The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surroga...The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.展开更多
Soil pollution(heavy metals and organic matter)is becoming more and more serious,phytoremediation has rapidly become a highly important method to deal with this problem.Therefore,the treatment and disposal of hyperacc...Soil pollution(heavy metals and organic matter)is becoming more and more serious,phytoremediation has rapidly become a highly important method to deal with this problem.Therefore,the treatment and disposal of hyperaccumulators have been a topic of concern.In this paper,carambola leaves are selected as feedstock considering that carambola is a potential hyperaccumulator.A series of tests were performed to discuss 6 main influencing factors on total gas yield and metal fixing using a non-thermal arc plasma setup,to investigate the feasibility of plasma treatment of hyperaccumulator and provide a new method to utilize the harvested hyperaccumulator.The maximum total gas yield reached approximately 85%at an airflow rate of 3 L/min,the processing time of 7 min,discharge power of 29.95 W with the addition of water(water:sample=1:1).A reducing or inert carrier gas or the addition of some specific inorganic additives at optimal conditions were in favor of increasing metal fixing efficiency.However,the effects of these factors usually have two sides,and some factors may have conflicting effects between gas yield and metal fixing,and.It is necessary to optimize these factors for achieving the desired goal.The obtained solid products exhibit the potential to fix metals and act as activated carbon.展开更多
Hydrogen is a kind of energy source with a characteristic of high calorific value and plasma is regarded as a good method of hydrogen production.Hydrogen produced from ethanol reforming using micro plasma can be utili...Hydrogen is a kind of energy source with a characteristic of high calorific value and plasma is regarded as a good method of hydrogen production.Hydrogen produced from ethanol reforming using micro plasma can be utilized for portable applications.The study introduces water/carbon ratio,residence time,and ethanol mass flow rate as the parameters of experimental conditions,and makes ethanol conversion,gas production rate,gas product selectivity,energy consumption,and efficiency of hydrogen production per unit as the evaluation parameters of ethanol reforming reaction.The experimental results showed that(1)in the argon micro plasma:the maximum ethanol conversion of 25.3%was obtained at residence time=2.1 ms,ethanol mass flow rate=0.01 g/s and S/C=1.0,and the peak value of hydrogen production of 18.7μmol/s was achieved at residence time=2.1 ms,ethanol mass flow rate=0.05 g/s and S/C=1.0;(2)in the air micro plasma:the maximum ethanol conversion of 37.4%was obtained at residence time=2.1 ms,ethanol mass flow rate=0.01 g/s and S/C=1.0,and the peak value of hydrogen production of 36.8μmol/s was achieved at residence time=2.1 ms,ethanol mass flow rate=0.03 g/s and S/C=3.0.These experimental results showed that the microreactor can substantially reduce the volume of the device while producing a large amount of output.展开更多
Wastewater from the spray absorption treatment of sludge drying gas is a kind of refractory wastewater with poor biodegradability.In this study,the free radicals generated from the double dielectric barrier were innov...Wastewater from the spray absorption treatment of sludge drying gas is a kind of refractory wastewater with poor biodegradability.In this study,the free radicals generated from the double dielectric barrier were innovatively used for the degradation of simulated spray wastewater.The effects of residence time,input power,initial pH,aeration rate,and discharge area on the degradation rate and COD(chemical oxygen demand)removal rate were investigated.The optimal conditions were as follows:residence time=120 min,input power=170.0 W,initial pH=5.54,aeration rate=0.9 mL/min,discharge area=10.8 cm^(2),and the initial concentrations of NH_(3),H_(2)S,methanethiol,trimethylamine,benzene and toluene were 250,250,50,50,50 and 100 mg/L,respectively.Meanwhile,it was also found that hydroxyl radical(⋅OH)played an important role in the degradation process.展开更多
