- Thesis topic: Advanced Degradation Methods for OPEs in E-Waste: Exploring Plasma and Furnace Technologies

- Doi: 

- Abstract: 

        With the rapid advancement of the high-tech industry, the accelerated replacement cycle of electronic products has led to a continuous increase in electronic waste (e-waste), which has become a pressing global environmental concern. In addition to the well-documented risks associated with heavy metals and plasticizers, the release of organophosphate esters (OPEs) during e-waste recycling and treatment has drawn growing attention. Widely used as flame retardants and plasticizers in electronic devices, OPEs exhibit high lipophilicity and bioaccumulation potential and have been shown to pose ecological and human health risks, including neurotoxicity and endocrine-disrupting effects. As such, OPEs are increasingly regarded as emerging indicators of pollution in e-waste management.
To address the environmental challenges posed by OPEs, the development of efficient and sustainable treatment technologies is urgently needed. This study evaluates the degradation performance and application potential of two advanced thermal and plasma-assisted oxidation technologies—microwave plasma and tubular furnace—on the removal of OPEs from e-waste. Printed circuit boards from information technology and household appliances were selected as test samples, and 17 representative OPE compounds (including TEP, TPrP, TBP, TPeP, TBEP, TEHP, TCEP, TCIPP, TDCPP, TPhP, EDP, CDP, o-TCP, m-TCP, p-TCP, BPDP, and TiPPP) were quantitatively analyzed. The initial OPE concentrations ranged from 16 to 202 ng/g in IT equipment samples and from 107 to 59,585 ng/g in household appliance samples, indicating considerable variability based on product type.
Experimental parameters included microwave plasma power settings of 800 w, 900 w, and 1000 w, and tube furnace temperatures of 400°C, 500°C, and 550°C. Post-treatment OPE concentrations ranged from 7 to 133 ng/g. Overall, microwave plasma showed variable removal efficiencies ranging from −9% to 93%, while tubular furnace treatment achieved more consistent removal rates between 38% and 96%. For chlorinated OPEs (Cl-OPEs), removal efficiencies ranged from −35% to 91% for microwave plasma and from 16% to 92% for the tubular furnace, demonstrating that both methods possess degradation potential but exhibit compound-specific variability.
Among six key OPEs (TBP, TBEP, EDP, TCIPP, TDCPP, and CDP), both treatment methods achieved average removal efficiencies exceeding 83% under all conditions, with TDCPP and CDP showing over 99% removal across both technologies, indicating high stability and reliability. These findings suggest that both microwave plasma and tubular furnace treatments are promising approaches for OPE degradation. However, their effectiveness depends strongly on operating conditions and the physicochemical properties of the target compounds, underscoring the importance of tailored process control to maximize environmental performance in real-world applications.

Keywords: microwave plasma, tube furance, organophosphate esters, e-waste, PCB