Plastic decomposes over millions of years, and considering that 311 million tons of plastics are discarded into landfills each year, our landfills are filling up at an alarming rate (Osman et al. . Our current model of dealing with our plastic is not sustainable (Osman et al. 301). This is why scientists are looking for alternative methods to deal with plastic waste. Researchers in Islamabad, Pakistan discovered that Aspergillus fumigatus Strain S45 that they believe is able to decompose polyester. They hypothesis that Strain S45 has ester enzyme that is capable of decomposing polyester PU.
The scientist began their experiment by isolating Aspergillus fumigatus Strain S45 from a soil sample from the plastic waste dump in Islamabad, Pakistan. …show more content…
The experiment was perform in triplicates to eliminate sample bias. The explanatory variable, which was a 250mg of PU, was placed into 100ml Erlenmeyer flask with 50ml of MSM and was inoculated with Aspergillus fumigatus Strain S45 spores. The response variable, 250mg of PU was placed into 100ml Erlenmeyer flask with 50ml of MSM. Every day for the next 30 days, the samples were dried and were weighted. Figure 2. shows that the control group did not show any change within its mass, which is to be expected considering the plastic takes millions of years to decompose. However, there was a 20% decrease in mass for the experimental group (Osman et al. 303). This showed that Aspergillus fumigatus Strain S45 supported the researcher hypotheses that Strain S45 displays the characteristics of degrading …show more content…
Figure 3. Shows that peaks at 1136.9, 1164.9, 1725.8, and 2956.2 have a significant decrease from the first IR test to the second IR test. The 1735 peak is an attribute of an ester and 1146 peak that displays the C-O-C chain show a decrease in their gradient (Osman et al. 306). This indicates there was a breakdown of the ester bonds. This further supported the researchers hypothesis that specific esterase is being used to breakdown PU.
Additionally, the Differential Scanning Calorimetry of PU film indicates there is a change in the chemical structure. Figure 5. shows that the control group had lower peak temperature and onset temperature peaks, whereas the onset and temperature peak are greater in test group (Osman et al. 308). The change of onset and temperature can be due to various things, but it is most likely due to a change in the crystalline structure of the PU sample itself.
Additionally, the scanning electron microscope (SEM) test showed there was a changes in topographic morphology of PU films. The samples were seen using the SEM on day one and day 30. Pits and holes were seen on the surface of the PU film were seen on day 30 that were not seen on day one as seen on Figure 4. Fungal hypae and spores growth were seen on the PU