Research On The Detection Of Metal Ions In Water Based On The Solution Cathode Glow Discharge Coupled With An Optical Filter Discrimination System

With the rapid development of modern industry and agriculture, water pollution is getting worse and worse. Therefore, an efficient and low-cost way to achieve the detection of metal ions in water is very necessary to the areas of environmental and food security. Nowadays, traditional methods of detecting metal ions in water mainly includes two categories, the first one is based on the principle of electrochemical detection method,this method has some disadvantages in terms of stability and selectivity, and another one is based on spectrum and mass spectrum technology, this method has disadvantages such as bulky and expensive detection equipment, which cannot meet the demand of the convenient detection and small-scaled equipment. Solution-cathode glow discharge(SCGD) emission spectrum detecting metal is a method for the detection of metal ions,which has obtained extensive focus in recent years. It is a highly efficient method for metal, but emission spectrum is usually collected by spectrograph, which makes the detection system more inconvenient and high-cost. In order to solve these problems, this thesis attempt to study on a new detection method based on the solution-cathode glow discharge emission spectrum technique coupled with optical filter discrimination technique, design and implement a new photoelectric detection device for metal ions in water.The detection device consists of a solution cathode discharge source generation part,the optical filter discrimination part and data acquisition section. The solid tungsten rod is used as the discharge anode, solution flows from the quartz capillary, and used as a discharge cathode. High-voltage is supplied for the source generation part and plasmas can be obtained. The optical filter discrimination part is consist of fused silica lens,adjustable slit and filter wheel. The data acquisition section is made up with a photomultiplier and a picoammeter. In this thesis, the principle of the photoelectric detection system based on the solution-cathode glow discharge coupled with optical filter discrimination system for detecting metal elements in water is introduced in theory firstly;and next step, a corresponding solution cathode discharge source device is constructed,and we design and achieve the optical filter discrimination part to select the atomic emission spectrum, and collect the data by the date acquisition section; finally, we test the entire detection system, optimize experimental conditions, study and analysis verticaldistributions of several kinds of metal elements emissions. On this basis, the work of detection for the metal elements of Na, K, Ca, Li, Sr, Rb and Cs included in the standard solution is finished through experimental testing, and the detection limits of Na, K, Ca, Li,Sr, Rb and Cs dissolved in the aqueous solution are 0.0007mg/L, 0.0028mg/L,0.4240mg/L, 0.0042mg/L, 2.1000mg/L, 0.0044mg/L, 0.0595mg/L, respectively. By the matrix effect experiment, we find that the signals of K is suppressed by the high concentrations of sodium, and when the concentrations of sodium reach a certain value,inhibitory effect reaches saturation, and leverage this feature, we detect and obtain the concentration of K in the physiological saline solution and the concentration of K is0.534mg/L.Compared with the common detection methods, solution-cathode glow discharge coupled with optical filter discrimination system has the advantages of small volume, low operation cost, real-time detection and low detection limit, which make this technology more suitable for detecting metal elements in the aqueous solution.