Currently, there is a global concern about the environmental problems related to plastic wastes. Cellulose acetate (CA) and polylactic acid (PLA) are the most frequently used biopolymers in the food packaging industry. In this work, TiO2 nanoparticles and β-cyclodextrin (βCD) have been incorporated into nanocomposite films made of PLA and CA and then evaluated under biodegradation assays in wastewater to assess the effects of both additives on the biodegradability of films. TiO2 nanoparticles clearly enhanced the biodegradability of CA and PLA; PLA-TiO2 nanocomposites disappeared after 60 days, whereas plain PLA remained present after 100 days. The presence of the additives provided an exponential growth to biological oxygen demand (BOD) profiles. FTIR spectra showed a much faster deacetylation of CA for the nanocomposites than for the bare CA, and XRD diffractograms showed that PLA nanocomposites became more amorphous than bare PLA. The thermal resistance of CA and PLA nanocomposites substantially decreased, while plain matrices remained fairly stable up to 60 days. SEM micrographs of CA and PLA nanocomposites presented voids and larger surface erosion than the plain matrices. βCD modification of TiO2 nanoparticles seems to have a protective effect on the biodegradation of the polymers with respect to the unmodified TiO2.
The aerobic biodegradation of PLA and CA polymers in aqueous medium was assessed in closed respirometers in accordance with standard procedure (ISO 14851:2020) for 100 days. Secondary sludge (activated sludge) from a local wastewater treatment plant (Arazuri, Spain) was employed as microbial inoculum.
Leire Goñi-Ciaurriz, Adrián Durán, Francisco J Peñas, Itziar Vélaz (2022) Enhanced biodegradation of polylactic acid and cellulose acetate nanocomposites in wastewater: Effect of TiO2 and β-cyclodextrin. EResearch Square https://assets.researchsquare.com/files/rs-2064652/v1/eb92277d-a2ce-48a0-afd2-911786ac3b59.pdf?c=1663752592