Systematic utilization of layered double hydroxide nanosheets for effective removal of methyl orange from an aqueous system by π-π stacking-induced nanoconfinement

Abstract

Systematic utilization of carbonated Mg-Al layered double hydroxide (LDH) nanosheets on methyl orange removal was investigated with a respect to particle dimension. LDHs with smallest dimension were synthesized carefully to have a small lateral size as well as high dispersibility. The other particles with medium and large sizes were prepared by hydrothermal treatment and urea hydrolysis to have larger size and higher crystallinity. According to kinetics and isotherm analyses, the smallest sized LDH showed effective adsorption of methyl orange (1250 mg/g-LDH) which was remarkable higher than the other LDHs with the larger lateral sizes. Compared with the larger lateral sized LDHs, the small sized ones were verified to utilize all the accessible adsorption sites of the nanosheets generating nanoconfinement of the methyl orange molecules. Transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD) patterns definitely indicated that the LDHs with ~40 nm of the lateral dimension could fully utilize the interlayer nanospace of the LDH. Monte-Carlo simulation suggested the intercalated methyl orange could be stabilized not only through electrostatic interaction with the LDH layer but also by π-π stacking between the methyl orange molecules, which is thought to be the driving force to replace carbonate anion.

Physicochemical Properties and Hematocompatibility of Layered Double Hydroxide-Based Anticancer Drug Methotrexate Delivery System

“…As the particle size and homogeneity are important factors regarding the toxicology of nanoparticles, a SEM study was carried out for the MTX-LDH powder and the size distribution was obtained ( Figure 2 ). It was revealed that the MTX-LDH particles have a pebble-like shape with a relatively large lateral size compared to thickness ( Figure 2 A), which is a typical shape of hydrothermally synthesized LDH particles [ 15 , 18 , 20 ]. Approximately 100 particles were randomly selected from the SEM images and the size distribution in terms of lateral size was illustrated with a histogram.…”

“…The layer-by-layer stacking between inorganic layers and interlayer anions is stabilized by electrostatic interaction, developing several tens of layers intervened by each other. It has been reported that LDH can accommodate a large amount of anionic drugs with high biological inertness and physicochemical stability [ 15 , 16 , 17 , 18 ]. The particle size of LDH can be easily controlled through adopting an appropriate synthesis route—coprecipitation, hydrothermal treatment, urea hydrolysis etc.…”

“…The particle size of LDH can be easily controlled through adopting an appropriate synthesis route—coprecipitation, hydrothermal treatment, urea hydrolysis etc. [ 19 ]—to have the optimum dimension for low systemic toxicity and high cellular delivery efficacy [ 18 , 20 ]. Incorporated drug or gene moieties are released in a controlled manner under weakly acidic conditions to provide target cells with payloads in a sustained manner [ 21 , 22 ].…”

Development of Mesopore Structure of Mixed Metal Oxide through Albumin-Templated Coprecipitation and Reconstruction of Layered Double Hydroxide

“…The metal oxide domains produced during thermal treatment can be connected by the trivalent metals migrated to tetrahedral site [23,24], resulting in intra-particle mesopores [25][26][27]. It is generally known that LDHs prepared by conventional coprecipitation method tend to have specific surface area (S BET ) around 20-60 m 2 /g [28][29][30], while the corresponding LDO had S BET higher than 100 m 2 /g [27,30].…”

Decomposition of glyphosate in water by peroxymonosulfate activated with CuCoFe‐LDH material

“…mH2O] xwith M 2+ (divalent metals), M 3+ (trivalent metals), and x (e.g., 0.2-0.4) is M 3+ /(M 2+ + M 3+ ) ratio. [14] LDHs as typical two-dimensional materials have received a lot of attention in various applications such as adsorption, [15,16] and catalyst or catalyst precursor, [17,18] energy storage and conversion, [19,20] and electrochemical analysis [21,22] . There are many choices of M 2+ and M 3+ transition metals, giving LDHs the ability to become heterogeneous catalysts with high PMS activation capacity for organic degradation in water.…”