Open AccessMg-Cr Layered Double Hydroxide Intercalated Oxalic Anion to Remove Cationic Dye Solutions: Rhodamine B and Methylene Blue
Publication year - 2020
Publication title -
journal of environmental treatment techniques
Language(s) - English
Resource type - Journals
ISSN - 2309-1185
DOI - 10.47277/jett/9(2)391
Subject(s) - rhodamine b , adsorption , hydroxide , methylene blue , layered double hydroxides , chemistry , intercalation (chemistry) , desorption , aqueous solution , coprecipitation , nuclear chemistry , inorganic chemistry , langmuir adsorption model , organic chemistry , catalysis , photocatalysis
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 32.154 mg g⁻1, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (139.526 mg g⁻1). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K2 values of pristine and modified Mg/Cr LDH for RhB and MB were 6.970, 0.001, 0.426, and 2.056 g mg⁻1 min⁻1, 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 <40 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 98% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.