The increasing global awareness of ecofriendly and sustainable production and products has encouraged the use of natural fibres and dyes. Although research has been undertaken on the sources and applications of natural dyes, only a few such sources have been used on a commercial scale due to the costs and complexity of the associated extraction and dyeing processes, lack of appropriate technologies, and challenges with respect to dye fastness and shadereproducibility. The present investigation was carried out to optimize the extraction of natural dye from the bark of the Syzygium cordatum (water berry) tree. The bark was collected from recently fallen trees and twigs pruned from old trees, since the latter have greater dye content than the younger ones. The bark was dried in an open room for two weeks, crushed with a hammer and ground into powder. The conditions for dye extraction using a methanol/water mixture, were optimized bymeans of Response Surface Methodology (RSM), with the help of Design Expert Version 7.0. The central composite design (CCD) was applied to design experiments for the evaluation of the interactive effects of the three most important extraction variables, namely temperature, time and liquor volume on 25g dye powder. The following optimized dye extraction conditions were found: 700C temperature, 51minutes extraction time and 1:16 for material-to-liquor ratio.
Keywords : Syzygium cordatum, natural dye, dye extraction, cotton dyeing.