Characterization based on silt retting method for extracting fibers from waste coconut husks

Against the backdrop of substantial global demand for natural fiber resources, coconut husk fiber, distinguished by its excellent properties, possesses promising application prospects; however, the current extraction and utilization rate of waste coconut husks remains low. In the development process, the extraction method for waste coconut husk fiber constitutes a significant challenge currently encountered. This study aims to propose a novel fiber extraction method—silt retting—and conducted comprehensive characterization of it, to enhance and expand the volume of usage and scope of application of coconut husk fiber. Through comparison of the fiber characteristics of different samples subjected to hand scraping, boiling water, water retting, and silt retting, employing stereomicroscopy (SM) and Field Emission Scanning Electron Microscopy (FESEM) to perform macrostructural and microstructural analysis of the fiber surfaces, and combining this with X-ray Diffraction (XRD) analysis to determine the crystallinity of the fibers, the removal of impurities under different retting methods was demonstrated, reflecting the physical characteristics of the fibers. Utilizing Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) to characterize the compositional makeup of the fibers, the biological extraction method employed in this experiment gently preserved the native composition of the fibers. Conducting Differential Thermal Analysis-Thermogravimetric Analysis (DTA-TGA) on the different fibers discovered that the silt-retting fiber sample exhibited the strongest thermal stability, capable of withstanding temperatures as high as 379 °C, thereby demonstrating the thermal properties of the fiber. Mechanical testing analysis indicated that the tensile strength of the treated fibers exhibited a reduction, but they still retained the inherent mechanical characteristics of the fiber. Through this experimental analysis, the technical scope and application fields of fiber extraction were broadened, and the utilization rate of waste coconut husks was improved. • Based on two coconut husk fiber extraction methods—water retting and hand scraping—this study develops a new extraction method: silt retting. • A comparison of the treatment effects of different samples shows that coconut fibers treated by silt retting also retain the inherent components of the fibers themselves. • By comparing the surface morphology and crystallinity of coconut fibers under different treatment methods, the extent of impurity removal on the fiber surface is clarified. • After silt retting treatment, the thermal stability of coconut fibers is significantly improved compared with those treated by water retting and hand scraping. • Tensile tests were conducted on coconut fibers treated by hand scraping, water retting, and silt retting, and the results indicate that all treatment groups retain the good mechanical properties of the fibers.