Rational Design of Mesoporous Carbon@TiO ₂ Core–Shell Microspheres for Chromium(VI) Adsorption

ABSTRACT Titanium dioxide (TiO 2 )‐based composite microspheres are engineered for the highly efficient removal of hexavalent chromium [Cr(VI)] from aqueous environments. Three architectures—hollow TiO 2 (H–TiO 2 ), core–shelled carbon@TiO 2 (CS@TiO 2 ), and core–shellmesoporous carbon@TiO 2 (MC@TiO 2 )—are synthesized. MC@TiO 2 exhibits a maximum adsorption capacity of 128.2 mg·g −1 , far exceeding CS@TiO 2 (6.0 mg·g −1 ) and H‐TiO 2 (2.8 mg·g −1 ). Adsorption follows the Langmuir isotherm and pseudo‑second‑order kinetics, with ∼90% equilibrium uptake within 5 min. The mesoporous carbon core enhances surface area and porosity, while protonated TiO 2 hydroxyl groups provide electrostatic Cr(VI) attraction. The TiO 2 shell ensures chemical stability under extreme acid environment. These results establish MC@TiO 2 as a robust, ultrafast platform for sustainable heavy‑metal remediation.