Investigation of Dyestuff Recycled from Wastewater Containing Indigo/Sulfur Dyes

Turkey is one of the important centers of denim fabric production in the world. Warp yarn is usually dyed using indigo and/or sulfur dyes according to the impregnation method. The common feature of these two dyes is that they are insoluble in water and dye temporarily with a reduction reaction. The recovery of dyes in wastewater is targeted. Wastewater containing indigo and sulfur dyes taken from İskur Denim was sedimented using the chemical flocculation technique and solid material was obtained after drying. The sedimentation process was affected by the pH of the environment, the mixing speed and the concentration of sedimentation chemicals. The best sedimentation was achieved by adding flocculators supplied by AKKİM to the wastewater sample in the pH range of 8-8.5. The obtained sludge was subjected to condensation reaction with the developed binding agent. The energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the dyes obtained from indigo and sulfur wastewater were determined as -4.78 eV and -4.04 eV, respectively, by cyclic voltammetry. These values are very close to the original dyes and give hope for dyeing performance.