Hydrolysis reaction rates

In our previous work [63], we studied the hydrolysis kinetics of lipase from Mucor javanicus in a modified Lewis cell (Fig. 4). Initial hydrolysis reaction rates (uri) were measured in the presence of lipase in the aqueous phase (borate buffer). Initial substrate (trilinolein) concentration (TLj) in the organic phase (octane) was between 0.05 and 8 mM. The presence of the interface with octane enhances hydrolysis [37]. Lineweaver-Burk plots of the kinetics curve (1/Uj.] = f( /TL)) gave straight lines, demonstrating that the hydrolysis reaction shows the expected kinetic behavior (Michaelis-Menten). Excess substrate results in reaction inhibition. Apparent parameters of the Michaelis equation were determined from the curve l/urj = f /TL) and substrate inhibition was determined from the curve 1/Uj.] =f(TL) ... 

Abiotic hydrolysis of pollutants in subsurface waters is pH dependent. The predominant pathways are acid-catalyzed, base-mediated, and neutral (pH-independent) hydrolysis. The acid-catalyzed hydrolysis reaction rate is dependent on proton concentration increases with a decrease in pH. This behavior occurs because the proton is not consumed in the reaction. 

As expected, mesoporous silica-supported sulfonic sites were able to catalyze the hydrolysis of cellobiose. Indeed, at 448 K, 90% of cellobiose was hydrolyzed within 30 min of reaction with an apparent activation energy ( = 130 kJ moF ) similar to that of reactions promoted by homogeneous organic acid catalysts [33]. The hydrolysis reaction rate is proportional to the concentration of hydrated... 

Morpholinoalkyl esters (see Figure 16.1 for chemical structures) ofthe potent nonsteroidal anti-inLammatory agent, diclofenac, were prepared and characterized regarding solubility and hydrolysis reaction rates (Tammara et al., 1994). The alkyl group provides a spacer between the carboxylic acid... 

The ethoxysilanes 3b and 3d are almost as reactive as the methoxy-substituted analogous silanes 3a and 3c. Usually, ethoxysilanes show a very much lower hydrolysis reaction rate than their methoxy counterparts. 

However, beeause this ehemieal is synthesized from the (eostly) sodium borohydride, and beeause its own hydrolysis reaction rate is too high, sulfurated borohydride is not a suitable alternative to hydrosulfite. But interestingly, this study suggests the need for milder and more selective reductive chemicals chemicals able to selectively and rapidly react with carbonyl groups, and not with water to any extent. 

Table 3 lists the kinetic rate expressions for each of the hydrolysis and fermentation reaction rates shown in Fig. 5 and in the mass balance equations of Tables 1 and 2. Each of the reaction rates were found to fit the data through trial and error, starting with the simplest model. For the hydrolysis reaction rates (rs,arch and / maltose), the simplest form was the Michaelis-Menten model without inhibition. For all other reaction rates which described fermentation kinetics, the simplest form was the Monod model without inhibition. More descriptive models were found in the literature and tested one by one until the set of kinetic rate equations with the best fit to the experimental data were determined. This was completed with the hydrolysis datasets first, then the complete SSF datasets. 

Parameter estimate results from best fit kinetic expressions are listed in Table 4 for each of the hydrolysis reaction rates and yield coefficients. Using these parameters, Fig. 7 compares measured to simulated data for the hydrolysis experiments using the MRE mixture at 100, 400 g/1, and the validation dataset. The values, coefficient of determination, for glucose are 0.99, 1.00, 0.97, respectively, indicating a good fit to all three datasets. 

In an alkaline medium the hydrolysis reaction rate is about 12 times greater than in an acidic one so it is important not to over-neutralize the feed. Clearly it may be desirable to operate under vacuum and with a short residence time. Continuous distillation would be preferred to batchwise. 

Urea synthesis method has recently been increasingly used for the LDH synthesis and is based on the precipitation of metal solution and on the urea hydrolysis. Urea is a very weak Bronsted base which is soluble in water, and the hydrolysis reaction rate can be regulated by the temperature mixture [20, 23]. The urea hydrolysis is carried out in two steps the reaction for the formation of the ammonium cyanate (NH CNO), which dictates the hydrolysis rate, and the reaction of the transition of cyanate to the ammonium carbonate. 

In the SulFerox process, carbonyl sulfide can be hydrolyzed to CO2 and H2S that is then reacted to elemental sulfur. However, the hydrolysis reaction rate is quite slow, and consequently the removal rate of COS is limited by the residence time in the contactor. For this reason, it would be expected that a sparged tower absorber would be much more effective at COS removal than the other contactor types. Carbon disulfide in the feed gas is first hydrolyzed to COS and then to CO2 and H2S. The net CS2 removal efficiency is therefore less than that for COS. If the contactor has ample residence time, the SulFerox process may remove as much as 30 to 60% of the carbonyl sulfide present in the sour gas. If the unit has a short residence time contactor, the removal rate for CS2 and COS may be less than 10%. 

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