2D/3D MXene/NiFeMn-layered double hydroxide decorated gelatin for removal of Cr(VI) and Congo red: Performance and mechanism

The discharge of toxic heavy metals and dyes into water is considered a principal reason for ecosystem deterioration. Therefore, the development of versatile adsorbents that can treat this threat is an urgent issue. On this basis, we designed and characterized a novel Ti3C2TX/NiFeMn-LDH@Gel composite to aptly remove hazardous hexavalent chromium ions Cr(VI) and organic Congo red dye (CR). Ti3C2TX/NiFeMn-LDH@Gel composite was facilely synthesized by introducing NiFeMn-layered double hydroxide and Ti3C2TX MXene into gelatin via a cross-linking reaction. Experimental data revealed that raising Ti3C2TX amount to 10 % in the matrix has dramatically promoted the adsorption aptitude of Ti3C2TX/NiFeMn-LDH@Gel towards Cr(VI) and CR. Freundlich model best described Cr(VI) and CR adsorption, with qmax reaching 423.73 mg/g, and 588.24 mg/g, respectively. Additionally, the adsorption kinetics of Cr(VI) and CR were fitted to the pseudo-second order model accompanied with spontaneity, randomness, and endothermic behavior. In addition, stability, and selectivity of Ti3C2TX/NiFeMn-LDH@Gel were investigated. Effect of ionic strength and interfering ions were explored as well. Besides, the recyclability test inferred superb adsorption capacities towards Cr(VI) and CR till the 5th cycle, revealing the potentiality of Ti3C2TX/NiFeMn-LDH@Gel towards anionic contaminants removal.