Preparation and Characterisation of Mg–Al Layered Double Hydroxides Intercalated with 2-Naphthalene Sulphonate and 2,6-Naphthalene Disulphonate

Abstract

A Mg-Al layered double hydroxide (Mg-Al LDH) has been modified with aromatic anions by a coprecipitation technique. This method is based on the anion-exchange characteristics of the hydrotalcite-type compound which intercalates various anions, including anions of organic acids, in the interlayer. The Mg-Al LDHs are intercalated with 2-naphthalene sulphonate (2-NS À ) and 2,6-naphthalene disulphonate (2,6-NDS 2À ) ions, which contain a naphthalene ring with one and two sulphonate (-SO 3 À ) groups in their structures, respectively. They are formed by the dropwise addition of a mixed aqueous solution of Mg(NO 3 ) 2 and Al(NO 3 ) 3 (Al/Mg mole ratio = 1/3) to a solution containing the individual organic anion at a constant pH of 10.0. The Mg-Al LDHs modified with aromatic anion are expected to recognize and selectively uptake hazardous aromatic compounds, such as bisphenol A, from aqueous solutions. The composite materials prepared were characterized by X-ray diffraction, FT-IR spectroscopy and chemical analyses.2-NS À was observed to be intercalated into the interlayer almost fully up to the accommodation expected based on the neutralisation of the positive charge of the host lattice. The intercalation of 2,6-NDS 2À was approximately 80% of the expected value, however. IR analysis results show that the organic anions are intercalated into the Mg-Al LDH without any significant change in their intrinsic structure.The X-ray diffraction data suggest that the intercalation of the organic anions under consideration was accompanied by an expansion in the basal spacing of the LDHs. The X-ray diffraction patterns of the 2-NS À -modified LDH suggested the formation of two types of LDHs showing different basal spacing at higher 2-NS À content. On the other hand, the 2,6-NDS À -modified LDH showed diffraction peaks, which corresponded to the basal spacing, with widely spreading peak angles and reduced intensity, suggesting the widely varying basal spacing of the Mg-Al LDH.

Uptake of Bisphenol A from Aqueous Solution by Mg–Al-Layered Double Hydroxides Intercalated with 2-Naphthalene Sulfonate and 2,6-Naphthalene Disulfonate

“…The contents of 2-NS and 2,6-NDS in 0.1 g of 2-NSÁMg-Al LDHs and 2,6-NDSÁMg-Al LDHs used in this study are presented in Tables 1 and 2, based on the results of element analyses. 22) The initial mole ratios of 2-NS or 2,6-NDS in the LDHs to bisphenol A in solution are also shown in the Tables. The increase of the initial mole ratio indicates the increase of the number of the naphthalene rings in the interlayer of the LDH added to bisphenol A solution.…”

“…In our latest study, both types of Mg-Al LDHs, which have 2-NS À and 2,6-NDS 2À , respectively, in the interlayer of Mg-Al LDH, were prepared by the dropwise addition of a mixed aqueous solution of Mg(NO 3 ) 2 and Al(NO 3 ) 3 to an aqueous ethanol solution of 2-NS-Na and to an aqueous solution of 2,6-NDS-Na 2 , respectively. 22) This paper describes the uptake of the aromatic compound, bisphenol A ( Fig. 1(c)), which is the representative endocrine disruptors, from aqueous solution using 2-NSÁMg-Al LDH and 2,6-NDSÁMg-Al LDH.…”

Cephradine Intercalated Mg-Al Layered Double Hydroxide

“…Works on the intercalation of the various organic molecules into the hydroxide layers have been exploited for various purposes and application [14,15] in many different areas such as bioactive agent [10], medicine [15,16,17], catalyst [18], anti-inflammatory drugs, [19,20,21] urea biosensor and supports [22], and decolorizing agents [23]. The production and use of drug must be controlled to minimize the potential damage to the environment and public health.…”

Hybrid Inorganic/Organic Composites of Layered Double Hydroxides Intercalated with Organic Acid Anions for the Uptake of Hazardous Substances from Aqueous Solution

“…The DS -in the solid particles was in a stable arrangement in the solid phase while simultaneously reacting rapidly with bisphenol A outside the particles. We examined the preparation and characterization of Mg-Al LDHs intercalated with 2-naphthalene sulphonate (2-NS -) and 2,6-naphthalene disulphonate (2,6-NDS 2-) (Kameda et al, 2006). 2-NS•Mg-Al LDH and 2,6-NDS•Mg-Al LDH, with 2-NS -or 2,6-NDS 2-intercalated in the interlayer of Mg-Al LDH, were prepared by dropwise addition of a mixed aqueous solution of Mg(NO 3 ) 2 and Al(NO 3 ) 3 at a Mg/Al molar ratio of 3.0 to an aqueous ethanol solution of 2-NS-Na or to an aqueous solution of 2,6-NDS-Na 2 at a constant pH of 10.0 and left standing at 30 °C for 1 h. The intercalated 2-NS -and 2,6-NDS 2-maintained their intrinsic molecular structure in the interlayer of Mg-Al LDH.…”