Preparation Of Mn-doped ZnS Quantum Dots,surface Modification For Time-resolved Analysis

With the rapid development of the economy and society,people's requirements for water quality will naturally be higher and stricter.National leaders have put forward higher task requirements for water resources,and more and more relevant laws,regulations and policies have provided more guarantees for water resources [1].At the same time,in the treatment of sewage wastewater,more demanding sewage treatment measures are needed,which has led people to pay more attention to the study of tailwater pollution in urban sewage plants.There are many common pollutants in water,including sugars and copper(?),which are also common pollutants in the tail water of municipal wastewater plants.Quantum dots are luminescent nanomaterials that can be used as novel semiconductor fluorescent probes.Quantum dots have many advantages,such as wavelength tunability,large Stokes shift,wide excitation spectrum,and narrow emission spectrum.Although the fluorescence properties of quantum dots have been widely used,there are interferences from background fluorescence and scattered light in fluorescence detection analysis,so we usually use room temperature phosphorescence analysis for quantum dots.Room temperature phosphorescence(RTP)can effectively avoid the interference of scattered light and autofluorescence,which makes room temperature phosphorescence a major candidate for luminescence sensors.In the second chapter of the thesis,a room temperature phosphorescence(RTP)method based on manganese-doped Zn S quantum dots(Mn-Zn S QDs)was used to detect heparin sodium.The positively charged octaaminopropyl oligosilicon(OA-POSS)and the negatively charged cysteine-coated manganese-doped Zn S quantum dots self-assemble into nanocomposites by electrostatic interaction in aqueous solution.When the higher negatively charged sodium heparin is added to the nanocomposite system,the RTP of the manganese-doped Zn S quantum dots is gradually attenuated,and this attenuated RTP signal is used to detect heparin sodium.The method proposed in this experiment is very suitable for the selective detection of carbohydrates similar to the sodium heparin structure in complex samples.The third chapter of the paper describes a method for the detection of Cu(?)based on a room temperature phosphorescent probe consisting of manganese-doped Zn S quantum dots coated with alginic acid.The carboxyl group whose surface of the quantum dot is not aligned with Zn2+ and Mn2+ can form a complex with Cu(?),and the formation ofalginate-doped Mn-doped Zn S quantum dots with long lifetime and ultra-wide Stokes shift The absorber complex,after coordinating with manganese-doped Zn S quantum dots,the residual carboxyl group of alginic acid can be strongly complexed with Cu(?),which strongly quenches the4T1-6A1 transition emission of Mn2+through internal filter effect.Thus an effective fluorescence quenching occurs.Therefore,the experimental results show that the use of RTP as an effective platform for detecting the signal output of Cu(?)is a good method for detecting Cu(?),and at the same time,alginic acid-coated manganese-doped Zn S.Quantum dots are also used for Cu(?)detection in tail water of wastewater treatment plants.They have excellent detection performance.This method has high sensitivity and high selectivity,and has no matrix interference.It is a simple,reliable and usable coexistence.A practical platform for the detection of Cu(?)in wastewater.