Activated carbons phenol adsorption

Nevskaia, D.M., Santianes, A., Munoz, V., et al. (1999). Interaction of aqueous solutions of phenol with commercial activated carbons an adsorption and kinetic study. Carbon, 37, 1065-74. 

In addition to surface area and the microporosity of the activated carbons, the adsorption of phenolic compounds has also been found to be influenced by the presence of carbon-oxygen groups on carbon surfaces and the pH of the carbon-solution suspension. Urano et al. found that the adsorption of phenolic compounds... 

Efremenko, I. and M. Sheintuch. 2006. Predicting solnte adsorption on activated carbon Phenol. Langmuir 22(8) 3614-3621. 

Mattson JS, Mark Jr HB, Malbin MD, Weber Jr WJ, Crittenden JV. Surface chemistry of active carbon specific adsorption of phenols. J Coll InterfSci 1969 31 116-130. 

Mangun, C. L., Daley, M. A., Braatz, R. D. and Economy, J., Effect of pore size on adsorption of hydrocarbons in phenolic-based activated carbon fibers. Carbon, 1998,36(12), 123 129. 

We wUl now touch upon some of these factors. First, let s look at what we mean by system isotherm. Freundlich liquid phase isotherm studies can be used to establish the adsorptive capacity of activated carbon over a range of different concentrations. Under standard conditions, the adsorptive capacity of activated carbon increases as the concentration increases, until we reach a point of maximum saturation capacity. An example of an isotherm for phenol is shown in Figure 8. 

The Freundlich liquid phase isotherm can be used to determine the effect of solubility on the adsorptive capacity of activated carbon over a range of different concentrations. Phenol is highly soluble due to its polar nature whilst, in comparison, tetrachloroethylene (PCE) has a low solubility due to being non-polar. In the isotherms illustrated, the concentration of phenol is low relative to its solubility limit and consequently, the adsorptive capacity peaks at 18% maximum (see Figure 9). In comparison the concentration of tetrachloroethylene is relatively close to its solubility limit and, accordingly, the adsorptive capacity is exceptionally good. 

Cost estimation and screening external MSAs To determine which external MSA should be used to remove this load, it is necessary to determine the supply and target compositions as well as unit cost data for each MSA. Towards this end, one ought to consider the various processes undergone by each MSA. For instance, activated carbon, S3, has an equilibrium relation (adsorption isotherm) for adsorbing phenol that is linear up to a lean-phase mass fraction of 0.11, after which activated carbon is quickly saturated and the adsorption isotherm levels off. Hence, JC3 is taken as 0.11. It is also necessary to check the thermodynamic feasibility of this composition. Equation (3.5a) can be used to calculate the corresponding... 

Activated carbon has high specific surface area with respect to its volume, and thus has high adsorption capacity. Activated carbon adsorption is considered to be one of the most versatile treatment technologies and can remove classical pollutants such as COD, TOC, BOD, and nitrogen, as well as toxic pollutants such as phenol, refractory organic compounds, VOCs, and soluble heavy metals.38 Activated alumina and peat have also demonstrated similar abilities. 

Caturla, F., Martin-Martinez, J.M., Molina-Sabio, M., Rodriguez-Reinoso, F., and Torregrosa, R. Adsorption of substituted phenols on activated carbon, / Colloid Interface Sci, 124(2) 528-534, 1988. 

Knettig, E., Thomson, B.M., and Hrudey, S.E. Competitive activated carbon adsorption of phenolic componnds, Environ. PoIIut (SeriesB), 12(4) 281-299, 1986. 

In the 19th century, various carbons were studied for their ability to decolorize solutions and adsorb compounds from gases and vapors. Commercial applications of activated carbon began early in the 20th century. Solutions containing phenols, acetic acid, herbicides, dyes, chlorophenols, cyanide and chromium have been successfully treated by carbon adsorption ( ). 

