Project Se(L)ect(i)vity (PTDC/EQU-EQU/6193/2020)

Mineral extraction from seawater brines has emerged as a viable solution to reduce Europe's reliance on imported Critical Raw Materials (CRM). However, the economic viability of this approach hinges on the local demand for sodium chloride, the primary product of such extraction processes. This study investigates the potential of residual brines, commonly known as "bitterns," generated during solar sea-salt extraction in traditional saltworks, as an alternative source of minerals. The Mediterranean region, encompassing South-European, North-African, Near East coasts, and parts of the Atlantic regions, is particularly conducive to exploring this prospect due to its extensive solar sea salt industry. Saltworks in the region, adopting various operational strategies based on feed quality or local climate conditions, produce different types of bitterns, each holding a latent resource potential that has remained largely unexplored. Within the framework of the EU-funded SEArcularMINE project, it was conducted an extensive analytical campaign to characterize bitterns collected from a diverse saltworks network. The analysis revealed the presence of sodium, potassium, magnesium, chloride, sulfate, and bromide in concentrations ranging from g/kg, while boron, calcium, lithium, rubidium, and strontium were found in the mg/kg range. Additionally, trace elements (TEs) such as cobalt, cesium, gallium, and germanium were detected at concentrations in the order of μg/kg. Detailed results on the composition of bitterns are presented, emphasizing the distinct characteristics observed at different sites. The estimated potential for mineral recovery from these bitterns is approximately 190 €/m3, considering the production capacity of about 9 Mm3 per year in the Mediterranean area. This finding underscores the significant contribution that mineral recovery from bitterns could make in securing access to CRMs for the European Union.

This work explores the application of Reverse Osmosis (RO) upcycled membranes, as Anion Exchange Membranes (AEMs) in Donnan Dialysis (DD) and related processes, such as the Ion Exchange Membrane Bioreactor (IEMB), for the removal of nitrate from contaminated water, to meet drinking water standards. Such upcycled membranes might be manufactured at a lower price than commercial AEMs, while their utilization reinforces the commitment to a circular economy transition. In an effort to gain a better understanding of such AEMs, confocal µ-Raman spectroscopy was employed, to assess the distribution of the ion-exchange sites through the thickness of the prepared membranes, and 2D fluorescence spectroscopy, to evaluate alterations in the membranes caused by fouling and chemical cleaning The best performing membrane reached a 56% average nitrate removal within 24 h in the DD and IEMB systems, with the latter furthermore allowing for simultaneous elimination of the pollutant by biological denitrification, thus avoiding its discharge into the environment. Overall, this work validates the technical feasibility of using RO upcycled AEMs in DD and IEMB processes for nitrate removal. This membrane recycling concept might also find applications for the removal and/or recovery of other target negatively charged species.

Properties such as particle orientation{,} flowability{,} packing{,} compaction{,} syringeability{,} suspension stability and dissolution are the most influenced by changes in the crystal habit and polymorphic form of a drug substance. The crystal habit of a drug substance (long-acting β2-adrenergic agonist (LABA)){,} as well as its purity and polymorphic stability{,} was studied after performing slurry tests with 1{,}2-dimethoxyethane : heptane solution at 50 °C. In these slurry tests{,} the product was kept suspended and undissolved{,} with agitation{,} for polymorphic conversion evaluation. Since no significant modifications were observed in the crystal shape and dimensions at 50 °C{,} a new slurry test was performed at a temperature above the melting point of the starting material (80 °C). In the latter test{,} it was possible to obtain crystals with increased dimensions by 480% compared with the starting material. Additionally{,} the desired polymorphic form (form I) was obtained as well as an acceptable purity of approximately 99%. These are promising results{,} not only for downstream purposes{,} but also concerning the bioavailability of the drug substance. This work shows that working at a temperature higher than the melting point of the compound seems to modify the crystal habit of the product.