Phenol, mass transfer coefficient

The next parameter required is the diffusion coefficient of phenol in water (/)lg). Here, we can assume the typical value of 10 m2/s. Then, the resulting mass transfer coefficient is 0.23 s-1. Subsequently,... 

The importance of a correct evaluation of kLa(03) or kla 02) was confirmed in a study on the simulation of (semi-)batch ozonation of phenol (Gurol and Singer, 1983). It was shown that a close match between the measured and the calculated data was only obtained when kLa(02) was measured as a function of the residual phenol concentration. The oxygen mass transfer coefficient was observed to change from kLa(02) = 0.049 s 1 at c(M) = 50 mg IF1 phenol to kLa(02) = 0.021 s- at c(M) = 5.0 mg L 1 phenol. 

Fortunately changes in k,a due to mass transfer enhancement from ozone decay can be neglected, as Huang et al. (1998) showed by example of cyanide ozonation in strongly basic solutions (pH = 12-14) in a system where the value of the purely physical liquid side mass transfer coefficient was not too low (kL° > 0.03 cm s l). This is supported further by the results from several ozonation experiments, which showed that no ozone decay occurs in the liquid film at lower pH values (phenol, pH = 10 (Metha et ah, 1989) 4-nitrophenol, pH = 8.5 (Beltran et ah, 1992 a)). 

Polcaro et al. (2003, 2005) verified that during the oxidation of organic compounds, such as phenol, diuron, 3,4-dichloroaniline, and triazines, the crucial point to obtain high Faradic yields is the rate of mass transfer of the reactant toward the electrode surface (Fig. 2.11). Thus, they developed an impinging cell that enabled them to obtain high mass-transfer coefficients (e.g., 10-4 m s-1). With this cell, at a current density of 150Am-2, they achieved a Faradic yield of 100%, up to the almost complete disappearance of the organic load. 

Similarly, Halwachs et al.16 compared the extraction of phenol to that of benzene in liquid-membrane systems. The mass transfer coefficient in the former case was estimated to be some two orders of magnitude... 

For the adsorption of micro-organics (p-nitrophenol, benzoic acid) in fixed-bed columns, the half breakthrough time increases proportionally with increasing bed depth but decreases inversely proportionally with increasing water flow rate [54,55]. By studying the adsorption of chloroethylenes on activated carhon fibers, Sakoda et al. [56] determined a linear relationship between the overall mass transfer coefficient (Kfu) and the flow rate Uo. The influence of temperature on file dynamic adsorption of phenol on fibrous activated carbon has also been demonstrated [57]. 

Wang and Wu [70] analyzed the extraction equilibrium of the effects of catalyst, solvent, NaOH/organic substrate ratio, and temperature on the consecutive reaction between 2,2,2-trifluoroethanol with hexachlorocyclotriphosphazene in the presence of aqueous NaOH. Wu and Meng [69] reported the reaction between phenol with hexachlorocyclotriphosphazene. They first obtained the intrinsic reaction-rate constant and overall mass transfer coefficient simultaneously, and reported that the mass transfer resistance of QX from the organic to aqueous phase is larger than that of QY from the aqueous to organic phase. The intrinsic reaction-rate constant and overall mass transfer coefficients were obtained in three ways. 

Hunter, et al. (28, 78) studied the extraction of phenol from kerosene as a core-liquid, with water as a wall-liquid, both liquids in turbulent flow. The data were interpreted by an equation similar to Eq. (10.12), and it was concluded that, over the limited range studied, the wall-liquid did not influence the mass-transfer coefficient for the core. Working with the liquids benzene and water over a wide range of flow rates for each, with acetic acid as the diffu- ini solute, Treybal and Work (82) showed that an equation at least as complex as Eq. (10.11) was necessary to describe the results and were therefore unable to determine the value of the constants. These observations reinforced the conclusions respecting the influence of each rate of flow on the degree of turbulence in both liquids. 

Murugesan, T., and R. Y. Sheeja. 2005. A Correlation for the Mass Transfer Coefficients During the Biodegradation of Phenolic Effluents in a Packed Bed Reactor. Separation and Purification Technology 42 (2) 103-110. 

The pseudo-first order rate constants (resp. coefficients) for the direct reaction of some compounds may almost be in the order of typical hydroxyl rate constants (kR > 10 M s ), due to high concentrations of the pollutants as well as mass transfer enhancement. For example, Sotelo et al. (1991) measured values of 6.35 106 and 2.88 106 M l s"1 for the dissociating hydroxylated phenols, resorchinol (1,3-dihydroxybenzene) and phlorogluci-nol (1,3,5-tn hydroxybenzene) respectively (pH = 8.5 and T= 20 °C). 

Modeling and optimization of MBSE and MBSS of a multicomponent metallic solution in HF contactors is discussed in ref. [77]. A short-cut method for the design and simulation of two-phase HF contactors in MBSE and MBSS with the concentration-dependent overall mass-transfer and distribution coefficients taking into account also reaction kinetics was suggested by Kertesz and Schlosser [47]. Comparison of performance of the MBSE and MBSS circuit with pertraction through ELM in case of phenol removal presented Reis [78] and for copper removal Gameiro [79]. 

The velocity and concentration profiles are developed along the HFs by means of the mass conservation equation and the associated boundary conditions for the solute in the inner fluid. This analysis separates the effects of the operation variables, such as hydrodynamic conditions and the geometry of the system, from the mass transfer properties of the system, described by diffusion coefficients in the aqueous and organic phases and by membrane permeability. The solution of such equations usually involves numerical methods. Different applications can be found in the literature, for example, separation and concentration of phenol, Cr(VI), etc. [48-51]. 

Polypropylene glycol was used as the diluent. The final form of the flat-sheet SLM system had uniform selectivity and good operational stabihty during continuous operation for more than 2 months. Mass-transfer rates measured were five times the values measured usually during the operation of commercially available silicone tubing-based systems [141]. The system developed by the authors had two more advantages. These were the reduced water flux and the minimum sodium ion transfer. The authors measured the partition coefficient of phenol between polypropylene glycol and water, and determined this to be equal to 84. This value increased to 134 if the aqueous phase contained 20% KCI. 

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