On-line Analytical System Design Of Heavy Metal Ion Based On Stripping Voltammetry For Oil And Gas Production Wastewater

When oil and natural gas are produced,the produced wastewater may contain heavy metal ions,and direct emissions will cause serious pollution to the environment.The state has issued policies and regulations requiring that the heavy metal ions in the waste water must be analyzed and processed to meet the emission standards.At present,the detection of heavy metal ions is usually done by laboratory or portable analyzers,which is not conducive to timely measurement and long-term evaluation.In view of this situation,the subject has designed a heavy metal ion on-line analysis system using stripping voltammetry to continuously detect heavy metal ions.Specifically include the following.(1)A multi-functional,high-precision automatic sample preparation and sample pretreatment system design proposal is proposed.Two-stage filtration device designed to achieve filtration accuracy of 50~200um,which can effectively filter out waste water particles;design automatic anti-cleaning function,can clean pipelines and filter devices,prevent sample residue and flow path blockage;design temperature control device,optimize PID The adjustment algorithm can accurately,stably and quickly adjust the temperature.The control error is lower than 0.1°C.With the ST L6470 motor drive scheme,the sampling needle positioning accuracy error is less than 0.3mm.With the quantitative device,the injection volume repeatability is less than 0.2%.(2)Integrated design of heavy metal ion on-line analysis system.The on-line analysis system is realized by integrating the automatic sample injection with the sample pretreatment system and the analysis system.The analysis system designs the signal generation and detection circuit based on stripping voltammetry;the lower computer software is designed in C language;and the upper computer software is designed in C#.(3)Establish an online measurement model of heavy metal ions.The first-order difference method is used to remove the large error data;the data is smoothed by a five-point smoothing filter algorithm;the elution peak current value is determined by a cubic spline interpolation algorithm;and the elution peak current value and the ion content linearity are obtained by leastsquares fitting.Regression model;optimization of parameters such as enrichment voltage,enrichment time,etc.,so that the elution peak current value is maximized when the elution waveform is clear;and the lead ion and cadmium ion in the solution are measured by a linear regression model to obtain the measurement result.The relative mean errors were 3.36% and 3.34%,respectively,and the repeatability was 3.04% and 4.0%,respectively,satisfying the analysis requirements.