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At section 3.3.6, model compounds studies using toluene as solvent to dissolve various sulfur model compound, the results shows average desulfurization efficiency with Thiophene is 86% and 39% for Benzothiophene. However, referring to Chapter 4, under protocol condition, various types of diesel, from low to high sulfur content, can reduce to less than 15 ppm. One possible reason that low desulfurization on Ts and BTs is possibly due to oxidation of toluene forming benzaldehyde with benzoic acid as a by product. Similar experiment has been done by Chandalla et al; toluene is dissolve in acetic acid and was oxidize air and using sodium bromide as the catalyst, and he confirm the by-product as benzaldehyde and benzoic acid by argentometric method (Chandalla, et al. 1984)Introduction: In section 3.3.6, model compounds studies using toluene as solvent to dissolve various sulfur model compound have been discussed at length. The results show average desulfurization efficiency with Thiophene is 86% and 39% for Benzothiophene. However, referring to Chapter 4, under protocol condition, various types of diesel, from low to high sulfur content, can reduce to less than 15 ppm. One possible reason for this observation is that that low desulfurization on Ts and BTs is due to oxidation of toluene forming benzaldehyde with benzoic acid as a by-product. A similar experiment has also been done by Chandalla, et al; according to him, toluene is dissolved in acetic acid and is oxidized air and using sodium bromide as the catalyst. Besides, he confirms the by-product as benzaldehyde and benzoic acid by argentometric method (Chandalla, et al., 1984).Due to oxidation, toluene is competing with model sulfur compound that result low selectivity to model compound.  In this situation, toluene cannot be used as a solvent for the model compounds studies. Other solvents – “sulfur free Valley oil” with extremely low sulfur content with <5 ppm have been used for the model compounds studies instead.Due to oxidation, toluene competes with model sulfur compound that results in low selectivity to model compound. In this situation, toluene cannot be used as a solvent for the model compounds studies. Contrary to above procedures, other solvents – “sulfur free Valley oil” with extremely low sulfur content with <5 ppm have been used for the model compounds studies.Result and Discussion          Table 3.10 and Figure 3.11 shows the summary results of various model sulfur compounds into their corresponding sulfones under efficient protocol conditions. Results shows the oxidation activity of these model sulfur compounds decrease in the order of DBT > 4,6-DMDBT > BT > 2MBT > T > 2ET > 2MT. By using “Sulfur free Valley oil”, all the model sulfur compounds can achieve average 98.2% sulfur reduction. These remarkable results indicate “sulfur” free diesel can be use as solvent to dissolve model sulfur compound under modified UAOD process.Result and Discussion:         Table 3.10 and Figure 3.11 illustrate the results summary of various model sulfur compounds into their corresponding sulfones under efficient protocol conditions. Results show that the oxidation activity of these model sulfur compounds decrease in the order of DBT > 4, 6-DMDBT > BT > 2MBT > T > 2ET > 2MT. By using “Sulfur free Valley oil”, all the model sulfur compounds can achieve average 98.2% sulfur reduction. These remarkable results fairy manifest that “sulfur” free diesel can be used as solvent to dissolve model sulfur compound under modified UAOD process.A plot of ln(Co/Ci) versus reaction time should be linear and the value of the apparent rate constant can be obtained by the slope of the linear relationship. Detail explanation of kinetic theory will be discussed at Chapter 5. Table ABC and Figure ABC shows the results of rate constant of model sulfur compounds. In our experiment, the oxidation of model sulfur compounds were carried out under pseudo first order conditions employing excess of H2O2. The fitting curve displayed a good linear relationship that confirmed the pseudo first order reaction kinetics.A plot of ln(Co/Ci) versus reaction time should be linear, and the value of the apparent rate constant can be obtained by the slope of the linear relationship. Detailed explanation of kinetic theory is discussed in Chapter 5. Table ABC and Figure ABC exhibit the results of rate constant of model sulfur compounds. In the present experiment, the oxidation of model sulfur compounds were carried out under pseudo first order conditions employing excess of H2O2. The fitting curve demonstrates a good linear relationship that confirmed the pseudo first order reaction kinetics.In a complex as diesel fuels, there exists competitive oxidation among organic sulfur compounds and other unsaturated constituents such as olefinic compounds. By comparing the rate constant of DBT in toluene and “sulfur free Valley oil” were 0.021 min-1 and 0.0228 min-1 respectively. Both case shows very similar rate constant. It can be conclude that by using modified UAOD process, oxidation of DBTs won’t affect neither organic solvent as model oil nor “sulfur free diesel.In a complex as diesel fuels, there exists competitive oxidation among organic sulfur compounds and other unsaturated constituents such as olefinic compounds. The results obtained by comparing the rate constant of DBT in toluene and “sulfur free Valley oil” were 0.021 min-1 and 0.0228 min-1 respectively. Both these cases present very similar rate constant. Therefore, it can be concluded that by using modified UAOD process, oxidation of DBTs will not affect either organic solvent as model oil or “sulfur free diesel.Results shows the oxidation activity of these model sulfur compounds decrease in the order of BT > 4,6-DMDBT > DBT > 2MBT > 2ET > 2MT > T. By using “Sulfur free Valley oil”, all the model sulfur compounds can achieve average 98.2% sulfur reduction. From section 3.3.6, BTs only achieve 40% conversion by using toluene as solvent, but by using “sulfur” free Valley oil as the solvent, it can achieve average 99% conversion. These remarkable results indicate “sulfur” free diesel can be use as solvent instead using toluene. Overall, three major types of organic sulfur compounds can all reduce to less than 15 ppm under modified UAOD process.Results manifest that the oxidation activity of these model sulfur compounds diminish in the order of: BT > 4,6-DMDBT > DBT > 2MBT > 2ET > 2MT > T. By using “Sulfur free Valley oil”, all the model sulfur compounds can achieve an average 98.2% sulfur reduction. From section 3.3.6, BTs achieve only 40% conversion by using toluene as solvent. However, if “sulfur” free Valley oil is used as the solvent, it can achieve an average 99% conversion. These off-the-mark outcomes signify that “sulfur” free diesel can be made use of as solvent instead of using toluene. Overall, three major types of organic sulfur compounds can all be reduced to less than 15 ppm under the modified UAOD process.Table 3.11 shows the rate constant with error with seven different kind of sulfur model compound. Since the oxidant was in excess amount, A plot of ln (Ci/Co) vs reaction time result a linear relationship that confirmed the pseudo first order reaction kinetics.Table 3.11 illustrates the rate constant with error with seven different kind of sulfur model compound. Since the oxidant was in excess amount, A plot of ln (Ci/Co) versus reaction time results a linear relationship that confirms the pseudo first order reaction kinetics. 

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