Study On Hydride Generation Assisted Solution Cathode Glow Discharge Technology

At present,the impact of human activities on the environment has become increasingly prominent,with statistics showing that environmental pollution of water bodies has a direct impact on human health.Solution Cathode Glow Discharge(SCGD)technology is widely used in environmental testing and other aspects due to its small size,good detection performance,low cost,and low power consumption.However,in terms of heavy metal detection,the sensitivity and anti-interference capability of the technique still need to be improved.In order to solve the above problems,the Hydride Generation-Solution Cathode Glow Discharge(HG-SCGD)method is proposed in this thesis,and the details of the study are as follows:1.This thesis builds the HG-SCGD device.First,the electrical and spectral characteristics of the system are analyzed,and the study found that there is a positive differential resistance between the two poles.In addition,the flow rate of argon gas and the inter-pole voltage show an inverse proportional relationship.And the inter-pole voltage increases with the increase of the distance between the electrodes.Based on the modified experimental device,the blank solution was passed into the hydride reaction cell to collect plasma spectra.The analysis shows that the emission spectrum intensity of NO and Ar is significantly enhanced compared with the Solution Cathode Glow Discharge system;at the same time,the emission spectra of all substances were found to be strongest in the positive column region of the plasma and were affected by the argon flow rate and pole spacing.2.In order to further analyze the plasma excitation mechanism of the HG-SCGD system on a microscopic perspective,this thesis explores the influence of argon flow rate and electrode spacing on the plasma radiation spectrum,and analyzes the plasma physics under different argon flow rates and electrode spacing conditions.The evolution law of the parameters is studied in combination with the plasma image.The experimental results show that the plasma vibrational temperature and the electron number density are significantly affected by the positive effect of the argon gas flow rate.The increase of the electrode spacing mainly only promotes the increase of the plasma rotational temperature,both the argon gas flow rate and the electrode spacing will affect the plasma morphology.3.Finally,this thesis analyzes tin(Sn)and mercury(Hg)based on the HG-SCGD system.The experiment analyzed the influence of sodium borohydride concentration,carrier gas flow rate,sample solution p H value,electrode spacing,discharge current and electrolyte flow rate on the system,and verified the best collection position of Sn and Hg radiation spectra.Subsequently,the anti-interference ability and stability of the system were analyzed,and the calibration models of Sn and Hg were established under the optimal experimental conditions,and the detection limits were calculated to be 6.85μg/L and 1.05 μg/L,respectively.All are lower than the detection limit of the traditional solution cathode glow discharge system.Finally,three actual water samples were collected to study the recovery rate of standard addition.The range of recovery rates of Sn and Hg addition was 99.16%-103.08% and 97.77%-101.34%,respectively.The above experimental results show that the assistance of hydride generation technology can significantly improve the sensitivity of the solution cathode glow discharge system to the detection of heavy metal elements in water,and it is suitable for the analysis of actual water samples.