Turning plastic bottles and orange peels into a recyclable catalyst for cleaner water
image: Porous biochar supported PET plastic waste MOF heterostructure as a novel, efficient and recyclable catalyst for acetaminophen degradation
Credit: Sivakumar Vigneshwaran, Do-Gun Kim & Seok-Oh Ko
Researchers have developed a light-driven catalyst made from two common waste materials, discarded PET plastic bottles and orange peels, that can efficiently break down acetaminophen in water. The study, published in Biochar, presents a sustainable strategy that links plastic upcycling with advanced water treatment.
Acetaminophen, widely used as a pain reliever and fever reducer, is frequently detected in wastewater because it is heavily consumed and not always fully removed by conventional treatment systems. Even at low concentrations, persistent pharmaceutical residues can raise concerns for aquatic ecosystems and long-term water quality. To address this challenge, the research team designed a hybrid photocatalyst that uses visible light to drive the degradation of acetaminophen.
The material, called PZM/BC, combines a zinc-based metal-organic framework with biochar derived from orange peel waste. The organic building blocks for the metal-organic framework were recovered from PET plastic waste, turning discarded bottles into useful chemical linkers. The orange peel biochar served as a porous, carbon-rich support that helped move electrons through the catalyst and improve the separation of light-generated charges.
“Our goal was to design a material that does more than remove a pollutant from water,” said the study’s corresponding author. “We wanted to show that waste plastics and biomass residues can be converted into a functional catalyst for environmental remediation.”
Under visible light, the PZM/BC catalyst showed strong activity toward acetaminophen degradation. The study found that the material achieved nearly complete removal of acetaminophen under optimized conditions, including a mildly acidic pH of 6.07, a catalyst dosage of 0.1 g L−1, and an initial acetaminophen concentration of 50 mg L−1. The catalyst maintained high degradation performance after repeated use, with about 98% efficiency retained over five cycles.
The team used a range of characterization methods, including UV-Vis diffuse reflectance spectroscopy, photoluminescence analysis, electrochemical impedance spectroscopy, Mott-Schottky measurements, and electron spin resonance. These tests showed that the hybrid structure promoted efficient charge separation and transport, which are key factors in photocatalysis. Electron spin resonance results indicated that hydroxyl radicals and photogenerated holes played major roles in breaking down acetaminophen.
The researchers also examined possible degradation pathways. Their findings suggest that acetaminophen molecules were attacked through several chemical routes, including bond cleavage, ring opening, oxidation, and other transformations that gradually converted the compound into smaller intermediates.
“What makes this system promising is the synergy between the PET-derived framework and the orange peel biochar,” the author added. “The biochar acts like an electron shuttle, while the metal-organic framework provides active sites for photocatalytic reactions. Together, they create a more efficient pathway for pollutant degradation.”
Beyond acetaminophen removal, the work points to a broader approach for designing sustainable catalysts. PET plastic waste is a growing global problem, while fruit peel residues are widely available biomass wastes. By combining these two streams into a reusable photocatalyst, the study offers a potential route toward circular materials for water treatment.
The authors note that further research is needed to test the catalyst in more complex water systems and to evaluate scale-up potential. Still, the findings demonstrate a promising proof of concept: everyday waste materials can be transformed into advanced tools for addressing pharmaceutical pollution in water.
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Journal Reference: Vigneshwaran, S., Kim, DG. & Ko, SO. Porous biochar supported PET plastic waste MOF heterostructure as a novel, efficient and recyclable catalyst for acetaminophen degradation. Biochar 6, 94 (2024).
https://doi.org/10.1007/s42773-024-00369-4
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About Biochar
Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.