An eco-friendly chitosan-genipin/SiO₂ composite for reactive orange 16 dye removal: Insights into adsorption...

The present work develops an effective bioadsorbent of cross-linked chitosan-genipin/SiO₂ adsorbent (CHI-GNP/SiO₂). The developed CHI-GNP/SiO₂ was employed for the removal of organic dye (reactive orange 16, RO16) from simulated wastewater. The optimization of the fundamental adsorption variables (CHI-GNP/SiO₂ dose, time, and pH) via the Box-Behnken design (BBD) was attained for achieving maximal adsorption capacity and high removal efficiency. The good agreement between the Freundlich isotherms and empirical data of RO16 adsorption by CHI-GNP/SiO₂ indicates that the adsorption process follows a multilayer adsorption mechanism. The reasonable agreement between the pseudo-second-order model and the kinetic data of RO16 adsorption by CHI-GNP/SiO₂ was obtained. The maximum RO16 adsorption capacity (q_max) of CHI-GNP/SiO₂ was identified to be 57.1 mg/g. The adsorption capacity of CHI-GNP/SiO₂ is attributed to its unique surface properties, including its highly porous structure and the presence of functional groups such as amino and hydroxyl groups. According to the results of this investigation, CHI-GNP/SiO₂ has the potential to be an adsorbent for the removal of acidic dyes from wastewater.