Carlos M. Pereira

Abstract Biomass-derived carbon dots (CDs) are gaining much interest in recent times, as they provide a sustainable option with abundant availability, a low cost and tunable luminescence. Herein, we report a simple green synthesis method to produce highly fluorescent CDs from Eucalyptus globulus leaves using the one-pot hydrothermal approach. The fabricated CDs exhibit strong blue fluorescence with an excitation and emission maxima of 320 nm and 445 nm, respectively. The highest quantum yield (QY) obtained was 60.7%. With the reported optical properties and biocompatibility, CDs can be looked at as a promising candidate for potential biosensing applications. Moreover, we employed a life cycle assessment (LCA) cradle-to-gate approach to study the environmental impacts of the synthesis strategy used for the fabrication of CDs. The results point out that citric acid is the main hotspot in CD synthesis, regarding environmental impacts in most categories. This justifies the introduction of biomass, which reduces the amount of citric acid, thus leading to a more sustainable synthesis strategy for fabricating CDs.

Abstract Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices.

Abstract Soybean is a legume with high technological functionality, commonly used by the food industry as an ingredient in different products. However, soybean is an allergenic food whose undeclared presence in processed foods may represent a public health risk. In this work, it was developed an efficient electrochemical immunosensor, targeting the soybean trypsin inhibitor (Gly m TI) allergen using commercial anti-Gly m TI IgG, aiming at detecting/quantifying minute amounts of soybean in different food formulations. For this purpose, model mixtures of different foods (sausages, cooked-hams, biscuits) were prepared to contain known amounts of soybean protein isolate (100,000-0.1 mg kg(-1)) and submitted to specific thermal treatments (autoclaving, oven-cooking, baking). The electrochemical immunosensor allowed quantifying down to 0.1 mg kg(-1) of soybean in the three food matrices, raw and processed (0.0012 mg of Gly m TI/kg of matrix). Accordingly, the immunosensor is suitable for detecting traces of soybean in raw, processed, and complex foods, thus protecting 99 % of soybean-allergic patients.

Abstract Purpose Pejao Mining Complex locates in Castelo de Paiva municipality and, until its closure in 1994, was one of the most important coal mines in the Douro Coalfield. This work aims to study the presence, quantify, and evaluate the dissemination of mercury (Hg), a potentially toxic element (PTE) of major public health concern by the World Health Organization (WHO), from a waste pile affected by coal fires.Materials and methods Samples from areas affected and unaffected by the combustion and from surrounding soil were collected from Fojo waste pile region. First, the Hg pseudo-total concentration was estimated for all collected samples by soil microwave-assisted digestion with aqua regia (USEPA 3051A). Then, a sequential extraction procedure (SEP), the USEPA 3200, was applied for Hg fractionation and speciation aiming to evaluate Hg mobility and bioavailability to surrounding ecosystems.Results and discussion The results obtained showed a Hg enrichment in soil samples when compared to Portuguese and international reference values for soils. Relatively to the Hg availability and mobility, although it predominates in the semi-mobile fraction, the waste pile materials exposed to combustion showed a concerning increase of Hg levels in the mobile fraction that contains the more labile Hg species, being a major source of environmental contamination by Hg.Conclusions This study allowed to conclude that combustion of mining residues increased Hg mobility, toxicity, and bioavailability, increasing the contamination potential of the coal waste pile. The methodology applied in this work can be replicated in other abandoned mines to monitor, control, and/or mitigate the Hg environmental impact in the surrounding soils and waters.

Abstract Lithium-sulfur batteries are a promising alternative to lithium-ion batteries as they can potentially offer significantly increased capacities and energy densities. The ever-increasing global battery market demonstrates that there will be an ongoing demand for cost effective battery electrode materials. Materials derived from waste products can simultaneously address two of the greatest challenges of today, i.e., waste management and the requirement to develop sustainable materials. In this study, we detail the carbonisation of gelatin from blue shark and chitin from prawns, both of which are currently considered as waste biproducts of the seafood industry. The chemical and physical properties of the resulting carbons are compared through a correlation of results from structural characterisation techniques, including electron imaging, X-ray diffraction, Raman spectroscopy and nitrogen gas adsorption. We investigated the application of the resulting carbons as sulfur-hosting electrode materials for use in lithium-sulfur batteries. Through comprehensive electrochemical characterisation, we demonstrate that value added porous carbons, derived from marine waste are promising electrode materials for lithium-sulfur batteries. Both samples demonstrated impressive capacity retention when galvanostatically cycled at a rate of C/5 for 500 cycles. This study highlights the importance of looking towards waste products as sustainable feeds for battery material production.