There ate many environmental applications of adsorption in practice and many others are being developed (Noble and Terry, 2004). Activated carbons and clays are frequently used for the removal of organic contaminants, such as phenol and aniline, both of which are prevalent in industry wastewaters and are known to have a significant negative impact on marine life and human health (IRIS, 1998 Dabrowski et al., 2005). Moreover, the adsorption on inexpensive and efficient solid supports has been considered a simple and economical viable method for the removal of dyes from water and wastewater (Forgacsa et al., 2004). Activated carbon, clays, coal, vermiculite, and other adsorbents have been used for this purpose. Specifically, adsorption can be employed in (Noble and Terry, 2004 Dabrowski, 2001) ... 

Diffusion-type models have been used for the adsorption of lead, copper, p-nitrophenol, phenol, p-bromophenol, p-toluene sulfonate and dodecyl benzene sulfonate on activated carbon (Hashimoto etal., 1977 Xiu and Li, 2000 Chen and Wang, 2004 Crittenden and Weber, 1978), and ion exchange of ammonia, lead, and other heavy metals on clinoptilolite (Inglezakis and Grigoropoulou, 2003 Cincotti et al, 2001 Semmens et al, 1978 Cooney et al, 1999). 

Experimental isotherm data for the adsorption of four solutes, phenol, p-bromophenol, p-toluene sulfonate, and dodecyl benzene sulfonate onto activated carbon are shown in Figures 1 to 4. The isotherm constants are estimated using a nonlinear parameter estimation program, and are shown in Table 1. The parameter estimation program uses the principal axis method to obtain the parameters, a, b and 3 that will minimize the sum of the squares of the differences between experimental and computed isotherm data. 

More recently, Kander and Paulaitis (16) have studied the adsorption of phenol onto activated carbon and measured its sorption equilibria from dense C02. These researchers found that temperature controlled the adsorption equilibria and that phenol uptake was negligibly effected by changes in the gas phase density. Such a result indicates that factors other then a solute s solubility in a dense gas play a key role in defining the adsorption equilibrium which accompany such processes. 

It is apparent from the Xm values listed in Table V that capacities for adsorption of the organic pesticides on active carbon are quite large, greater on a molar basis than phenol and sulfonated 2-dodecylbenzene, and greater on a weight basis than any of the three other compounds. On the other hand, the fo"1 values, except for parathion, indicate approach to saturation adsorption only at relatively high residual concentrations. 

Example 8.8 A wastewater containing 25 mg/L of phenol and having the characteristic breakthrough of the previous example is to be treated by adsorption onto an activated carbon bed. The flow rate during the breakthrough experiment is 0.11 mVs this is equivalent to a surficial velocity of 0.0088 m/s. The XIM ratio of the bed for the desired effluent of 0.06 mg/L is 0.02 kg solute per kg carbon. If the flow rate for design is also 0.11 mVs, design the absorption column. Assume the influent is introduced at the top of the bed. The packed density of the carbon bed is 721.58 kg/ml... 

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... 

Experiments were performed in batch reactors at 21 1°C with a continuous stirring at 300 rpm and some ratio solid/solution fixed at 2.26 g.L for dry pulp and 0.3 g.L for activated carbon. A pre-hydration of 90 min of the pulp was necessary and the pH of the solution was stabilized at 5.5. Equilibrium times were deduced from the kinetics. The mixed metallic solutions had equimolar initial concentrations (8.10 mol.L ). The influence of benzaldehyde, benzoic acid and phenol on the fixation of Cu onto the pulp was conducted using 100 mg.L (expressed in TOC) of organic compounds. The adsorption on the mixture of sorbents of phenol and Cu ions was carried out with 50 mg.L of each components. 

The kinetic adsorption studies in different types of adsorbers were performed with two phenolic compounds of PNP and PCP on activated carbon. A technique of isotherm stepwise linearization has been proposed and applied to approximate nonlinear isotherms for GAC adsorption. The results showed that pore and surface diffusivity are estimated satisfoctorily using this stepwise linearization technique. This study also showed that the apparent diffusivity (De), which possesses concentration dependence, could be estimated on LCB by applying the technique in high-adsorption region. 

---