This study was carried out to determine the efficiency of nitrogen (N) doses (0, 30, 60, and 90 kg N ha −1 ) under supplemental potassium (K) application (50 kg K 2 O ha −1 ) on black cumin in 2011 and 2012. The results showed that increased N levels resulted in increasing seed yield and N and K contents in seed, while oil content decreased. The seed yield and oil yield were peaked at the doses of 60 kg N ha −1 and 50 kg K ha −1 . An increase in N doses caused a reduction in oil content regardless of K supply. Saturated fatty acids and oleic acid were slightly increased by K application, while minor changes in linoleic acid were detected. It was concluded that 60 kg N ha −1 with supplemental K application should be advised for enhancement in seed yield, oil yield, and N and K contents in seeds of black cumin without significant changes in fatty acid composition.
The kinetics of the hydrolysis of benzaldehyde dimethyl acetal has been studied using a circulated batch
reactor in dioxane. Amberlite IR-120, in its acidic form, was used as a heterogeneous catalyst. Kinetic expression
for the formation of acetal was also determined since the reaction is reversible. In the temperature range
298−328 K, the equilibrium constant for hydrolysis of benzaldehyde dimethyl acetal was found to be K
e =
exp(8.67 − 1880/T) mol·L-1 where T is the absolute temperature in Kelvin. In the presence of catalyst, the
reaction has been found to occur between an adsorbed water molecule and a molecule of acetal in the bulk
phase (Eley−Rideal model). It was also observed that benzaldehyde adsorbed by the catalyst has an inhibiting
effect on the reaction rate. From this model it was concluded that the reaction is a “surface reaction control”
and its rate will be given by the expression −r
W = [k(m/V)(C
A
C
W − ((C
BA
C
M
2)/K
e))]/[1 + K
BA
C
BA + K
W
C
W]
where concentrations are in the unit of mol·L-1. It was shown that temperature dependency of the hydrolysis
rate constant can be given by k = exp(9.4 − 4915/T) L2·(g-dry resin)-1·mol-1·min-1. The adsorption equilibrium
constants related to benzaldehyde and water were also calculated to be K
BA = exp(7292/T − 24.9) L·mol-1,
K
W = exp(1296/T − 4.4) L·mol-1, respectively.
The hydrogenolysis of pure and biodiesel byproduct glycerol in the presence of Raney nickel catalyst using an autoclave was studied. The effects of stirring speed, temperature, amount of catalyst, H 2 pressure, and glycerol content on the conversion of glycerol, the yield of liquid products, and the selectivity of 1,2-propanediol were investigated, and the results were compared to chemically pure glycerol and crude glycerol from biodiesel production. All the experimental results obtained from the use of crude glycerol from biodiesel production were close to those obtained from the use of chemically pure glycerol. The highest conversion of glycerol (80%) was achieved under the conditions of 35 g catalyst L −1 solution, 20% glycerol content, 40 bar H 2 pressure, 400 rpm stirring speed, and 230°C temperature for the chemically pure glycerol. In order to reach the highest liquid products yield (95%) and the 1,2-propanediol selectivity (54%), the catalyst amount was decreased from 35 g catalyst L −1 solution to 7 g catalyst L −1 solution while the other conditions were unchanged. On the other hand, the highest conversion of glycerol (74%) and the highest selectivity of 1,2-propanediol (50%) for the crude glycerol were obtained under the same reaction conditions with those obtained in the use of chemically pure glycerol while the liquid products yield was 74% under the reaction conditions of 21 g catalyst/L solution, 20% glycerol content, 40 bar H 2 pressure, 400 rpm stirring speed, and 200°C temperature. According to the obtained results, increasing the temperature and amount of catalyst led to the increase in the glycerol conversion and decrease in the liquid products yield and in the 1,2-propanediol selectivity. The glycerol conversion decreased and the liquid products yield and the 1,2-propanediol selectivity increased with the increasing hydrogen pressure.
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