Water for textile industry

Water for textile industryMD.AZMERI LATIF BEG

M. Sc in Textile Engineering

Specialized in Apparel

Manufacturing, Processing and

Designing

The fresh water is rarely used directly for drinking purposes, as the water gets contaminated with impurities during its transportation to the city reservoir. Even, the water which is to be used for textile industrial process also needs a pretreatment. For instance water for textile industry should not contain too much of iron, as it causes staining of fabric. Water for food industry cannot afford to have manganese, as it causes staining of containers and adversely affects the taste and quality of material cooked in that water. The boiler feed water should not contain excess of salts of calcium and magnesium, as they consume more heat due to insulation of containers and pipes by deposition of scales.

Water for textile industry

Water in textile industry: The textile fibers, including wool, silk and cotton is prepared for fabrication by scouring processes which involve the use of quantities of water. The standards of purity required are high in all cases but very with the specific operations.

Wool scouring- in wool scouring, all fresh water is added in the third or final scouring tank from which the wool emerges in its finished condition. Impurities in the water that will have cling to the fiber therefore are obviously out of place and will have the same deleterious effect in subsequent processes as imperfect scouring. Suspended impurities are clearly undesirable, organic matter being especially deleterious. Therefore waters polluted by sewage or organic industrial wastes and turbid waters are always purified before use in scouring-tanks.


A second and even more important class of impurities consists of those substances which unite with soaps used in scouring to form insoluble soaps. These substances iron, aluminum, calcium, and magnesium, destroy their equivalent values of soap for detergent purposes thereby making necessary the use of an excessive amount of soap. In addition the insoluble soaps sticks closely to the fiber and make efficient scouring very difficult. On this account they are more detrimental to the process than inorganic suspended matter composed largely of colloidal particles of clay. Priest man states that water containing 30 English degrees of hardness (428 parts per million of calcium carbonate) cannot be used for satisfactory washing and adopts 50 of hardness (71 parts per million of calcium carbonate) as the limit of hardening constituents for a satisfactory water supply.


In scouring by the two-stage process of steeping

and scouring, the importance of pure water is

even greater for in addition to the effect of

hardness in the scouring operation, the recovery

of potash from the steep water will be rendered

somewhat more expensive and the purity of the

product will be decreased by the saline

constituents of the water. In this case all mineral

impurities not merely the hardening constituents

have a deleterious effect.


In scouring by violate solvents and subsequent washing, since no soaps used, purity of water is a minor consideration. Suspended matter of course is undesirable. If the wash water is utilized for the recovery of potash, all dissolved impurities will cause scale in the evaporators and all will decrease the purity of the potash produced. Each 100 parts per million of mineral solids in the water will reduce the purity of the potash by approximately 1 percent. If the wool is scoured by one of the newer detergents such as the suffocated alcohol products like lgepone6 then the hardness in the water will be of less subsequence. This is due to the fact that the calcium and magnesium compounds of these detergents are soluble, hence do not because a loss of detergent power and more particularly do not precipitate on and foul the surface of the wool.

Water used for rinsing the wool after scouring may amount to as much as 100 gallons for each pound of wool scoured. This water should be free from suspended matter, but otherwise requires no special qualities.


Silk industry uses- in the silk industry pure waters are required, as in wool scouring, to conserve soap and prevent contamination from sticky precipitates.

In the first stage of silk manufacturing, the raw silk is soaked in a strong solution of soap containing meat’s foot oil. This process is necessary to give the silk operation. With water containing lime and magnesium in large amounts, the soap forms a characteristic curd precipitate which mats the fiber and causes considerable difficulty in winding the silk. Furthermore, the precipitate clings to the fibers, forming soap specks which later harden the silk at these points.


The next operation that of boiling off requires the use of greater quantities if both soap and water. The deleterious results of unsuitable water here are. Therefore intensified where lime spots form, the silk may become discolored and the fiber will crack.

Weighting is largely affected by the lime and magnesium content of the water used in previous operations. Lime spots prevent the absorption of the tin solution at such points, since the fiber is there covered by the sticky lime precipitate. The result is lack of uniformity in weighting and hungry spots which later in the dyeing operation produce uneven coloring of the fabric.

Brighter colors are said to be produced with soft waters, using less dye, than with other water containing large amounts of the alkali-earth elements.


