Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this stud...Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this study,the effects of paint layers on metal surfaces during LIBS classification were investigated.LIBS spectra were collected from metal surfaces painted with black and white paints by ablation with a nanosecond pulsed laser(wavelength=1064 nm,pulse width=7 ns).For the black-painted samples,the LIBS spectra showed a broad background emission,emission lines unrelated to the target metals,large shot-to-shot variation,and a relatively low signal intensity of the target metal,causing poor classification accuracy even at high shot numbers.Cleaning the black paint layer by ablating over a wide area prior to LIBS analysis resulted in high classification accuracy with fewer shot numbers.A method to determine the number of cleaning shots necessary to obtain high classification accuracy and high throughput is proposed on the basis of the change in LIBS signal intensity during cleaning shots.For the white-painted samples,the paint peeled off the metal surface after the first shot,and strong LIBS signals were measured after the following shot,which were attributed to the nanoparticles generated by the ablation of the paint,allowing an accurate classification after only two shots.The results demonstrate that different approaches must be employed depending on the paint color to achieve high classification accuracy with fewer shot numbers.展开更多
为寻找质优价廉的析氢催化剂,本研究以废旧金属网为单室微生物电解池(MEC)阴极,在不同外加电压下考察其制氢性能.同时利用16S r DNA扩增测序技术分析原接种污泥、MFC和MEC阳极微生物的菌落特点.实验结果表明,随着外加电压的增大,MEC产...为寻找质优价廉的析氢催化剂,本研究以废旧金属网为单室微生物电解池(MEC)阴极,在不同外加电压下考察其制氢性能.同时利用16S r DNA扩增测序技术分析原接种污泥、MFC和MEC阳极微生物的菌落特点.实验结果表明,随着外加电压的增大,MEC产生的最大电流密度和周期运行时间分别呈现增大和缩短的趋势.外加0.7 V电压时,废旧金属网阴极MEC的氢气产率和电能回收率分别达到0.330±0.012 m^3H2·m^-3·d^-1和177.0±5.6%,远高于0.5 V时的数值,与0.9 V时相差不大.废旧金属网阴极MEC的产氢能力可以和Pt/C阴极MEC相媲美,且具有良好的运行稳定性.16S r DNA扩增测序结果显示培养环境对微生物的富集与淘汰有很大影响.在外加电场环境中MEC阳极的优势菌落地杆菌属(Geobacter)得到很大程度富集,相对丰度高达79.4%以上.展开更多
基金supported by the R&D Center for Valuable Recycling (Global-Top R&D Program)of the Ministry of Environment (No.2016002250003)。
文摘Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this study,the effects of paint layers on metal surfaces during LIBS classification were investigated.LIBS spectra were collected from metal surfaces painted with black and white paints by ablation with a nanosecond pulsed laser(wavelength=1064 nm,pulse width=7 ns).For the black-painted samples,the LIBS spectra showed a broad background emission,emission lines unrelated to the target metals,large shot-to-shot variation,and a relatively low signal intensity of the target metal,causing poor classification accuracy even at high shot numbers.Cleaning the black paint layer by ablating over a wide area prior to LIBS analysis resulted in high classification accuracy with fewer shot numbers.A method to determine the number of cleaning shots necessary to obtain high classification accuracy and high throughput is proposed on the basis of the change in LIBS signal intensity during cleaning shots.For the white-painted samples,the paint peeled off the metal surface after the first shot,and strong LIBS signals were measured after the following shot,which were attributed to the nanoparticles generated by the ablation of the paint,allowing an accurate classification after only two shots.The results demonstrate that different approaches must be employed depending on the paint color to achieve high classification accuracy with fewer shot numbers.
文摘为寻找质优价廉的析氢催化剂,本研究以废旧金属网为单室微生物电解池(MEC)阴极,在不同外加电压下考察其制氢性能.同时利用16S r DNA扩增测序技术分析原接种污泥、MFC和MEC阳极微生物的菌落特点.实验结果表明,随着外加电压的增大,MEC产生的最大电流密度和周期运行时间分别呈现增大和缩短的趋势.外加0.7 V电压时,废旧金属网阴极MEC的氢气产率和电能回收率分别达到0.330±0.012 m^3H2·m^-3·d^-1和177.0±5.6%,远高于0.5 V时的数值,与0.9 V时相差不大.废旧金属网阴极MEC的产氢能力可以和Pt/C阴极MEC相媲美,且具有良好的运行稳定性.16S r DNA扩增测序结果显示培养环境对微生物的富集与淘汰有很大影响.在外加电场环境中MEC阳极的优势菌落地杆菌属(Geobacter)得到很大程度富集,相对丰度高达79.4%以上.
