Periodic Reporting for period 1 - IONIC BARRIER (pH-driven ionic barrier-based techniques to recover precious metals from urban mines)
Período documentado: 2022-02-01 hasta 2024-01-31
Precious elements such as gold (Au), palladium (Pd), and platinum (Pt) are highly valued in global economies, however, their scarcity in the earth’s crust poses potential risks to future supply chains. Besides, the frequent replacement of electrical and electronic devices has resulted in a growing volume of e-wastes, with precious metal (PM) contents increasingly surpassing those found in natural ore deposits. It is therefore important to design appropriate techniques to recycle e-wastes and retrieve the PMs for reprocessing to meet the increasing industrial demands. This is particularly crucial from the viewpoints of resource sustainability and environmental safety, owing to the advantage of generating income through recycling and shielding the environment from pollution threats caused by the indiscriminate disposal of e-wastes. With focus on designing innovative materials and technologies to curtail the above-mentioned problems, the scientific advancement and breakthrough results can inspire other researchers and industries to explore creative solutions for environmental challenges. This can lead to a broader culture of collaboration, innovation, problem-solving and public awareness. The overall objective of this project is to design and develop ionic barrier-based techniques for PM recovery from urban mines (e-wastes). The project utilizes the properties and advantages of adsorption and hydroxide precipitation/crystallization to design high internal pH-driven ionic barrier-based protocols to recover PMs from aqueous solutions by employing polyelectrolyte complexation. The project aims to create a domestic valuable raw materials source for the European manufacturing and hi-tech industries by shifting towards a circular economy and lessening the European Union’s dependence on raw material imports.
The work conducted in this project is broadly divided into three stages, viz., phase transition study, adsorbent fabrication, and selective metal recovery evaluation. The work begun by systematically studying the phase behaviors of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(styrenesulfonate sodium salt) (PSS) polyelectrolyte complex (PEC) systems so as to understand their phase transformations as functions of charge stoichiometry and ionic strength. KBr was a better dopant compared to NaCl. Next, capsules were formed by dropping the coacervates at 1.7 M KBr into either deionized water (DW) or DW-methanol (MeOH) mixtures ranging from 0 – 50% MeOH. In another step, viscous polyethyleneimine (PEI) was added to the coacervate prior to forming the capsules. Consequently, the capsules were characterized and evaluated for selective adsorption of PMs. The capsules showed selectivity towards Au in multimetal mixtures of PMs and heavy metals (HMs). The selectivity was found to be dependent on concentration, contact time, and stirring speed. This work has been published and is freely available online at Chemical Engineering Science 274 (2023 118688, doi.org/10.1016/j.ces.2023.118688). In the absence of Au, the capsules were selective towards Pt and Pd, and the addition of PEI effectively boosted up the adsorption efficiency because it possesses numerous cationic amine groups that can bind the anionic Pt and Pd complexes. Among several tested eluents, thiourea achieved a complete desorption efficiency for the PMs.
The project has been actively promoted through workshops, seminars, conferences, journal article publications, and social media posts. The workshops and seminars are mainly done across different units within the host institution and partners. The researcher has an active presence on social media platforms, such as LinkedIn, Facebook, and X (formerly Twitter), where he engages with the public and share highlights of the project, its results and other activities relating to the project. The researcher has participated in five conferences and presented various aspects of the project results and the evolving innovations in the field. The researcher has published one research and two review articles as first author in direct relation to the project (all open access), and several other papers during the fellowship. These articles are available on the academic webpages of the researcher, e.g. Google Scholar and ResearchGate, as well as the host university library. For every article published, it is announced and shared on social media with hashtags of the project acronym, keywords, the EU, and MSCA. The researcher granted an interview to the Horizon Magazine EU where he spoke extensively about the project and its goals. The interview titled, “To secure raw materials, Europe turns to recycling” and edited by Tom Cassauwers was published in November 2023. The researcher also featured in the famous MSCA-IF fellow of the week series for the month of October 2023, where he also provided some information about the project.
The project has been actively promoted through workshops, seminars, conferences, journal article publications, and social media posts. The workshops and seminars are mainly done across different units within the host institution and partners. The researcher has an active presence on social media platforms, such as LinkedIn, Facebook, and X (formerly Twitter), where he engages with the public and share highlights of the project, its results and other activities relating to the project. The researcher has participated in five conferences and presented various aspects of the project results and the evolving innovations in the field. The researcher has published one research and two review articles as first author in direct relation to the project (all open access), and several other papers during the fellowship. These articles are available on the academic webpages of the researcher, e.g. Google Scholar and ResearchGate, as well as the host university library. For every article published, it is announced and shared on social media with hashtags of the project acronym, keywords, the EU, and MSCA. The researcher granted an interview to the Horizon Magazine EU where he spoke extensively about the project and its goals. The interview titled, “To secure raw materials, Europe turns to recycling” and edited by Tom Cassauwers was published in November 2023. The researcher also featured in the famous MSCA-IF fellow of the week series for the month of October 2023, where he also provided some information about the project.
The current state-of-the-art processes for recovering PMs includes synthesizing adsorbents with specific ligands that exhibit selectivity, adopting the technique of ion imprinting to synthesize materials with cavities, and ionic barrier materials that require adjusting the pH of the metal solutions to achieve the desired separation results. With the innovation of successfully creating ionic barrier adsorbents with inherently high internal pH for selective recovery of PMs, this project can progress beyond state-of-the-art and help to address some of the limitations of the present techniques. Here, the high pH gradient is enabled by the strategic formulation of water/MeOH to control the release of salt, however, progress in state-of-the-art could further lead to immobilization of inorganic alkaline materials. In this research, PDADMAC and PSS were used, however, different types of polyelectrolytes can be explored. Moreover, evolving innovation suggests that introduction of a third polyelectrolyte, such as the case of adding PEI into the PDADMAC/PSS binary system at the complexation stage could provide extra relaxation and improve chain mobility and tunability. Therefore, future state-of-the-art approaches may thoroughly examine ternary systems as part of optimization efforts towards improving processability of the binary PEC systems.
This project holds significant social importance owing to its potential to address pressing environmental and public health issues related to pollution. It supports the effort toward environmental sustainability and carbon neutrality through circularity of e-wastes, potentially fulfilling some of the United Nation's Sustainable Development Goals (SDGs), especially SDGs 3 and 6. Particularly, the social significance of the project includes promotion of public health, environmental conservation, opportunities for local and EU regional businesses including NGOs that are focused on environmental protection activities. The international significance includes technological innovation and advancement, fostering of international collaboration. Finally, dissemination of the knowledge generated from the project can promote global adoption of sustainable waste treatment practices, foster international collaboration and shape policy making.
This project holds significant social importance owing to its potential to address pressing environmental and public health issues related to pollution. It supports the effort toward environmental sustainability and carbon neutrality through circularity of e-wastes, potentially fulfilling some of the United Nation's Sustainable Development Goals (SDGs), especially SDGs 3 and 6. Particularly, the social significance of the project includes promotion of public health, environmental conservation, opportunities for local and EU regional businesses including NGOs that are focused on environmental protection activities. The international significance includes technological innovation and advancement, fostering of international collaboration. Finally, dissemination of the knowledge generated from the project can promote global adoption of sustainable waste treatment practices, foster international collaboration and shape policy making.