Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation

Abstract

Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants.

Ternary Layered Double Hydroxides (LDHs) Based on Co‐, Cu‐Substituted ZnAl for the Design of Efficient Photocatalysts

“…Contrarily, the surface area of the LDH material is generally around 15 m 2 g –1 and this value doesn't vary much as a function of LDH composition (Table S2). Therefore, it could be assumed that the difference in adsorption can be mainly explained by the zeta potential as observed in our previous work . Besides, a possible exchange of intercalated layered species was neglected since the intercalated molecule of this work, CO 3 2– , is known for its high stability and could not be exchanged with any other anionic ions such as orange II, which has low charge density compared to CO 3 2–…”

“…Synthesis of Layered Double Hydroxides (LDH): LDH materials were synthesized by a co‐precipitation method at constant pH (CPC) as reported in the literature and also optimized in our group . Aqueous solution containing a given amount of metal salts (50 mL, total cation concentration of 0.4 m ) was slowly added (0.3 mL min –1 ) to an ammonium nitrate buffer solution (20 mL, pH = 9, 0.1 m , mixture of ammonia solution with HNO 3 ) by using a peristaltic pump while keeping the pH fixed at 9 with use of a mixture of Na 2 CO 3 (0.25 m ) and NaOH (0.1 m ) solution.…”

“…As a matter of the fact, LDHs could be good candidates for designing photoactive materials through tuning of physicochemical properties such as ternary metal substitution, or exchange of anionic ions . Recently, our group reported the influence of Co, Cu substitution in the framework of MgAl‐CO 3 –LDH in order to design efficient catalysts for a H 2 O 2 ‐assisted dark Fenton‐like reaction for the degradation of organic pollutants . A synergic effect of mixing two transition metals was observed, as steps of slow reaction rates could be avoided.…”

A novel three-dimensional hierarchical CuAl layered double hydroxide with excellent catalytic activity for degradation of methyl orange

“…25 Jean Fahel and coworkers investigated the CoCuAl-LDH which exhibited excellent catalytic activity on the dye degradation of orange II. 26 Hongtao Lu and coworkers prepared and applied CuZnFe-LDH as a heterogeneous Fenton-like oxidation catalyst for the degradation of acetaminophen. 27 Meanwhile, Cu-containing derivatives of have been widely studied.…”

Enhanced Photocatalytic Activity of a Molybdate‐Intercalated Iron‐Based Layered Double Hydroxide

“…The brucite layers of LDHs are constituted by sheets of edge‐shared MO 6 octahedra and act as doped semiconductors. Recently, both modified and unmodified LDHs have been reported for applications in selective photocatalysis …”