Development and optimisation of a non conventional extraction process of natural dye from olive solid waste using response surface methodology (RSM)

Dyes obtained from different natural sources have emerged as an important alternative to synthetic dyes. In this study, optimisation of natural colorant non-conventional extraction technique from olive waste was investigated using response surface methodology. The combined effects of extraction conditions on total phenolic content (TPC) and relative color strength (K/S) were studied using a three-level three-factor Box-Behnken design. The optimum conditions for dye extraction were found to be 0.14 mol/L, 62.11 min, 71.23 degrees C and 4.5 g for sodium hydroxide concentration, extraction time, temperature, and mass of the waste, respectively. The efficiency of extraction under these optimum conditions was found to be 1133.86 mg/L of phenolics and relative colour strength (KIS) equal to 23.22. Further, Fourier Transform Infrared Spectroscopy was used to identify the major chemical groups in the extracted dye. (C) 2014 Elsevier Ltd. All rights reserved.