Synthetic dyes are commonly used for graphite depression in poly-metallic flotation circuits; however,these dyes can be very expensive. The aim of this study is to evaluate performance of certain low-cost alternative ...Synthetic dyes are commonly used for graphite depression in poly-metallic flotation circuits; however,these dyes can be very expensive. The aim of this study is to evaluate performance of certain low-cost alternative depressants for a complex lead-zinc(Pb-Zn) ore rich in graphite(Gr-C) on a conventional mini pilot-scale flotation circuit. The reagents used were commercial and industrial grade starch; agro-based waste-sugarcane bagasse and charred(burnt) bagasse powder. The primary evaluation criteria were quality(grades) of lead and zinc concentrates, their recoveries(%), and graphite rejection(%) in the tails.Benchmark tests using nigrosine as graphite depressant showed 94.3% rejection of Gr-C. The results with commercial starch were found as effective with 93.8% graphite rejection. Furthermore, bagasse powder showed potential in improving product quality(36.4% and 65.6% Pb grade and recovery) with an intermediate effectiveness in graphite rejection(85.6%). The order of effectiveness in Gr-C rejection follows nigrosine % commercial starch > bagasse > industrial starch > charred bagasse. In addition, the effect these depressants on silver(byproduct) grade and recovery was also investigated.展开更多
Low-cost, highly efficient catalysts for hydrogen evolution reaction(HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides(2 D Mo S2)...Low-cost, highly efficient catalysts for hydrogen evolution reaction(HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides(2 D Mo S2) have been conducted due to their remarkable catalytic properties.However, most of the reported syntheses are time consuming,complicated and less efficient. The present work demonstrates the production of Mo S2/graphene catalyst via an ultra-fast(60 s) microwave-initiated approach. High specific surface area and conductivity of graphene delivers a favorable conductive network for the growth of Mo S2 nanosheets, along with rapid charge transfer kinetics. As-produced Mo S2/graphene nanocomposites exhibit superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of62 m V, high cathodic currents and a Tafel slope of43.3 m V/decade. Beyond excellent catalytic activity, Mo S2/graphene reveals long cycling stability with a very high cathodic current density of around 1000 m A cm^-2 at an overpotential of 250 m V. Moreover, the Mo S2/graphene-catalyst exhibits outstanding HER activities in a temperature range of 30 to 120°C with low activation energy of36.51 k J mol^-1, providing the opportunity of practical scalable processing.展开更多
Seeking catalysts with high electrocatalytic activity for ambient-condition N2 reduction reaction (NRR) remains an ongoing challenge due to the chemical inertness of N2.Herein,defect-rich WS2 nanosheets (WS2-x) were d...Seeking catalysts with high electrocatalytic activity for ambient-condition N2 reduction reaction (NRR) remains an ongoing challenge due to the chemical inertness of N2.Herein,defect-rich WS2 nanosheets (WS2-x) were designed as an efficient electrocatalyst for NRR,which were prepared via vulcanizing the oxygen-vacancy-rich tungsten oxide in a vacuum tube.The sulfur defects were conducive to the adsorption and activation of N2.In neutral electrolyte of 0.1 mol L^(-1)Na2SO_(4) at-0.60 V vs.reversible hydrogen electrode,such WS2-xoffered a high Faradaic efficiency of 12.1%with a NH3generation rate of 16.38μg h-1mg-1cat..展开更多
We develop here a simple wet chemistry to prepare covalent functionalized graphenes （FGs） through epoxide aminolysis espe- cially under alkaline aqueous condition. Remarkably, a series of typical monoamines, such as...We develop here a simple wet chemistry to prepare covalent functionalized graphenes （FGs） through epoxide aminolysis espe- cially under alkaline aqueous condition. Remarkably, a series of typical monoamines, such as industrial Huntsman Jeffamine M-2070 and M-2005 polymer with hydrophilic or hydrophobic polyetheramine chains, positively-charged 2-amino-N,N,N- trimethylpropanaminium, negatively-charged sulfanilic acid, even oligopeptide sequence, can be effectively grafted on the platelets of graphene oxide precursor with covalent functionalization and partially reduced features. This strategy provides the researchers a facile and convenient approach to design and synthesize solution processable, biocompatible and functionalized graphenes for the potent applications in electronic inks, drug carriers and biomedicines. Expansion of the current study is actively ongoing in our laboratory.展开更多
Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of...Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of the interface and humidity responsive actuators primarily limit their applications. Herein, by experimentally optimizing interface of bimorph structure, we build graphene oxide/ethyl cellulose bidirectional bending actuators — a case of bimorphs with fast and reversible shape changes in response to environmental humidity gradients. Meanwhile, we employ the actuator as the engine to drive piezoelectric detector. In this case, graphene oxide and ethyl cellulose are combined with chemical bonds, successfully building a bimorph with binary synergy strengthening and toughening. The excellent hygroscopicity of graphene oxide accompanied with huge volume expansion triggers giant moisture responsiveness greater than 90 degrees. Moreover, the open circuit voltage of piezoelectric detector holds a peak value around 0.1 V and exhibits excellent reversibility. We anticipate that humidity-responsive actuator and detector hold promise for the application and expansion of smart devices in varieties of multifunctional nanosystems.展开更多
基金The author is grateful to the management and staff of Center Research Development laboratory(HZL,Debari),India for their support with this research and permitting to publish the work.
