Reducing salt use in dyeing of cotton fabrics with mono and bi-functional reactive dyes and investigation of organic salt use

Reactive dyestuffs are widely used in textile industry due to their high fastness, affordable cost and wide color range advantages. However, the application of these dyestuffs causes environmental problems such as high total dissolved solids and wastewater load. In order to overcome these problems, different studies have been carried out on the modification of reactive dyestuffs, dyeing machines or cotton fiber and ecological wastewater treatment. In this study, considering the exhausting, fixing and washing steps in reactive dyeing, dyeing with dyestuffs with high fixation yield and using biodegradable organic salts instead of inorganic salts is aimed to conduct ecological and sustainable reactive dyeing. It is thought that significantly reduce in the amount of unfixed dyestuff in wastewater and increase in color yield by higher dye exhaustion will greatly benefit sustainability. In the experimental study, 3 reactive dyestuffs (Reactive Red 180, Reactive Red 24, Reactive Red 195) with different structures and functionalities were used and dyeing processes were carried out with different concentrations of 4 different organic salt (trisodium citrate, NTA, glutamate, polyacrylic acid sodium salt) alternatives instead of inorganic salt (NaCl). Environmentally friendly dyeing recipes were generated to minimize the salt and water consumption. The color data obtained from ecological dyeing were compared with the classical dyeing process used NaCl. After dyeing, color yields of each sample were measured and the obtained numerical values were analyzed in SPSS and Minitab software and evaluated statistically. Consequently, the use of organic salts, trisodium citrate and glutamate, at lower concentrations in dyeing imparted favorable results and higher dyeing efficiency values were obtained. Compared to the classical dyeing process, results have been indicated that efficient reactive dyeing with less waste salt load to the environment can be conducted by consuming less chemicals.