Initial experiments were set to investigate the suitable mixture ratio of the two solvents used
(acetone and methanol) with the reflux extraction protocol, which is one of the conventional
extraction procedures of pulp samples. The acetone and methanol solvent mixture was
chosen due to the fact that polar solvents can extract a larger range of organic compounds
from pulp samples.[20] This can be explained by the fact that at higher temperatures the
polarity of polar solvents decreases (heating a polar solvent while keeping it in a liquid
state decreases dielectric constant to that of non-polar solvents), which allows it to capture
compounds ranging from semi-polar to non-polar.[23,24] Also, the chosen solvents are less
hazardous compared to chlorinated and benzene-related solvents such as dichloromethane
(DCM), chloroform, and benzene.[20] The effect of the concentration of the two solvents
in the mixture on the yield of extractives was investigated by varying the concentration of
acetone (40, 50, and 60% v/v) in methanol. At this stage, temperature was fixed at 80◦C,
extraction time at 2 h, and volume of solvent at 60 mL. It was observed that the ratio of
40:60% v/v acetone/methanol gave the highest results of extracted lipophilic extractives.
Optimal extraction time of lipophilic extractives using reflux extraction was then
determined and later compared with that of USLE. The percentage of lipophilic extractives
obtained was calculated using Equation (1).
Initial experiments were set to investigate the suitable mixture ratio of the two solvents used(acetone and methanol) with the reflux extraction protocol, which is one of the conventionalextraction procedures of pulp samples. The acetone and methanol solvent mixture waschosen due to the fact that polar solvents can extract a larger range of organic compoundsfrom pulp samples.[20] This can be explained by the fact that at higher temperatures thepolarity of polar solvents decreases (heating a polar solvent while keeping it in a liquidstate decreases dielectric constant to that of non-polar solvents), which allows it to capturecompounds ranging from semi-polar to non-polar.[23,24] Also, the chosen solvents are lesshazardous compared to chlorinated and benzene-related solvents such as dichloromethane(DCM), chloroform, and benzene.[20] The effect of the concentration of the two solventsin the mixture on the yield of extractives was investigated by varying the concentration ofacetone (40, 50, and 60% v/v) in methanol. At this stage, temperature was fixed at 80◦C,extraction time at 2 h, and volume of solvent at 60 mL. It was observed that the ratio of40:60% v/v acetone/methanol gave the highest results of extracted lipophilic extractives.Optimal extraction time of lipophilic extractives using reflux extraction was thendetermined and later compared with that of USLE. The percentage of lipophilic extractivesobtained was calculated using Equation (1).
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