Preparation and Effect of Gamma Radiation on The Properties and Biodegradability of Poly(Styrene/Starch) Blends

Phylloplane fungus Curvularia dactyloctenicola VJP08 effectively degrades commercially available PS product

Polystyrene (PS), a widely produced plastic with an extended carbon (C-C) backbone that resists microbial attack, is produced in enormous quantities throughout the World. Naturally occurring plasticizers such as plant cuticle and lignocelluloses share similar properties to synthetic plastics such as hydrophobicity, structural complexity, and higher recalcitrance to degradation. In due course of time, phytopathogenic fungi have evolved strategies to overcome these limitations and utilize lignocellulosic waste for their nutrition. The present investigation focuses on the utilization of phylloplane fungus, Curvularia dactyloctenicola VJP08 towards its ability to colonize and degrade commercially available PS lids. The fungus was observed to densely grow onto PS samples over an incubation period of 30 days. The morphological changes showcased extensive fungal growth with mycelial imbrication invading the PS surface for carbon extraction leading to the appearance of cracks and holes in the PS surface. It was further confirmed by EDS analysis which indicated that carbon was extracted from PS for the fungal growth. Further, 3.57% decrease in the weight, 8.8% decrease in the thickness and 2 °C decrease in the glass transition temperature (Tg) confirmed alterations in the structural integrity of PS samples by the fungal action. GC-MS/MS analysis of the treated PS samples also showed significant decrease in the concentration of benzene and associated aromatic derivatives confirming the degradation of PS samples and subsequent utilization of generated by-products by the fungus for growth. Overall, the present study confirmed the degradation and utilization of commercially available PS samples by phylloplane fungus C. dactyloctenicola VJP08. These findings establish a clear cross-assessment of the phylloplane fungi for their prospective use in the development of degradation strategies of synthetic plastics.

Influence of nitric acid on biodegradation of polystyrene and low-density polyethylene by Cephalosporium species

Petroleum-based polymers are not susceptible to microorganisms because of its high molecular weight. Acid treatments convert the polymers into a more oxidized form having low molecular weight. The present in-vitro degradation study focuses on the potential of Cephalosporium species to degrade acid-treated polystyrene (PS) and low-density polyethylene (LDPE) films. A weight loss of around 12% and 13% was achieved for PS and LDPE films respectively in eight weeks of treatment with Cephalosporium species. Fourier transform infrared spectroscopy analysis showed the formation of hydroxyl and carbonyl groups in nitric acid treated PS and LDPE films, respectively. Scanning electron microscopy indicated modifications in the surface morphology of PS and LDPE films after chemical and microbial treatment. An increase in crystallinity of pre-treated polymer samples was observed after fungal treatment. The observations of present study confirmed the enzymatic deterioration and assimilation of pre-treated PS and LDPE samples by the microbial species.

Predicting the global environmental distribution of plastic polymers

This study represents the first quantitative global prediction of the mass distribution of six widespread polymers, plus plastic fibers and rubber across four environmental compartments and 11 sub-compartments. The approach used probabilistic material flow analysis for 2015, with model input values and transfer coefficients between compartments taken from literature. We estimated that 3.2 ± 1.8 Mt/year of polyethylene, 1.3 ± 0.8 Mt/year of polypropylene, 0.5 ± 0.3 Mt/year of polystyrene, 0.3 ± 0.15 Mt/year of polyvinyl chloride, 1.6 ± 0.9 Mt/year of polyethylene terephthalate and 2.4 ± 1.2 Mt/year of plastic fibers enter the environment. Combining all plastic, including rubber, 4.9 ± 1.3, 4.8 ± 1.9 and 1.8 ± 1.2 Mt/year accumulated in the soil, ocean, and freshwater, respectively. Urban soils and ocean shorelines were predicted as hotspots for plastic accumulation, accounting for 33% and 25% of total plastic, respectively. The floor of freshwater systems and the ocean were predicted as hotspots for high density plastic such as polyethylene terephthalate, polyvinyl chloride and plastic fibers. Furthermore, 59% of environmental rubber was predicted to accumulate in soil. The findings of this study provide baseline data for quantifying plastic transport and accumulation, which can inform future ecotoxicity studies and risk assessments, as well as targeting efforts to mitigate plastic pollution.

