Adsorption of naphthalene derivatives on different macroporous polymeric adsorbents

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Figure 1 Equilibrium adsorption isotherms at 30 C for 1-naphtbol on XAD-series polymeric adsorbents:( x )XAD-2; (*)XAD-4; (A )XAD-7; (O)XAD-8
The initial concentration C, and residual concentration (CJ were measured using a 7520 model UV spectrophotometer (Shanghai Analytical Instruments Factory) at the maximum wavelength (L&l of the adsorbence. These wavelength were determined for each compounds according to reference [6].
(Receivai in Gemmy 27 April 1997; amepted 30 May 1997)
ABSTRACT
The adsorption of I-naphthol, 2- naphthol, I-naphthylamine and 2- naphthylamine fi-om aqueous solutions on macroporous polymeric adsorbents was studied. The equilibrium data were fitted to Freundlich-type isotherms and the equilibrium constauts K, and n were obtained. The values of the adsorption capacity depend on the surface area of adsorbents, the chemical properties of naphthalene derivatives, as well as the polarity of adsorbents. 91997 Elsevier Science Ltd KEY WORDS: macroporous polymeric adsorbents, naphthalene derivatives, adsorption
derivatives, one group of PAHs, often occur as a result of effluents fi-om dye in~ediate However, the effectiveness of biological processes against naphthalene
EXPERIMENTAL Materiels
The polymeric adsorbents used in this study were Amberlite XAD-2, XAD-4, XAD-7 and XAD-8 obtained from Rohm-haas Company. Adsorbents were reflux extracted with absolute alcohol for two hours and washed with 4% aqueous HCl and NaOH solution alternatively twice, then washed with distilled water and dried at 100 C until the constant weight was reached. The naphthalene derivatives studied in the adsorption experiment were 1-naphthol, 2-naphthol, naphthylamine and 2-naphthylamine. All the compounds were of A.R. grade. l-
Methods
The adsorption of naphthalene derivatives was performed as follows: 0.25g polymeric adsorbent was introduced in a flask bottle. Then, 200 cm3 of aqueous solution of naphthalene derivatives with known concentration was added to each flask. The flasks were then shaked (1OOrpm) in a G25 model incubator shaker (New Brunswick Scientific Co. Inc.) at 30C for 48 hours. The initial concentrations(C,,) of solutions were 200,400,600,800 and 1OOOmg/L respectively.
2270 and 2- naphthylamine from aqueous solution with high concentration. Research was focused on the effect of surface area and polarity of the adsorbents and the characteristics of the adsorbates on the adsorptive properties, as well as the adsorption isotherms were determined.
on adsorption of naphthalene derivatives from aqueous solution with high concentration, as the actual situation in induskal ef%ents tnzitment may be, with these polymeric adsorbents have been reported. In this paper, four commonIy used macroporous adsorbents Amberlite XAD-2, XAD4, XAD-7 and XAD8 were used to adsorb a series of naphthalene derivatives such as I -naphthol, 2-naphthol, I-naphthylamine 2269
RESULTS AND DISCUSSION Adsorption Isotherms
Equilibrium adsorption isotherms at 3O’ for the four compounds on the four XAD polymeric adsorbents C are shown in Figure l-4 respectively. It is well known that the Freundlich equation has the general form[7] q,=KF. C c l’ n (1)
INTRODUCTION Many of the poIynuckar enviromnental aromatic hydmcarbons(PAH), probably the most widespread of all chemical Naphthalene and its
contankan ts, are known to be carcinogenic or cocarcinogenic.
production.
derivatives removal is not
satisfactory because they can not be degraded through biological treatment[ I]. Adsorption is considered a prominent method for treatment of effluents containing organic substances. Compared with classical adsorbents such as the silica gels, aluminas and the activated carbons, the macroporous polymers is a more attractive alternative because of the wide range of pore structures and surface chamcteristics[2]. The use of these poIymeric adsorbents for the treatment of efkluents containing benzoid compounds has been widely studied[3]. There are also example-s of adsorbing trace naphthalene compounds with polymeric adsorbents for drinking water preparation[4,5]. However, few systematic studies
where KP and l/n are characteristic constants. Equation (1) linearizes in logarithmic form log q, = log KF+l/n log C, (2)