Nanocage Structure Derived from Sulfonated β-Cyclodextrin Intercalated Layered Double Hydroxides and Selective Adsorption for Phenol Compounds

Abstract

Nanocage structures derived from decasulfonated β-cyclodextrin (SCD) intercalated ZnAl- and MgAl- layered double hydroxides (LDHs) were prepared through calcination-rehydration reactions. The ZnAl- and MgAl-LDH layers revealed different basal spacings (1.51 nm for SCD-ZnAl-LDH and 1.61 nm for SCD-MgAl-LDH) when contacting SCD, while producing similar monolayer and vertical SCD orientations with cavity axis perpendicular to the LDH layer. The structures of the SCD-LDH and carboxymethyl-β-cyclodextrin (CMCD)-LDH intercalates were fully analyzed and compared, and a structural model for the SCD-LDH was proposed. The thermal stability of SCD after intercalation was remarkably enhanced, with decomposition temperature increased by 230 °C. The adsorption property of the SCD-LDH composites for phenol compounds (the effects of adsorption time and phenol concentration on adsorption) was investigated completely. The monolayer arrangement of the interlayer SCD did not affect the adsorption efficiency toward organic compounds, which verified the highly swelling ability of the layered compounds in solvents. Both composites illustrated preferential adsorptive efficiency for 2,3-dimethylphenol (DMP) in comparison with other two phenols of hydroquinone (HQ) and tert-butyl-phenol (TBP), resulting from appropriate hydrophobicity and steric hindrance of DMP. For the two phenols of HQ and TBP, SCD-MgAl-LDH gave better adsorption capacity compared with SCD-ZnAl-LDH. The double-confinement effect due to the combination of the parent LDH host and intercalated secondary host may impose high selectivity for guests. This kind of nanocage structure may have potential applications as adsorbents, synergistic agents, and storage vessels for particular guests.

Hyper-crosslinked β-cyclodextrin porous polymer: an adsorption-facilitated molecular catalyst support for transformation of water-soluble aromatic molecules

“…2, the adsorption capacity for 4-chlorophenol was up to 1.10 mmol g –1 at the equilibrium concentration of 0.7 mmol L –1 ; and the values of K d for the BnCD-HCPP were in the range of 10 3 –10 6 mL g –1 , much higher than those of other β-cyclodextrin-based adsorbents reported previously (Table S1†). 9 These values suggest BnCD-HCPP to be a highly effective adsorbent for aromatic molecule removal. Overall, the K d values decreased with an increase in the equilibrium concentration of the adsorbates, especially in the lower concentration range.…”

Inorganic nanolayers: structure, preparation, and biomedical applications

“…[58][59][60][61] Also, halogen anions and perchlorate anions have been removed by LDH application. [62][63][64][65] Organic 32,[67][68][69][70] In water-treatment plants, disinfection is an important procedure, and currently halogens and ozone are employed as disinfectants. However, there are certain issues with respect to these disinfectants, such as the fact that they can form genotoxic and carcinogenic by-products in the presence of organic compounds.…”

A new, low-cost adsorbent: Preparation, characterization, and adsorption behavior of Pb(II) and Cu(II)

“…Layered double hydroxides (LDHs) are low cost anion-exchanging lamellar materials with good adsorptive properties [28][29][30] that allow their various applications such as catalysts and catalyst precursors [31], two-dimensional solid-state nano-reactors and adsorbents [32][33][34][35], or scavengers for certain guests [36,37], and other functional materials. Structurally [38], LDHs have the characteristics of anion exchange, which make them adsorb mainly inorganic pollutants such as phosphate [39], borate [40], fluoride [41], and other organic anions [42,43] as well as metal ions in the form of anionic Cr (VI) [44].…”