Analysis Of Heavy Metal In Soil By X-ray Fluorescenc Spectrometry

Heavy metals in the field of chemistry is defined as a density greater than the metal element 4.5g/cm, when the heavy metal content in soil was significantly higher than the background value, the ecological environment will be affected, a phenomenon known as heavy metals contaminated soil. As human activity on soil more frequently, heavy metal contamination of soil is more and more serious, has been a serious threat to the environment and health of human beings. While traditional chemical analysis to detect heavy metals in terms of element content in soil has a high accuracy, but because of its longer measurement time, the need for strong acid digestion sample pre-treatment process, tedious and time-consuming, and the reagents used in the process of digestion also cause secondary pollution, so it was not suitable for mass rapid detection of heavy metal content in soil.X-ray fluorescence analysis technique has a high sensitivity analysis, the detection limit of most elements of the ppm level; a wide range of elements analyzed, generally can detect more than 90 types of elements from Be to U; and analysis speed, then you can know the general measurement measure Results. This method is for the detection of heavy metals in soil and pollution evaluation fast and effective method, when the soil is fully able to meet the urgent need of environmental contamination rapid qualitative and quantitative investigation of heavy metals in the soil requirements.Experiment IED-2000T portable fluorescence analyzer for the measurement of heavy metals in soil analysis. IED-2000T portable fluorescence analyzer is using the Ag target X-ray tube and high-resolution micro-electric cooling Si-PIN semiconductor detector, the instrument tube voltage 30kV tube current excitation conditions 5uA under Granular soil samples the impact of the size, firmness (sample preparation pressure), sample water content, saturated thickness of the sample preparation, instrument measuring time and other factors on the measurement results were discussed.Through the above analysis study made the following findings:1. Studies show that soil sample measurement conditions were optimized, can significantly improve the analysis of the results of XRF analysis. The most suitable soil samples test conditions:dried (moisture content<5%) 5g sample, after ZHM-1B-type sample mill grinder, with a pressure of 15MPa pressure sample, the measurement time is 200s.2. Using multiple regression, nonlinear curve fitting and LTP intensity correction method of precision X-ray fluorescence analysis methods were evaluated,10 times repeated measurements of the same sample calculated Cr, Cu, Zn, Pb of RSD were less than 10% It illustrates the XRF analyzer with good accuracy.3. Discussion of the room elements characteristic absorption and enhancement, experiments show, Cu element of Cr have significantly enhanced the effect of Zn Cu mainly doublet effect, the smaller the impact of Pb.4. Soil samples collected around Chengdu orchard Cr, Cu, Zn, Pb content by X-ray fluorescence analysis, combined with different correction equation between heavy metal element absorption enhancement effect correction, the measured value analysis and recommendation value for comparison. Shows, multiple linear regression and nonlinear curve fitting correction effect is significantly better than LTP intensity correction method.