Application Of Pyrite And Calcium Fluoride Nanomaterials In Fluorescence Detection Of The Impurities Of Traditional Chinese Medicine And Pharmaceutical Wastewater Treatment

Quantum dots（QDs）are often used to construct the fluorescence sensing systems due to their unique optoelectronic properties and are widely used in the analysis field.However,when there are complex interfering substances,especially the interfering substances with similar structures and chemical properties,the selectivity is not obvious,so the improvement of their selectivity is particularly important.Molecularly imprinted polymers（MIPs）have a wide applicability,good plasticity,and high selectivity.When MIPs are combined with fluorescent QDs,the obtained composite materials will have high sensitivity and high selectivity.Especially,in constructing the molecularly imprinted ratiometric fluorescence sensor,the ratio of fluorescence intensity of two fluorescence materials is used as the signal,it can effectively reduce the influence of the external factors from the environment and make the results more accurate.Therefore,many molecularly imprinted ratiometric fluorescence sensors have been developed and applied to the detection of the various analytes.In the pharmaceutical process,a large amount of organic wastewater is produced,which will have a great impact on the ecological environment and people’s life safety.Photocatalytic treatment technology is considered as a promising pharmaceutical wastewater treatment method.At present,photocatalytic treatment technology is faced with the problems of the expensive photocatalytic materials and complex preparation methods.Therefore,it is urgent to develop a photocatalytic material with low cost,environmentally friendly and simple preparation method.In this paper,three kinds of molecularly imprinted ratiometric fluorescence sensors were prepared by using multi-color fluorescent FeS₂QDs,multi-color fluorescent CaF₂ QDs,CdTe QDs,the metal-organic framework derived Fe S₂ QDs and carbon dots as fluorescence combinations,respectively.The optical detection behaviors of the three sensors on the target molecules were studied and the selective recognition abilities were investigated in detail.In addition,FeS₂/Carbon Black photocatalytic material was also synthesized by a solvothermal method,and its optimal catalytic degradation conditions were systematically studied.The main contents of this paper are as follows:（1）A molecularly imprinted ratiometric fluorescence sensor for the fluorescence detection of aconitine（ACO）was prepared.By controlling the reaction temperature,time and the raw molar ratios,Fe S₂ QDs emitting blue,green,yellow and red fluorescence were synthesized by a solvothermal method.On this basis,using yellow fluorescence FeS₂ QDs（y-FeS₂）as the reference signal and blue fluorescence FeS₂ QDs（b-FeS₂）as the response signal,combined with molecular imprinting technology,a molecularly imprinted ratiometric fluorescence sensor（y-FeS₂@SiO₂@b-FeS₂@MIPs）was prepared by precipitation polymerization.The quenching effect of ACO on the fluorescence of the sensor atλ_em=443 nm can be used to detection of ACO with a linear range of 0.05-5.0μM and a detection limit of 23.7 nM（S/N=3）.The selective recognition experiment showed that this sensor had an obvious selective recognition ability for ACO.In addition,the sensor was successfully applied to the detection of ACO in traditional Chinese medicine Fuzi Lizhong pills.（2）A molecularly imprinted ratiometric fluorescence sensor for the fluorescence detection of 5-hydroxymethylfurfural（5-HMF）was prepared.CaF₂ QDs emitting purple,blue,green and yellow fluorescence were synthesized by a solvothermal method.On this basis,using red fluorescence CdTe QDs as the reference signal and yellow fluorescence CaF₂ QDs as the response signal.In order to improve selectivity,β-cyclodextrin（β-CD）and methacrylic acid（MAA）were used as bifunctional monomers.Then,a molecularly imprinted ratiometric fluorescence sensor（CdTe@SiO₂@CaF₂@MIPs）was prepared.The quenching effect of 5-HMF on the sensor atλ_em=599 nm can be used for detection of 5-HMF with a linear range of 0.1-6.0μg/mL and a detection limit of 0.043μg/mL（S/N=3）.The selective recognition experiment showed that this sensor had an obvious selective recognition ability for5-HMF.The sensor was successfully applied to the detection of 5-HMF in honey with satisfactory results.（3）A molecularly imprinted ratiometric fluorescence sensor for the fluorescence detection of pentachlorobenzene（PeCB）was prepared.The green fluorescent metal-organic framework derived FeS₂ QDs and red fluorescent carbon dots were synthesized by a solvent thermal method.On this basis,PeCB based FeS₂@MIPs was prepared by gel-sol method.Taking FeS₂@MIPs as the response signal and the red fluorescence emission CDs@SiO₂ as the reference signal,the molecularly imprinted ratiometric fluorescence sensor was prepared.The quenching effect of PeCB on sensor atλ_em=583 nm can be used for detection of PeCB with the linear range of 0.5-10.0μmol/L and the detection limit of 0.251μmol/L（S/N=3）.The selective recognition experiment showed that the sensor had an obvious selective recognition ability to PeCB.The sensor has been successfully used to detect PeCB in traditional Chinese medicine Asarum with satisfactory results.（4）FeS₂/CB nanocomposite,an efficient photocatalytic material,was prepared by a simple solvothermal method using FeCl₃.6H₂O as iron source,L-cysteine as sulfur source,and ethylene glycol as solvent.The optimal conditions for degradation of organic pollutants in pharmaceutical wastewater was explored using FeS₂/CB nanocomposite without the addition of hydrogen peroxide（H₂O₂）.The optimal degradation conditions are as follows:p H value was 6.0,the concentration of pollutants was 30mg/L,and the dosage of FeS₂/CB was 0.75 g/L.The degradation rates of methylene blue,bisphenol A and ofloxacin in 60 minutes were 95.2%,82.1%,and 78.2%,respectively.In addition,the results of stability experiments showed that the catalyst still maintained high photocatalytic efficiency after five repeated uses.