This paper is concerned about the application of glow discharge plasma for the remediation of petroleum pollution of the sea.We used diesel fuel as the processing target and conducted a series of lab-scale studies.Sev...This paper is concerned about the application of glow discharge plasma for the remediation of petroleum pollution of the sea.We used diesel fuel as the processing target and conducted a series of lab-scale studies.Several factors including the discharge voltage,gas flow rate,the concentration of NaCl,initial temperature,and initial concentration of diesel fuel can influence the performance of glow discharge plasma systems on removal efficiency of diesel fuel.To determine the optimal reaction conditions,the diesel degradation rate and energy efficiency were calculated.The experiment result for 2178 mg/L diesel fuel solution treatment was that removal efficiency of 93.3%was achieved after 12 min treatment with the energy yield of 17 g(kWh)^(−1).Higher voltage leads to larger removal efficiency,while the energy yield may be reduced.The removal efficiency of diesel fuel reached the maximum at the gas flow rate factor 700 mL/min,decreased with an increase in gas flow rate,and became a minimum value when the gas flow rate is 1000 mL/min as a result of the unstable discharge.Decreasing the concentration of sodium chloride can cause an increase in the removal efficiency of diesel fuel,because the conductivity tended to significantly increase the degradation efficiency.Moreover,temperature and initial concentration are demonstrated to have little influence on the rate constant,but higher initial concentration favors higher energy efficiency.During the remediation of diesel fuel,pH decreases to 2.76,while the conductivity of the solution and temperature are increased,especially for the temperature,which has an increase from 25℃ to 63℃.展开更多
The coal-fired flue gas spraying wastewater is a kind of refractory mixed wastewater with poor biodegradability.In this study,the degradation of model coal-fired flue gas spraying wastewater was studied by using disch...The coal-fired flue gas spraying wastewater is a kind of refractory mixed wastewater with poor biodegradability.In this study,the degradation of model coal-fired flue gas spraying wastewater was studied by using discharge free radicals produced by double-dielectric barrier discharge.The degradation rate of pollutants,chemical oxygen demand removal rate and other indicators were detected,and the influence of different conditions on the degradation effect was analyzed.The optimal parameters are as follows:residence time 120 min,input power 170.0 W,initial pH value 3.79,and aeration rate 1.8 mL/min.The initial concentrations of acetone,formaldehyde,chloroform,benzene and toluene were 100,100,100,and 100 mg/L,respectively.Furthermore,it is proved that the discharge area is independent of the degradation rate.Through the analysis of the mechanism,it is found that·OH is an important factor affecting the degradation rate of pollutants in model coal-fired flue gas spraying wastewater.展开更多
基金supported by the Foundation for Innovative Research Groups of National Natural Science Foundation of China (No. 51621005)China Postdoctoral Science Foundation (No. 2018M630672)
文摘The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.
基金The project is supported by the Zhejiang Natural Science Foundation of China(LZ20F010001)the National Natural Science Foundation of China(61871409).
文摘Soil pollution(heavy metals and organic matter)is becoming more and more serious,phytoremediation has rapidly become a highly important method to deal with this problem.Therefore,the treatment and disposal of hyperaccumulators have been a topic of concern.In this paper,carambola leaves are selected as feedstock considering that carambola is a potential hyperaccumulator.A series of tests were performed to discuss 6 main influencing factors on total gas yield and metal fixing using a non-thermal arc plasma setup,to investigate the feasibility of plasma treatment of hyperaccumulator and provide a new method to utilize the harvested hyperaccumulator.The maximum total gas yield reached approximately 85%at an airflow rate of 3 L/min,the processing time of 7 min,discharge power of 29.95 W with the addition of water(water:sample=1:1).A reducing or inert carrier gas or the addition of some specific inorganic additives at optimal conditions were in favor of increasing metal fixing efficiency.However,the effects of these factors usually have two sides,and some factors may have conflicting effects between gas yield and metal fixing,and.It is necessary to optimize these factors for achieving the desired goal.The obtained solid products exhibit the potential to fix metals and act as activated carbon.
基金The project is supported by the Zhejiang Natural Science Foundation of China(LZ20F010001).