文摘Synthetic dyes are commonly used for graphite depression in poly-metallic flotation circuits; however,these dyes can be very expensive. The aim of this study is to evaluate performance of certain low-cost alternative depressants for a complex lead-zinc(Pb-Zn) ore rich in graphite(Gr-C) on a conventional mini pilot-scale flotation circuit. The reagents used were commercial and industrial grade starch; agro-based waste-sugarcane bagasse and charred(burnt) bagasse powder. The primary evaluation criteria were quality(grades) of lead and zinc concentrates, their recoveries(%), and graphite rejection(%) in the tails.Benchmark tests using nigrosine as graphite depressant showed 94.3% rejection of Gr-C. The results with commercial starch were found as effective with 93.8% graphite rejection. Furthermore, bagasse powder showed potential in improving product quality(36.4% and 65.6% Pb grade and recovery) with an intermediate effectiveness in graphite rejection(85.6%). The order of effectiveness in Gr-C rejection follows nigrosine % commercial starch > bagasse > industrial starch > charred bagasse. In addition, the effect these depressants on silver(byproduct) grade and recovery was also investigated.
基金supported by Auburn UniversityIntramural Grants Program (AU-IGP)
文摘Low-cost, highly efficient catalysts for hydrogen evolution reaction(HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides(2 D Mo S2) have been conducted due to their remarkable catalytic properties.However, most of the reported syntheses are time consuming,complicated and less efficient. The present work demonstrates the production of Mo S2/graphene catalyst via an ultra-fast(60 s) microwave-initiated approach. High specific surface area and conductivity of graphene delivers a favorable conductive network for the growth of Mo S2 nanosheets, along with rapid charge transfer kinetics. As-produced Mo S2/graphene nanocomposites exhibit superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of62 m V, high cathodic currents and a Tafel slope of43.3 m V/decade. Beyond excellent catalytic activity, Mo S2/graphene reveals long cycling stability with a very high cathodic current density of around 1000 m A cm^-2 at an overpotential of 250 m V. Moreover, the Mo S2/graphene-catalyst exhibits outstanding HER activities in a temperature range of 30 to 120°C with low activation energy of36.51 k J mol^-1, providing the opportunity of practical scalable processing.
基金supported by the National Natural Science Foundation of China (21874079)the Natural Science Foundation for Outstanding Young Scientists of Shandong Province (ZR2018JL011)+3 种基金the Key R&D Project of Shandong Province (GG201809230180)Taishan Scholars Program of Shandong Province (tsqn201909088)the Outstanding Youth Innovation Team of Universities in Shandong Province (2019KJA027)the Science & Technology Fund Planning Project of Shandong Colleges and Universities (J16LA13 and J18KA112)。
文摘Seeking catalysts with high electrocatalytic activity for ambient-condition N2 reduction reaction (NRR) remains an ongoing challenge due to the chemical inertness of N2.Herein,defect-rich WS2 nanosheets (WS2-x) were designed as an efficient electrocatalyst for NRR,which were prepared via vulcanizing the oxygen-vacancy-rich tungsten oxide in a vacuum tube.The sulfur defects were conducive to the adsorption and activation of N2.In neutral electrolyte of 0.1 mol L^(-1)Na2SO_(4) at-0.60 V vs.reversible hydrogen electrode,such WS2-xoffered a high Faradaic efficiency of 12.1%with a NH3generation rate of 16.38μg h-1mg-1cat..
基金supported by the Ministry of Science and Technology of China (2014CB239402, 2013CB834505, 2013CB834804)the National Natural Science Foundation of China (91427303, 21372232, 21204052)+1 种基金the Key Research Programme of the Chinese Academy of Sciences (KGZD-EW-T05)the Foundation of Director of TIPC
文摘We develop here a simple wet chemistry to prepare covalent functionalized graphenes （FGs） through epoxide aminolysis espe- cially under alkaline aqueous condition. Remarkably, a series of typical monoamines, such as industrial Huntsman Jeffamine M-2070 and M-2005 polymer with hydrophilic or hydrophobic polyetheramine chains, positively-charged 2-amino-N,N,N- trimethylpropanaminium, negatively-charged sulfanilic acid, even oligopeptide sequence, can be effectively grafted on the platelets of graphene oxide precursor with covalent functionalization and partially reduced features. This strategy provides the researchers a facile and convenient approach to design and synthesize solution processable, biocompatible and functionalized graphenes for the potent applications in electronic inks, drug carriers and biomedicines. Expansion of the current study is actively ongoing in our laboratory.
基金financially supported by the National Basic Research Program of China (2015CB932302)National Natural Science Foundation of China (U1432133, 11621063, 21701164)+2 种基金National Program for Support of Top-notch Young Professionalsthe Fundamental Research Funds for the Central Universities (WK2060190084, WK2060190058)supported from the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology
文摘Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of the interface and humidity responsive actuators primarily limit their applications. Herein, by experimentally optimizing interface of bimorph structure, we build graphene oxide/ethyl cellulose bidirectional bending actuators — a case of bimorphs with fast and reversible shape changes in response to environmental humidity gradients. Meanwhile, we employ the actuator as the engine to drive piezoelectric detector. In this case, graphene oxide and ethyl cellulose are combined with chemical bonds, successfully building a bimorph with binary synergy strengthening and toughening. The excellent hygroscopicity of graphene oxide accompanied with huge volume expansion triggers giant moisture responsiveness greater than 90 degrees. Moreover, the open circuit voltage of piezoelectric detector holds a peak value around 0.1 V and exhibits excellent reversibility. We anticipate that humidity-responsive actuator and detector hold promise for the application and expansion of smart devices in varieties of multifunctional nanosystems.
