Effect of SO2 concentration

Reactivity of absorbent prepared from oil palm ash for flue gas desulfurization Effect of SO2 concentration and reaction temperature... 

Tao, J., Dykes, S. I., and Kilmartin, P. A. (2007). Effect of SO2 concentration on polyphenol development during red wine micro-oxygenation. J. Agric. Food Chem. 55, 6104-6109. 

The effect on the average Ca(OH>2 conversion of changing the amount of Ca(0H)2 in the reactor is illustrated by Figure 8 which shows the Ca(0H>2 conversion when the amount of Ca(OH)2 in the reactor was reduced from 4 to 1 g, keeping the SO2 concentration at 1000 ppm and the relative humidity at 50%. From Figure 8 it can be seen that the amount of Ca(OH)2 present in the reactor makes a difference during the first minutes of reaction, but the effect is less marked at later times. These results are consistent with the effect of SO2 concentration discussed above. When more Ca(0H)2 is present in the reactor, more SO2 is removed at the entrance of the reactor, so the Ca(0H>2 present farther down in the reactor "sees" a lower concentration of SO2, and the reaction rate is slower. At later times when the SO2 removal is lower the amount of Ca(0H)2 present will not be as important. 

Figure 3. The effect of SO2 concentration on the dynamic adsorption capacity...

FIGURE 20.40 Effect of SO2 concentration on the pH achieved after 1 h in a cloud at the levels of HNO3, O3, and H2O2 indicated and at water-phase volume ratios wi = 10 and 10. ... 

Fig. 18.6 describes the effect of SO2 concentration on intercept SO2 oxidation efficiency. It indicates that ... 

The effect of the concentration of dissolved sulfite, the reactive base, on SO2 removal in Equation 10 can be represented as ... 

The dependence on fraction neutralization and total anion concentration should reflect the extent to which the bisulfite activity is not proportional to total dissolved SO2. As expected, the dependence on f is quite small, since dissolved SO2 is present primarily as bisulfite at pH 3.5 to 5.0. The effect of anion concentration is in the direction expected since bisulfite activity would be reduced by ion pairing in more concentrated solutions. 

The other variables tested, i.e. temperature, amount of Ca(0H)2 and S02 concentration have a lower impact on the reaction rate. The different effect of S02 concentration at low and high relative humidity can be explained by assuming that the reaction has zero order kinetics in SO2 and that at low relative humidity the reaction rate is mass transfer controlled while at high relative humidities the reaction is controlled by reaction kinetics. 

The steady state OH concentration was inferred from the rate of CO2 formation via Reaction (7). The effect of SO2 on this system was tested by adding SO2 concentrations up to 172 ppm. The surprising result was that the rate of CO oxidation was not significantly reduced. This observation implies that the oxidation of SO2 does not terminate the HO chain and does not result in the net removal of OH radicals. Therefore the generalized Reaction (5) cannot be correct. 

Addition of SO2 retards the oxidation of moist stoichiometric CO/O2 mixtures (Fig. 65), but at the same time the rate becomes more sensitive to increases in the CO or O2 concentration, which accelerate the oxidation. Also, when SO2 is present, addition of N2 causes a further retardation. The effects of SO2 appear to be independent of the vessel surface [372]. HCl and iodine are effective inhibitors of the wet reaction [357]. In the presence of iodine the influence of the surface largely disappears [374]. 

The effect of SO2 poisoning was investigated both for the decomposition of NO and for its reduction over Cu/ZSM-5 (349). It was found that the catalytic activity for NO decomposition completely disappeared after addition of SO2. In contrast, the catalytic activity for NO reduction by propylene in the presence of O2 was only slightly lowered by the presence of SO2. This result suggests that selective reduction of NO by hydrocarbons has potential for practical applications. The O2 concentration is important for maintaining a high activity level, in particular in the presence of sulfur. O2 addition initially increases the N2 yield, but at higher O2 concentration the yield decreases. 

Rate coefficients, 2 > were calculated for each of the two assumptions regarding O atom concentration. The sets of rate coefficients so obtained at various distances above the flameholder were averaged and combined with a value of 6 kcal. moIe for the activation energy of (12) to obtain values of 1.5 x 10 and 6.7 x 10 P.mole". sec at 784° and 1300 °K, respectively. (The 6 kcal.mole" value was taken from a paper by Whittingham ° who obtained it from calculations based on the inhibiting effect of SO2 on the oxidation of phosphorus and silane.)... 

The effects of low concentrations of sulphur dioxide upon the rates of O3 and NO formation in irradiated mixtures of NO2 and air have been investigated, in an effort to determine the reasons for formation of increased tropospheric concentrations of O3 near the plumes of power plants emitting S02. No such effects were observed for SO2 concentrations up to lOp.p.m. when the experiments were repeated with added Cl2 however an increase in the O3 concentration was observed, and a chain-reaction mechanism involving formation of the ClOO species has been suggested to explain the observations. Further two-dimensional modelling calculations of O3 depletion rates have been described. The importance of establishing the fraction F of the removal rate of 0( D) by N2O... 

In wine preserved with regular, light sulfuring, the sulfite combination of ethanal (CH3-CHOH-SO3H), stable in an acid medium, is the most prevalent form (Volume 1, Section 8.4.1). When grapes have been heavily sulfured, the ethanal concentration increases and may exceed 100 mg/1, also combined with sulfite. This sulfite combination of ethanal protects yeast from the antiseptic effects of SO2. 

Effect of pH Miiller-Thurgau and Osterwalder (1914) were the first to observe that sulfurous acid and its salts were effective as preservatives only in acid media. Perry and Beal (1920) confirmed this by finding that with more acid solutions the lower the concentration required to inhibit fermentation and mold growth. Bioletti and Cruess (1912) did not find that acidity or sugar content was involved in the decrease in antiseptic effect of SO2 in ripe as compared with unripe grapes. Subsequently however, Cruess and Irish (1932), Cruess (1932), and Cruess et al. (1931) in their investigations of the effect of pH on toxicity of sulfurous acid and... 

However, the dissolvent effect of SO2 is manifest in rose winemaking, since the phenolic compound concentration is low in this case. In fact, SO2 can be detrimental to white winemaking. This dissolvent effect may also affect red grapes if they are insufficiently ripe, and pigment extractability is poor. In that case, snlfiting facilitates anthocyanin extraction in the early stages, especially during cool-temperature maceration (Section 12.5.2). 

The data in Table 12.11 demonstrate the effectiveness of SO2 in destroying laccase. Three different wines receive 0, 50 and 100 mg of sulfur dioxide per liter. The second column indicates the combination rate, which is particularly elevated in wine 1. This wine also has the lowest residual free SO2 concentrations. The following columns indicate the decrease in laccase activity (expressed in arbitrary units) after sulfiting. In wine 3, the enzyme has not totally disappeared within 15 days of sulfiting at a high concentration (10 /g/hl). 

Research has concentrated on the devastating effects of SO2, and there is surprisingly little information available about other forms of air pollution. The only other pollutants so far identified as having a major effect on lichens are fluorine and fertilizer dust. 

The experimental results are in general agreement with the theoretical model. The observed effects of chloride concentration on SO2 removal efficiency for a limestone-based... 

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