Hydrothermal Synthesis of Modified Hydrophobic Zn–Al-Layered Double Hydroxides Using Structure-Directing Agents and Their Enhanced Adsorption Capacity for p-Nitrophenol

Abstract

Hollow microspheres of hierarchical ZnAl-layered double hydroxides (LDHs) were synthesized by a simple hydrothermal method using hexamethylenetetramine as precipitating agent, sodium dodecyl benzene sulphonate (SDBS) as surfactant and sodium tartrate, sodium citrate and sodium salicylate (SS) as structure-directing agents, respectively. Characterization results of the microspheres synthesized indicate that the modified ZnAl-LDHs formed a variety of morphologies, surface areas and pore volumes. The hierarchical porous ZnAl/SDBS-LDH prepared using SS possesses the highest surface area (128.9 m 2 /g) and the greatest pore volume (0.37 cm 3 /g). A possible formation mechanism of the special three-dimensional nanostructures from the primary LDH nanosheet building units is proposed on the basis of the interaction between SS molecules and LDH crystals. The size of the channel height is approximately equal to the diameter of the intercalated anion SDBS, indicating that SDBS is in a vertical single-layer arrangement. Using p-nitrophenol as model pollutant, the effects of initial concentration of p-nitrophenol and contact time on the adsorption of p-nitrophenol using various ZnAl-LDHs were investigated by performing a series of experiments. Results of these experiments indicate that the microsphere hydrophobic ZnAl/SDBS-LDH modified using SS has a maximum p-nitrophenol adsorption capacity of 101.6 mg/g.

Zn-Co layered double hydroxide modified hematite photoanode for enhanced photoelectrochemical water splitting

“…LDHs are a class of layered anionic clays with positively charged layers and charge-balancing anions located in the interlayer region, and they can be represented by the formula [M 2+ 1−x M 3+ x (OH) 2 ] q+ (X n− ) q/n ·yH 2 O [32][33][34]. The versatility in both chemical composition and structural morphology of LDH materials makes it possible …”

Raman Spectroscopy for Characterization of Hydrotalcite-like Materials Used in Catalytic Reactions

“…These materials can be prepared by several methodologies other than coprecipitation. An alternative is the hydrothermal method, which permits obtaining high particle size and high product purity [3,4]. This method is similar to the co-precipitation, meantime, after stirring the suspension is transferred to a Teflon autoclave for hydrothermal treatment.…”

“…This method is similar to the co-precipitation, meantime, after stirring the suspension is transferred to a Teflon autoclave for hydrothermal treatment. The temperature and aging time influences directly in the crystallinity and morphology uniformity of the material [3][4][5][6][7][8]. Urea hydrolysis is a satisfactory example of hydrothermal synthesis in which urea is used as a source of carbonates and hydroxyls anions, providing better crystallinity due to very slow precipitation [9][10][11].…”