文摘Hydrogen is a kind of energy source with a characteristic of high calorific value and plasma is regarded as a good method of hydrogen production.Hydrogen produced from ethanol reforming using micro plasma can be utilized for portable applications.The study introduces water/carbon ratio,residence time,and ethanol mass flow rate as the parameters of experimental conditions,and makes ethanol conversion,gas production rate,gas product selectivity,energy consumption,and efficiency of hydrogen production per unit as the evaluation parameters of ethanol reforming reaction.The experimental results showed that(1)in the argon micro plasma:the maximum ethanol conversion of 25.3%was obtained at residence time=2.1 ms,ethanol mass flow rate=0.01 g/s and S/C=1.0,and the peak value of hydrogen production of 18.7μmol/s was achieved at residence time=2.1 ms,ethanol mass flow rate=0.05 g/s and S/C=1.0;(2)in the air micro plasma:the maximum ethanol conversion of 37.4%was obtained at residence time=2.1 ms,ethanol mass flow rate=0.01 g/s and S/C=1.0,and the peak value of hydrogen production of 36.8μmol/s was achieved at residence time=2.1 ms,ethanol mass flow rate=0.03 g/s and S/C=3.0.These experimental results showed that the microreactor can substantially reduce the volume of the device while producing a large amount of output.
基金supported by the National Natural Science Foundation of China(No.61871409)Zhejiang Natural Science Foundation of China(No.LZ20F010001).
文摘Wastewater from the spray absorption treatment of sludge drying gas is a kind of refractory wastewater with poor biodegradability.In this study,the free radicals generated from the double dielectric barrier were innovatively used for the degradation of simulated spray wastewater.The effects of residence time,input power,initial pH,aeration rate,and discharge area on the degradation rate and COD(chemical oxygen demand)removal rate were investigated.The optimal conditions were as follows:residence time=120 min,input power=170.0 W,initial pH=5.54,aeration rate=0.9 mL/min,discharge area=10.8 cm^(2),and the initial concentrations of NH_(3),H_(2)S,methanethiol,trimethylamine,benzene and toluene were 250,250,50,50,50 and 100 mg/L,respectively.Meanwhile,it was also found that hydroxyl radical(⋅OH)played an important role in the degradation process.
基金The project is supported by the National Natural Science Foundation of China(61871409)。
文摘This paper is concerned about the application of glow discharge plasma for the remediation of petroleum pollution of the sea.We used diesel fuel as the processing target and conducted a series of lab-scale studies.Several factors including the discharge voltage,gas flow rate,the concentration of NaCl,initial temperature,and initial concentration of diesel fuel can influence the performance of glow discharge plasma systems on removal efficiency of diesel fuel.To determine the optimal reaction conditions,the diesel degradation rate and energy efficiency were calculated.The experiment result for 2178 mg/L diesel fuel solution treatment was that removal efficiency of 93.3%was achieved after 12 min treatment with the energy yield of 17 g(kWh)^(−1).Higher voltage leads to larger removal efficiency,while the energy yield may be reduced.The removal efficiency of diesel fuel reached the maximum at the gas flow rate factor 700 mL/min,decreased with an increase in gas flow rate,and became a minimum value when the gas flow rate is 1000 mL/min as a result of the unstable discharge.Decreasing the concentration of sodium chloride can cause an increase in the removal efficiency of diesel fuel,because the conductivity tended to significantly increase the degradation efficiency.Moreover,temperature and initial concentration are demonstrated to have little influence on the rate constant,but higher initial concentration favors higher energy efficiency.During the remediation of diesel fuel,pH decreases to 2.76,while the conductivity of the solution and temperature are increased,especially for the temperature,which has an increase from 25℃ to 63℃.
基金supported by enterprise projects(No.YT2017,No.YG1908).
文摘The coal-fired flue gas spraying wastewater is a kind of refractory mixed wastewater with poor biodegradability.In this study,the degradation of model coal-fired flue gas spraying wastewater was studied by using discharge free radicals produced by double-dielectric barrier discharge.The degradation rate of pollutants,chemical oxygen demand removal rate and other indicators were detected,and the influence of different conditions on the degradation effect was analyzed.The optimal parameters are as follows:residence time 120 min,input power 170.0 W,initial pH value 3.79,and aeration rate 1.8 mL/min.The initial concentrations of acetone,formaldehyde,chloroform,benzene and toluene were 100,100,100,and 100 mg/L,respectively.Furthermore,it is proved that the discharge area is independent of the degradation rate.Through the analysis of the mechanism,it is found that·OH is an important factor affecting the degradation rate of pollutants in model coal-fired flue gas spraying wastewater.
