Adsorption of Chlorinated Phenols from Aqueous Solution By Surfactant-Modified Pillared Clays

Abstract

Abstract--New pillared clay-based adsorbents have been prepared by incorporating a nonionic surfactant of general formula C~z_~4H25_290(CH2CHzO)sH (commercial name, Tergitol 15S-5), during the synthesis of the aluminum hydroxide pillaring reagent. Different loadings of surfactant have been examined. The presence of the surfactant enhanced the adsorption capacity of the clay toward 3-monochlorophenol from aqueous solution. On the basis of adsorption results for a series of clays with increasing surfactant loadings, the best adsorbent was obtained at a surfactant loading of 255 mg/g of clay. At this loading, the surfactant occupies the micropores, as well as the mesopores and the external surfaces of the pillared clay. Analysis of the adsorption isotherms for 3-monochlorophenol, 3,5-dichlorophenol, 3,4,5-trichlorophenol and pentachlorophenol at different pH shows that the most energetic adsorption sites are the surfactant-occupied micropores between pillars. Additional binding of chlorinated phenols occurs at surfactant sites on external surfaces and mesopores. Upon calcination at 500~ the clay is converted to a conventional aluminapillared clay with a basal spacing near 16 A. This calcined product can be reused as an adsorbent for chlorinated phenols by readsorbing fresh surfactant. The recycled adsorbent exhibits performance properties comparable to the original adsorbent. These results demonstrate the feasibility of utilizing a surfactant-modified pillared clay as a recyclable adsorbent and combustion catalyst for environmental pollutants.

Interaction between Organic and Inorganic Pollutants in the Clay Interlayer

“…Numerous reactions of clays with or-ganic substances have been reviewed by Rausell-Colom and Serratosa (1987). From all the previous and also the more recent investigations by Boyd et al (1988), Zielke and Pinnavaia (1988), Sawhney and Gent (1990), Michot and Pinnavaia (1991), and Jaynes and Boyd (1991), it is apparent that the determination of the adsorption interactions of organic pollutants (e.g., halohydrocarbons or aromatic hydrocarbons) and clay minerals is an important factor in elucidating the fate of organic contaminants as they diffuse through soils.…”

Separation of chlorophenols using columns of hydroxyaluminium interlayered clays

“…Hydroxyaluminium interlayered montmorillonite (Al-mont) was prepared by exchanging Na § montmorillonite (Wyoming) with a hydroxy-Al polycation (AlI304(OH)24(H20)7~) followed by dehydration at 350~ (Michot & Pinnavaia, 1991). The specific area was 130 m2g -1 (BET) and the interlayer distance, as determined by X-ray diffraction was 14 h,.…”

Pilarização de argilas e perspectivas de aplicação e de pesquisa agronômica e ambiental

“…Em outro contexto, agora com moléculas orgânicas, KONSTANTINOU et al (2000) afi rmam que as argilas pilarizadas são potentes adsorventes de herbicidas, ao constatar que elas apresentam alta afi nidade por herbicidas dos grupos da triazina, da molinate e da acetanilida. Além da capacidade adsortiva das argilas ser superior, o material pode ser reutilizado por "reciclagem térmica", após calcinação do material contendo as moléculas orgânicas adsorvidas (MICHOT & PINNAVAIA, 1991), sem destruição da estrutura lamelar do sólido empregado, o que o torna mais viável economicamente.…”