Utilization of epoxy thermoset waste to produce activated carbon for the remediation of nano-plastic contaminated wastewater

Abstract

Nano-plastic (NP) pollution is a growing concern due to the introduction of plastic debris into wastewater streams and its breakdown into small fragments reaching nano-sized scale. This study explores the potential of adsorption by activated carbon (AC) as a low-cost solution for NP contamination, focusing on AC derived from thermoset epoxy, a non-recyclable plastic. The optimized AC product exhibiting a high surface area (1705 m2/g) and yield (31 %) was produced through chemical activation with KOH after comparison to other K-containing activating agents (K2CO3, KOAc) and preliminary investigation of key activation conditions. The AC effectively adsorbed synthesized PET NPs (≤350 nm) through multilayer physical adsorption, showing a monolayer capacity of 325 mg/g based on the AD-Langmuir model (R2 = 0.963). Furthermore, 94 % recovery of NP (100 mg/L) was achieved at an AC loading of 750 mg/L, indicating improved capacity for NP adsorption compared to commercial AC. Overall, the epoxy-based AC showed potential to significantly reduce NP pollution in wastewater effluents by a simple batch adsorption method, while simultaneously valorizing a non-recyclable plastic waste stream. Future work is required to fully optimize the conversion process and to improve the interaction of NP with AC such that full recovery can be achieved.