The Optimization of Synthetic Indigo Dye Using Phosphate Acid Catalyst


As the technology advances, the natural dye substance now replaced by the synthetic dyeing substance. The using of natural dyeing substance, however still maintained especially in the process of making batik. Batik fabric which made by natural dye substance is more expensive due to its highly artistic value, non carsinogen, eco-friendly as well as its exclusivity. Natural blue dyeing substance can be extracted from indigo plant thtrough hidrolysis and oxidation reaction. Indikan glycosides in the leaves of the indigo plant produces indoksil hydrolyzed and glucose. Oxidized Indoksil blue substance is obtained. On phospat acid hydrolysis reaction acts as a catalyst. The purpose of this research is to obtain the optimum operating conditions for the manufacture of the indigo dyeing substance.

The indigo plant that is used is about 5 months old, using the tools including reactor, stirrer, aerator, and oven. The optimazion of the parameter are the concentrate of phospat acid 0.001 – 1 M and the ration of the substance/solvent    2.5 – 10 g/125 g solvent. The indigo dyeing substance is analyzed using gravimetry method.

The result data of the experiment are analysed using RSM method, the model that is apropriate is the linear model, and the mathemathic equation is Y= 0.12 A – 0.035 B + 0.35. The optimum operation condition is on the 0,5 mol/L of the concentration of phospat acid and the ingredients comparison is 6.25 g/125 g solvent and the concentration of the dyeing substance is 34.98%.

Keywords: indigo dyeing substance, hydrolisis, oxidation, optimum