Biochar doped recycled PLA for carbendazim detection in environmental water using additive manufactured electrodes

Additive manufacturing electrochemistry offers transformative potential for developing bespoke, low-cost electrodes for electroanalytical applications. However, ensuring sustainability in this rapidly expanding field is essential, requiring alignment with green chemistry principles, the circular economy, and the United Nations Sustainable Development Goals (SDGs). This study addresses this challenge by developing the first biochar-based conductive additive manufacturing feedstock, combining recycled PLA, bio-based castor oil, carbon black, and softwood-based biochar (SWP10). Filaments with varying SWP10 content (1–40%) were produced, with up to 20 wt% SWP10 (SWP10-20) maintaining good printability. Electrochemical characterisation identified SWP10-2.5 (2.5 wt%) as the optimal composition, achieving improved electrochemical performance while enhancing sustainability. Both SWP10-2.5 and SWP10-20 were tested for electroanalytical applications, demonstrating their effectiveness in detecting carbendazim, an important environmental contaminant. The electrodes exhibited low limits of detection (57 nM for SWP10-2.5 and 78 nM for SWP10-20) and wide linear ranges (0.2–40 μM), outperforming several previously reported sensors. Furthermore, both electrodes were successfully applied for the detection of carbendazim in spiked real river and lake water samples, achieving recoveries between 92.5% and 107.2%. These results demonstrate that by optimising biochar and carbon black ratios, it is possible to enhance the sustainability of conductive additive manufacturing materials without compromising electrochemical or electroanalytical performance. This work highlights a pathway toward more environmentally friendly electroanalytical platforms, supporting the SDGs while addressing real-world challenges in environmental monitoring and sensor development. • First biochar-based conductive additive manufacturing filament developed for electrochemical applications. • Optimised filament compositions enhance both electrochemical performance and sustainability. • Sensitive detection of carbendazim, achieving a wide linear range (0.2–40 μM) and a low detection limit (57 nM). • Successful application in real environmental water samples, detecting carbendazim with high recovery rates. • Demonstrates the synergy between performance and sustainability, advancing green electroanalytical sensing.