Isotherm 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]. 

Let us call this the donor-acceptor complex proposal, similar to that presented recently for adsorption of substituted nitrobenzenes and nitrophenols on mineral surfaces [739]. The experiments on which this proposal is based are (1) isotherms of phenol, nitrobenzene, and m- and / -nitrophenol on one commercial activated carbon at pH = 2-7 and very low solute concentrations ( <1.5% of the solubility limit of these species [6]) and (2) detailed infrared (internal reflection) spectroscopic analysis of the surface after adsorption of / -nitrophenol. Interestingly, neither in this study, nor in any subsequent study that supports this mechanism, has a similar analysis been performed with carbons containing varying concentrations of carbonyl surface groups. Also of interest is that the authors dismiss the electrostatic explanation of the reported pH effects by assuming that the isoelectric point of the carbon (which was dried at 200°C for 12-24 h) was ca. 2.4. 

Figure 4.2S Competitive isotherms of phenol and p-cresol on an octadecylsilica. In these two figures, the top isotherm is the single solute isotherm. Isotherms denoted A, B, and C correspond to solutions with 1 3,1 1, and 3 1 mole ratios of phenol and p-cresol, respectively, (a) Competitive isotherms of p-cresol. (b) Competitive isotherms of phenol. Reproduced with permission from J. Jacobson, J. Frenz and Cs. Horvdth, Ind. Eng. Chem. (Res.), 26 (1987) 43 (Fig. 4), 1987 American Chemical Society, (c) Competitive isotherms of N-benzoyl D- (o) and L-alanine v>) in the racemic mixture single component isotherms of N-benzoyl D- (+) and L-alanine (A). Reproduced with permission from S.C. Jacobson, A. Felinger and G. Guiockon, Biotechnol. Progr., 8 (1992) 533 (Fig. 2), 1992 American Chemical Society.

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 11.7 Sorption isotherms of phenol from aqueous solutions on Macronet MN-200 and MN-150 at 20°C. (After [53].)...

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 3.22 Composite isotherms of phenol-benzene binary solntions on Spheron-6 and Spheron-C. (After Puri, B.R., mActivated Carbon Adsorption, I.H. Snffet and M.J. McGuire, Eds., Ann Arbor Sci. Publ., Ann Arbor MI, 1981, p. 353. With permission.)... 

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... 

Dramatic effects of oxidation and reduction of the carbon surface on the adsorption of phenol and nitrobenzene were first shown by CoughUn and Ezra (1968). Surface oxygen functionalities were increased by oxidation with arruno-nium thiosulfate solution, and reduction was performed with zinc amalgam in HCl solution. The isotherms of phenol on three carbon samples are shown in... 

Figure 5.15. Isotherms of phenol at 30 °C on Columbia carbon. LC325 untreated. LC3250 oxidized. LC3250R oxidation followed by reduction. From Coughlin and Ezra, 1968, with permission.

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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