Research On A Portable Water Quality Heavy Metal Cr(?) Detection System Based On Graphene Nanomaterials

With the rapid development of economy and industry,the heavy metal ion pollution in water,especially for hexavalent chromium(Cr(?)),is serious in China.Cr(?)is easily absorbed and stored in human bodies,inhibiting enzymatic activity,interfering protein and ribonucleic acid synthesis,which gives rise to cancer.Frequent large-scale human poisoning incidents had occurred for many times.Chromium determination in the water,becoming one of the must-test environmental indexes,plays a crucial role in prevention,protection and governance of heavy metal in water.The traditional Cr(?)detection method was given priority to manual analysis in laboratory,time consuming and complex operation.Meanwhile,the most of the instruments are big,high power consuming,expensive and difficult to apply for off-site detection.Therefore,the study on a portable sensor or system for Cr(?)detection with the features of small volume,low cost,simple operation and on-site determination is of great importance.In this paper,portable electrochemical heavy metal detection system for Cr(?)in water based on graphene nanomaterials was proposed for heavy metal on-site determination.the main research content concludes:(1)an electrochemical heavy metal detection system for Cr(?)in water based on graphene nanomaterials combined with the technology of nanomaterials and electrochemical sensing was proposed.The electrochemical perparation method of graphene nanomaterials was studied.Graphene film modified electrode was made to show the performance of electrocatalytic capability for heavy metal Cr(?).The linear range,stability and anti-interference of the sensor were also shown.The results demonstrated the sensor can meet the detection requirement according to the national quality standard of I-V class water;(2)a new type of portable electrochemical heavy metal Cr(?)detection system was designed and achieved,which applied the technology of microcomputer and mobile phone appliance.The design of hardware: the STM32F103 chip was selected as the microcontroller.CS5532 and DA8552 were respectively ADC and DAC conversion chip.The serial port communication was realized by the conversion chip PL2303,and wireless communication was implemented by bluetooth module.The software design includes two parts: the slave computer and the host computer.The slave computer program was programmed by single-chip computer C language on the software development platform of Keil ?Vision5 to achieve the corresponding programfunction of the system hardware module;The host computer is a mobile application developed on the App Inventor development platform,which realizes the sending,displaying and saving of the host computer data and commands.The comprehensive performance of the portable instrument was tested with the heavy metal Cr(?)standard water samples provided by the Chinese environmental standard sample center,comparing the test results got on the CHI630 e electrochemical analyzer(Chenhua Instrument Corporation).The results indicated,in the range of Cr(?)concentration of national standard I-V class water,the test results of the designed detection system was in accordance with that of CHI630 e.The system can be verified with the capability of Cr(?)fast determination and the functions of data optimization,display and storage in a stable manner by test.The system with low power consumption is easy to carry and operate,which has application value of subject research of the detection of heavy metal Cr(?)on site for water quality.