Effect of pulping method on the quality of paper produced from banana stem fibre

Abstract

The rising demand for paper and the pressure on forest resources has created the need to explore alternative raw materials for pulp and paper production. Agricultural residues such as banana pseudostem are abundant and underutilized, yet they contain significant amounts of fibrous components suitable for papermaking. This study investigated the suitability of banana pseudostem for paper production by comparing two pulping methods, soda pulping and mechanical pulping. The chemical composition of the banana pseudostem was first determined. Results showed that the pseudostem contained 60.7% alpha-cellulose, 18.57% hemicellulose, 16.46% lignin, 4.6% extractives, 4.82% pectin, and 1.2% ash on dry weight basis. These values were within the ranges reported in literature, although cellulose, hemicellulose and pectin were slightly higher than expected. This indicated that the pseudostem is a rich source of fibrous material for papermaking. Both chemical pulping and mechanical pulping were found to be applicable when extracting fibres from banana stems for paper production. The percentage yield of fibres was 59% and 94.6% from chemical pulping and mechanical pulping respectively. The percentage composition of acid-insoluble lignin was 9.8% and 15.75% in chemically and mechanically pulped fibers respectively. Mechanical pulping yields more fibers but with a high composition of acid-insoluble lignin which leads to undesirable paper properties such as reduced brightness and yellowing over time. Mechanically pulped fibres can hence only be used to make low-grade paper products such as newsprint and packaging board. Chemical pulping was found to have lower percentage yield of fibres but with low percentage composition of acid-insoluble lignin content which makes the fibers suitable for production of brighter and more durable paper products that are standard for quality printing and writing. Paper sheets were then produced from both soda pulping and mechanical pulping methods. The physical properties of the sheets were tested. Soda pulp paper recorded higher tensile strength (0.3139kN/m) and tensile index (4.487 Nm/g) compared to mechanical pulp paper (0.2180 kN/m tensile strength and 2.565 Nm/g tensile index). The density of soda pulp sheets was also greater (0.707 g/cm³) than that of mechanical pulp sheets (0.5515 g/cm³). In terms of brightness, soda pulp papers appeared lighter and more uniform, while mechanical pulp papers were darker and slightly brownish due to retained lignin. The results showed that chemical pulping (soda pulping) produced stronger, denser, and brighter papers compared to mechanical pulping, although mechanical pulping was simpler and required fewer resources. Overall, banana pseudostem was confirmed to be a suitable alternative raw material for papermaking, and its utilization can contribute to waste management and sustainable paper production.