Enhanced bifunctional adsorption of anionic and cationic pollutants by MgAl LDH nanosheets modified montmorillonite via acid-salt activation.

A novel H+ and Cl− intercalated montmorillonite@MgAl LDH (MMT-N) nanocomposite was prepared by a one-step hydrothermal method following acid-salt treatment. The MMT-N prepared by the advanced modification method contains low CO2–3contamination, high specific surface area, and high porosity. By enhancing the ion exchange of montmorillonite and LDH, efficient removal of anionic and anionic dyes was achieved without the introduction of another cation contamination. The adsorption kinetics of methyl orange (MO) and methylene blue (MB) are in accordance with the pseudo-second-order model, and the maximum adsorption amounts of methylene blue and methyl orange reached 815.998 mg g−1 and 399.836 mg g−1, respectively. The coefficient of determination (R2) and the corrected Akaike Information Criterion (AICc) revealed that the adsorption isotherm data of MO and MB on MMT-80 fitted well with Freundlich isotherm, signifying that the adsorption process was dominated by chemisorption. And the adsorption of MO and MB by MMA-80 was endothermic and exothermic, respectively. The "intercalation-split mechanism" and "ion exchange" mechanisms of MO and MB in MMA-80 were also investigated. This study provides an efficient method for the synthesis of high-performance bifunctional adsorbents for cationic and anionic pollutants and offers potential applications for practical wastewater purification. [Display omitted] • The material after acid salt treatment exhibits superior adsorption performance for anionic and cationic dyes. • The cation exchange of montmorillonite and the anion exchange characteristics of LDH are skillfully utilized without introducing other cation pollutants. • The adsorption mechanism including the "intercalation-split mechanism" and "ion exchange mechanism" mechanism was also investigated. [ABSTRACT FROM AUTHOR]