In the production of activated carbon from PVC, there may be two stage process : the first stage is the dehydrochlorination of PVC to obtain char rich in carbon and the second is the activation of char at high temperature to obtain high surface area. The latter process requires high energy consumption and the yield is very low. Therefore, instead of this process, the method to attach acidic functional groups on the surface of the char was used.
Compared were two methods of dehydrochlorination of PVC : thermal decomposition by heating PVC directly and dehydrochlorination by using sodium hydroxide solution. While the former method gave more aromatic structures to the char than the latter, the char obtained by either method had basically polyene structures. Dehydrochlorination by using NaOH solution showed second order reaction and the activation energy of 21.8 Kcal/mole.
The PVC char was oxidated with HNO₃ solution of 3N-7N concentrations and showed the ion exchange capacity of 3-4 m-equivalent HNO₃/g-char. Although the surface area of the char was not over 8 m²/g-char, its adsorption capacity of lead ion was nearly the same as that of activated carbon with large surface area treated with HNO₃ solution.