Investigating on properties of soda-AQ pulp produced from terjin (Saccharum ravennae)

The reduction of forest wood resources has increased the necessity of using alternative primary resources including weedy non-wood plants, wood of fast-growing trees and agricultural residues in papermaking industries. On the other hand, most of the country's agricultural waste is consumed in animal husbandry industries, and wood farming also faces many challenges due to costs such as removing the roots after cutting the tree. Hence the need to use a weedy non-wood raw material seems essential. terjin (Saccharum ravennae) is one of the native weedy non-wood resources of the country, which has a good distribution in the country, and so far, its potential for use has not been evaluated. Therefore, the purpose of this research is to investigate the chemical and morphological characteristics of terjin, as well as the production and evaluation of refined and unrefined soda-anthraquinone pulp from it as a raw material to offer to papermaking industries.

In this research, terjin leaves were obtained from Gorgan region located in Golestan province. In order to measure the biometric characteristics of terjin, the samples were cut using the Franklin method, and then the dimensions of its fibers were measured using an optical microscope, and then their biometric coefficients were calculated. In order to measure the chemical properties of the fibers, the samples were first grinded and then their chemical properties, including the percentage of ash, extractives, lignin (klason) and cellulose were also measured based on the TAPPI standard. In order to prepare pulp from terjin, the samples were cooked at different levels of time (30 and 60 minutes) and chemical (alkalinity 14, 16 and 18%) under a temperature of 160 °C and 0.1% anthraquinone consumption, and then their yield, freeness and kappa number was measured. In the following, the pulps were refined to freeness of 350 ± 20 ml CSF, and then handsheet paper with a grammage of 60 g/m2 was prepared from refined and unrefined pulps, and their physical, optical and resistance characteristics were measured by TAPPI standards. Finally, the results were evaluated and analyzed using one-way analysis of variance and Duncan's test in SPSS software environment.

The results showed that the length, diameter, lumen diameter and wall thickness of the fibers were 1.85 mm, 10.82 µm, 5.32 µm and 2.75 µm, respectively; and biometric coefficients including Slenderness ratio, Flexibility coefficient and Runkel ratio were 171.14, 49.12 and 103.60 respectively. Its chemical composition included percentage of ash, extractive, lignin and cellulose were 5.75, 2.53, 26.73 and 44.63 respectively. The results of pulping showed that with the increase of alkalinity percentage and cooking time, yield, kappa number and freeness of pulp decreased. Also, the results showed that refining and increasing the alkalinity percentage and cooking time increase the density, decrease the opacity and increase the resistance characteristics of pulp. According to the results, the brightness increased with the increase in alkalinity percentage, while the increase in cooking time and the use of refining treatment did not have a significant effect on the brightness of the soda-anthraquinone pulp obtained from terjin. According to the results, the best characteristics were obtained after refining the pulp obtained from cooking at 18% alkalinity for 30 and 60 minutes, and also at 16% alkalinity for 60 minutes.

In general, terjin has better morphological and chemical characteristics than many non-woody plants, and in some cases, such as fiber length, its characteristics are comparable to hardwood. Also, refined and unrefined soda-anthraquinone pulp of terjin has relatively good and acceptable papermaking characteristics, and it can be suggested to the papermaking industry as a part of the raw material for the production of pulp.