Green synthesis and characterization of functionalised Cr2CTX-OH MXene as an efficient adsorbent for malachite green dye

Water security faces increasing threats from industrial pollutants, especially persistent organic dyes like Malachite Green (MG). These dyes are highly toxic and resistant to degradation, leading to serious ecological and health risks. The present report portrays the microwave-assisted synthesis of the Cr 2 AlC MAX phase, and selective etching and alkalisation were performed to synthesize functionalised Cr 2 CT X -OH MXene. XRD analysis revealed the formation of Adsorption tests in batches were carried out at a pH of 6.75, and the results revealed that the functionalised MXene is an extremely efficient adsorbent. A number of parameters, including contact time, adsorbent dosage, and the initial dye concentration, have played an essential part when evaluating the performance. Kinetic analysis followed the pseudo-second-order model (R 2 = 0.998). The calculated equilibrium adsorption capacity (q e,cal = 1.855 mg/g) closely matched the experimental values (q e,exp = 1.583 mg/g). According to the results of the isotherm studies, the Freundlich model is a good fit for the process (R 2 = 0.894). The fact that the Freundlich constant (n) equals 2.45 demonstrates that multilayer adsorption on a variety of surfaces appears to be favorable. The kinetic experiments showed that the removal efficiency was stable when the dosage was dropped to 20 mg, and it reached its greatest point of around 52% after 120 min. On the other hand, when we optimized the dosage of the adsorbent to 0.05 g, the maximum removal efficiency climbed to 91.6%. Through the use of mathematical modelling of the adsorption data, major advances in knowing about the mechanism were made. These insights were obtained. The kinetics results indicate that a pseudo-second-order model controls the process, as evidenced by R 2 value of 0.998. In light of this, it appears that the availability of active surface sites is the factor that determines the rate-limiting stage in the chemisorption process. In terms of the isotherms, the equilibrium data indicate that the Freundlich isotherm model offers the best match (R 2 = 0.894), which indicates that multilayer adsorption takes place on a heterogeneous surface. By using reduced HF concentrations and a quicker, cheaper method of microwave-assisted synthesis, Cr 2 CT X -OH MXene can now be developed with a safe, scalable alternative to traditional synthesis methods. As opposed to the popular Ti 3 C 2 TX MXenes that have been studied extensively, this research investigates the ability of Cr-Based MXenes to absorb malachite green through modified surface functionalization combined with enhanced surface area and strong positive charge. In addition, current work revealed the novel application of Cr 2 CT X -OH MXene that has been created by microwave-assisted synthesis to remove malachite green. Its special surface chemical properties and unique adsorption method make it distinctive from other MXene systems. • Microwave-assisted synthesis rapidly converts Cr₂AlC MAX to functionalized Cr₂C–OH MXene with lower energy use. • Cr₂C–OH MXene shows high adsorption efficiency (up to 91.6%) for Malachite Green at near-neutral pH. • Adsorption follows pseudo-second-order kinetics (R² = 0.998), indicating a chemisorption mechanism. • Freundlich isotherm (R² = 0.894) confirms favorable multilayer adsorption on heterogeneous MXene surfaces. • Electrostatic and π–π interactions drive adsorption, enabling scalable wastewater treatment applications.