Transforming Waste PET Bottles into High-Value MOF Adsorbents for the Removal of Emerging Pollutants from Wastewater

Abstract

Aggressive urbanization and globalization have led to severe environmental consequences in the past few decades. Among the major environmental challenges, water scarcity and plastic pollution are one of the most concerning. Waste polyethylene terephthalate (PET) bottles, a durable and non-biodegradable plastic, takes centuries to degrade and has damaging consequences for aquatic and human life. On the other hand, several emerging contaminants in wastewater have called for new research to control their spread and reduce environmental impact. Pharmaceuticals are one of the emerging contaminants from the industrials and hospitals that are classified as a concerning and emerging contaminant in wastewater. This Master’s thesis addresses this dual challenge of waste PET bottle and pharmaceutical pollution in wastewater by upcycling waste PET bottles into a metal organic framework, an emerging adsorbent for wastewater treatment. Disodium terephthalate (DST), which is made by alkaline hydrolysis of PET, is used as the organic ligand in this study to convert PET waste into useful aluminum-based metal-organic frameworks (Al-MOFs) in a sustainable and economical manner. The synthesis complies with green chemistry and the circular economy by avoiding hazardous solvents and energy-intensive processes. Several characterization techniques were used to thoroughly characterize the resultant Al-DST MOFs. The successful creation of distinct, thermally stable, porous Al-DST structures with large surface areas that are suitable for adsorption was confirmed by characterization. Batch experiments were conducted to evaluate the adsorption efficiency of the as-synthesized Al-DST MOFs against Tetracycline (TC), a common antibiotic and a typical developing contaminant. The adsorption efficiency was evaluated by varying several parameters, including pH, contact time, starting concentration, and temperature. The Al-DST MOFs demonstrated excellent reusability over multiple cycles, rapid adsorption kinetics, and a high TC adsorption capacity. The Langmuir isotherm and pseudo-second-order kinetic models provided the best description of the adsorption data, demonstrating chemisorption-mediated uptake and monolayer adsorption onto a homogenous surface. This work demonstrates the potential of Al- DST MOFs extracted from waste PET bottles as efficient adsorbents in eliminating pharmaceutical contaminants from wastewater in addition to providing a sustainable and easily accessible route for PET upcycling. The plan offers a promising future for addressing the problems of plastic pollution and water contamination while also supporting the development of renewable materials