Adsorption of Safranin onto Sugarcane Bagasse-Derived Activated Carbon: Adsorbent Characterization, Process Optimization, Kinetic Modeling, and Equilibrium Isotherm Studies

Abstract

The discharge of synthetic dyes into aquatic environments poses significant environmental and health concerns, necessitating the development of efficient and sustainable treatment methods. This study investigated the adsorption of safranin dye onto activated carbon derived from sugarcane bagasse through material characterization, process optimization, kinetic modeling, and equilibrium isotherm analysis. Scanning electron microscopy revealed that activation transformed the compact fibrous structure of raw sugarcane bagasse into a highly porous material with well-developed cavities and cracks. Fourier transform infrared spectroscopy confirmed the presence of hydroxyl, carbonyl, and other oxygen-containing functional groups, while Brunauer–Emmett–Teller analysis showed an increase in surface area from 278.969 m²/g to 364.914 m²/g after activation. Plackett–Burman screening identified adsorbent dosage and dye concentration as the most significant factors influencing safranin removal. Optimization using central composite design predicted a maximum removal efficiency of 99.50% at an adsorbent dosage of 1.14 g/L and dye concentration of 116.53 mg/L. Adsorption kinetics followed the pseudo-second-order model (  = 0.9990), while equilibrium data were best described by the Temkin isotherm model (  = 0.9928). The findings demonstrate that sugarcane bagasse-derived activated carbon is an effective, low-cost, and sustainable adsorbent for dye-contaminated wastewater treatment