CHEMICAL MODIFICATIONS OF NATURAL FIBERS FOR IMPROVED COMPOSITE PERFORMANCE AND DYE LIQUOR TREATMENT

Abstract

The hydrophilic nature, mechanical properties, thermal stability and adsorption capacities of the chemically modified and unmodified three different natural fiber materials, namely coir fiber (Eleas coniferus), palm kernel fiber and empty fruit bunch fiber (Elias guinensis) were studied. The fibers were cleansed with 2% hot detergent solution using detergent liquor ratio 1:100, rinsed thoroughly with distilled water and oven-dried to constant weight, before being chemically modified using sodium hydroxide(𝑁𝑎𝑂𝐻), alkaline hydrogen peroxide (𝐻2𝑂2) and acidified acetic anhydride (𝐶𝐻3𝐶𝑂)2𝑂. The first two treatments led to fiber weight reduction, while the acidified acetic anhydride treatment gave the fibers weight increment. All the treated fibers were found to be of less hydrophilic nature, better mechanical properties, higher thermal stablilities as well as better adsorption surfaces/capacities than the untreated ones. These were confirmed by gravimetric analysis, Instron Universal Testing Machine, Thermogravimetric Analyser and the Scanning Electron Microscope (SEM) respectively. Fourier Transform Infrared Spectra (FT-IR) was used to determine the functional groups while the Scanning Electron Microscope (SEM) gave fiber mophology that showed smoother surfaces in modified fibers than unmodified fibers. Leuco form of indigo was prepared by dissolving in 96% ethanol to effect a complete dissolution using 𝑁𝑎2𝑆2𝑂4, 𝑁𝑎𝐶𝑙 and 𝑁𝑎𝑂𝐻. The dye solution contains 1000 mg of indigo dye, 20 ml of 96% ethanol, 100 mg of 𝑁𝑎2𝑆2𝑂4, 10 mg of 𝑁𝑎𝐶𝑙 and 10 mg of 𝑁𝑎𝑂𝐻. The indigo dye solution was standardized using U/V visible spectrophotometer at 410 nm. The adsorption capacities (removal efficiency) of both the treated and untreated fibers for the dye were determined by using the natural fibers as adsorbents, varying concentration, time and temperature. Descriptive statistical analysis was used to treat the data obtained and the results obtained from the adsorption analysis were further used for isotherm, kinetics and thermodynamics studies.