Effect of Alkali Concentration

This paper presents new data on dissolution kinetics. The effects of alkali concentration, size of the cation, and salt addition were studied. The influence of segmental mobility on dissolution was elucidated by measuring the temperature coefficients of the dissolution rates. Experiments were also carried out to study the relation between the chemical structure of a polymeric Inhibitor and Its effectiveness 1n retarding dissolution. Based on these results,... 

Effect of Alkali Concentration. Figure 7A depicts that the variation of the conversion of glycol lignin with sodium hydroxide concentration reaches a plateau at about 60%. Also, the ether soluble material remains constant... 

Figure 7. Effect of alkali concentration on conversion and product yields (logioR0 = 7.7).

Various bituminous coals were demineralized by an experimental two-step leaching process in which the ball-milled coals were first treated with a hot alkaline solution and then with a dilute mineral acid. Different alkalis and acids were studied to determine their relative effectiveness. In addition, the effects of alkali concentration, treatment temperature, and treatment time were evaluated. Under the best conditions, the process reduced the ash content of the coals by 85-90% and the total sulfur content by 70-90%. As the temperature of the alkaline treatment was raised from 150 to 345 C, the removal of sulfur increased greatly whereas the recovery of organic matter declined. When a 1 M sodium carbonate solution was employed for the treatment, the recovery of organic matter was 91-97% for various coals treated at 250 C and 79-89% for the same coals treated at 300 C. 

The effects of alkali concentration appeared relatively minor in most Instances. However, for Lower Kittanning coal an alkali concentration of 1.0 appeared optimun for removing sulfur in the first step whereas a smaller concentration (0.2 M) resulted in a lower ash content overall for the two-step process. 

Figure 3 Effect of alkali concentration on the extent of hydrocellulose degradation at 120°C for 1 h. (From Ref. 108.)...

Effect of Concentration of Reactants. Increase in the concentration of the hydrolyzing reagent would naturally be expected to speed up the reaction, other things being equal, but A high concentration sometimes leads to undesirable by-products. The effect of alkali concentration on the hydrolysis of allyl chloride is shown in Table 13-3. It is seen that a high alkalinity leads to an increase in the side reaction which forms diaUyl ether and a lower yield of the primary product, allyl alcohol. 

TABLE 1 Effect of Alkali Concentration on Film Capacitance in Modeling Oil (7.5 mmol/L Oleic Acid)/Alkali Systems... 

Alkalization Mwaikambo et al. were one of the earher groups who adopted various techniques to analyze the effect of alkali treatment on different natural fibers. Even though they did not conduct mechanical testing of composites, their investigation is vital in understanding the effect of alkali concentrations on the crystallinity index of the fibers. Their studies showed that lower concentrations of alkali would result in... 

Figure 12.6 Relation between c stalline transition rate and NaOH concentration [53]. Table 12.7 Effect of alkali concentration on the tensile properties of ramie yarns [53].

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