Detection Of Heavy Metal Ions In Water Based On Paper Microfluidic

Since the 21st century,due to the development of industrial construction,abundant industrial wastes have been polluted into the sea and river,containing heavy metal ions.These discharged heavy metal ions have the characteristics of wide distribution,long retention time,difficult to be decomposed by nature,and will be enriched into human body with the progress of food chain,causing great threat to human health.Due to the great harm of heavy metal ions,the concentration of heavy metal ions in nature has always been an important indicator of environmental health.Therefore,the detection of heavy metal ions in water has become a hot research field.There are many types of traditional heavy metal ion detection technology,including atomic fluorescence spectrometry,stripping voltammetry,atomic absorption spectrometry,inductively coupled plasma method,etc.the detection equipment used in these methods is expensive and difficult to handle,and the pretreatment process of detection samples is complex,the detection cost is high,and it is not suitable for water sample detection in a large range of areas.In this study,the paper-based microfluidic chip is used as the carrier to realize the real-time detection of heavy metal ions in water,and meet the requirements of low cost and accuracy of heavy metal ions detection.The main research contents are as follows:(1)According to the theory of capillarity,the transport process of fluid in porous media such as filter paper is studied.The whole process of filter paper porous media wicking was studied by using COMSOL software.The pattern design of paper-based microfluidic chip was carried out,the processing technology was formulated,and the performance of the chip was tested to verify the practicability of the chip.(2)Through the study of urease hydrolysis and color reaction based on paper-based microfluidic chip,taking urease activity,urea concentration and phenolphthalein solution concentration as single experimental variables,the optimal observation time of color reaction was analyzed and the optimal experimental parameters were set.Using the optimal experimental parameters,the paper-based chip was used as the substrate to repeat the color experiments for many times,which proved the reliability of the chip.(3)The paper-based microfluidic chip based on the optimal combination of experimental parameters was used to detect heavy metal ions.Different concentrations of copper ions and cadmium ions were mixed with urease solution.The inhibition effect of different incubation time and ion concentration on urease activity was studied by controlling the change of incubation time and ion concentration,and the inhibition model of copper and cadmium ions was established The concentration standard curve of the preparation effect.The effect of heavy metal ion concentration on the inhibition rate of urease activity was studied,and the inhibition effect of copper ion solution,cadmium ion solution and mixed ion solution on urease activity was compared.