Phenol Concentration

Phenol quahty tests and analyses can be divided into two categories wet lab and Hquid and gas chromatography. In the wet lab, phenol is tested for pH, sohdification point, solubiUty in water, bromine index, color, and distillation ranges. Phenol concentration, impurities, and CHP contents are analy2ed using highly automated Hquid and gas chromatography. 

Phenol fumes are irritating to the eyes, nose, and skin. According to the National Institute for Occupational Safety and Health (NIOSH), exposure to phenol should be controUed so that no employees are exposed to phenol concentrations >20 mg/m, which is a time-weighted average concentration for up to a 10-h work day, 40-h work week. Phenol is very toxic to fish and has a nearly unique property of tainting the taste of fish if present in marine... 

Prepare an alkaline solution of the phenol concentrate by placing 4.0 mL of a tri-n-butyl phosphate layer in a 5 mL graduated flask and then adding 1.0 mL of the tetra-n-butylammonium hydroxide do this for each of the four solutions. The reference solution consists of 4 mL of the organic layer (in which the phenol is undissociated) plus 1 mL of methanol. Measure the absorbance of each of the extracts from the four test solutions and plot a calibration curve. 

In general acid catalysis, the rate is increased not only by an increase in [SH ] but also by an increase in the concentration of other acids (e.g., in water by phenols or carboxylic acids). These other acids increase the rate even when [SH ] is held constant. In this type of catalysis the strongest acids catalyze best, so that, in the example given, an increase in the phenol concentration catalyzes the reaction much less than a similar increase in [H30 ]. This relationship between acid strength of the catalyst and its catalytic ability can be expressed by the Breasted catalysis equation ... 

Phenol concentration. When phenol is used to preserve a vaccine its concentration must not exceed 0.25% wA or, in the case of some vaccines, 0.5% w/v. Phenol is estimated by the colour reaction with amino-phenazone and hexacyanoferrate. 

Ammonia stripping also removes cyanide, phenols, and other VOCs typically found in cokemaking wastewater. Phenols may also be removed by conversion into nonodorous compounds or into crude phenol or sodium phenolate by either biological means (phenol concentration <25 mg/L) or by physical processes.21 However, the Koppers dephenolization process is considered to be quite effective as it lowers the phenol content by 80 to 90% in ammonia still wastes. In this process a stream stripping process followed by mixing in a solution of caustic soda results in renewal of pure phenol with the flue gas.8... 

One common application of liquid-liquid extraction is the removal and recovery of phenol and compounds of phenol from wastewaters. Although phenol can be removed by biological treatment, only limited levels can be treated biologically. Variations in phenol concentration are also a problem with biological treatment, since the biological processes take time to adjust to the variations. 

Li et al. [76] confirmed that efficacy of phenol degradation depends on microbubble formation. In their experiments, they observed no change in phenol concentration if micro-bubble formation was stopped. The phenol decomposition rate was found maximum in the case when O2 was passed in the solution due to highest micro-bubble formation followed by air and N2 respectively. 

Mayr U, Treutter D, Santos-Buelga C, Bauer H and Fuecht W. 1995. Developmental changes in die phenol concentrations of Golden Delicious Apple fruits and leaves. Phytochemistry 38 115. 

Phenol content (measured as gallic acid equivalents) increased initially in fresh-cut carrot treated with different sanitizers and later decreased in a different pattern for each treatment (Ruiz-Cruz and others 2007). Washing treatments significantly affected phenol content. Comparing sanitized shredded carrots with controls (unwashed and water washed), a sharp increase with a maximum value at days 3 and 6 (5.6 to 6 mg/ 100 g) was found, followed by a decline. Final phenol concentration was 0.7 to 1.3 mg/ 100 g for all treatments at the end of the storage period (Ruiz-Cruz and others 2007). 

Results suggest that the biofilm was stable over 2 months. The microorganism appeared vital and active even after repeated cyclic exposure to anaerobic conditions. In fact, phenol uptake measured was always recorded as soon as aerobic conditions were established. A slight increase of the phenol concentration was... 

Fig. 6 Acid orange 7 and phenol concentration in the internal loop airlift reactor operated with Pseudomonas sp. 0X1 biofilm on natural pumice. (A) Aerobic phase. Gas air. Liquid continuous feeding of phenol supplemented synthetic medium. (AN) Anaerobic phase. Gas nitrogen. Liquid batch conditions, dye supplemented medium...

Aerobic phase Steady state values of phenol concentration (40 mg/L) and biofilm thickness (170 pm) were approached after a 5 h transient period, which reproduces fairly well the experimental dynamical patterns reported in Fig. 6. However, biomass was present also in the liquid phase as a consequence of biofilm detachment. 

