Research On Hydrogel Decontamination System Based On Acetyl Perborate

Although“Convention on the prohibition of the development,production,stockpiling and use of chemical weapons and on their destruction”was signed by many countries,the Chemical Warfare Agents were still used by some countries and organizations disrupting the security and stability of the international community.Therefore,the decontamination of Chemical Warfare Agents is of great significance for the maintenance of public safety.Peroxide decontaminants have the advantages of mild reaction and environmentally friendly,but the stability of peroxides is generally poor.The traditional water-based decontaminants could effectively decontaminate Chemical Warfare Agents,but it has the disadvantage of producing large amount of waste water,and poor suppression effect to the chemical agent,which could cause secondary pollution to the environment.In order to solve these problems,a new type of APB/hydrogel decontamination system with acetyl perborate（APB）,a more stable peroxide,as active component was constructed in this paper.The research contents and innovative findings of this paper are as follows:（1）The Preparation and characterization of APBAnhydrous sodium tetraborate and peracetic acid（PAA）were used as reactants to prepare APB.Based on the content of PAA in APB sample,the effects of the ratio of reactants,reaction temperature,post-treatment solvent and drying method on the preparation of APB were studied.The optimum conditions for the preparation of APB were determined as follows:T=35℃,molar ratio of PAA/anhydrous sodium tetraborate=1.6:1,ethanol as the post-treatment solvent and freeze-drying.The content of PAA in APB prepared under these conditions could reach about 26%.The physicochemical properties of APB were characterized by FT-IR,Raman spectroscopy,SS-NMR,ICP-OES and DSC.Carbonyl group and peroxy bond of APB were confirmed,and the molecular formula of APB was deduced as Na₂B₄C₈H₂₀O₁₂.（2）Study on the decontamination effect of APB2-CEES was selected as the simulant of Chemical Warfare Agents mustard（HD）,and the degradation effect of 2-CEES in APB solution were measured under different molar ratios of APB to 2-CEES（APB/2-CEES）.It was found that 2-CEES could be completely degraded within 10 min when APB/2-CEES=1,which suggested that APB solution could degrade 2-CEES effectively.Malathion was used as a simulant of Chemical Warfare Agent VX and its degradation process were studied by ³¹P{¹H}NMR.Firstly,the degradation effects of malathion were studied under different molar ratios of APB to malathion（APB/malathion）conditions,and the results showed that the types of phosphorus products increased with the increase of APB/malathion molar ratios.Malaoxon was the only phosphorus product when APB/malathion=5:1.Phosphate trimer began to appear when the mole ratio was 10.when the mole ratio was more than 40,dimethyl phosphate began to generate.When APB/malathion=5:1,10:1 20:1,40:1 and 60:1,the degradation efficiency of malathion in 47.5 min was 13.25%,22.57%,53.35%,82.19%and 100%,respectively.In order to reduce the amount of APB needed,different activators were used to activate APB solution to degrade malathion.The results showed that carbonate(CO₃^2-)could effectively activate APB solution to degrade malathion.Malathion was completely degraded in APB/CO₃^2-solution（APB/malathion=10:1）in 10 min.The degradation process of malathion in APB/CO₃^2-solution could be inferred as follows:malathion was rapidly oxidized to malaoxon firstly,and then malaoxon was further hydrolyzed to dimethyl phosphate in the presence of OH^-.From the degradation kinetics after quenching the reactive oxygen species with the corresponding scavengers,it could be concluded that RC·was the key active specie which promoted the oxidation of malathion to malaoxon.The presence of singlet oxygen（¹O₂）,superoxide anion（O₂^-·）and hydroxyl radical（·OH）in the activated system were testified by chemiluminescence（CL）and Electron Paramagnetic Resonance（EPR）tests,but they had little effect on the degradation of malathion.The effects of ions（HCO₃^-,Cl^-and NO₃^-）and fulvic acid（FA）in natural water on malathion degradation in APB/CO₃^2-solution were investigated.The results showed that the effects of above ions on the degradation were not obvious,but FA could compete with malathion for active species,thus inhibiting malathion degradation.（3）Study on APB hydrogel decontamination systemAn in-situ polymerized PVA/borax hydrogel and four kinds of formulated hydrogels were prepared,and their properties were characterized.Based on the adhesion and viscosity of the hydrogel,a hydrogel formulation（Hydrogel-2）consisting of guar gum,xanthan gum,phospholipid,coconut oil alkanolamide（BX-6502）and canola oil was determined.Hydrogel decontamination system APB/Hydrogel-2 was constructed and the decontamination efficiency of three typical Chemical Warfare Agents（HD,VX,GD）in which was tested.The developed hydrogel disinfection system can be uniformly dispersed on the alkyd paint iron plate by the dispersing device,and the adhesion effect is excellent.The above results indicated that APB/Hydrogel-2decontamination system had a broad application prospect in the field of Chemical Warfare Agents decontamination.