Azo dye removal using rice husk-based nanobiochar-chitosan composite: Integration of Taguchi optimization and ANN modeling

In the present research, rice husk agrowaste was recycled to produce nanobiochar-chitosan composite (NBC-CSC) for the removal of toxic Everzol black dye from aqueous media. The synthesized composite was characterized via Fourier Transform Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy coupled with Energy Dispersive X-ray. The process optimization was carried out utilizing Taguchi L25 orthogonal array and the maximum 99.32 % removal was achieved from the optimized conditions. Freundlich and Sips model (R² = 0.99) both confirmed the multilayer adsorption, whereas the kinetics fitted the pseudo-second-order model (R 2 = 0.99). Error analysis also confirmed the fitness of the selected models. Thermodynamic parameters indicated spontaneous and endothermic behavior. Artificial Neural Network (ANN) was also applied, which presented good performance (R² = 0.97) comparable with that of the Taguchi model (R² = 0.99). Additionally, NBC-CSC removed 97.31 % of the dye from actual textile effluent and the desorption study showed excellent reusability 94–51 % indicating its excellent feasibility for wastewater treatment. Integrating Taguchi optimization and ANN modeling, this work presents a novel combination strategy for azo dye removal using eco-friendly and reusable adsorbent. Limitations consist of the need for continuous-flow studies and prospects include optimization of regeneration, scale-up and techno-economic evaluation for real-world implementation. • Nanobiochar–chitosan composite was synthesized using rice husk for adsorption of Everzol dyes. • The Taguchi design resulted in 99.32 % removal and 181 mg/g adsorption capacity. • ANN model was also applied which provided satisfactory prediction (R² = 0.97). • Statistical error analysis supported the accuracy and reliability of the applied isotherms and kinetic models. • Desorption study was also performed and revealed the good desorption efficiency (94 %).