Resin-Mediated pH Control of Metal-Loaded Ligand Exchangers for Selective Nitrogen Recovery from Wastewaters

CO2-driven ion exchange for ammonium recovery from source-separated urine

Nitrogen recovery from urine and CO2 utilization are both vital for achieving a circular economy and mitigating climate change. Divided engineering solutions have been proposed to address either problem, but there is still a lack of integrated technologies to simultaneously tackle the two tasks. We demonstrated CO2-driven ion exchange for nitrogen recovery (CIXNR) from urine and evaluated the process in Malawi. By comprehensively studying the ion exchange chemistry using a proton-form weak acid cation exchanger (WAC-H), we revealed the suppressed adsorption capacity caused by counterion releasing. Regulating aqueous pH optimized the WAC-H capacity, particularly, by the natural buffering capacity provided by bicarbonate in the hydrolyzed urine. CO2 regeneration achieved over 75 % nitrogen recovery in a multi-cycle test with synthetic hydrolyzed urine. A higher CO2 pressure resulted in faster regeneration kinetics due to a lower aqueous pH and higher proton concentration gradient. Our field outreach activity in Malawi indicated future research demand in adapting the system for resource-limited, rural, and no-electricity areas. We envision this study to inspire more integrated solutions to tackle both circular economy and climate actions and call for more field outreach activities to facilitate urine technology adoption in developing countries.

Material Design Strategies for Recovery of Critical Resources from Water

Population growth, urbanization, and decarbonization efforts are collectively straining the supply of limited resources that are necessary to produce batteries, electronics, chemicals, fertilizers, and other important products. Securing the supply chains of these critical resources via the development of separation technologies for their recovery represents a major global challenge to ensure stability and security. Surface water, groundwater, and wastewater are emerging as potential new sources to bolster these supply chains. Recently, a variety of material-based technologies have been developed and employed for separations and resource recovery in water. Judicious selection and design of these materials to tune their properties for targeting specific solutes is central to realizing the potential of water as a source for critical resources. Here, the materials that are developed for membranes, sorbents, catalysts, electrodes, and interfacial solar steam generators that demonstrate promise for applications in critical resource recovery are reviewed. In addition, a critical perspective is offered on the grand challenges and key research directions that need to be addressed to improve their practical viability.

Integrated data-driven cross-disciplinary framework to prevent chemical water pollution

Access to a clean and healthy environment is a human right and a prerequisite for maintaining a sustainable ecosystem. Experts across domains along the chemical life cycle have traditionally operated in isolation, leading to limited connectivity between upstream chemical innovation to downstream development of water-treatment technologies. This fragmented and historically reactive approach to managing emerging contaminants has resulted in significant externalized societal costs. Herein, we propose an integrated data-driven framework to foster proactive action across domains to effectively address chemical water pollution. By implementing this integrated framework, it will not only enhance the capabilities of experts in their respective fields but also create opportunities for novel approaches that yield co-benefits across multiple domains. To successfully operationalize the integrated framework, several concerted efforts are warranted, including adopting open and FAIR (findable, accessible, interoperable, and reusable) data practices, developing common knowledge bases/platforms, and staying vigilant against new substance "properties" of concern.