The effect of jumping of the maximal hydroperoxide concentration after the introduction of hydrogen peroxide is caused by the following processes. The cumyl hydroperoxide formed during the cumene oxidation is hydrolyzed slowly to produce phenol. The concentration of phenol increases in time and phenol retards the oxidation. The concentration of hydroperoxide achieves its maximum when the rate of cumene oxidation inhibited by phenol becomes equal to the rate of hydroperoxide decomposition. The lower the rate of oxidation the higher the phenol concentration. Hydrogen peroxide efficiently oxidizes phenol, which was shown in special experiments [8]. Therefore, the introduction of hydrogen peroxide accelerates cumene oxidation and increases the yield of hydroperoxide. 

Phenols usually terminate two chains in the oxidation of hydrocarbons and solid polymers (see Chapter 15). The study of the/ value dependence on partial dioxygen pressure showed, however, that the stoichiometric coefficient of inhibition has a tendency to increase with decreasing the dioxygen pressure and, in an inert atmosphere, it is markedly higher than in dioxygen [83]. The results of/ value estimation (f—vi/vInH, phenol concentration was measured spectroscopically) are given in Table 19.13. 

In the calculation results, shown in Figure 28.4, phenol concentration decreases with time at a constant rate for about the first 30 days of reaction. Over this interval, the concentration is greater than the value of K, the half-saturation constant, so the ratio m/(m + K ) in Equation 28.9 remains approximately constant, giving a zero-order reaction rate. Past this point, however, concentration falls below K and the reaction rate becomes first order. Now, phenol concentration does not decrease linearly, but asymptotically approaches zero. 

Use the same space time and inlet phenol concentrations specified for part (a). Comment on any differences in the effects of oxygen on the yield and selectivity in the noncatalytic... 

In a typical experiment, the sample is a solution (e.g., in benzene) of both the ferf-butoxyl radical precursor (di-tert-butylperoxide) and the substrate (phenol). The phenol concentration is defined by the time constraint referred to before. The net reaction must be complete much faster than the intrinsic response of the microphone. Because reaction 13.23 is, in practical terms, instantaneous, that requirement will fall only on reaction 13.24. The time scale of this reaction can be quantified by its lifetime rr, which is related to its pseudo-first-order rate constant k [PhOH] and can be set by choosing an adequate concentration of phenol, according to equation 13.25 ... 

The actual limit value of rr, below which the time constraint is met for a given transducer, is somewhat ambiguous. For a 0.5 MHz transducer (response time 2 xs), Mulder et al. [297] set this limit at 60 ns, based on the observation of a maximum of amplitude of the photoacoustic wave with the concentration of phenol and calculating rr from the rate constant of reaction 13.24, k = 3.3 x 108 mol-1 dm3 s-1 [298]. Later, Wayner et al. [293] empirically choose 100 ns as that limit and used laser flash photolysis results to adjust the phenol concentration until the lifetime of reaction 13.24 was less than that limit. In any case, the safest way of ensuring that the time constraint is being met is to verify it experimentally by varying the concentration of substrate until the observed waveform reaches a maximum (or, equivalently, until the final A0bs77 value reaches a maximum). 

To check that phenol was not self-associated at the concentration used, Sousa Lopes andThompson repeated the calibration experiments (i.e., the study of the temperature variation of el) for several phenol concentrations. Good linear plots of A against c at each temperature were observed, indicating that the Lambert-Beer law is valid and that the self-association is negligible. 

Permeability coefficients for phenol in isolated skin patches from nude mice have been determined (Behl et al. 1983). The permeability coefficient increased as the concentration of the applied aqueous phenol solution increased doubling the concentration from 20 to 40 g/L resulted in a 12-fold increase in mean permeability coefficient (0.007-0.085 cm/hour). The value obtained for the permeability coefficient when 60 g/L was applied to the skin patch (0.169 cm/hour) was similar to that obtained for skin patches in which the stratum comeum had been removed. It was concluded that phenol concentrations exceeding 20 g/L may destroy a diffusion barrier normally provided by the intact stratum comeum, permitting increased percutaneous absorption. 

Human exposure to low levels of phenol is widespread because it is contained in many consumer products including mouthwashes, gargles, tooth drops, throat lozenges, and ointments (Douglas 1972 EPA 1980). Phenol is a normal product of protein metabolism, and it is also a metabolite of benzene. In persons not exposed to phenol or benzene, the total phenol concentration in the urine generally does not exceed 20 mg/L and is usually <10 mg/L (ACGIH 1991). 

A study of workers from phenol production facilities did not find an association between phenol and mortality from various causes, including cancer (Dosemeci et al. 1991). Urinary levels of total phenol have been shown to correlate with atmospheric phenol concentration when there is limited dermal exposure, and no exposure to benzene (ACGIH 1991 Ohtsuji and Ikeda 1972). 

Levels of total urinary phenol (phenol plus phenol conjugates) measured at the end of the workshift correlated with atmospheric phenol concentrations, suggesting that this measurement may be useful in predicting recent exposure to phenol vapor. 

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