Fabrication of Hierarchically Porous “Fish Cage”‐like Carbonaceous Nanomaterials via Soft Template‐assisted Strategy for Cr Removal: Accelerated Stepped Adsorption and Enhanced Coordination Effect

Abstract The negative impact of heavy metal pollution, specifically chromium (VI), on human health is well‐documented. To solve this issue, hollow anisotropic hierarchically porous “Fish Cage”‐like carbonaceous nanomaterial (N,S‐HFC‐180) with multi‐active groups is synthesized. Hierarchically porous structure provides stepped adsorption effect. The addition of K 2 C 2 O 4 leads to an increase in the specific surface area of N,S‐HFC‐180 to 1914.21 m 2 g −1 (an increase of ~552 times compared to HFC‐180). Thiourea introduces multi‐active groups that act as “Barbs” in “Fish Cage”, further reducing Cr(VI) to Cr(III) and sequestrating Cr(III) by coordination effect. Subsequent batch studies suggest that N,S‐HFC‐180 exhibits a high removal capacity of 164.29 mg g −1 for Cr(VI) at pH=2. The kinetics and isotherm analyses display an outstanding maximum adsorption capacity of 393.88 mg g −1 at 298 K. In addition, even after seven cycles, the removal rate of Cr(VI) using N,S‐HFC‐180 remains>85.00 %, and it effectively reduces the concentration of electroplating wastewater from 55.82 to 0.14 mg L −1 . Pore filling, chemical reduction and chelation, hydrogen bond and electrostatic attraction are the primary adsorption drivers. The results suggest that, the recoverable N,S‐HFC‐180 highlights its viability for practical applications in wastewater treatment processes.