Valorization of Polyethylene Terephthalate Waste into Activated Carbon for Used Cooking Oil Purification
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Date
2025-06
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Addis Ababa University
Abstract
This study focused on producing AC from post-consumer polyethylene terephthalate (PET) bottles for the purification of Used Cooking Oil (UCO), addressing two critical environmental concerns: plastic waste and oil pollution. AC was prepared using a double activation method with potassium hydroxide (KOH) at 800°C for 2 hours. The optimal sample was produced at an impregnation ratio of 1:1 (KOH to PET), resulting in a BET surface area of 984.9 m²/g. Comprehensive characterization was conducted using BET and BJH analyses, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA). The adsorption process was optimized for free fatty acid (FFA) removal, achieving a maximum efficiency of 68.2% under conditions of 112 minutes of contact time, a 7.5% (w/v) adsorbent dosage, and a mixing speed of 240 rpm. Under these conditions, the oil's peroxide value (PV) was reduced by 77.21%, and lightness increased by 3.51 units. Kinetic modeling revealed that the adsorption followed a pseudo-second-order model with an R² value of 0.9657. However, the pseudo-first-order (R² = 0.9644) and intraparticle diffusion (R² = 0.9522) models also demonstrated reasonable fits. The PET-derived AC exhibited competitive, and in some cases superior, performance compared to biomass-based alternatives, indicating its potential as a sustainable and effective material for UCO purification.
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Keywords
Adsorption, Activated Carbon, Polyethylene Terephthalate, Used Cooking Oil, Free Fatty Acid, Optimization, Kinetic Study