The UV-Vis spectrophotometric studies of natural dye absorption on a Sida-rhombifolia/Cotton blended fabric

The environmental considerations in natural dye have gained prominence in the contemporary textile processing industry. Natural dyes  have been exploited from a variety of plants. Some of these natural dyes have no substantive for cellulose fabrics so requires assistance  of mordant during its application. Techniques were developed to extract dyes from red sandal wood (RSW) and avocado seed (AS) for the dyeing of Sida-rhombifolia blended fabric (SRBF). Solvent (ethanol and acetone) extraction method was found suitable for the dye  extraction from red sandal wood and avocado seed. UV-Vis spectrophotometric studies were investigated on the dye absorption. Dyeing  with RSW exhibited better rate of absorbance colour than AS dye. The concentration of each dye was determined using a calibration  curve. The R2 = 0.9669 for RSW and R2 = 0.9895 for AS values accompanied the calibration curve and were considered good. Absorbance/ exhaustion of dyes were determined and characterization was done by carrying out kinetic/equilibrium absorption and the  thermodynamic absorption of isotherms. The kinetic and thermodynamic studies of red sandal wood dyes have higher rate of dyeing and  higher affinity value of 28.3KJ/mol-1 at 80°C for SRBF than avocado seeds with affinity value of 14.09KJ/ mol-1 . The enthalpy and  entropy of dyeing were also found to be positive for both dyes, hence confirming the increasing randomness at the solid/solution  interface during the absorption of dyes. Washing and Rubbing Fastness properties were investigated according to the British Standard  (EN BS 20105). The results ranged from 4-5 according to grey scale standard indicating that the colour on a dyed fabric can strongly resist  fading out when washed or rubbed against a white fabric. It can be concluded that natural plants in Cameroon have considerable  potentials as a source of natural dye.