Experimental Study On Detection Of Heavy Metal Pb In Water Based On Algal Enrichment-XRF Spectroscopy

Heavy metal pollution in water is a major environmental problem facing my country.Realizing the rapid detection of heavy metals in water is of great practical significance for preventing and controlling heavy metal pollution in water,ensuring the safety of water ecosystems and human health.Compared with the field sampling-laboratory analysis method,XRF spectroscopy has the advantages of non-destructiveness and fast analysis speed of the sample to be tested,and is an effective technical means for the rapid detection of heavy metals in the field.There are problems such as poor spectral stability and low sensitivity.In view of the above problems,this paper takes the heavy metal Pb in water as the research object and algae as the adsorbent to carry out an experimental study on the detection of heavy metal Pb in water based on the combination of algae enrichment and XRF spectroscopy,and determine the suitable algae suitable for the efficient adsorption of heavy metal Pb in water.Species and their algal cell state,to construct the optimal experimental conditions for efficient enrichment of heavy metal Pb in water,and to establish an XRF quantitative analysis method based on algal enrichment of heavy metal Pb in water to achieve quantitative detection of heavy metal Pb in actual water.（1）In order to achieve efficient enrichment of heavy metal Pb in water,First,the adsorption characteristics of four freshwater microalgae,Chlorella pyrenoidosa,Scenedesmus dimorphus,Microcystis aeruginosa,and Merismopedia under different growth periods and different cell states,on heavy metal Pb were studied.Through comparative analysis,it is clear that the four selected freshwater microalgae have fast adsorption characteristics to heavy metal Pb²⁺,and the adsorption efficiency can reach the maximum value in 5-10 min;the adsorption characteristics of four freshwater microalgae to heavy metal Pb²⁺are affected by the growth period The influence law of Pb²⁺is different to some extent,but they all show that the adsorption effect of Pb²⁺is the best when cultured to the third day;Chlorella pyrenoidosa,Scenedesmus dimorphus and Microcystis aeruginosa all showed better adsorption performance of live algal cells for heavy metal Pb²⁺,and the adsorption efficiency had good stability within 5-60 min;In contrast,in a short period of time,the adsorption of heavy metals Pb²⁺by inactivated algal cells was slightly better than that of live algal cells.Comparative analysis of the adsorption characteristics of four kinds of freshwater microalgae on heavy metal Pb²⁺,Scenedesmus dimorphicus and Chlorella pyrenoidosa showed better adsorption characteristics,among which Scenedesmus dimorphicus had better adsorption performance for higher concentrations of heavy metal Pb^2+,The adsorption performance of Chlorella pyrenoidosa to lower concentrations of heavy metal Pb²⁺was better.（2）Using Chlorella pyrenoidosa as the adsorbent,the optimum adsorption conditions for the efficient enrichment of heavy metal Pb in water were studied.Studies have shown that the p H value of the reaction solution and the reaction temperature have a certain effect on the adsorption of heavy metal Pb by Chlorella pyrenoidosa.It was confirmed that the p H value of 7 and the reaction temperature of 25°C were the optimal adsorption reaction conditions for the adsorption of heavy metal Pb by Chlorella pyrenoidosa.Under the optimal adsorption conditions,the adsorption performance of100mg/L Chlorella pyrenoidosa on different concentrations of heavy metal Pb was explored,and the heavy metal Pb in the concentration range of 0.012～0.35mg/L had excellent adsorption effect;The differences in the adsorption performance of Chlorella pyrenoidosa for heavy metals Pb and As were compared and analyzed.The study showed that Chlorella pyrenoidosa had excellent adsorption performance for Pb,but the adsorption ability for As was weak.,therefore,using Chlorella pyrenoidosa as the adsorbent to enrich the heavy metal Pb in the water body and carry out the XRF spectrum measurement and analysis can effectively avoid the interference and influence of the coexisting As on the XRF characteristic spectrum of Pb.（3）Under the optimal adsorption conditions with as the adsorbent,the enrichment amount of the adsorption reaction solution during the enrichment process of heavy metal Pb in water was studied,and 10 m L was determined as the optimum sample enrichment amount;Under the optimal adsorption reaction and enrichment experimental conditions,a rapid quantitative detection method of heavy metal Pb in water based on Chlorella pyrenoidosa enrichment-XRF spectroscopic detection was established.Detection performance of heavy metal Pb in water.The study shows that the initial concentration of heavy metal Pb in the reaction solution has a good linear relationship with the net integral fluorescence intensity of the Lαcharacteristic spectrum peak of Pb element in the enriched sample,and the correlation coefficient R2is 0.9900.When the enrichment amount of the sample is 10 m L,The detection limit of this method is 0.0072mg/L,which is lower than the Class I water quality standard limit of 0.01mg/L in"Environmental Quality Standard for Surface Water（GB 3838-2002）";his method adopts the standard addition method to detect the heavy metal Pb in the actual water samples of Paihe,Kuanghe,Nanfeihe,Silihe and Shiwulihe in Hefei City.The water heavy metal detection method based on the combination of algae enrichment and XRF spectroscopy can be well applied to the rapid detection of actual water bodies.The research results of this paper provide a method basis for the development of on-site rapid monitoring techniques and instruments for heavy metals in water.