| The problem of heavy metals pollution in water is becoming more and more serious situation.According to policies of "Water Pollution Control Action Plan" and " 13th Five-Ye ar Plan of Eco-environmental Protection",there is a need to strengthen the pre-warning,prevention and control of water pollution.Therefore,the research and development of pre-treatment technology and detection technology of environmental pollutants in water provides government with technical support for to formulate water pollution control measures and decision-making,which is of significance for ensuring water environmental safety.In view of this,based on the performance evaluation of the continuous digestion instrument development by our research group,two methods for rapid enrichment and detection of mercury ions in water were developed with the detection target of mercury ions.The main conclusions are as follows.(1)Taking the actual dyeing wastewater and tannery wastewater as objects and the effects of digestion conditions on the digestion efficiency of continuous digestion instrument were studied by comparing graphite digestion with microwave digestion.The results showed that the optimum digestion conditions for dyeing wastewater were as followsrthe ratio of H2O2/HNO3 was 5/1,the digestion temperature was 140 ? and the recovery rate of standard addition was between 8 0%and 1 20%,the digestion efficiency was the same as that of graphite digestion.The optimum digestion conditions for tannery wastewater were as follows:the ratio of H2O2/HNO3 was 5/1,the digestion temperature was 160 ?,the recovery rate of standard addition experiment was between 90%and 120%,and the digestion efficiency was compaeable to graphite digestion and microwave assisted digestion.The results showed that the self-developed continuous digestion method is suitable for the pretreatment of actual dyeing and tanning wastewater,and has a good application value in field.(2)The carbon cloth composite electrodes deposited by gold nanoparticles were prepared by multi-potential step method with hydrophilic carbon cloth as the substrate.The electrochemical method for detection mercury in water was established based on the prepared composite electrode,and the flow detection was established.The effects of electrolyte type,stripping method and flow rate on electrochemical detection of mercury in water were studied.The results showed that the detection limit of mercury in water was 0.6 ?g/L and the linear range was 2?200 ?g/L under the condition that the electrolyte was 0.2 M hydrochloric acid,and the stripping method was square wave voltammetry.The spiked recovery experiment of the actual water sample showed that the spiked recovery of the method was between 92%and 109%,and had high stability(relative standard deviation<5%).The results showed that the continuous flow detection of water samples was achieved by the established flow detection reaction tank.The optimum speed was 1 mL/min,and it has the advantages of short detection time and high stability and the potential application value in the rapid detection of mercury.(3)The fiberglass filter paper was used as the vector to prepare the suitable extraction material for detection of mercury in water by redox method on the surface of the gold nanoparticles.The influence of the extraction time,extraction temperature and oscillation rate on the extraction efficiency were investigation.The results show that the optimum process for mercury extraction in water was the extraction temperature at 60 ?,and extraction for 10 min with the oscillating speed of 150 rpm.Under the optimum extraction conditions,the detection limit of mercury was 0.03 ug/L,the linear range was 0.1?20 ug/L and there exhibited good reproducibility between different composite fiber filter paper.The results showed that fiberglass filter paper-solid phase microextraction can be used for the separation and enrichment of mercury in water,and it can be used in combination with thermal desorption atomic absorption spectrometry to achieve rapid analysis of mercury. |
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