Biodegradation of petroleum based and bio-based plastics: approaches to increase the rate of biodegradation

Plastic production and consumption are on the rise due to their variety of uses. Plastics often accumulate in the environment and pose a risk due to the lack of a viable strategy for their safe disposal. Even prohibiting plastic covers does not solve the problems of plastic waste generation. Plastics are degraded by various microbes, although at a very slow rate. In addition, efforts to enhance plastic degradation efficiency by microbes are rarely addressed. This paper describes the biodegradation of both petroleum-based and bio-based plastics, as well as studies on plastic biodegradation in both the Indian and global scenarios. This paper also discusses the biochemical and molecular aspects of plastic biodegradation, which are essential since they disclose more about how bacteria break down plastics. We also shed light on initiatives to boost biodegradation rates using various strategies in this article. Understanding the enzymes and genes involved in biodegradation would also help researchers figure out how to use them to enhance microorganism's ability to degrade plastic.

A Review of Nonbiodegradable and Biodegradable Composites for Food Packaging Application

The dependency on nonbiodegradable-based food packaging, increase in population growth, and persistent environmental problems are some of the driving forces in considering the development of biodegradable food packaging. This effort of green packaging has the potential to solve issues on plastic wastes through the combination of biodegradable composite-based food packaging with plant extracts, nanomaterials, or other types of polymer. Modified biodegradable materials have provided numerous alternatives for producing green packaging with mechanical strength, thermal stability, and barrier performance that are comparable to the conventional food packaging. To the best of our knowledge, the performance of nonbiodegradable and biodegradable composites as food packaging in terms of the above properties has not yet been reviewed. In this context, the capability of biodegradable polymers to substitute the nonbiodegradable polymers was emphasized to enhance the packaging biodegradation while retaining the mechanical strength, thermal stability, barrier properties, and antioxidant and antimicrobial or antibacterial activity. These are the ultimate goal in the food industry. This review will impart useful information on the properties of food packaging developed from different polymers and future outlook toward the development of green food packaging.

Green Design of Novel Starch-Based Packaging Materials Sustaining Human and Environmental Health

A critical overview of current approaches to the development of starch-containing packaging, integrating the principles of green chemistry (GC), green technology (GT) and green nanotechnology (GN) with those of green packaging (GP) to produce materials important for both us and the planet is given. First, as a relationship between GP and GC, the benefits of natural bioactive compounds are analyzed and the state-of-the-art is updated in terms of the starch packaging incorporating green chemicals that normally help us to maintain health, are environmentally friendly and are obtained via GC. Newer approaches are identified, such as the incorporation of vitamins or minerals into films and coatings. Second, the relationship between GP and GT is assessed by analyzing the influence on starch films of green physical treatments such as UV, electron beam or gamma irradiation, and plasma; emerging research areas are proposed, such as the use of cold atmospheric plasma for the production of films. Thirdly, the approaches on how GN can be used successfully to improve the mechanical properties and bioactivity of packaging are summarized; current trends are identified, such as a green synthesis of bionanocomposites containing phytosynthesized metal nanoparticles. Last but not least, bioinspiration ideas for the design of the future green packaging containing starch are presented.

Synergistic effect of UV and chemical treatment on biological degradation of Polystyrene by Cephalosporium strain NCIM 1251

The present study approaches the capability of Cephalosporium strain NCIM 1251 to degrade pre-treated polystyrene films. Polystyrene was initially treated with UV for the introduction of oxygen molecules in pure polystyrene samples. UV treatment inserts aliphatic ketones functional group in polystyrene whereas it created C-C stretching after chemical treatment in UV-treated polystyrene as analyzed by Fourier-transform infrared spectroscopy (FTIR). The gravimetric study confirmed a decline in the weight of the pre-treated polystyrene by 20.62 ± 1.47% after 8 weeks of the incubation period. pH, total dissolved solids (TDS), and conductivity of mineral salt media were correlated with the extent of biodegradation. Treatment with UV and acid increased the thermal stability of pure polystyrene, whereas thermal stability decreased in pre-treated polystyrene after incubation with Cephalosporium strain NCIM 1251 as studied by Thermogravimetric analysis (TGA). Scanning Electron Microscopy (SEM) analysis observed revisions in the morphology and surface patterns in pre-treated polystyrene after inoculation with Cephalosporium strain NCIM 1251. The observed findings suggest that the Cephalosporium strain NCIM 1251 could be efficient for the decomposition of pre-treated polystyrene.