Extraction, characterization, and improvement of banana stem and water hyacinth cellulose fibers as reinforcement in cementitious composites

Abstract

A sequential treatment for cellulose isolation from the banana stalk (BNSF) and water hyacinth (WHCF) based on the simultaneous fractionation of hemicelluloses and lignin by alkaline peroxide extraction has been studied. The crude cellulose was then purified by using an acetic acid-nitric acid mixture and further bleached with acidified sodium chlorite. The isolated cellulose was subject to analyses of associated hemicelluloses and lignin content. The structural changes between crude and purified celluloses were revealed by using FT-IR, TGA, and XRD analyses. The successive alkaline and bleaching treatments led to a significant loss in hemicelluloses and lignin, enrichment of the cellulose fraction, and increase in cellulose crystallinity but led to 3.1% to 5.4% degradation of the original cellulose. The crystallinity index of isolated cellulose was found to be increased from 38% to 90% for WHCF and 62% to 95% for BNSF. The cement composite with purified WHCF and BNSF exhibited comparable flexural strength to pure cement. The results showed that the flexural strength of the composites with 2.33 wt% of α-WHCF, 2.33 wt% of α-BNSF, and without fibers was 13.89 10.65 and 8.65 MPa, respectively. In other words, the flexural strength of the composite with α-WHCF was improved by 125%.