Efficient synthesis and investigation of waste-derived adsorbent for water purification. Exploring the impact of surface functionalization on methylene blue dye removal

Abstract

In pursuit of sustainable water management, the preparation of adsorbent materials via waste upcycling for water purification practices plays a decisive role. The sulphonated biochar, PiNe–SO3H, employed to target the methylene blue dye adsorption, was successfully synthesized via a mild, step-economical chemical carbonization-functionalization reaction. The presence of SO3H groups on the PiNe–SO3H surface played a critical role in significantly enhancing the adsorption capacity. The observed MB dye uptake was predominantly attributed to chemisorption processes as evidenced by the results from kinetics, thermodynamics, and isotherms. To further confirm the role of -SO3H in the adsorption mechanism, a comparison was made with other PiNe materials lacking sulphonic groups, highlighting the superior adsorption capacity of PiNe–SO3H. Additionally, a fast and efficient regeneration process was proposed to develop a truly waste minimized protocol, enabling the recovery of up to 94 % of the ethanolic mixture used during this step.