Production of Cellulose From Different Species of Banana (Musa Paradisiaca) Mid Rib Waste: A Sustainable Raw Material for Industrial Applications

Technical Summary: Production of Cellulose from Banana Mid Rib Waste

Problem Statement
The global paper and pulp industry has historically relied on wood fiber as the primary raw material for cellulose production. This dependence has driven deforestation and increased the cost of cellulose, while the combustion of fossil fuels for industrial processes has exacerbated greenhouse gas emissions. Concurrently, agricultural residues, particularly in developing nations like Nigeria, are often underutilized, leading to environmental and health concerns. While banana pseudo-stems have been investigated for cellulose extraction, there is a specific gap in research regarding the potential of banana mid-rib waste from different local species (Musa paradisiaca) as a sustainable feedstock for industrial applications.

Methodology
The study investigated four distinct species of banana mid-rib waste commonly found in Nigeria: Ibo banana, Saro, Paranta, and Ogede omini. The research followed a structured experimental protocol:

• Sample Preparation: Mid-ribs were separated from leaves and cut into 0.05 m diameter pieces.
• Pulping Process: An alkaline sulphite chemical pulping method was employed. Samples (250 g) were treated with a white liquor solution consisting of a 1:1 ratio of Sodium Hydroxide (NaOH) and Sodium Hydrogen Sulphite (NaHSO3). The reaction occurred in an autoclave at 0.14–0.165 MPa pressure for 90 minutes.
• Chemical Characterization:
  • Extractives: Determined via Soxhlet extraction using an ethanol/acetone mixture (1:2).
  • Lignin: Quantified using the 72% H2SO4 method followed by dilution and reflux.
  • Holocellulose: Isolated using sodium chlorite (NaClO2) and glacial acetic acid in a water bath (70–80°C).
  • Alpha Cellulose & Hemicellulose: Alpha cellulose was isolated using 17.5% NaOH; hemicellulose content was calculated by subtracting alpha cellulose from holocellulose.
  • Solubility Tests: Conducted for 1% NaOH, cold water, and hot water.
• Morphological Analysis: Fiber dimensions (length, diameter, lumen width, cell wall thickness) and derived ratios (Runkel, Flexibility, Slenderness, Coefficient of Rigidity) were measured using an optical digital microscope. Surface morphology was further analyzed via Scanning Electron Microscopy (SEM).
• Chemical Identity: Fourier Transform Infrared Spectroscopy (FTIR) was used to confirm the chemical functional groups of the extracted cellulose.

Key Results
The study yielded quantitative data on the efficiency of cellulose extraction and the physical properties of the fibers:

• Cellulose Yield: The pulping process resulted in cellulose yields ranging from 30.20% to 40.10%.
  • M. paradisiaca (Paranta) produced the highest yield at 40.10%.
  • M. paradisiaca (Ogede omini) and M. paradisiaca (Ibo banana) yielded approximately 35.30% and 35.25%, respectively.
  • M. paradisiaca (Saro) produced the lowest yield at 30.20%.
• Holocellulose and Alpha Cellulose: Holocellulose content ranged from 71.01% to 80.00%, with Paranta showing the highest value. Alpha cellulose content was approximately 30% across the species, with Paranta, Ibo, and Ogede omini reaching ~30.00–30.01%.
• Fiber Morphology:
  • Fiber Length: Ranged from 1.63 mm to 2.86 mm. Paranta exhibited the longest fibers (2.86 mm), which is significantly higher than the 1.05–1.36 mm range typical of 18 Nigerian wood species.
  • Fiber Diameter: Ranged from 19.13 µm to 21.51 µm, exceeding the 15.22 µm observed in M. excelsa wood.
  • Lumen Width: Ranged from 10.05 µm to 12.64 µm, superior to the 8.89 µm minimum recorded for M. excelsa.
  • Ratios: The Runkel, Flexibility, and Slenderness ratios indicated that the fibers possess properties conducive to high tensile strength and good sheet formation.
• Spectroscopic Confirmation: FTIR analysis confirmed the presence of characteristic cellulose functional groups, including hydroxyl (3272.6 cm⁻¹), methoxyl, and carbonyl groups, validating the chemical identity of the extracted material.
• SEM Analysis: Micrographs revealed a suitable alignment of cellulose fibers, confirming their structural integrity for industrial use.

Significance and Claims
The authors claim that banana mid-rib waste represents a viable, sustainable, and low-cost alternative to wood fiber for cellulose production. The study concludes that:

1. Industrial Viability: The morphological properties (long fiber length, appropriate diameter, and favorable rigidity coefficients) of the extracted cellulose compare favorably with wood cellulose, making it suitable for pulp and paper production, as well as other industrial applications requiring high tensile strength.
2. Environmental Impact: Utilizing this abundant agricultural waste addresses the issue of unutilized biomass in Nigeria, potentially reducing environmental pollution associated with waste disposal while mitigating the pressure on forest resources.
3. Economic Potential: The process offers a pathway to generate value-added products from waste materials that are currently discarded, providing a cheap bioresource for the bio-economy.

The paper does not propose new experimental methods or future applications beyond the scope of the tested pulping process and characterization, maintaining a focus on validating the current potential of these specific banana species as raw materials.