A new cataluminescence sensor for carbon tetrachloride using its catalytic reduction by hydrogen on palladium/carbon surface

A new cataluminescence (CTL) sensor was developed based on the chemiluminescence (CL) emission from the catalytic hydrodechlorination of carbon tetrachloride on the surface of palladium/carbon catalyst. The factors influencing the CTL signal, such as the catalyst, carrier gas, gas flow rate, temperature and the CL wavelength, were investigated in detail. Under the optimal conditions, the linear range of the CTL intensity versus concentration of carbon tetrachloride was 4.7–235 μg/mL (R = 0.9944, n = 7), with a limit of detection of 0.7 μg/mL (σ = 3). GC/MS results suggest that the possible CTL mechanism of the reduction is the formation of CCl3 radicals. The CCl3 radicals combine with H free atoms or capture hydrogen atoms from H2 molecules to form excited CHCl3 intermediates, which decay from the excited-state to the ground giving CTL emission for the detection. It is also found that some benzene derivatives with α-H of branched-chain, such as toluene, ethylbenzene and xylenecan, can play a role of catalyst in the reaction.