Effect of chemical treatment on biological degradation of high-density polyethylene (HDPE)

The present study deals with capacity of Cephalosporium species to degrade high-density polyethylene (HDPE). HDPE was treated with nitric acid to make it susceptible to microorganisms. Chemical treatment with nitric acid introduces carbonyl and nitro functional groups in HDPE as confirmed by Fourier transform infrared spectroscopy analysis. Gravimetric analysis showed a decrease in weight of the polymer by 7.18 +/- 0.15% after 20 days of incubation period. Reduction in the weight of polymer confirmed the ability of Cephalosporium species to utilize HDPE for their growth. The pH of liquid culture media was found to decrease, whereas total dissolved solids and conductivity increase with the incubation period. Scanning electron microscopy analysis showed changes in morphology of films inoculated with Cephalosporium species. Decrease in crystallinity observed using X-ray diffraction studies further confirmed the degradation of pre-treated HDPE. The observed results reveal that the Cephalosporium species could be effectively used for the degradation of pre-treated HDPE under laboratory conditions.