The study of ZnAl and ZnFe layered double hydroxide on the catalytic dechlorination and fire safety of polyvinyl chloride

The effect of OZnAl-LDH and OZnFe-LDH on the catalytic dechlorination, thermal decomposition and smoke suppression of polyvinyl chloride (PVC) during pyrolysis processes was investigated and compared. The thermal degradation and combustion behavior of the PVC composites were investigated by thermogravimetric analysis and cone calorimetry, respectively. The results indicate that the addition of LDHs brought about the improved thermal stability and reduced heat release of PVC composites at high temperature. The smoke suppression properties of the composites are investigated by steady-state tube furnace. The results revealed that the toxic gases such as CO, CH4, NOx and N2O were inhibited by both two LDHs, but the OZnAl-LDH has better effect on the smoke suppression. Subsequently, the char layer was investigated by scanning electron microscopy-energy-dispersive spectrometry and Raman analysis. The results indicated that the LDHs can promote the dechlorination of PVC and form graphitized structures. Generally, OZnAl-LDH and OZnFe-LDH can be potential catalysts for waste disposal and improve the fire safety of PVC.