Cotton industry uses – the cotton industry has long recognized the value of soft water in its operations. The boiling-off requires the use of resin soap in large amounts, which soap, like others, is waste fully consumed by calcium and magnesium in the water. The precipitates formed are resonates of calcium and magnesium, which are just as troublesome in later operations as the corresponding oblates and starts. Spots, difficult to wash out, dye and bleach are formed and a uniform white, so essential in this industry, is almost impossible to obtain. It is characteristic of silks and coattails produced by plants using soft water that the fabric has a softer feel not at all like the harsh feel of fabrics produced with waters containing large amounts of the hardening constituents. In the manufacture of textiles therefore, the necessity for a clear colorless water containing as little calcium and magnesium as possible is obvious unless newer detergent are use.


Rayon industries- in the rayon industry as in the case of natural fiber the water must be high purity to give best results. Water must be soft because lime and magnesium salts which are responsible for hardness of water also cause hardness of finish on rayon and interfere with the level dyeing. Traces of iron in the water may be highly detrimental as evidenced in a rayon plant operating on the Niagara River. In this plant splotchy discolorations were noted in the product and after much effort, were finally traced to the presence of less than 0.5p.p.m. of iron in the wash water. When this was removed by suitable treatment the difficulty cleared up.


Water for dyeing and bleaching- involving as it does

the use of such small amounts of chemicals and large

amounts of water to produce delicate coloring effects,

the dyeing of fabrics often presents chemical problems

of considerable difficulties. The solution of these

problems often hinges on the proper choice or treatment

of water used in the process. Water containing large

amounts of calcium is unsuitable and even ruinous for

use in dyeing with aniline colors, but is essential to the

successful use of logwood or weld, dyed on a mordant

of iron or aluminum.

Water for dyeing and bleaching

Calcium and magnesium act very much alike in dyeing. Some of the effects of these constituents are as follows: Heavy tar like precipitates from when such aniline colors as methyl violet, malachite green, magenta and safranine are dissolved in waters high in calcium and magnesium. This tar like precipitate sticks to the fiber and results in uneven dyeing, poor shades and that annoying defects of rubbing off. Magenta and safranine are peculiarly susceptible to the influence of these constituents, the effect being noticeable in changes in both color and intensity of the coloring material. Color is wasted and flat shades are produced in dyeing with Turkey red or cochineal scarlet.


On the other hand in dyeing with alizarin it is necessary to have calcium carbonate present to cause complete saturation of the mordents, but when calcium and bicarbonate radicals are present, carbonic acid is freed, calcium carbonate is precipitated by the heat and the bath takes a violet color due to the formation of a compound of calcium and alizarin. If the solution is boiled the lime lake deposits as a violet powder and the bath cannot be used. Thus it can be seen that calcium may be helpful or detrimental to dyeing according to circumstances, but as a rule calcium and magnesium salts result in UT1 even dyeing, fading colors, spotted effects, off-shades, and a waste of color.


Iron is very objectionable impurity. Dull and flat colors are frequently caused by this constituent especially when dyeing on a mordant. If water contains iron in any appreciable amounts, it is practically useless for dyeing or printing with alizarin or for any of the coal-tar colors that are fixed on a tannin mordant. Also in bleaching iron is a troublesome constituent. The iron is oxidized bleach solutions causing yellow, brown or muddy white effects. This difficulty can be partially remedied by acid treatment, but there is then danger of injuring the fabric. Lau8ndries have much the same difficulty with ferruginous waters. It is therefore evident that a water suitable for dyeing and bleaching should be free suspended matter, low content of iron as soon as possible.

Water for Apparel washing, processing and finishing

In apparel washing, processing, dyeing and finishing need water. Water is an inevitable part of textile and apparel processing industry Water for a textile plant may come from various sources. But this water can not be used directly in textile processing because it contains various salts. These salts are mainly the carbonates (CO3

2-), Hydrogen carbonates or bi-carbonates (HCO3

-), Sulphates (SO42-) and Chlorides

(Cl-) of Calcium (Ca2+), and Magnesium (Mg2+). These are called hardness in the water. These must be removed though water treatment plant. An study said that need 170 liter water to process a knit fabric. Apparel finishing is the last part of a end product so water must be purified before using.

Environment

Water for textile industry