A variety of MgAl-layered double hydrotalcites (MA-LDHs-x) with different Mg/Al molar ratios (1 : 3–5 : 1) were prepared by a novel solid-thermal approach. The obtained MA-LDH-x catalysts were characterized by various techniques. These results confirm the successful preparation of MA-LDHs-x with a high degree of crystallinity, large BET surface areas, and unique nanosheet structures with controllable hexagonal morphology. In addition, MA-LDHs-x possess tunable OH− group contents, which could be correlated with the molar ratio of Mg/Al. As a result, the MA-LDH-x catalysts exhibited better catalytic performance in carbonyl sulfide (COS) hydrolysis (COS conversion: 100% at 130 °C for MA-LDHs-3 : 1 vs. 38% at 130 °C for commercial Fe2O3) and H2S selective oxidation (H2S conversion: 100% at 150 °C for MA-LDHs-3 : 1 vs. 41% at 150 °C for commercial Fe2O3) than commercial desulfurization catalysts. Superior activities found in MA-LDH-x catalysts were attributed to their controllable 2D nanosheet structures, and the unique structural characteristics enhance the mass transfer of guest molecules. Notably, the exposed OH− base sites of MA-LDHs-x efficiently activate the acid COS and H2S, which facilitate the COS hydrolysis to H2S, and the selective H2S oxidation to elemental sulfur.
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 (R 2 ) 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.
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