Rapid Detection System Of Cr⁶⁺ In Soil Based On Spectral Absorption Technology

With the development of economy, a chapter of environmental problems have takenplace in China. Taking the heavy metal as an example, it harms human’s life greatly. Theheavy metal in the soil can invade the body through the food chain, and causes body aches,dementia and so on. Therefore, we should test the heavy metal ion in the soil accurately,fleetly and succinctly.By absorption spectroscopy, this paper makes the coloration theory of testing chromiumions by spectrophotometric method definite and clear. I design the Heavy metal detectionsensor, divide the hardware part of the sensor into two parts: optical sensing module andsignal processing module, and introduce the hardware part, principle of work and purpose ofevery module. At last, I introduce the structural design and function of the software system.Many test methods of the heavy metal ion in the soil requires that we should extract the heavymetal ion from the soil first of all. It could easily make errors because of the lowconcentration of the heavy metal in the soil. This paper optimizes the design of the soilpreparation equipment on the basis of soil analysis technical specifications, establishes anidea of Semi-automatic pretreatment system, to provide the theoretical basis and technicalguidance for the sampling and testing, and optimizes the design of the condition ofpre-treatment to improve the efficiency.To make the detection more accurate and fleet, I design a series of condition experimentsto choose the best reaction condition. For example:1. I did the waveband scanner for thechromium ions and DPCI coordination compound, and come to the conclusion that themaximum absorption wavelength is540nm.2. I ensured the Acidity control range.3. Iconfirmed the developing time to make the test more accurate.4. I investigated the boilingduration and reaction temperature, and come out that this experiment doesn’t need to boil, wecan test it at room temperature. It can save time.5. I ensure the dosage of color developingagent.Under the optimized condition, I come to the conclusion that the working curve of Cr⁶⁺,y=0.03471x-0.0032.(y is absorbance, x is the concentration unit, μg·mL^-1)The concentrationof Cr⁶⁺ranges from0.500μg·mL^-1 to10.00μg·mL^-1. Reading range of absorbance is from0.03to0.35. This paper discusses the influence of interfering ion to reduce the interferencefactor and prove the feasibility of absorption spectroscopy.