(2019) 1:6
Omer et al. BMC Chemical Engineering
Page 4 of 6
Discussion The lumen width of the bark (9.3 μ m) indicated that these fibers should collapse easily upon beating, result- ing in improved interfibre bonding in the pulp and producing compact and low porosity sheet. The core had lower fiber dimensions and inferior morphological indices, indicating the bark as better pulpable material. This clearly showed by Runkel index and flexibility coef- ficient. Both two types of fibers could be classified in third group of Istas Classification [28], characteristic for fibers with fairly thick walls and rather narrow lumen. Although there is still controversy in accepting morpho- logical data in predicting the properties of the pulp, the multi-regression technique seems undoubtedly valuable in showing which morphological characters are import- ant in the pulp properties. The amount of ash and silica content showed that ash composed of a high proportion of inorganic components other than silica. This should increase the alkali consumption and may cause some problems at waste liquor recovery [29]. The high silica content causes diffi- culties in the regeneration of chemical pulping, but might be beneficial in total chlorine free (TCF) bleaching where sometimes silicates are added for stabilization of cellulose. A high hot water soluble content also indi- cated a higher accessibility of the cell wall components to pulping liquor. Therefore, pre-extraction of the raw material before cooking might help to decrease the chemical consumption and obtain useful substances.
properties with relatively higher of 21% soda-AQ pulp properties. The highest viscosity was for 21% soda-AQ which reflected positively for all strength properties especially at high degree of freeness except for tear resistance. Due to adverse effect of the large amount of fines produced, all soda-AQ had low initial brightness since alkali treat- ment induces darkening of the pulp as shown in (Fig. 4). Table 3 The Chemical components of Abelmoschus esculentus (okra) whole stalks Chemical Composition, % Whole stalks Ash 6.3 Total Silica 1.6 Solubility in Hot water 4.1 Coldwater 0.4 Alcohol (Ethanol) 1.2 Ethanol: cyclohexane(1:2) 1.1 1%NaOH 27.6 Kurschner- Hoffer cellulose 48.5 Alfa-cellulose 43.7 Pentosans 19.3 Lignin 15.3 Total Extractives 9.3 Cellulose to lignin ratio 3.2
Table 4 Pulping results and strength properties of hand-sheets obtained from Abelmoschus esculentus okra stalks Pulping Process 15% Soda-AQ 18% Soda-AQ
21% Soda-AQ
Pulping results
Kappa number
29.6
27.8
22.2
ISO brightness, % Viscosity, ml g − 1
19.6
20.4
22.3
1010
1045
1065
Strength properties
Initial pulp freeness,
SR
Apparent density, g cm − 3
25
0.52
0.61
0.61
50
0.62
0.65
0.67
Breaking length, Km
25
7.5
8.1
8.1
50
8.1
8.3
8.5
Tensile index, N m g − 1
25
40.1
43.2
45.3
50
60.2
61.4
63.1
Tear index,, m N m 2 g − 1
25
7.8
7.4
7.2
50
5.6
5.6
5.7
Burst index, K Pa m 2 g − 1
25
2.2
2.1
2.3
50
3.6
3.9
3.7
Folding endurance, log 10 n
25
06
0.9
0.9
50
1
1
1.1
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