Use of activated carbon from NiO modified Polyethylene Terephthalate plastic bottle waste to optimize natural gas storage in Adsorbed Natural Gas (ANG) technology

Abstract

Storage and transportation of natural gas are major challenges in optimizing energy use. To overcome the challenges, Adsorbed Natural Gas (ANG) technology offers a promising alternative for increasing storage capacity at lower pressures. Therefore, this study aims to explore the efficiency of waste polyethylene terephthalate (PET) bottles converted into activated carbon through pre-treatment, carbonization, chemical activation with 4 M KOH, and physical activation using N₂ flow. Modification of activated carbon was carried out using NiO metal impregnation at concentrations of 0.5%, 1%, and 2% to enhance adsorption performance. The results of characterization using iodine number, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) showed that the 2% NiO-impregnated sample had the highest surface area of 997.65 m²/g. Natural gas adsorption and desorption testing showed that this material achieved the maximum storage capacity of 138.9 g/kg at 28°C and 9 bar, with superior performance compared to non-impregnated samples and several previously reported ANG adsorbents. These results showed that combining NiO modification with KOH-activated PET waste improved methane uptake beyond commercial activated carbons and provided an environmentally sustainable solution for plastic waste valorization.