Free chlorine is one of the key water quality parameters in tap water.However,a free chlorine sensor with the characteristics of batch processing,durability,antibiofouling/antiorganic passivation and in situ monitorin...Free chlorine is one of the key water quality parameters in tap water.However,a free chlorine sensor with the characteristics of batch processing,durability,antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging issue.In this paper,a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS(Micro-Electro-Mechanical System)is proposed.A liquid-conjugated Ag/AgCI reference electrode is fabricated,and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine detection.The sensor demonstrates an acceptable limit of detection(0.056 mg/L)and desirable linearity(R^(2)=0.998).Particularly,at a potential of+2.5 V,hydroxyl radicals are generated on the BBD electrode by electrolyzing water,which then remove the organic matter attached to the surface of the sensor though an electrochemical digestion process.The performance of the fouled sensor recovers from 50.2 to 94.1%compared with the initial state after self-cleaning for 30 min.In addition,by employing the MEMS technique,favorable response consistency and high reproducibility(RSD<4.05%)are observed,offering the opportunity to mass produce the proposed sensor in the future.A desirable linear dependency between the pH,temperature,and flow rate and the detection of free chlorine is observed,ensuring the accuracy of the sensor with any hydrologic parameter.The interesting sensing and selfcleaning behavior of the as-proposed sensor indicate that this study of the mass production of free chlorine sensors by MEMS is successful in developing a competitive device for the online monitoring of free chlorine in tap water.展开更多
A simple protocol for the sulfur-promoted conversion of aromatic aldehydes to aromatic nitriles has been developed.This strategy enables the one-pot conversion of inexpensive and readily available aromatic aldehydes i...A simple protocol for the sulfur-promoted conversion of aromatic aldehydes to aromatic nitriles has been developed.This strategy enables the one-pot conversion of inexpensive and readily available aromatic aldehydes into highly valuable aromatic nitriles using a cheap inorganic ammonium salt as the nitrogen source in the absence of metals.Significantly,a broad scope of substrates was explored using this strategy,and various groups,including alkyl,alkoxyl,alkylthiol,hydroxyl,amino,aryl,alkenyl,cyano,carboxyl,and borate ester groups were tolerated,and good to excellent yields were achieved in most cases.Additionally,polycyclic aromatic aldehydes and heteroaromatic aldehydes also could be converted to the corre-sponding nitriles with satisfactory yields.This method can be utilized as a powerful tool for the cyanation of complex molecules.展开更多
基金supported by a grant from the National Science Foundation of China(61871243).
文摘Free chlorine is one of the key water quality parameters in tap water.However,a free chlorine sensor with the characteristics of batch processing,durability,antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging issue.In this paper,a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS(Micro-Electro-Mechanical System)is proposed.A liquid-conjugated Ag/AgCI reference electrode is fabricated,and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine detection.The sensor demonstrates an acceptable limit of detection(0.056 mg/L)and desirable linearity(R^(2)=0.998).Particularly,at a potential of+2.5 V,hydroxyl radicals are generated on the BBD electrode by electrolyzing water,which then remove the organic matter attached to the surface of the sensor though an electrochemical digestion process.The performance of the fouled sensor recovers from 50.2 to 94.1%compared with the initial state after self-cleaning for 30 min.In addition,by employing the MEMS technique,favorable response consistency and high reproducibility(RSD<4.05%)are observed,offering the opportunity to mass produce the proposed sensor in the future.A desirable linear dependency between the pH,temperature,and flow rate and the detection of free chlorine is observed,ensuring the accuracy of the sensor with any hydrologic parameter.The interesting sensing and selfcleaning behavior of the as-proposed sensor indicate that this study of the mass production of free chlorine sensors by MEMS is successful in developing a competitive device for the online monitoring of free chlorine in tap water.
基金This work was supported by the Key Project Program of the Educational Department of Hunan Province(No.18A069)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.QL20210148)+3 种基金the Scientific Research Foundation of Hunan Provincial Education Department(No.19C0522)the Scientific Research Foundation of Hunan Institute of Technology(No.2018HY011)the Project of Innovation Team of the Ministry of Education(No.IRT_17R90)Hunan 2011 Collaborative Innovation Center of Chemical Engineering&Technology with Environmental Benignity and Effective Resource Utilization.
文摘A simple protocol for the sulfur-promoted conversion of aromatic aldehydes to aromatic nitriles has been developed.This strategy enables the one-pot conversion of inexpensive and readily available aromatic aldehydes into highly valuable aromatic nitriles using a cheap inorganic ammonium salt as the nitrogen source in the absence of metals.Significantly,a broad scope of substrates was explored using this strategy,and various groups,including alkyl,alkoxyl,alkylthiol,hydroxyl,amino,aryl,alkenyl,cyano,carboxyl,and borate ester groups were tolerated,and good to excellent yields were achieved in most cases.Additionally,polycyclic aromatic aldehydes and heteroaromatic aldehydes also could be converted to the corre-sponding nitriles with satisfactory yields.This method can be utilized as a powerful tool for the cyanation of complex molecules.
