Congo red dye adsorption onto cationic amino-modified walnut shell: Characterization, RSM optimization, isotherms, kinetics, and mechanism studies

Congo red (CR) dye contamination in aquatic ecosystems often threatens human and aquatic health. This work synthesized a chemically modified, cationic amino-modified walnut shell (CMWS) adsorbent to treat CR dye -contaminated water. Central composite design (CCD) using standard response surface methodology design was performed to understand optimal conditions for removing dye with minimal experimentation. Maximum removal efficiency (94.12%) was achieved through CMWS than the raw walnut shell (RWS). Hydrogen bonding, pore filling, and electrostatic attractions effectively removed CR dye using CMWS. To understand cost-effectiveness and practical applicability, an adsorption-desorption analysis of CMWS was performed up to the third cycle with a removal efficiency of 82.18% with biomass loss of 26%. This study recommends CMWS as a potential adsorbent for CR dye removal and is worth investigating in the future.

Automated summary

This study synthesized a chemically modified, cationic amino-modified walnut shell (CMWS) adsorbent to effectively remove CR dye contamination from water. Through the experimental design, optimal conditions for dye removal were determined, and CMWS demonstrated higher removal efficiency than raw walnut shell (RWS). The study also analyzed the cost-effectiveness and practical applicability of CMWS, finding it to be a potential adsorbent for CR dye removal.