Construction Of Imidazolium Ionic Liquid Modified Molecular Sieve And Its Selective Separation Of Inorganic Arsenic

Arsenic（As）is one of the most common metal elements in na-ture.It is volatilized into the atmosphere,natural water and soil by volcanic eruption and natural evaporation.Through the enrichment of animals and plants and then absorbed by the body.Arsenic is a very strong carcinogenic substances,classified as type I category ca-rcinogens by World Health Organization（WHO）and International Agency for Research on Cancer（IARC）,the toxicity of inorganic a-rsenic is much greater than organic arsenic.Rice and rice products are the staple food for most people in the world and one of the ke y sources of arsenic exposure.Therefore,the detection of inorganic arsenic in rice and rice products has a guiding significance for the safety assessment of arsenic.The separation of different forms of ar-senic is accomplished by solid phase extraction,liquid chromatogra phy,gas chromatography,etc,expensive and cumbersome.Therefore,the establishment of a highly selective,easy operate,low cost of in organic arsenic detection method for rice and rice products in the s eparation,quantitative analysis of inorganic arsenic is very importan t.SBA-15 is a common all-silicon-based molecular sieve material w-ith a large amount of hydroxyl groups on its surface.Widely used in the heavy metal adsorption because of its large surface area,sha-pe rules,structural stability,low cost,good dispersion in the sampl-e solution.In this paper,SBA-15 modificated by 1-methylimidazole and used in separation,enrichment of of inorganic arsenic,quantifie-d by hydride generation-atomic fluorescence spectrometry.The research is as follows:（1）Synthesis of the material,tested by field emission scanning electron microscopy,field emission transmission electron microscopy,X-ray powder diffraction,Fourier infrared spectrum,77 K N₂ adsorp tion-desorption isothermal,X-ray photoelectron spectroscopy,Zeta po-tential.The results showed that 1-methylimidazole was successfully grafted onto SB A-15,had characteristic group in the relevant literature;after modificted,the morphology and size of SBA-15 had little change,pore size and specific surface area become smaller.The mod-ified surface area of the material was 391.4282 m²/g,pore size wa-s 6.0323 nm,pore volume was 0.6805 cm³/g,the zeta potential wa s 11.5.（2）The first step,using As⁵⁺,MA,DMA standard solution,the adsorption rate as an indicator,quantitative detected by hydride generation-atomic fluorescence spectrometry,studied the effects of the amount of adsorbent,adsorption time,pH,and temperature on t headsorption performance of As⁵⁺.The results showed that the adso-rption rate of As⁵⁺,MA,DMA were 95%,14%,5%at the conditi-ons of pH=3.4 and 15 min ultrasonic adsorption by 5 mg 1-MIIL@SBA-15,temperature had little effect on the adsorption.The adso-rption process is in accordance with Langmuir model and quasi-sec ond order kinetic model.The second step,using desorption rate as an index,studied the effect of concentration,volume,desorption tim-e on the desorption of As⁵⁺.The results showed that the optimum desorption conditions were as follows:the desorption rate was over 99%,after 5 min ultrasonic desorption by 5 mL,0.75 mol/L hydrochloricacid.（3）10 mL of 0.06 M HNO3-H2O2 was used as digestion system,and the inorganic arsenic was extracted by microwave digestion at 95℃ for 30 min.The adsorption/desorption conditions of As⁵⁺ in the sample solution were further optimized on the basis of the previous experiment,quantified by HG-AFS.The results showed that the recovery of inorganic arsenic was 93%at the condition of pH=4,ultrasonic adsorption for 20 min by 50 mg 1-MIIL@SBA-15,and desorption by 5 mL,1.0 mol/L hydrochloric acid through 5 min ultrasonic desorption.（4）Application of 1-MIIL@SBA-15 for seperation and enrichment of inorganic arsenic in rice samples and baby rice.The results showed that the method could effectively enrich and quantification of the inorganic arsenic arsenic in rice.The average recoveries were between 92.3-94.2%,RSD<2%,LOD=8.776 ng/kg.The average content of inorganic arsenic in brown rice and rice were 179.2,109.8 μg/L,and the contents of inorganic in ordinary baby rice and organic baby rice were 145.2 and 89.8 μg/L,respectively.