RESUMO
New approaches are needed to both reduce and reuse plastic waste. In this context, poly(vinyl chloride) (PVC) is an appealing target as it is the least recycled high-production-volume polymer due to its facile release of plasticizers and corrosive HCl gas. Herein, these limitations become advantageous in a paired-electrolysis reaction in which HCl is intentionally generated from PVC to chlorinate arenes in an air- and moisture-tolerant process that is mediated by the plasticizer. The reaction proceeds efficiently with other plastic waste present and a commercial plasticized PVC product (laboratory tubing) can be used directly. A simplified life-cycle assessment reveals that using PVC waste as the chlorine source in the paired-electrolysis reaction has a lower global warming potential than HCl. Overall, this method should inspire other strategies for repurposing waste PVC and related polymers using electrosynthetic reactions, including those that take advantage of existing polymer additives.
RESUMO
An estimated 6.3 billion metric tons of post-consumer polymer waste has been produced, with the majority (79%) in landfills or the environment. Recycling methods that utilize these waste polymers could attenuate their environmental impact. For many polymers, recycling via mechanical processes is not feasible and these materials are destined for landfills or incineration. One salient example is the superabsorbent material used in diapers and feminine hygiene products, which contain crosslinked sodium polyacrylates. Here we report an open-loop recycling method for these materials that involves (i) decrosslinking via hydrolysis, (ii) an optional chain-shortening via sonication, and (iii) functionalizing via Fischer esterification. The resulting materials exhibit low-to-medium storage and loss moduli, and as such, are applicable as general-purpose adhesives. A life cycle assessment demonstrates that the adhesives synthesized via this approach outcompete the same materials derived from petroleum feedstocks on nearly every metric, including carbon dioxide emissions and cumulative energy demand.
RESUMO
This paper presents the Solid Waste Management Index (SWaMI) for Higher Education Institutions (HEIs). The main objectives are to present how SWaMI was developed, to apply the Index in three different universities in Brazil and one in United States, to statistically compare the results and to present an analysis of these HEIs under the SWaMI assessment dimensions perspective. The SwaMI fills a gap regarding a specific waste management tool for HEIs decision makers, considering the responsibility of educating and training future leaders and the need to insert the sustainable waste management discussion in its end activities. Criteria were selected through literature review and divided in dimensions, further weighted according to their significance in waste management. These weights were discussed and stipulated based on expert opinion using the Budget Allocation Process (BAP) weighting method. The individual indexes for each dimension were further combined into a composite index through the Linear Aggregation Method. Main findings shows that when comparisons were deployed between HEIs, no statistical significance was noticed when the means were compared between universities using ANOVA with Tukey test. Nevertheless, when comparing each dimension within each HEI, there was significant difference between the Policy and Management dimension and the other three dimensions of the evaluation criteria at USP. Researchers concluded that the SWaMI provides decision makers with graphic results concerning HEIs solid waste management situation, hence, it allows the creation of a baseline data on how the current system works, pointing out the dimensions that present the greatest weakness allowing to perform benchmarking between buildings, institutes, and even between HEIs.