Wastewater modeling of Cr (VI) adsorption by sulfonated lignin of pine cones: equilibrium, kinetics, and isotherm study

Water is vital to life, so preserving it from pollution is an important issue. Chromium, in its various oxidation states, poses a significant threat to water contamination. This study analyzes the sulfonation process, which improves the Cr (VI) adsorption capability of lignin (a bio-adsorbent generated from pine cones), to produce sulfonated lignin (SL). The optimal pH for Cr (VI) adsorption was 2. Within the first ten minutes, uptake was rapid; however, it slowed thereafter and eventually reach