catalytic performance of high concentrations of tetracycline solution(40 mg/L)than those of the Z@b/bi,Z@b,bOb and ZnO photocatalysts toward the visible-light-driven *** enhanced photocatalytic mechanism can be proposed as follows:(ⅰ)3D hierarchical heterojunction provided more active sites and accelerated the separation of charge carriers for photocatalytic TC;(ⅱ)formation of oxygen vacancies on the surface over Z@b/bi-Ni by in-situ reduction of bi^(0) and Ni doping could serve as the active sites for oxygen activation to adsorb free O_(2) and generate more superoxide radicals;(ⅲ)SPR effect of bi metal were beneficial to carrier separation and also act as the active site to trap O_(2) *** work clarified the role of unique morphologies,surface plasmonic resonance(SPR)effect of metal bi,and Ni doping in Z@b/bi-Ni,and its photocatalytic reaction mechanism was proposed by a series of experiments,characterization and DFT calculations,arousing a new perspective to design hierarchical heterojunction photocatalysts.

关键词： Hierarchical heterojunction Oxygen vacancies Doping Ni SPR effect Photocatalysis

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Thermally and mechanically stableβ-cyclodextrin/cellulose acetate nanofibers synthesized using an environmentally benign procedure

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International Journal of Smart and Nano Materials 2017年第1期8卷 1-19页

作者： Lebea N.Nthunya Monaheng L.Masheane Soraya P.Malinga Edward N.Nxumalo bhekie b.mamba Sabelo D.Mhlanga Nanotechnology and Water Sustainability Research Unit College of ScienceEngineering and TechnologyUniversity of South AfricaJohannesburgSouth Africa Department of Applied Chemistry and the DST/Mintek Nanotechnology Innovation Centre-Water Research Node University of JohannesburgJohannesburgSouth Africa

Electrospun cyclodextrin(CD)-based nanofibers with capabilities to remove pollutants from water have been synthesized and *** high-quality nanofibers presented here were synthesized in two simple steps that involved in-situ electrospinning of the nanofibers and all nanocomponents,followed by the reduction of silver(Ag+)and iron(Fe3+)ions to nanoparticles using an environmentally benign process that involved irradiation of the electrospun fibers using a tailor-made UV-equipped furnace at low *** the previously reported study it was observed that Ag and Fe nanoparticles effectively removed a range of different strains of Gram-negative and Gram-positive bacteria from *** such,this study focused on improving the thermal and mechanical properties of the nanofibers prepared from polymer blends ofβ-CDs with cellulose acetate(CA)and small additions(2 wt%)of functionalized multiwalled carbon nanotubes(fMWCNTs).The electrospinning parameters were varied to determine the optimum conditions for preparation of uniform nonbeaded ***-free and uniform nanofibers were obtained at a polymer concentration of 32%at the ratio of 1:1β-CDs:CA,syringe injection flow rate of 0.7 mL h−1,15 cm between the tip of the spinneret and the collector,and a voltage of 16 *** addition of f-MWCNTs was found to improve the tensile strength of the nanofibers by twofold,relative to nanofibers with no *** thermal degradation of the nanofibers was improved by a magnitude of 50°*** study has shown that adding small amounts of f-MWCNTs improved the thermal stability and mechanical strength of the CD/CA nanofibers significantly.

关键词： β-Cyclodextrins cellulose acetate mechanical strength nanofibers thermal stability

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Fe_(3)O_(4)对黄铜矿在酸性硫酸铁溶液中铜溶解氧化还原反应的影响

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Transactions of Nonferrous Metals Society of China 2024年第6期34卷 1965-1975页

作者： Kolela J NYEMbWE Elvis FOSSO-KANKEU Frans WAANDERS Martin MKANDAWIRE Didier K NYEMbWE bhekie b mamba Water Pollution Monitoring and Remediation Initiatives Research Group School of Chemical and Minerals EngineeringFaculty of EngineeringNorth-West UniversityPotchefstroomSouth Africa Department of Mining Engineering College of Science Engineering and TechnologyUniversity of South AfricaFlorida Science CampusJohannesburgSouth Africa Department of Metallurgy Faculty of Engineering and Built EnvironmentUniversity of JohannesburgDoornfonteinJohannesburgSouth Africa Department of Chemistry School of Science and TechnologyCape Breton UniversityCanada School of Mining Metallurgy and Chemical EngineeringFaculty of Engineering and the Built EnvironmentUniversity of JohannesburgJohannesburgSouth Africa Institute for Nanotechnology and Water Sustainability College of Science Engineering and TechnologyUniversity of South AfricaFlorida Science CampusJohannesburgSouth Africa

由于钝化层的形成,黄铜矿(CuFeS_(2))在氧化条件下浸出通常具有溶解速率缓慢的特点。为了将黄铜矿浸出过程中的钝化效应降至最低并提高铜的回收率,研究了CuFeS_(2)在不同pH值(1.0、1.5和1.8)和温度(25和50℃)条件下浸出时,向Fe_(2)(SO_(... 详细信息

