How to solve the residual smell of denim cloth？

(1) For the residual hydrogen sulfide gas in denim fabrics, suitable desizing methods can be used in the washing process of clothing to minimize the hydrogen sulfide smell. At present, the most successful desizing aids include desizing enzyme DL and hydrogen peroxide.

Desizing enzyme DL does not need to adjust the pH value or add other additives when using it. When cold water is directly added to the washing machine and rotate the machine to make it uniform, then the temperature is raised to 50°C, desizing for 15-20 minutes, Desizing Enzyme DL can not only reduce the odor, but also improve the hand feel and improve the effect of subsequent cellulase washing. Desizing with hydrogen peroxide needs to control the decomposition rate of hydrogen peroxide, otherwise the desizing will be incomplete and the smell will not be removed cleanly.

By using it with the oxygen bleaching stabilizer SS, it can not only control the decomposition speed of hydrogen peroxide, remove the odor, but also prevent the fading of the sewing thread used in denim clothing. Generally, desizing at 50°C for 15-20 minutes.

(2) The residual odor of chlorine bleaching is mainly caused by the insufficient reduction of the chlorine-containing components after bleaching into sodium chloride. The use of appropriate dechlorinating agents can effectively reduce the residual odor.

For the dechlorination treatment after chlorine bleaching, the common dechlorination agents on the market are sodium thiosulfate, hydrogen peroxide (hydrogen peroxide) and dechlorin DC.

The baking soda has strong reducibility and can reduce the bleaching water, but after dechlorination, it is easy to leave sulfur on the fabric, causing the fabric to turn yellow; in addition, the dechlorination is not clean, and the treated clothing has a clear smell of chlorine. In addition, the baking soda itself is unstable. The sulfur dioxide produced after high-temperature heating is toxic and has a strong stimulating effect on the eyes, skin, mucous membranes and respiratory tract, and endangers the health of the operators.

Hydrogen peroxide and bleaching water show reducing properties together, which can reduce the hypochlorite in the solution to salt, thereby achieving the effect of dechlorination. However, due to the weak reducing power, the dechlorination is not clean, the residual chlorine is serious, and the chlorine smell is obvious.

Dechlorine DC is a white powder. It is mainly used to remove residual chlorine on the fabric after rinsing denim garments, replacing the sodium bicarbonate. The dosage is only 50% of the sodium bicarbonate. Thorough dechlorination, greatly reducing chlorine overflow during the dechlorination process, improving the working environment, and leaving no residual chlorine and sulfur smell on the fabric. In the washing process, the residual liquid in the washing machine does not need to be discharged after the chlorine bleaching is completed, and it can be added directly to achieve the purpose of energy saving and water saving.

(3) The odor residue after high manganese rinsing is mainly caused by the neutralizer itself. Sodium metabisulfite is cheap, and the neutralized cloth has good whiteness, but it will release sulfur dioxide, which is serious. Related companies began to develop and use some related alternative products, such as odorless modified sodium metabisulfite or other non-odorous chemicals, such as hydroxylamine sulfate and manganese removal crystals.

Hydroxylamine sulfate is colorless or white crystals, soluble in cold water, ethanol and methanol, and has strong reducibility. But it is expensive. Although it does not release odorous gas, the COD/BOD value in wastewater is very high.

Manganese removal crystal is a new type of neutralizer, a white semi-crystalline solid, the solubility in water is lower than that of hydroxylamine sulfate, and it has strong reducibility. Its price is much lower than hydroxylamine sulfate and does not release odorous gas. Compared with other neutralizers, the COD/BOD in wastewater is extremely low. The denim clothing after treatment has better background color than sodium metabisulfite.

As long as the green chemicals are selected in the denim washing process, and the appropriate dosage and technology are used, the residual odor of the clothing can be minimized and the discomfort brought to consumers during the later wearing process can be reduced.