Pedro M. S. M. Rodrigues

Abstract This study analyses the Portuguese Corporate Income Tax (CIT) exemption provided under Article 53 of the Tax Benefits Code (TBC). This exemption applies exclusively to entities responsible for managing integrated systems of specific waste flows, such as packaging, tyres, used oils and electronic equipment, batteries and accumulators, and end-of-life vehicles. Duly licensed under the General Waste Management Regime (WMR), these entities benefit from tax exemption on reinvested profits or those allocated to legally designated purposes. The results show that, between 2013 and 2022, this exemption was used by the eligible entities despite the amounts claimed annually being relatively modest compared to the total tax benefits granted by the Portuguese government. This may be attributed to the limited number of entities eligible, given the legal requirement for licensing under the WMR, and to the narrow scope of the benefit itself, which applies only to profits that are either reinvested or allocated to legally defined purposes. Nevertheless, this measure has the potential to contribute to the sector’s economic competitiveness, ensuring reinvestment in technology and more efficient processes, strengthening beneficiary entities’ role in promoting the circular economy and the implementation of the European Union directives for waste management. It will also specify the Portuguese tax system's ability to integrate environmental objectives into public policies, highlighting the relevance of extra-fiscal instruments in driving the green transition and supporting the achievement of the global Sustainable Development Goals (SDGs). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2026.

Abstract Waste separation is a crucial step toward sustainable waste management. Understanding public perception and participation in this process is essential for its success. This study evaluates public perception and participation in the selective collection of general waste and biowaste in Guarda, Portugal, identifying key motivations, barriers, and areas for improvement. A cross-sectional analytical study was conducted using an online survey with 205 residents. Results indicate that 83.4% (95% CI: 77.9%-88.0%) of participants separate waste in the household, while workplace separation is lower (65.9%, 95% CI: 59.2%-72.1%). Paper and cardboard are the most frequently separated materials, whereas used cooking oil receives the least attention (95% CI: 16.5%-30.6%). Regarding biowaste, 92.2% (95% CI: 87.9%-95.3%) of respondents understand the concept, and all recognize its environmental benefits. However, 43.4% (95% CI: 36.8%-50.3%) are unaware of the municipal biowaste collection network, and 57.1% (95% CI: 50.2%-63.7%) find the existing infrastructure inadequate. Municipalities should expand and optimize waste collection systems to improve participation while strengthening public awareness campaigns. Social media is the preferred information channel (91.2%, 95% CI: 86.8%-94.5%), but traditional outreach methods, such as school initiatives and community meetings, could enhance engagement. Addressing infrastructure gaps and promoting consistent separation practices across different settings are key to optimizing waste management. This study highlights the need for improved public engagement and infrastructure to ensure the success of selective waste collection, particularly for biowaste, contributing to enhanced sustainability efforts in the region. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2026.

Abstract Micro- and nanoplastics (MNPs) are an important atmospheric aerosol constituent. However, there still needs to be a standard procedure for their sampling and size fractionation, which is an obstacle to the aggregation and critical analysis of results obtained by different research groups. This review focuses on the sampling and fractionation methodologies used for MNPs. Moreover, a streamlined, simplified methodology for sampling and fractionation is proposed.

Abstract Green carbon-based materials (GCM), i.e., carbon materials produced using renewable biomass or recycled waste, ought to be used to make processes sustainable and carbon-neutral. Carbon nanomaterials, like carbon dots and the nanobichar families, and carbon materials, like activated carbon and biochar substances, are sustainable materials with great potential to be used in different technological applications. In this review, the following four applications were selected, and the works published in the last two years (since 2022) were critically reviewed: agriculture, water treatment, energy management, and carbon dioxide reduction and sequestration. GCM improved the performance of the technological applications under revision and played an important role in the sustainability of the processes, contributing to the mitigation of climate change, by reducing emissions and increasing the sequestration of CO<inf>2</inf>eq.