Valorisation of PKM-2 Moringa oleifera leaves waste for adsorption of Titan Yellow dye from aqueous solution, modelling with RSM and ANN

Abstract

Water pollution from synthetic dyes poses significant environmental and health challenges, necessitating efficient and sustainable treatment methods. Titan Yellow (TY) dye, widely used in dyeing and textile industries, is challenging to remove due to its stable composition. However, optimizing treatment processes remains crucial for improving efficiency and applicability. Many potential adsorbents remain underexplored, highlighting the need for further research. This study investigates acid-functionalised Periyakulam 2 (PKM-2) Moringa oleifera leaves powder as an eco-friendly biosorbent for TY dye removal. Biosorbent characterisation by FTIR, XRD, and SEM–EDX demonstrated that hydrogen bonding, π–π, and electrostatic interactions were the main mechanisms involved in Titan Yellow dye adsorption. SEM images showed a highly porous surface before adsorption, which became less porous post-adsorption, confirming effective dye uptake. Response surface methodology-Box–Behnken design (RSM-BBD) optimised adsorption parameters, achieving 99.81% dye removal at 1.58-g biosorbent dosage, 32.30-mg/L initial concentration, pH 7.31, and 188.17-min contact time. An artificial neural network (ANN) model predicted adsorption behaviour with an R² of 0.998. Adsorption followed the nonlinear pseudo-second-order (PSO) kinetic model, while equilibrium data best fit the nonlinear Langmuir isotherm. Model validation using statistical metrics confirmed prediction accuracy. This research contributes to SDGs 3, 6, 9, and 12 by developing a sustainable water treatment solution using agricultural waste. Acid-functionalised PKM-2 M. oleifera leaves demonstrate high efficiency, non-toxicity, and sustainability for industrial dye removal, promoting clean water solutions, and environmental sustainability.