Impurities of Water on Textile Wet Processing:
Water impurities can have a significant impact on textile wet processing. It can seriously affect quality of wet processing and even damage the fibers depending on their nature and concentration. Contaminants in water can interfere with the chemical reactions that occur during various stages of textile production, including dyeing, printing, and finishing. The presence of minerals, organic matter, and other impurities in water can cause color changes, fading, and other issues that affect the quality of the finished product.
Impurities in water can also scale formation on the surfaces of machinery and equipment, reducing their efficiency and lifespan. This can increase costs associated with maintenance and replacement.
Effect of Water Impurities on Textile Wet Processing:
The quality of water to be used in a process house decides the ultimate quality of cloth like whiteness, brightness of color etc. The main impurities in water are turbidity and color, iron and manganese, alkalinity and hardness. The quality of water received in the textile mills depends on their history. The major water impurities and their effects on textile wet processing are briefly discussed below:
1. Organic Matter, Turbidity and Color:
Turbidity and color are usually due to presence of organic matter in water and these detract 1 brightness of the bleached and purity of shade of the dyed goods. The organic matter whether dissolved or suspended also breeds micro organisms that may develop mildew, fungi etc. which in turn produce colored spots, foul smell and even holes in the fibrous material. The microorganism also grows inside the water pipes and chokes these and sometimes even dissolves the pipe-metal.
2. Mineral Salts:
Calcium, magnesium, and iron minerals can cause scaling and deposits on equipment, reducing efficiency and increasing maintenance costs. The presence of mineral salts can affect the pH of the processing solution, which can in turn affect the effectiveness of detergents, bleaches, and other chemicals used in the process. The mineral salts can also interfere with the bonding of dyes to the fibers, leading to poor colorfastness and fading.
3. Hardness:
Hardness creates many other undesirable effects in wet processing. The textile dyes for each fiber are designed to have low solubility in water and these become difficult to dissolve in very hard water. Due to insufficient solubility the dye-shade becomes weaker and may also produce spots on the dyed fabric. Further on heating or on coming in contact with alkalis during dyeing and soaping, calcium and magnesium ions are precipitated on fabrics as whitish carbonates and hydroxide particles. Hard water can also cause scaling and deposits on equipment, reducing efficiency and increasing maintenance costs.
4. Total Dissolved Solids:
In addition to hardness causing calcium and magnesium salts, water contains other dissolved salts that are mainly sodium cations and chloride, sulphate and bicarbonate anions. These sodium salts increase TDS of water and also create many difficulties in processing of textiles. Dyes of low solubility are likely to be precipitated even in softened water of high TDS on dissolving and the same can happen in preparing printing pastes. Presence of excessive amount of sodium ions also gives a damp and limp handle to the finished fabric due to their tendency to hold water. High TDS in the boiler feed water causes foaming and carry over Problems that lower efficiency of the boilers and also create difficulties in processing. Excessive concentration of sodium ions in boiler water also accelerates corrosion of the iron plates due to their high electrical conductivity. Such waters also require more frequent blow-downs and result in f loss.
5. Dissolved Gases:
Water normally has small quantities of oxygen and carbon dioxide dissolved in it. The latter reacts with steel pipes carrying water and steam, to form soluble ferrous bicarbonates. The dissolved ferrous ions, besides producing unsightly stains, catalyze reactions of hypochlorite and hydrogen peroxide during bleaching and damage cotton goods by lowering their strength and even making holes. The dissolved oxygen can cause serious damage to the boilerplates by converting the ferrous bicarbonate, formed initially, into ferric oxide and releasing carbon dioxide to react again with more iron. The reaction continues till the entire dissolved oxygen is exhausted by reacting with the boiler-plates. Oxygen in water also wastes the reducing agents like dithionite that is used in application of vat dyes.
References:
- Chemical Technology in the Pre-Treatment Processes of Textiles by S. R. Karmakar
- Theory and Practice of Water and Wastewater Treatment, Second Edition By Ronald Droste and Ronald Gehr
- Basic Principles of Textile Coloration By Arthur D Broadbent
You may also like:
- Parameters of Water for Textile Wet Processing Industry
- Potential Problems Caused by Hard Water in Textile Wet Processing Industry
- Physical and Chemical Properties of Water Used in Textile Wet Processing
- Impact of Water in Textile Wet Processing
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
