Novel Photochemical Reaction Of Bismuth And Arsenic And Is Analytical Application

With the continuous development of geochemistry,the sensitive and selective methods are required for the detection of trace and ultra-trace elements in environmental samples.Analytical detection of trace and ultra-trace elements in environmental samples is an important part of environmental geochemistry research.However,in the field of environmental geochemistry,the research on trace and ultra-trace elements lacks accurate,reliable and sensitive analytical methods.Therefore,the development of a simple,efficient and sensitive elemental analysis method is of great significance for the analysis and detection of trace and ultra-trace elements in environmental samples.Due to the good physical and chemical properties of metal bismuth（Bi）,its application in various industries is more and more extensive.However,recent studies have shown that Bi has certain toxicity to human body,animals and plants.Widely application increases the possibility of potential threat for human being.As is well known,arsenic（As）is a toxic element which can cause cancer for human.However,the toxicity of As is highly relied on its existing species.Usually,inorganic arsenic is much more toxic than organic arsenic,and inorganic arsenic is classified as a primary carcinogen.The toxicity of As（Ⅲ）is 60 times more than that of As（Ⅴ）.In 1993,the World Health Organization（WHO）stipulated that the concentration of As in drinking water should not less than 10 ng mL^-1.As in the environmental water sample,As exists mainly in inorganic form.The source of organic arsenic is mainly due to the action of aquatic organisms and the content is low.Therefore,it is of great significance for the speciation analysis of inorganic arsenic in environmental water samples.Inductively Coupled Plasma Mass Spectrometry（ICP-MS）is one of the most efficient and widely used instruments for the analysis of trace and ultra-trace elements.It has high sensitivity,low detection limit,wide linear range and simultaneous detection of multiple elements and so on.UV-induced chemical vapor generation（UV-PVG）is using low-molecular-weight organic acid（LWMAs）which is photolyzed by ultraviolet light to generate strong oxidation and reducing free radicals to convert target elements into volatile substances.It has been used as sample introduction method for atomic spectrometry.The method has the advantages of sample introduction efficiency,alleviated matrix interference,and simple operation.However,the PVG efficiencies of some elements are low,resulting in low analytical sensitivity.Metal-organic framework materials（MOFs）are porous materials that have been developed extremely rapidly in recent years,which are formed by metal ions or metal ion clusters and organic linkages through bonding.They have extremely high specific surface area and extremely large pores.Therefore,they are widely used in the field of photocatalysis and contaminant removal.The use of MOFs materials in PVG as photocatalyst is expected to develop sensitive method for the determination of analytes.The specific work includes the following two parts.（1）In previous report,the generation efficiency of Bi is low,and the matrix interference is serious.Studies have shown that the transition metal ion Fe（Ⅲ）has a great effect on the photochemical vapor generation of Bi,but the interference from Co（Ⅱ）is obvious.MOFs materials are a good adsorbent and have many applications in the field of photocatalysis.In this work,iron and 1,3,5-benzenetricarboxylic-Fe-BTC,a Fe-containing metal-organic frameworks material,was synthesized and firstly used as a platform integrating the sample matrix separation,pre-concentration,and photocatalysis for the highly selective determination of elements by PVG.Fe-BTC was not only severed as the photocatalyst for the PVG of Bi（Ⅲ）but also as an efficient absorbent for separation of analytes from sample matrix.Compared to previous PVG system,the performance of tolerating interferences towards co-existing ions of the proposed method has been greatly improved after using Fe-BTC based matrix separation.Thus,the excess of 10 mg L^-1 of Co（Ⅱ）,100 mg L^-1 of Cu（Ⅱ）,Ni（Ⅱ）and Fe（Ⅲ）caused no obvious interferences for 1μg L^-1 of Bi determination.This method was successfully applied for the analysis of Bi in complicated sample matrixes of soil（GBW07401）,sediment（GBW07310）,nickel-iron alloy（GBW01622）and nickel alloys（GBW01641）by external calibration method.（2）At present,the speciation method of inorganic arsenic is mainly based on the combination of separation and detection technology,which is inevitably time-consuming and labor-intensive.In recent years,iron-based MOFs have developed rapidly in the field of arsenic adsorption and removal.Therefore,this study developed a combination of iron-based MOFs and UV-induced chemical vapor generation to achieve rapid separation and high sensitivity detection of inorganic arsenic in water samples,which was successfully applied for the analysis of environmental water samples.In this experiment,inorganic arsenic was separated by selective adsorption of the MOFs,and its concentration was detected by UV-induced chemical vapor generation.Compared with the traditional morphological analysis method,the method simple and sensitive.