Adsorption isotherms of phenols

The membrane developed in this work and a cottunercial activated carbon F-400 (Calgon), which is widely used in various water treatments, were used for adsorption experiments. The adsorption isotherms of phenol were measured according to the following batch adsorption method. The sealed vial was placed in a constant-temperature water bath kept at 25 T . The samples were well stirred, using a magnetic stirrer overnight (Sakoda et al, 1991). 

The adsorption capacity of the activated carbon membrane for thus particular adsorbate was similar to that of F-400, suggesting the possibility that the adsorption capacity is increased by somehow developing larger micropores within the carbonized microspheres. In spite of their different compounds of polymer latex. Membranes A and B had almost the same amounts of adsorption. Figure 3 Adsorption isotherms of phenol... 

FIG. 18 Effect ol pH on the adsorption isotherms of phenol on polarized carbon Hbers. (Adapted from Ref. 420.)... 

We shall refer to this as the n n interaction argument. It has been formulated ba,sed on the following experiments (1) adsorption isotherms of phenol, nitrobenzene, and sodium benzenesulfonate on a series of activated carbons and carbon blacks and (2) characterization of the surface chemistry of as-received and chemically modified carbons. The authors did not report the pH in fact, this word is not even mentioned in any of their papers on this subject [450,331,332]. 

Hamdaoui, O. and Naffrehoux. E.. Modeling of adsorption isotherms of phenol and chlorophenols onto granulai- activated carbon. Part I. Two-parameter models and equations allowing determination of thermodynamic parameters, J. Hazardous Mater., 147, 381, 2007. 

Figure 11.16 Adsorption isotherms of phenol (298 K) on the activated carbons obtained at different activation temperatures (pH = 6, unless indicated). (Reproduced by permission of Elsevier. Copyright 2004. Reprinted fixjm Reference [65a]).

Adsorption of phenol and its derivatives from aqueous solutions on active carbons and carbon blacks has been the subject matter of a large number of investigations. Jaroniec and coworkers,Enrique et al. Worch and Zakke, and Magne and Walker studied the adsorption of several phenols from aqueous solutions and found that the adsorption was partly physical and partly chemical in character. Aytekin, ChapUn, and Kiselev and Krasilinkov observed that the adsorption isotherms of phenol from aqueous solutions were step-wise, suggesting the possibility of rearrangement of phenol molecules in the adsorbed phase and their interaction with active sites on the carbon surface. Morris and Weber, however, found that the adsorption isotherms of phenols on active carbons show two plateaus, even... 

FIGURE 3.2 Adsorption isotherms of phenol on ACF-307 before and after oxidation. (After Bansal, R.C., Aggarwal, D., Goyal, M., and Kaistha, B.C., Indian J. Chem. TechnoL,... 

FIGURE 7.11 Adsorption isotherms of phenol from aqueous solutions of moderate concentration on (a) carbon blacks and (b) activated carbons. (After Puri, B.R., Bhardwaj, S.S., and Gupta, W.J., Indian Chem. Soc., 53, 1095, 1976. With permission.)... 

Sample BET Plots of Reversible Adsorption of Phenol Plateau of the Reversible Adsorption Isotherm of Phenol Conventional BET (N2) Method... 

Lu and Serial (2004) conducted an adsorption isotherm of phenolics on two types of ACFs with different pore sizes and GAC F400 to investigate the impact of PSD of activated carbon on the adsorption of phenolics (Figures 6.3 and 6.4). In order to study the impact of molecular oxygen on the adsorptive capacity, two types of isotherms were conducted. One was conducted in the presence of molecular oxygen (oxic isotherm) and the otha in the absence of molecular oxygen (anoxic isotherm). 

Fig 9 3 Adsorption isotherm of phenol on activated carbon from alcohol-water mixtures of different ratios... 

Currently, because of the frequency of their occurrence in wastewaters, the adsorption of phenolic compounds on carbons and the influence of surface oxygen complexes on their uptake are the most frequently studied, Radovic et al. (1997). It is well established that an increase in surface acidity of AC, after an oxidation, causes a decrease in phenol adsorption from dilute aqueous solution. For example. Figure 8.8 shows the adsorption isotherms of phenol on oxidized carbons, Mahajan et al. (1980). There was a large decrease in phenol uptake after oxidation, the effect of oxidation not being trivial. This phenol uptake progressively increased as the surface acidity decreased, and the oxidized sample (heat treatment temperature (HTT) 950 °C) had the same adsorption capacity as the original carbon (about 1.5 xmolg" ). 

Figure 8.8. Adsorption isotherms of phenol on AC with different degrees of oxidation (Mahajan et al., 1980 Moreno-Castilla, 2004).

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