Fibre extraction and characterization from coconut husks waste for industrial application

Abstract

Coconut trees are grown in tropical countries along the coastal regions of Asia, Africa, and Latin America. One of the coconut’s product whose full potential has not been exploited adequately is the husk, a fibrous part of the coconut fruit which forms the largest component of the fruit. Husks are byproducts of nut extraction after mature fruit harvesting or the cutting of the immature fruit for access to the liquid used as a thirst quencher. This produces husk, a biowaste that is either discarded in the open or burned, posing environmental challenges. Because of the bulkiness of the husk and abundance in the coastal region, there results heap of waste. If this waste could be developed into high-value applications, then the potential of coconut waste could be realized. This study aimed to characterize the products of husk waste extraction from mature and immature coconut fruits for industrial use. The specific objectives were to determine the quantities of coconut husk waste along the Kenyan coastline resulting from immature coconut fruit; to extract fibers from mature and immature coconut husk waste; and to characterize the properties of the decorticated fibers. From a survey carried out, a total of 70 tons coconut husk waste is generated along the Kenya coastal region. For this research work, 384 husk waste samples were collected and sun-dried for six months before fiber extraction, alkali treatment, and characterization. The fiber diameter was measured to be between 123.09μm to 197.44μm. Fiber density was determined to be between 1073.30 kg/m 3 and 2941.38 kg/m 3 a variation due to chemical treatment of the fiber, which altered the diameter, a dimension used in density calculation. Tensile strength ranged from 104.36MPa to 267.10MPa for the fibers. This can be attributed to the non-uniformity of the fiber with intrinsic diameter in which the irregularities increase defects in the fiber. The alkali treatment of fiber extracted from mature and immature coconut husk waste both presented minor changes in Fourier Transform Infra-Red spectra for treated coir fibers. The thermal stability for both types of fibers was improved after the alkali treatment because of the elimination of hemicellulose and lignin. The surface morphology of the untreated coconut fibers revealed a fine and smooth surface whereas that of treated fibers exhibited a rough and fine surface as a result of the removal of impurities. Alkali treatment also decreased fiber diameter and resulted in a rougher surface. Decortication realized coir of various sizes and coco peat. In conclusion, there is significant waste generated from the coconut husk waste which can be extracted by decortication. Evaluation of characterized coir demonstrated usage in industrial application. Optimization of alkalization parameters to explore their influence on fiber properties is recommended.