【目的】建立一种多壁碳纳米管（MWCNTs）分散固相萃取气相色谱法（GC）检测蔬菜中多种农药残留的分析方法,为气相色谱法快速检测蔬菜中农药残留提供一种新的材料和应用方法。【方法】采用分散固相萃取法,10.00 g样品用10 m L乙腈提取,...【目的】建立一种多壁碳纳米管（MWCNTs）分散固相萃取气相色谱法（GC）检测蔬菜中多种农药残留的分析方法,为气相色谱法快速检测蔬菜中农药残留提供一种新的材料和应用方法。【方法】采用分散固相萃取法,10.00 g样品用10 m L乙腈提取,加入1.00 g Na Cl和4.00 g无水Mg SO4液液分离,取1 m L乙腈提取液用150 mg无水Mg SO4和15 mg多壁碳纳米管进行分散固相净化,运用气相色谱微电子俘获检测器（GC-u ECD）进行分析检测,通过添加回收试验对方法进行考察,基质匹配标准液外标法定量对蔬菜中23种农药进行检测。【结果】在0.05~1.00 mg/kg添加范围内,23种农药的添加回收率为73.0%~98.4%,相对标准偏差（RSD,n=5）为1.3%~11.0%,方法的定量限（LOQ）为0.02~0.05 mg/kg。采用该方法对市场样品进行检测,无目标农药检出。【结论】多壁碳纳米管作为分散固相吸附剂与气相色谱联用,在回收率、检出限及精密度等方面均能满足农药残留分析的要求,且成本明显低于商品化基质分散吸附剂,可在蔬菜农药残留检测分析中推广应用。展开更多
We propose a method to estimate the natural frequencies of the multi-walled carbon nanotubes （MWCNTs） embedded in an elastic medium. Each of the nested tubes is treated as an individual bar interacting with the adja...We propose a method to estimate the natural frequencies of the multi-walled carbon nanotubes （MWCNTs） embedded in an elastic medium. Each of the nested tubes is treated as an individual bar interacting with the adjacent nanotubes through the inter-tube Van der Waals forces. The effect of the elastic medium is introduced through an elastic model. The mathematical model is finally reduced to an eigen value problem and the eigen value problem is solved to arrive at the inter-tube resonances of the MWCNTs. Variation of the natural frequencies with different parameters are studied. The estimated results from the present method are compared with the literature and results are observed to be in close agreement.展开更多
采用均匀沉淀法制备纳米SnS/多壁碳纳米管(MWCNTs)复合物,利用场发射扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和热重分析仪(TGA)对其形貌和组成进行表征。将纳米SnS/MWCNTs复合物10 mg超声分散在1.0 mL 5%(体积分数)全氟化树脂溶液中...采用均匀沉淀法制备纳米SnS/多壁碳纳米管(MWCNTs)复合物,利用场发射扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和热重分析仪(TGA)对其形貌和组成进行表征。将纳米SnS/MWCNTs复合物10 mg超声分散在1.0 mL 5%(体积分数)全氟化树脂溶液中,分取8.0μL滴涂于处理好的玻碳电极(GCE)表面,得到修饰电极(纳米SnS/MWCNTs/GCE)。以纳米SnS/MWCNTs/GCE为工作电极,铂丝电极为对电极,饱和甘汞电极为参比电极,采用循环伏安法(CV)、电化学阻抗谱法(EIS)和差分脉冲伏安法(DPV)对纳米SnS/MWCNTs/GCE电化学性能进行考察,研究了2,4-二氯苯酚(2,4-DCP)在纳米SnS/MWCNTs/GCE上的电化学行为。结果表明:在pH 7.0的磷酸盐缓冲溶液中,纳米SnS/MWCNTs/GCE对2,4-DCP有明显的电催化作用和较高的选择性;2,4-DCP的浓度在0.05~3.00μmol·L^(-1)内与DPV响应的氧化峰电流呈线性关系,检出限(3S/N)为2.3×10^(-8)mol·L^(-1);按照标准加入法对水样进行回收试验,2,4-DCP回收率为92.0%~101%。展开更多
The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-...The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.展开更多
文摘【目的】建立一种多壁碳纳米管（MWCNTs）分散固相萃取气相色谱法（GC）检测蔬菜中多种农药残留的分析方法,为气相色谱法快速检测蔬菜中农药残留提供一种新的材料和应用方法。【方法】采用分散固相萃取法,10.00 g样品用10 m L乙腈提取,加入1.00 g Na Cl和4.00 g无水Mg SO4液液分离,取1 m L乙腈提取液用150 mg无水Mg SO4和15 mg多壁碳纳米管进行分散固相净化,运用气相色谱微电子俘获检测器（GC-u ECD）进行分析检测,通过添加回收试验对方法进行考察,基质匹配标准液外标法定量对蔬菜中23种农药进行检测。【结果】在0.05~1.00 mg/kg添加范围内,23种农药的添加回收率为73.0%~98.4%,相对标准偏差（RSD,n=5）为1.3%~11.0%,方法的定量限（LOQ）为0.02~0.05 mg/kg。采用该方法对市场样品进行检测,无目标农药检出。【结论】多壁碳纳米管作为分散固相吸附剂与气相色谱联用,在回收率、检出限及精密度等方面均能满足农药残留分析的要求,且成本明显低于商品化基质分散吸附剂,可在蔬菜农药残留检测分析中推广应用。
文摘We propose a method to estimate the natural frequencies of the multi-walled carbon nanotubes （MWCNTs） embedded in an elastic medium. Each of the nested tubes is treated as an individual bar interacting with the adjacent nanotubes through the inter-tube Van der Waals forces. The effect of the elastic medium is introduced through an elastic model. The mathematical model is finally reduced to an eigen value problem and the eigen value problem is solved to arrive at the inter-tube resonances of the MWCNTs. Variation of the natural frequencies with different parameters are studied. The estimated results from the present method are compared with the literature and results are observed to be in close agreement.
文摘采用均匀沉淀法制备纳米SnS/多壁碳纳米管(MWCNTs)复合物,利用场发射扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和热重分析仪(TGA)对其形貌和组成进行表征。将纳米SnS/MWCNTs复合物10 mg超声分散在1.0 mL 5%(体积分数)全氟化树脂溶液中,分取8.0μL滴涂于处理好的玻碳电极(GCE)表面,得到修饰电极(纳米SnS/MWCNTs/GCE)。以纳米SnS/MWCNTs/GCE为工作电极,铂丝电极为对电极,饱和甘汞电极为参比电极,采用循环伏安法(CV)、电化学阻抗谱法(EIS)和差分脉冲伏安法(DPV)对纳米SnS/MWCNTs/GCE电化学性能进行考察,研究了2,4-二氯苯酚(2,4-DCP)在纳米SnS/MWCNTs/GCE上的电化学行为。结果表明:在pH 7.0的磷酸盐缓冲溶液中,纳米SnS/MWCNTs/GCE对2,4-DCP有明显的电催化作用和较高的选择性;2,4-DCP的浓度在0.05~3.00μmol·L^(-1)内与DPV响应的氧化峰电流呈线性关系,检出限(3S/N)为2.3×10^(-8)mol·L^(-1);按照标准加入法对水样进行回收试验,2,4-DCP回收率为92.0%~101%。
基金supported by the Natural Science Foundation of Hubei Province (No.2009CDA050)the New Century Excellent Talents in University (No. NCET-10-0137)the National Natural Science Foundation of China (No. 51072143)
文摘The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.