由于钝化层的形成,黄铜矿(CuFeS_(2))在氧化条件下浸出通常具有溶解速率缓慢的特点。为了将黄铜矿浸出过程中的钝化效应降至最低并提高铜的回收率,研究了CuFeS_(2)在不同pH值(1.0、1.5和1.8)和温度(25和50℃)条件下浸出时,向Fe_(2)(SO_(4))_(3)−H_(2)SO_(4)浸出剂中添加磁铁矿(Fe_(3)O_(4))对铜溶解速率的影响。结果表明,溶液pH值、电位和温度在溶解过程中起着关键作用。在pH 1.8、50℃和400 mV的条件下,Fe_(3)O_(4)−CuFeS_(2)混合体系中铜的回收率达到最大值(70%),而未添加Fe_(3)O_(4)时,CuFeS_(2)中铜的回收率较低(48%)。添加Fe_(3)O_(4)有助于维持较高的氧化还原值。添加Fe_(3)O_(4)还使活化能从79.04 kJ/mol降低到53.69 kJ/mol。这表明,当Fe_(3)O_(4)存在时,由于形成了更易溶解的中间体斑铜矿(Cu_(5)FeS_(4))和辉铜矿(Cu_(2)S),CuFeS_(2)更易被氧化。两种溶解过程都受到矿物表面的化学控制。此外,对浸出残渣的矿物学分析表明,当无Fe_(3)O_(4)存在时,作为表面钝化物的黄钾铁矾浓度较高。因此,添加Fe_(3)O_(4)减少了钝化层的形成,提升了铜的回收率。

关键词：黄铜矿溶解磁铁矿电偶钝化

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在TiO_(2)@C/Fe_(2)O_(3)纳米片阵列上电还原硝酸根制氨:揭示水热碳的影响

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Science China Materials 2023年第11期66卷 4367-4376页

作者：吴璇马爱静刘丹李雪倩周颖康 Alex T.Kuvarega bhekie b.mamba 李虎桂建舟 State Key Laboratory of Separation Membranes and Membrane Processes School of Material Science and TechnologyTiangong UniversityTianjin 300387China Tianjin Key Laboratory of Green Chemical Technology and Process Engineering School of Chemical Engineering and TechnologyTiangong UniversityTianjin 300387China School of Chemistry Tiangong UniversityTianjin 300387China Institute for Nanotechnology and Water Sustainability College of ScienceEngineering and TechnologyUniversity of South AfricaFlorida 1709JohannesburgSouth Africa Ningxia Coal Industry Co. Ltd.CHN ENERGYYinchuan 750011China

电化学硝酸根还原制氨(NRA)可以同时实现硝酸盐废水处理和氨合成,是一种很有前途的环保节能策略.目前构建高效的电催化剂是人们关注的焦点.本文构建了TiO_(2)@C/Fe_(2)O_(3)纳米片阵列作为高效催化剂,采用多种表征手段系统研究了水热碳... 详细信息

电化学硝酸根还原制氨(NRA)可以同时实现硝酸盐废水处理和氨合成,是一种很有前途的环保节能策略.目前构建高效的电催化剂是人们关注的焦点.本文构建了TiO_(2)@C/Fe_(2)O_(3)纳米片阵列作为高效催化剂,采用多种表征手段系统研究了水热碳的引入对NRA性能的影响.我们发现水热碳既可作为良导体实现电荷的快速传递,又可作为还原剂引入更多的氧空位,实现了“一石二鸟”催化剂构建策略.与TiO_(2)/Fe_(2)O_(3)相比,TiO_(2)@C/Fe_(2)O_(3)具有更高的NRA性能,硝酸盐转化率为88.6%、氨选择性为83.4%、法拉第效率为85.3%、氨收率为0.2176 mmol h^(-1)cm^(-2).此外,在9次循环实验后,TiO_(2)@C/Fe_(2)O_(3)的高活性仍得以保持,证实了TiO_(2)@C/Fe_(2)O_(3)出色的稳定性.此外,我们利用电化学准原位电子自旋共振实验、电化学原位衰减全反射傅立叶变换红外测量和在线差分电化学质谱法推导了可能的NRA反应途径.这种引入水热碳中间层的策略可为开发新型NRA电催化剂开辟新的途径.

关键词： ammonia electrocatalysis nitrate TiO_(2) hydro-thermal carbon

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从水中去除有机污染物的单一功能化环式糊精聚合物

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水处理信息报导 2008年第5期 43-44页

作者： mamba, b.b.

水对于民用、工业、农业和娱乐业均是一种重要的资源。但是目前由于水系统中有机污染物的累积导致水质明显恶化。常用的水处理技术不能成功去除这些污染物，达到理想的含量。近期的研究表明，环式糊精纳孔聚合物能够从水中吸附污染物使... 详细信息

水对于民用、工业、农业和娱乐业均是一种重要的资源。但是目前由于水系统中有机污染物的累积导致水质明显恶化。常用的水处理技术不能成功去除这些污染物，达到理想的含量。近期的研究表明，环式糊精纳孔聚合物能够从水中吸附污染物使之达到ppb级。我们已经论证了功能化环式糊精聚合物能够提高对某些有机污染物的吸附能力。文中我们报告了几种不溶的单取代环式糊精聚合物和“纳海绵体”。研究显示这些聚合物对于从水溶液中吸附对硝基酚和五氯苯酚具有提高的能力。

关键词：有机污染物环式糊精聚合物功能化水质吸附能力水处理技术 ppb级

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