Work

Selective upcycling of brominated epoxy resin by subcritical water ammonia process with waste copper-based catalyst: Production of high purity methyl pyrimidine/phenols and copper recovery

Year: 2024

Type: article

Abstract: Tetrabromobisphenol A epoxy resin (TBBPAER) is the main non-metallic component of electronic waste. The scale of electronic waste production and the accompanying TBBPAER waste disposal problems represent a great opportunity for chemical upcycling. But the chemical upcycling of TBBPAER faces great challenges due to its high bromine content and thermally stability. In this study, a subcritical water ammonia (SWA) process combined with waste copper-based catalyst (WCC) selectively converted TBBPAER in high yields (63.46 % at 300°C for 15 min and 73.66 % for 60 min) to low molecular-weight liquid products including high value-added methyl pyrimidine and phenols. The electron transfer among multivalent copper species contained in the WCC promoted the production of free radicals OH, O 2 − , NH 2 , and :NH, which resulted in the efficient conversion of TBBPAER and a 99.29 % of debromination ratio. The molecular chain of TBBPAER was snipped by OH and NH 2 to produce tetrabromobisphenol A groups (TAG) and ternary carbon groups (TCG). The further degradation of TAG resulted in the producing of phenol chemicals with a purity of 91.8 % (GC peak area%). The further cyclization of TCG induced by :NH produced methyl pyrimidine with a purity of 91.9 % (GC peak area%). The formation of copper ammonia complex led to the leaching/recovery of 86.6 % of copper from the WCC. The SWA-WCC approach demonstrated how TBBPAER waste could be a viable feedstock for the producing of high value-added methyl pyrimidine and phenol chemicals. This study provided a novel sustainable strategy for synchronous treatment/upcycling of the two different wastes of TBBPAER and WCC. The leaching toxicity test of Cu and Zn for the solid residue after the co-treatment showed that their leaching concentrations were much lower than the hazardous waste standard.

Source: Separation and Purification Technology

DOI: 10.1016/j.seppur.2024.129827

Authors: Fu-Rong Xiu, Jiali Wang, Yingying Qi

Institution: Xi'an University of Science and Technology

Language: English

Topic: Subcritical and Supercritical Water Processes

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $3,790