(222f) Unlocking the Potential of Phosphate Industry and Tannery Waste: Synthesis of Functional MOFs, Mesoporous Silicas, and Zeolite Via a Sustainable Valorization Route

The large-scale production of a variety of end products, such as energy, electronics, fertilizers, etc. has led to a dramatic increase in the number and size of several industries, which then generate hazardous pollutants that are all too often released into the surrounding environment. Increasing levels of pollution is driving the research community to discover new ways to capture toxic pollutants from industrial waste streams and also to valorize industrial waste through the subsequent production of valuable commodities. One way to valorize waste products is to convert them into functional materials. Among the various useful products that can be synthesized from waste, the preparation of porous physical adsorbents has attracted recent attention. Metal-organic frameworks (MOFs), mesoporous silicas, and zeolites are among the various functional solid-state sorbents that have shown huge promise for many industrially relevant applications. However, overcoming obstacles ahead, such as the difficulty of producing those porous sorbents at a scale due to the high cost of the precursors used to assemble them is critical. Preparing porous materials from waste sources could help to overcome the sustainable production challenge while simultaneously valorizing the waste and addressing environmental concerns. There are various types of local and industrial waste, which could be explored. In this work, the transformation of phosphate rock tailings and phosphogypsum, solid waste products generated in huge amounts from the different value chains of the phosphate industry, into advanced Ca-MOFs, heterometallic mesoporous silicas, and zeolites, as well as the simultaneous valorization of tannery effluents and waste plastic bottles into water adsorbing Cr-terephthalate MOFs, will be highlighted. The combination of tannery effluent and organic linker extracted from waste plastic bottles led to a successful assembly of Cr-terephthalate (Cr-BDC) MOFs with potential application for water harvesting. The waste from the phosphate industry served as silica, alumina, and calcium sources leading to the assembly of various zeolites, mesostructured adsorbents, and functional Ca-MOFs, with promising potential for various applications, including carbon capture, heavy metal removal from wastewater, and alcohol dehydration. In some cases, advanced heterostructures with enhanced adsorption properties were obtained that are otherwise difficult to be prepared from pure commercial-grade precursors. The structural attributes of the prepared porous sorbents and their performance in different applications were confirmed by various techniques including XRD, SEM-EDX, FTIR, TGA-DSC-MS, TEM, NMR, ICP-OES, N₂ sorption at cryogenic conditions, CO₂ sorption at different temperatures, and room temperature water, methanol, and ethanol sorption analyses. The advances made in this study represent significant progress in applying sustainability principles and pave the way for circular economy targets.

References:

1. Ali Mohammed Yimer, Ayalew H. Assen, Ikrame El Mghaimimi, Omar Lakbita, Karim Adil, Youssef Belmabkhout, Unlocking the potential of phosphogypsum waste: Unified synthesis of functional metal-organic frameworks and zeolite via a sustainable valorization route, Chem. Eng. J. 2024, 479, 147902. https://doi.org/10.1016/j.cej.2023.147902
2. Achraf Delhali, Ayalew H. Assen, Aminat Mohammed, Karim Adil, Youssef Belmabkhout, Enabling simultaneous valorization of tannery effluent and waste plastic via sustainable preparation of Cr-BDC MOFs for water adsorption, Rep. 2023, 13, 14653. https://doi.org/10.1038/s41598-023-41840-9.