A MgCr-based layered double hydroxide (LDH) was synthesized by a coprecipitation method, followed by an
intercalation process using an oxalic anion. The materials were characterized using X-ray diffraction analysis, FT-IR spectroscopy, and pH pzc measurement. The materials were then applied as adsorbents for removal of
methylene blue (MB) and
rhodamine B (RhB) from aqueous solution. Pristine Mg/Cr LDH exhibited RhB adsorption capacity of ۳۲.۱۵۴ mg g⁻۱, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (۱۳۹.۵۲۶ mg g⁻۱). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K۲ values of pristine and modified Mg/Cr LDH for RhB and MB were ۶.۹۷۰, ۰.۰۰۱, ۰.۴۲۶, and ۲.۰۵۶ g mg⁻۱ min⁻۱, respectively. The thermodynamic study identified that the adsorption of both dyes onto the LDHs was a spontaneous process and can be classified as physical adsorption with adsorption energies of <۴۰ kJ/mol. Moreover, the desorption and regeneration experiments indicated the high economic feasibility and reusability of the LDHs. By using HCl as the optimal solvent, the LDHs could desorb as much as ۹۸% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.A MgCr-based layered double hydroxide (LDH) was synthesized by a coprecipitation method, followed by an
intercalation process using an oxalic anion. The materials were characterized using X-ray diffraction analysis, FT-IR spectroscopy, and pH pzc measurement. The materials were then applied as adsorbents for removal of
methylene blue (MB) and
rhodamine B (RhB) from aqueous solution. Pristine Mg/Cr LDH exhibited RhB adsorption capacity of ۳۲.۱۵۴ mg g⁻۱, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (۱۳۹.۵۲۶ mg g⁻۱). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K۲ values of pristine and modified Mg/Cr LDH for RhB and MB were ۶.۹۷۰, ۰.۰۰۱, ۰.۴۲۶, and ۲.۰۵۶ g mg⁻۱ min⁻۱, respectively. The thermodynamic study identified that the adsorption of both dyes onto the LDHs was a spontaneous process and can be classified as physical adsorption with adsorption energies of <۴۰ kJ/mol. Moreover, the desorption and regeneration experiments indicated the high economic feasibility and reusability of the LDHs. By using HCl as the optimal solvent, the LDHs could desorb as much as ۹۸% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.
