Development and evaluation of modified whetlerite, an adsorbent material for in situ degradation of sulphur mustard

Abstract Whetlerite carbon, which is in use in nuclear, biological and chemical filtration systems can degrade highly volatile chemical warfare gases such as phosgene, cyanogen chloride, hydrogen cyanide, etc. Degradation of vesicants such as sulphur mustard (HD) over whetlerite has not been extensively studied, except that the probability of some hydrolysis has been reported. In order to investigate the latter and incorporate HD degradation capability to the filter adsorbent, indigenous whetlerite carbon containing sodium hydroxide was further impregnated with various in situ degradation capable impregnants. The prepared adsorbent materials (impregnated modified whetlerite systems) were studied for in situ degradation of HD at ambient temperature. Degradation kinetics monitored by GC/FID was found to be pseudo-first-order. Kinetic rate constant and half-life values of degradation were calculated. Hemimustard, thiodiglycol, 1,4-oxathiane, sulphoxide and vinyl-2-chloroethyl sulphide were found to be the degradation products with modified whetlerite (MWh) and modified whetlerite impregnated with 11-molybdo-1-vanadophosphoric acid (MWh/V1) systems indicating that oxidative, hydrolytic and dehydrohalogenation decompositions are responsible for HD degradation. Effect of moisture on HD degradation was also studied on MWh and MWh/V1 systems, indicating that the rate of degradation increases with increasing moisture content.