The high performance of multi-metal layered double hydroxides (LDHs) in the removal of organic dyes

In this work, both samples MgNiAl– LDH and MgNiFe–LDH hydrotalcites were utilized to remove the anionic dye Congo Red (CR) from an aqueous solution. Samples characterization was carried out by X-ray diffraction (XRD), infrared spectroscopy (IR) and Thermogravimetric/Differential Scanning Calorimetry (TG/ DSC). Various parameters were investigated, including the initial dye concentration, adsorbent mass, contact time, solution pH,
and temperature. Using classical pseudo-first-order, second-order, and intraparticle diffusion models, adsorption kinetics were investigated. The dynamical data fit well with the pseudosecond order kinetic model. The equilibrium adsorption data were analyzed using three linear adsorption models: Langmuir, Freundlich and Temkin. The findings showed that the Langmuir isotherm adequately predicts experimental results with an ideal correlation coefficient. The isothermal Langmuir model revealed a maximum adsorption capacity of qmax of 5548 mg/g for the MgNiFe–LDH and of 4043mg/g for MgNiAl-LDH. This result is very useful when selecting sorbents to improve removal technology in the aquatic environment