indigo has been widely used as a dye in the industrial dyeing due to its good color fastness in dyeing cellulose fibers. However, excess reducing agent, "insurance powder (Na 2 S 2 o 4)", was always used in the actual production of the factory, sparking serious pollution (water pollution and air pollution). Herein, we developed a practical and environment-friendly indirect electrochemical reduction of indigo, and applied this method for cloth dyeing. The electrochemical device was designed in the combination of source of electro-catalytic reduction and dyeing. The iron-triethanolamine-calcium gluconate (Fe-TEOA-Ca) complex played a role of key intermediate, and ultrasonic wave was found to speed up the indirect electro-catalytic process. The electrochemical performance of intermedia was improved by calcium ion addition. Washed with oxalic acid solution, the dyed fabric could achieve the level of color fastness in industry standard. Generally speaking, our method leads to a green route for indigo reduction using electrochemistry, which may change the crafting process of indigo dyeing in industry.

The production of denim clothing has been broadly applied with the sodium hypochlorite washing technique, the parameters of which influence immensely on the effect of washing. It is the unclear declaration of the correlations between parameters of this technique and the final effects that makes it difficult to reduce the cost of washing in an efficient way. In this essay, L25(35) Orthogonal experimental design method has been adopted to process chlorine bleaching experiment, by using parameters of the technique as the input parameters ( the time, sodium hypochlorite concentration, temperature), and by using after-washing effects as output response ( including K/S value, the bending stiffness, the warp-weft tensile breaking strength). Secondly, building agency theory model for the input-output correlation by utilizing response surface methodology in multivariate second-order to test the accuracy of the model, and to analyze how input parameters correlate to the result of chlorine bleaching. At last, based on the agency model, there will be raised up with the optimization model for production cost of the denim chlorine bleaching technique, which is solved by genetic algorithm method that could satisfy the purpose of reducing costs.