Joaquim C.G. Esteves da Silva

Abstract TiO2 nanoparticles are promising photocatalysts due to their oxidizing strength and inertness. However, their inability to efficiently absorb visible light limits industrial applications that could use sunlight. The addition of carbon dots to TiO2 has been recently shown to have the potential to address this issue by enhancing the visible light-driven photocatalytic efficiency of the resulting nanocomposites. However, concrete data on their sustainable development and fabrication is lacking. Herein, we performed a life cycle assessment (LCA) study to understand the environmental impacts of different TiO2-carbon dots nanocomposites with enhanced visible light-driven photocatalytic activity. It was found that the nanocomposites with the highest photocatalytic activity were the ones whose synthesis was associated with lower environmental impacts. Furthermore, the carbon dots generally have little to moderate contributions to most impact categories, except for marine eutrophication. Finally, the most critical parameter was found to be the source of TiO2 for the nanocomposites.

Abstract This work aims to conduct a Life Cycle Assessment (LCA) of seamless leggings produced by a Portuguese textile company, following a “cradle-to-gate” approach. This includes all life cycle stages from raw material production to the packaging of the seamless leggings, ready to leave the company gate. Primary data for the foreground processes were obtained from the actual industrial practices of the Portuguese company, complemented by data from the ecoinvent V3.5 life cycle inventory database and literature sources, primarily for the background processes. The ReCiPe 2016 Midpoint (E) V1.02 methodology was employed to evaluate potential environmental impacts, using the SimaPro V8.5.2 LCA software. Results indicate that the production and spinning of fibers have the highest environmental impacts, mainly due to their high energy consumption. Dyeing operations are more impactful than confection operations, particularly contributing to water use and freshwater ecotoxicity. Therefore, efforts to reduce overall environmental impacts should initially focus on these life cycle stages. Switching the electricity source from the national grid mix to entirely photovoltaic energy resulted in a significant reduction in several environmental impact categories, including a 30% reduction in global warming potential. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

Abstract Herein we report a visible-light-active photocatalytic nanocomposite (NC50:50) prepared from carbon dots (CDs) and TiO2 nanoparticles, which was applied to the photodegradation of organic dyes in water. The CDs incorporated corn stover, a major agricultural waste, and were prepared via hydrothermal treatment. Using a visible- light irradiation source and the dye methylene blue as a representative of the organic dyes class, we observed that a 374 % enhancement of the catalytic performance was achieved by adding CDs relative to bare TiO2. This was possible due to increased visible-light absorption and better photonic efficiency. Tests using reactive species scavengers indicated that three active species (superoxide anion, hydroxyl radicals, and electrons) were responsible for the photodegradation process, differing from bare TiO2 in which only the hydroxyl radical has a relevant role. Photocatalytic degradation was also observed toward Rhodamine B, Orange II and Methyl Orange. Finally, we performed a life cycle assessment (LCA) study to assess and analyse the associated environmental impacts of NC50:50 compared with other alternatives, which revealed that NC50:50 is the alternative resulting in the least environmental impacts. In summary, NC50:50 could, under visible-light irradiation, efficiently remove different organic dyes while incorporating organic waste materials and reducing the impacts associated with their use. We expect that this study provides a base for a more environmentally sustainable design of visible- light-active photocatalysts via waste upcycling.

Abstract Groundwater is a critical resource in semi-arid regions like Morocco's Guire Basin, yet pollution and overexploitation threaten its sustainability. This study evaluates the groundwater quality of the Guire aquifer (Eastern High Atlas) using an integrated approach combining hydrochemical, isotopic (delta O-18, delta H-2, delta C-13), multivariate statistical, and Geographic Information System (GIS) analyses alongside the Water Quality Index (WQI). Sixteen wells were monitored for physicochemical parameters (pH: 7-7.9; EC: 480-3004 mu S/cm; BOD5: 1.03-30.5 mg/L; COD: 10.2-45.75 mg/L) and major ions, revealing widespread exceedances of Moroccan standards for Cl-, HCO3-, Mg2+, Ca2+, and NH4+. WQI classified 81% of samples as Poor to Unsuitable for drinking (WQI: 51-537), driven by elevated Cl-, Na+, and SO42- from Triassic evaporite dissolution and NO3- (up to 45 mg/L) from agricultural runoff. Stable isotopes (delta O-18: -7.73 parts per thousand to -5.08 parts per thousand; delta H-2: -66.14 parts per thousand to -44.20 parts per thousand) indicate Atlantic-influenced recharge at 900-2200 m altitudes, with a delta O-18-delta H-2 slope of 5.93 reflecting evaporation during infiltration. Strontium (Sr2+/Ca2+: 0.0024-0.0236) and bromide (Br/Cl: 8.47 x 10(-5)-9.88 x 10(-4)) ratios further confirm evaporitic dominance over anthropogenic contamination. This work provides actionable insights for policymakers, advocating for targeted restrictions on fertilizers, enhanced monitoring near evaporite zones, and artificial recharge initiatives. By linking geogenic/anthropogenic contamination to governance strategies, this study advances sustainable groundwater management in semi-arid regions.

Abstract <jats:p>Mozambique soils are known for having an unbalanced agronomic and environmental composition that results in poor agricultural production yields. However, agriculture is the main economic activity of Mozambique, and soils must be characterised for their elemental deficiencies and/or excesses. This paper sampled nine farms from the Manica and Sussundenga districts (Manica province) in three campaigns in 2021/2022, 2022/2023, and 2023/2024 (before and after the rainy seasons). They were subjected to a physical–chemical analysis to assess their quality from the fertility and environmental contamination point of view. Attending to the physical–chemical properties analysed, and for all the soils and sampling campaigns, a low concentration below the limit of detection for B of &lt;0.2 mg/Kg for the majority of soils and a low concentration of Al &lt; 0.025 mg/Kg for all the soils were obtained. Also, higher concentrations for the majority of soils for the Ca between 270 and 1634 mg/Kg, for the Mg between 41 and 601 mg/Kg, for the K between 17 and 406 mg/Kg, for the Mn between 13.6 and 522 mg/Kg, for the Fe between 66.3 and 243 mg/Kg, and for the P between &lt;20 and 132 mg/Kg were estimated. In terms of texture and for the sand, a high percentage between 6.1 and 79% was found. In terms of metal concentrations and for all the soils of the Sussundenga district and sampling campaigns, a concentration above the reference value concentration for the Cr (76–1400 mg/Kg) and a concentration below the reference value concentration for the Pb (5–19 mg/Kg), Ba (13–120 mg/Kg) and for the Zn (10–61 mg/Kg) were evaluated. A multivariate data analysis methodology was used based on cluster and discriminant analysis. The analysis of twenty-three physical–chemical variables of the soils suggested four clusters of soils characterised by deficiencies and excess elements that must be corrected to improve the yield and quality of agricultural production. Moreover, the multivariate analysis of the metal composition of soil samples from the second and third campaigns, before and after the rainy season, suggested five clusters with a pristine composition and different metal pollutant compositions and concentrations. The information obtained in this study allows for the scientific comprehension of agricultural soil quality, which is crucial for designing agronomic and environmental corrective measures to improve food quality and quantity in the Manica and Sussundenga districts and ensure environmental, social, and economic sustainability.</jats:p>