Development Of Polymer Membrane Potential Sensor And Its Application In Environmental Detection

With the rapid development of our economy,the scale and output of most industrial enterprises have increased year by year,so the problems in the process of production become increasingly obvious.The problem of detecting pollutants in wastewater is still serious.Among them,sulfate,nitrate,sulfide and metal ion pollutants are common pollutants.At present,the main methods for the determination of these pollutants are gas phase molecular absorption spectrometry,chromatography,iodimetry,spectrophotometry,titration,etc.,but these methods often have to undergo complex chemical treatment,or high cost,easy to produce secondary pollution,to a certain extent,limiting the application of these methods.In order to solve the problem of pollutant ion detection,a polymer membrane potential sensor（ISEs）which was proposed based on the research achievements in supramolecular chemistry.This kind of sensor has good selectivity,low cost,fast response,wide application range,portability and can be used in combination with other instruments.In this paper,by observing some protein structures with specific recognition in nature,weak interactions such as hydrogen bonds are arranged in the middle of a large cavity to construct a variety of ion identifiers.Following this idea,hydrogen bond was modified on the molecular skeleton with biped structure to construct the ionophore of hydrogen sulfide/hydrogen sulfate,and the tripod nitrate ionophore with arylacetylene as molecular skeleton was prepared.Using tris（2-aminoethylamine）as scaffold,a three-legged foldable sulfate carrier and a circular sulfate ionophore interacting with hydrogen bond were constructed,in order to improve the structural rigidity of the original metal ionophore crown ether.a metal ionophore based on macrocyclic/non-cyclic aromatic pyridone folds was constructed by built-in hydrogen bonds.After completing the design of the ionophore structure,the optimal ionophore composition was determined by measuring the selective modes of different ionophores,ion sites and different plasticizers in different ratios,and the structure of the ionophore was optimized.The performance of the constructed ionophore was judged by measuring the ion selectivity coefficient by the solution method.The double-layer membrane method is used to measure the binding constant of the carrier and the target ion in the polymer membrane to judge the selectivity of the ionophore to the target ion.The binding constant of the sensor constructed in this paper is better than the existing detection methods.The polymer membrane potential sensor was prepared by doping the constructed ionophore into the polymer membrane.the sensor has a good Nernst response to the three anions and metal ions mentioned above,and its selectivity shows the anti-Hofmeister sequence pattern.Then the effect of p H on the potential response,response range,detection limit and stability were measured.All the anion potentiometric sensors show good detection range and lower detection limit:the linear range of hydrogen sulfide/hydrogen sulfate potentiometric sensor is 5×10^-5M～1×10^-2M,and the detection limit is 1×10^-6M,while the linear range of nitrate potentiometric sensor is 5×10^-6M～1×10^-2M,the detection limit is 5×10^-6～1×10^-1M,and the slope is 58.7 m V/dec.The slope of the constructed sulfate potential sensor is-29.8 m V/dec,the linear range is 1×10^-6～1×10^-1M,and the detection limit is 5×10^-7M.And the metal ion potential sensor shows good Nernst response to K⁺,Cu²⁺and Hg²⁺.Four kinds of sensors are used to detect all kinds of water samples in real life（mineral water,tap water,river water,drinking water and neomycin tablet samples）and compared with the existing detection methods.the results show that the detection data of all kinds of sensors constructed in this paper are very consistent with those of the existing methods.It further shows that the potential sensor can be used in practical samples with good selectivity,wide detection range and high stability,and has very high potential application value.The ionophore and its corresponding sensor constructed in this paper solve the problem that it is difficult to construct anion ionophore,provide a new idea for the construction of new ionophore,and further broaden the types of ionophore.it is beneficial to the construction of new potential sensors.