Pretreatment of Plastic Waste: Removal of Colorants from HDPE Using Biosolvents

Kinetic adsorption of methyl blue dye from aqueous solution by PVC/PVC-based copolymer containing quaternary amine

The present study has investigated the use of a blend polymer polyvinyl chloride/polyvinyl chloride-graft-poly[2-(dimethylamino) ethyl methacrylate containing a quaternary amine in its structure (PVC/PVC-g-PDMAEM(N⁺)) as an adsorbent for the removal of methyl blue dye from aqueous solution. The synthesized polymer blend has been characterized by Fourier Transform Infrared Spectroscopy (FT-IR), scanning Electron Microscope-energy-dispersive spectroscopy (SEM-EDX), and the scanning Spectrophotometer Ultraviolet-visible (UV-Vis). The adsorption studies have been performed by batch experiments. Moreover, the pH effect, adsorbent dose, initial dye concentration, and contact time effect have been explored. Furthermore, the kinetic experimental data have been analyzed using pseudo-first and pseudo-second-order models. The results have shown that the adsorption process is more described by the pseudo-second-order model with a high determination coefficient. The equilibrium adsorption data have been analyzed using three widely applied isotherms: Langmuir, Freundlich, and Tempkin. The best fit was found to be Freundlich isotherm with maximum monolayer adsorption of Methyl Blue (MB) equal to 142.86 mg/g, which was observed at pH = 7. The results have indicated that the PVC/PVC-g-PDMAEM(N⁺) blend polymer is an efficient adsorbent for removing anionic dyes from wastewater.

Review of polymer technologies for improving the recycling and upcycling efficiency of plastic waste

Human society has become increasingly reliant on plastic because it allows for convenient and sanitary living. However, recycling rates are currently low, which means that the majority of plastic waste ends up in landfills or the ocean. Increasing recycling and upcycling rates is a critical strategy for addressing the issues caused by plastic pollution, but there are several technical limitations to overcome. This article reviews advancements in polymer technology that aim to improve the efficiency of recycling and upcycling plastic waste. In food packaging, natural polymers with excellent gas barrier properties and self-cleaning abilities have been introduced as environmentally friendly alternatives to existing materials and to reduce food-derived contamination. Upcycling and valorization approaches have emerged to transform plastic waste into high-value-added products. Recent advancements in the development of recyclable high-performance plastics include the design of super engineering thermoplastics and engineering chemical bonds of thermosets to make them recyclable and biodegradable. Further research is needed to develop more cost-effective and scalable technologies to address the plastic pollution problem through sustainable recycling and upcycling.

Evaluating the applicability of the Ames test for cosmetic packaging assessment by comparing carcinogenic risk levels of migrants from plastics with biological detection limits

Risk assessments for cosmetic packaging are required according to the EU Cosmetics Regulation (EC) No. 1223/2009, however, the assessment method is well-established for food packaging but limited for cosmetic packaging. In food packaging assessments, Cramer class III TTC (90 μg/day) is applied as the threshold for systemic toxicity when the Ames test including the process of sample concentration steps provides the negative results. However, the human health risks of mutagenic and carcinogenic migrants at exposure levels where the Ames test with the concentrated samples cannot detect are unclear. In the present study, to confirm the applicability of the Ames test for cosmetic packaging assessments, the toxicological data on 37 candidate migrants with Ames test-positive results was collected. For these migrants, the carcinogenic risk levels through cosmetics use were compared to the detection levels of the Ames test for concentrated samples. Regarding at least 32 migrants, the case study showed the negative result from the Ames test incorporating the sample concentration process would indicate negligible mutagenic and carcinogenic risks of packaging extracts. Therefore, application of the Ames test to cosmetic packaging assessments would be helpful to ensure the safety for mutagenicity and carcinogenicity as well as use Cramer-TTC for systemic toxicity.

Assembly strategies for polyethylene-degrading microbial consortia based on the combination of omics tools and the "Plastisphere"

Numerous microorganisms and other invertebrates that are able to degrade polyethylene (PE) have been reported. However, studies on PE biodegradation are still limited due to its extreme stability and the lack of explicit insights into the mechanisms and efficient enzymes involved in its metabolism by microorganisms. In this review, current studies of PE biodegradation, including the fundamental stages, important microorganisms and enzymes, and functional microbial consortia, were examined. Considering the bottlenecks in the construction of PE-degrading consortia, a combination of top-down and bottom-up approaches is proposed to identify the mechanisms and metabolites of PE degradation, related enzymes, and efficient synthetic microbial consortia. In addition, the exploration of the plastisphere based on omics tools is proposed as a future principal research direction for the construction of synthetic microbial consortia for PE degradation. Combining chemical and biological upcycling processes for PE waste could be widely applied in various fields to promote a sustainable environment.

Current Prospects for Plastic Waste Treatment

The excessive amount of global plastic produced over the past century, together with poor waste management, has raised concerns about environmental sustainability. Plastic recycling has become a practical approach for diminishing plastic waste and maintaining sustainability among plastic waste management methods. Chemical and mechanical recycling are the typical approaches to recycling plastic waste, with a simple process, low cost, environmentally friendly process, and potential profitability. Several plastic materials, such as polypropylene, polystyrene, polyvinyl chloride, high-density polyethylene, low-density polyethylene, and polyurethanes, can be recycled with chemical and mechanical recycling approaches. Nevertheless, due to plastic waste’s varying physical and chemical properties, plastic waste separation becomes a challenge. Hence, a reliable and effective plastic waste separation technology is critical for increasing plastic waste’s value and recycling rate. Integrating recycling and plastic waste separation technologies would be an efficient method for reducing the accumulation of environmental contaminants produced by plastic waste, especially in industrial uses. This review addresses recent advances in plastic waste recycling technology, mainly with chemical recycling. The article also discusses the current recycling technology for various plastic materials.