Pod-inspired MXene/porous carbon microspheres with ultrahigh adsorption capacity towards crystal violet

Abstract

This study reports on the preparation of pod-inspired superadsorbent materials, named as CPCM@MXenes. They have been synthetized by the assembly of chitosan-based porous carbon microspheres (CPCM) and the MXene of Ti3C2Tx formulae resulting from the Ti3AlC2 MAX phase. In a first step, the MXene composed of stacked sheets was delaminated into few-layers and nanosheets, being impeded their re-stacking due to the interposition of the incorporated CPM carbon spheres and providing an elevated specific surface area (>1, 800 m2/g). In this way, the CPCM@MXenes are porous materials presenting a 3D structural arrangement where the MXene single sheets delimited the microscopic morphology and the physicochemical surface properties that extraordinarily improve the adsorption capacity. We report here first results indicating that CPCM@MXenes are micro/nano-structured materials provided of super-efficient adsorbent behavior successfully tested in the adsorption and removal of crystal violet from water. This dye has been here selected as a molecular pollutant model. The CPCM@MXenes show a maximum of adsorption capacity close to 2, 750 mg/g, which at our best knowledge is the highest adsorbed amount of dye per mass unit never reported, for carbon-based materials. The adsorption process was consistent with the Langmuir adsorption isotherm and the quasi-second-order kinetic models. The adsorption mechanism can be attributed to the synergistic effects of physical adsorption, π-π stacking effect, hydrogen bonding and electrostatic interactions. The extraordinary adsorption efficiency of CPCM@MXenes in the removal of crystal violet could be potentially applied to many other molecular pollutants using simulated aqueous environment. In addition, these superadsorbents are provided of good recyclability allowing their easy reuse.