Design Of On-line Instrument For Tracing The Ions Of As And F In Drinking Water

The damage of Fluorine mainly affects chewing, digestive function and bone. The damage of Arsenic mainly affects skin, causing carcinoma, deformity and mutation of cell. Fast and accurate tracing the ions concentration of Arsenic and Fluorine in drinking water is strong significant. In addition, a correct judgment of the sources of pollutants can form an effective control of the pollution. The thesis is divided into three parts:hardware of on-line instrument for tracing the ions of As and F in drinking water; software of on-line instrument for tracing the ions of As and F in drinking water; the source apportionment studies of ions distribution in drinking water based on multivariate statistical analysis.Hardware of on-line instrument for tracing the ions of As and F in drinking water including mechanical design and circuit design. Mechanical design is consist of automatic injection system, the pre-treatment device and working electrode automatic replacement device. The automatic injection system is comprised by peristaltic pump, Syringe pump, multi-pass substrate and solenoid valve. It can effectively reduce the number of peristaltic pump, precisely extract the amount of liquid and provide an efficient, low cross-contamination and high reproducibility injection. Pre-treatment device achieves the liquid, drain and exhaust orderly. It also improves the effect of digestion reaction and enhances the controllability of digestion process. In addition, the automatic electrode replacement for the detection of Arsenic can enhance the single-use time cycle of instrument and achieve no man unattended in a long time. The circuit of the instrument contains a data acquisition card of USB-6212, control circuit for automatic liquid injection system, potentiostat circuit of three-electrode electrochemical measurement and weak current signal detection circuit. Due to the signal of sensor to dectect the ion of Arsenic in drinking water is relatively weak, the circuit have a good prohabitaion for noise by the methods of analyzing the noise characteristics and establishing the system noise model. The results show that the automatic detection system has high accuracy and sensitivity. Electrochemical measurement system can replace electrochemical workstation for the measurement of differential pulse anodic stripping voltammetry. If the output in range of-5V to+5V, the error output of constant potential does not exceed3mV. The resolution of weak current signal detecting circuit is2nA. Software of on-line instrument for tracing the ions of As and F in drinking water including the design of detection process for the automatic detection system, sending the results and data based on the data transmission module, controling for automatic injection system (including solenoid valves, peristaltic pump, syringe pump and digestiontank), differential pulse stripping voltammetry for the detection of Arsenic, processing and de-noising for the detection data of Arsenic based on wavelet analysis, the calculation for stripping peak area and concentration of Arsenic Reaspmable detection process is avoiding excessive human interference and making the instrument completely automated measurement. The interface of on-line instrument for tracing the ions of As and F in drinking water is friendly and simple to operate. It can set important parameters and grasp the instrument’s real-time state. The automatic detection system has the function of remote boot and data backhaul. Stable server system and data transmission module undertake the server for sending the reception of start signal and the results. Due to the adoption of de-noising based on the wavelet analysis and specific calculation method for peak area of electrochemical data, it can quickly and accurately calculate the concentration of Arsenic in drinking water.Source apportionment of the ion distribution in drinking water based on multivariate statistical analysis is researched. The multivariate statistical analysis includs positive matrix factorization, non-negative matrix factorization, cluster analysis, principal component analysis. In this work, qualitative and quantitative source apportionment studies of the ion distribution in drinking water from Tuoketuo, Inner Mongolia, China based on the above four proposed methods. The estimates of source pollution concluded by the above four proposed methods are consistent. The pollution can be divided into two categories:the first class includ more Arsenic, Lead and Sulfur in water, such pollution may due to the phosphate and sulfate/sulfide, galena, lead and zinc, as well as the natural weathering of lead-zinc material and aluminum and potassium-rich clay mineral contamination. The second class is composed by other ions such as Calcium, Silicon, and Sodium. The pollution may be caused by the carbonate mineral (e.g. calcite), magnesium carbonate ores (e.g. dolomite), and several other types of silicate minerals.