Rendering Bio-inert Low-Density Polyethylene Amenable for Biodegradation via Fast High Throughput Reactive Extrusion Assisted Oxidation

Abstract

An energy e cient high throughput pre-treatment of low density polyethylene (LDPE) using a fast reactive extrusion (REX) assisted oxidation technique followed by bacterial attachment as an indicator for bioamenability was studied. Silicon dioxide (SiO 2 ) was selected as a model oxidizing and catalytic reagent with the REX process demonstrated to be effective both in the presence and absence of the catalyst.Optimized 5-minute duration pretreatment conditions were determined using Box-Behnken design (BBD) with respect to screws speed, operating temperature, and concentration of SiO 2 . The crystallinity index, carbonyl index and weight loss (%) of LDPE were used as the studied responses for BDD. FTIR and DSC spectra of the residual LDPE obtained after pretreatment with the REX assisted oxidation technique showed a signi cant increase in residual LDPE carbonyl index from 0 to 1.04 and a decrease of LDPE crystallinity index from 29% to 18%. Up to 5-fold molecular weight reductions were also demonstrated using GPC. Optimum LDPE pretreatment with a duration of 5 minutes was obtained at low screw speed (50 rpm), operating temperature of 380-390 C and variable concentration of SiO 2 (0 and 2% (w/w))indicating that effective pretreatment can occur under noncatalytic and catalysed conditions. Bio lms were successfully formed on pretreated LDPE samples after 14 days of incubation.Furthermore, the technique proposed in this study is expected to provide a high throughput approach for pretreatment of pervasive recalcitrant PE based plastics to reduce their bio inertness.

Plastic waste to sustainable solutions: accelerating the biodegradation of syn-thetic plastics

“…AIMPLAS, in collaboration with TUS and IMGGE (partners of BioICEP project), set up the optimisation of reactive extrusion for further biodegradation of LDPE. This set of experiments showed that LDPE was efficiently converted into bio-amenable LDPE using an energyfavourable, industrially scalable reactive extrusion process (Ferrero et al, 2022). Best conditions were found using low screw speed (50 rpm), an operating temperature of 380ºC, and catalytic and non-catalytic conditions.…”

Biodegradation of cassava starch modified low density polyethylene by Bacillus cereus and Pseudomonas aeruginosa isolated from waste dumpsite

“…These recalcitrants are generated and accumulated in the in the environment which needs many years for complete deterioration [3]. Pollution caused by polyethylene include blockage of drainages, soil, water and air contaminations [4]. Apart from that, the three dimensional Low-density polyethene (LDPE) is a major cause of environmental pollution due to its high tensile strength, lightness, resistance to water, and microbial attack [2].…”