Adsorption of benzene derivatives on allophane
Introduction
Some clay minerals have a high activity for ion exchange, adsorption, and catalyst uses, and they are also available for water purification (Xu et al., 1998, Bergaya et al., 2006, Cea et al., 2007). Environmental water purification is a very important subject in today's world because of the serious problems resulting from the bad management of some chemicals in the past. Clay minerals in soil spontaneously purge some chemicals in the natural world. The chemicals are expected to be decomposed while they are adsorbed on the clay minerals by the biological actions reported in a paper (Fisenko, 2004).
Some benzene derivatives, such as dialkyl phthalate, have been suspected of being endocrine disruptors. Besides polluting soil and groundwater, such compounds may affect animal/human fertility and reproduction.
Allophane, a natural clay mineral distributed throughout the world, is a hydrated aluminosilicate (1 − 2SiO2·Al2O3·5 − 6H2O) having a 3.5−5.0 nm-sized hollow spherical structure with 0.3−0.5 nm-sized defects on its surface (Kitagawa, 1971, Henmi and Wada, 1976, Wada and Wada, 1977, Hall et al., 1985, van der Gaast et al., 1985). The walls in the hollow spheres consist of two layers, inner silica and outer alumina layers, and hydroxyl groups or water of hydration on their surface. Some studies suggest that these surfaces have a high ability to adsorb ionic or polar pollutants due to an amphoteric ion-exchange activity (Theng, 1972, Clark and McBride, 1984, Hanudin et al., 1999, Gustafsson, 2001, Hashizume et al., 2002, Jara et al., 2006) and high surface area (Kitagawa, 1971, Hall et al., 1985). Allophane has, in part, been applied to wall materials to control humidity in the air. However, only a small amount of allophane distributed throughout the world has been utilized, and its chemical properties have not been effectively utilized. Basic studies on the adsorption of harmful aromatic molecules are needed. However, there is no report describing the detailed structure of aromatic molecules adsorbed on allophane.
In this study, we have investigated the absorption properties for benzene derivatives, i.e., benzoic acid, phthalic acid, benzaldehyde, ethyl benzoate, and diethyl phthalate, by allophane in order to assess its utilization as an absorbent for water purification. The adsorption was quantitatively evaluated by measuring UV absorption spectra, and the adsorption structure was determined by examining the IR spectra.
Section snippets
Materials
Benzoic acid (reagent grade), phthalic acid (S, = special, grade), benzaldehyde (S grade), and ethyl benzoate (S grade), purchased from Wako Pure Chemicals, were used without further purification (Scheme 1). Diethyl phthalate (reagent grade) was purchased from Kanto Chemicals and was used without further purification. Water, which was deionized and then distilled, was used as a solvent. Hydrochloric acid (S grade) and sodium hydroxide (S grade), purchased from Wako Pure Chemicals, were used
Adsorption of esters
The spectrum of diethylphthalate exhibited two peaks at 235 and 276 nm and a strong band at less than 210 nm (Fig. 1). The intensity of these bands very slowly decreased with time and reached equilibrium after around 30 days, when the absorbance was reduced by 92%. The amounts of diethylphthalate and ethyl benzoate adsorbed per gram of allophane were 2.3 ± 0.2 and 1.6 ± 0.1 × 10− 5 mol g− 1. The amounts of these compounds adsorbed on allophane increased with their concentration and approached their
Conclusions
UV and IR spectroscopic measurements revealed that allophane adsorbed benzoic acid, phthalic acid, benzaldehyde, ethyl benzoate, and diethyl phthalate. Benzoic acid, phthalic acid, and benzaldehyde formed benzoate or phthalate anions on the positive sites of the hydrated alumina surface of allophane. In the case of adsorption from an acidic solution, a small amount of a neutral species of benzoic acid was detected. Ethyl benzoate and diethyl phthalate were adsorbed by interaction of the
Acknowledgments
This work was supported in part by a Grant-in-Aid for Scientific Research (A No. 14208070) from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government. The authors thank Dr. T. Matsumoto of Tochigi Research Institute for kindly providing the allophane.
References (21)
- et al.
The interaction of acetaldehyde and acetic acid with the ZnO surface
J. Catal.
(1983) - et al.
Adsorption behavior of 2,4-dichlorophenol and pentachlorophenol in an allophanic soil
Chemosphere
(2007) - et al.
The role of citrate and phthalate during Co(II) coprecipitation with calcite
Geochim. Cosmochim. Acta
(2006) - et al.
Adsorption of dicarboxylates on nano-sized gibbsite particles: effects of ligand structure on bonding mechanisms
Colloids Surf., A Physicochem. Eng. Asp.
(2003) - et al.
Handbook of clay science
(2006) - et al.
Cation and anion retention by natural and synthetic allophane and imogolite
Clays Clay Miner.
(1984) A new long-term on site clean-up approach applied to non-point sources of pollution
Water Air Soil Pollut.
(2004)- et al.
Microcalorimetric and infrared studies of ethanol and acetaldehyde adsorption to investigate the ethanol steam reforming on supported cobalt catalysts
J. Phys. Chem., B
(2005) Modelling competitive anion adsorption on oxide minerals and an allophane-containing soil
Eur. J. Soil Sci.
(2001)- et al.
Size distribution of allophane unit particles in aqueous suspensions
Clays Clay Miner.
(1985)
Cited by (30)
Synthesis of allophane from rice husk ash and its use as a phosphate adsorbent: A novel approach
2022, Journal of Environmental Chemical EngineeringStructural alterations of synthetic allophane under acidic conditions: Implications for understanding the acidification of allophanic Andosols
2020, GeodermaCitation Excerpt :Therefore, how the microstructure of allophane changes during soil acidification is a key to understanding the soil acidification of allophanic Andosols and thereby warrants in-depth investigation. However, so far the studies on the microstructural alterations of allophane and the related mechanisms under acidic conditions are still rare, and most of them are focused on allophane’s identification (Higashi and Ikeda, 1974; Pérez et al., 2016), synthesis and purification(Ohashi et al., 2002; Wada, 2011), neoformation (Farmer et al., 1980; Parfitt and Kimble, 1989; Gerard et al., 2007; Li et al., 2020), adsorption of guest species (Nishikiori et al., 2009; Harsh, 2012; Matsuura et al., 2013; Silva-Yumi et al., 2018), and material applications (Toyota et al., 2017; Deng et al., 2019). This situation is partly due to the small particle size and poor crystallinity of allophane, requiring highly challenging analytical techniques.
Water retentivity of allophane–titania nanocomposite films
2020, Applied Catalysis B: EnvironmentalClay–polymer nanocomposites: Progress and challenges for use in sustainable water treatment
2020, Journal of Hazardous MaterialsDecontamination application of nanoclays
2020, Clay Nanoparticles: Properties and ApplicationsNovel hierarchically porous allophane/diatomite nanocomposite for benzene adsorption
2019, Applied Clay ScienceCitation Excerpt :Allophane (1-2SiO2·Al2O3·5-6H2O), a natural clay mineral widespread throughout the world, is a hydrated aluminosilicate. It has a hollow spherical structure with an outer diameter of 3.5–5.0 nm and a perforated wall about 0.7–1.0 nm thick (Nishikiori et al., 2009; Matsuura et al., 2013), meaning that the sphere contains a 1.5–3.6 nm diameter interior void. The wall of the hollow sphere is proposed to be composed of a curved gibbsite-like sheet with monomeric SiO4 tetrahedra attached to it (Parfitt and Hemni, 1980; Johan et al., 1997).