José Eduardo Castanheiro’s research while affiliated with Universidade de Évora and other places

The sustainability of the planet is based on reducing the use of fossil fuels and greenhouse gas emissions. The recovery of biomass waste puts economically valuable materials into circulation, which can successfully replace fossil fuels and which would otherwise be sent to landfills. Based on the review of several published works, we observe that the referenced processes to value biomass or biomass waste are not necessarily the most profitable and environmentally friendly. The most used methods to valorize biomass and biomass waste are mainly based on researchers knowledge and experience, neglecting some methods that are more appropriate or developing technologies. The valorization of biomass and biomass wastes should promote the production of products with the highest added value, and it must also be environmentally friendly and cost-effective. This manuscript proposes a hierarchy for the use of various valorization processes of biomass waste, from various agricultural activities, urban solids waste, food processing industries, and even wood industries. The proposed hierarchy is based on a number of recommendations aimed at increasing the use and valorization of biomass, in order to reach the objective of carbon neutrality and to comply with the principles of the circular economy.

In this study, we investigated the preparation of char and activated carbon (ACs) materials derived from water bottle waste collected from waste collection point in Tunis. The materials were synthesized using a rotary horizontal furnace on a lab/pilot scale and through chemical activation. Characterization of the carbon materials was performed using nitrogen adsorption isotherms at 77K and SEM-EDX analysis. Furthermore, we examined the effectiveness of the ACs in removing the antibiotics 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide (sulfamethoxazole-C10H11N3O3S) and 5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine (trimethoprim) from aqueous solutions. The results revealed a maximum adsorption capacity of 108.17 mg g⁻¹ (85.34%) for sulfamethoxazole and 98.11 mg g⁻¹ (89.73%) for trimethoprim on the PET-KOH-1:1-800 °C sample. Additionally, we analyzed the adsorption kinetics, fitting the data to pseudo-first and -second-order models, and studied the equilibrium isotherms using the Langmuir and Freundlich equation models. These findings suggest significant potential for the application of ACs derived from plastic bottle waste in the treatment of wastewater containing antibiotics. Overall, our study highlights the feasibility of utilizing waste materials for the synthesis of valuable carbon-based adsorbents with promising adsorption capabilities. This research contributes to the ongoing efforts towards sustainable waste management and environmental remediation.

This work presents some preliminary results on the direct use of untreated biomass from agricultural activities as adsorbents for water treatment. Waste was also used to produce activated carbons (ACs) by chemical activation with KOH. The efficacy of agricultural waste such as stubble, sawdust from Teak (Tectona Grandis), fibers from Imbondeiro (Adansonia digitata L.), bamboo flowers, and other regional plants were tested on methylene blue (MB) removal from the aqueous phase. Adsorption studies were conducted in a batch system and the influence of kinetics, pH, and temperature was evaluated. The adsorption performance of the natural adsorbents was significantly high concerning MB. In particular, Imbondeiro presented a maximum removal capacity of 188.3 mg per gram. This amount was similar to or even higher than the values obtained on ACs produced by their predecessors at 873 K. The studies were finished by constructing slow filters containing natural adsorbents or ACs. The maximum amounts of MB removed on a continuous flux were lower than those obtained for a diversity of untreated biomass types on a batch system. However, these amounts were comparable to the published results obtained on a diversity of untreated biomasses in batch mode.

This paper describes the influence of the regeneration treatments on 4-chloro-2-methyl-phenoxyacetic acid (MCPA)-loaded activated carbons (ACs) on adsorption-desorption cycles with two commercial ACs, Merck and Norit 1240 X ( Norit 1240 X was used in a granular and powder form). The ACs were saturated with MCPA and then submitted to four regeneration cycles, by washing with ethanol, NaOH solutions and washed with NaOH solutions followed by a thermal treatment. The ACs regenerated with ethanol showed a better performance concerning the successive adsorption-desorption cycles. On the first cycle, the MCPA desorbed, from washing with ethanol, from all ACs was higher than 99%. After a fourth adsorption-desorption cycle, washing regeneration combined with thermal treatment allowed excellent regeneration results. The amount of MCPA adsorbed on Norit 1240 X AC was higher than the amount adsorbed in the first cycle. MCPA adsorption kinetic data were analyzed by applying pseudo-first-order, pseudo-second-order, and Weber-Morris models. The pseudo-second-order fit better fit to the data and the Weber-Morris representation allows confirming that on Norit 1240 X, in a granular form, the pore diffusion was the limiting factor concerning the MCPA adsorption.

The increase in agricultural production and food quality has forced the growing use of plastics in various activities. The plastic wastes are partially recycled in or outside Portugal; nevertheless, the contaminated wastes are sent to landfill. It is crucial to consider new models for their valorization at a regional level and from a circular economy perspective. In the scope of the Placarvões project, a study was elaborated, which included the types and quantities of plastics used in the irrigation area of the Alqueva Dam, in southern Portugal. The crops that use the most plastic are intensive olive groves, almonds, and table grapes, which represent more than 91% of total plastic waste. The production of activated carbons (ACs) is a solution to avoid plastics landfill. ACs were produced from plastic used on food packaging (PB-Samples) and sheeting film (PS-Samples) by activation with K2CO3. ACs presented well-developed textural properties (PB-K2CO3-1:1–700 and PS-K2CO3-1:1–700 exhibited a volume of 0.32 and 0.25 cm³ g⁻¹ and an apparent surface area of 723 and 623 m² g⁻¹, respectively). Both ACs performed very well concerning four pesticide removals from the liquid phase. This solution is very promising, such these ACs could be applied in effluent treatments on a large scale.