Taguchi Approach for Optimizing Carbonization Parameters of Tea Waste To Enhance Adsorptive Biochar Properties

Tea waste particularly is produced in large quantities worldwide but remains underexplored as a biochar precursor compared to biomass sources. This study investigates the optimization of synthesis process parameters for biochar derived from raw tea waste using the Taguchi design compared to conventional optimization strategies due to quickly identify key parameters, reduce experimental cost, and enhance process robustness. Key variables included grinding time (10–30 min), hydrothermal carbonization (HTC) temperature (160–200 °C), HTC time (8–12 h), and chemical activation using phosphoric acid (0.0–1.0 mol L⁻¹). Grinding time was specifically considered due to its influence on particle size and surface area, where excessive grinding may induce agglomeration and reduce adsorption performance. A Taguchi L9 orthogonal array was employed to identify the most significant parameters affecting the removal of 2,4-Dichlorophenol from wastewater. Analysis of variance (ANOVA) revealed that chemical activation, HTC temperature, and grinding time were statistically significant, while HTC time had negligible influence. Under optimal conditions grinding time of 10 min, HTC temperature of 200 °C, HTC time of 8 h, and chemical activation of 1.0 mol L⁻¹, the Taguchi model predicted a removal efficiency of 75.31%, while the experimental value was 70%, showing 94.08% prediction accuracy. These results confirm that Taguchi-based optimization significantly enhances biochar properties such as surface area, thermal stability, and morphology. The findings demonstrate the potential of tea-waste-derived biochar as a cost-effective, scalable, and high-performance adsorbent for chlorophenol remediation in wastewater treatment.