What is pH? Importance of pH in the textile industry.

Introduction

The pure water is neutral. When the acid dissolves in water, the pH will be less than 7 (25 °C). When dissolved in a base, or alkaline water, the pH is higher than 7. A solution of a strong acid, like hydrochloric acid, at a concentration of 1 mol dm−3 has a pH of 0.  Strong alkali solution, like sodium hydroxide, at a concentration of 1 mol dm−3, has a pH of 14. For this reason, the measuring pH values ​​are mostly between 0 to 14, although negative pH values ​​and values ​​above 14 are completely possible. While pH is a logarithmic scale, the difference in one pH unit is equal to ten times the difference in hydrogen ion concentration.

What is pH?

The decimal logarithm of the reciprocal of the hydrogen ion activity in a solution is called pH. The pH scale indicates the concentration of hydrogen ions in the logarithmic and contrast solutions. This is because the formula used to calculate the pH is associated with the base 10 logarithms of the molar density of the hydrogen ions in the solution. Exactly, pH is the negative of the base 10 logarithms of the activity of the H+ ion.

Shaker machine for pH

Importance of pH in the textile industry

The pH value of textiles refers to the acid and alkaline components of the fabric residue, which is one of the limited indicators of harmful substances affecting human health. The National Standard GB 18401-2010 "Basic Technical Specification for National Textile Products" stipulates that the pH value of textile products for children and direct skin appearance should be controlled between 4 and 8.5. The pH value of textile products that are not directly exposed to the skin should be controlled from 4 to 9 If the products need to be treated with the following processing techniques, the pH value can be relaxed from 0 to 10.5 to 4.

In general, human skin pH ranges from 5.5 to 7 and is weakly acidic. The high pH value of textiles will destroy the weakly acidic environment of the skin on the surface of the human body, cause itching and expose the skin to other pathogenic bacteria and even cause dermatitis and other symptoms.

Also, the high or low pH value of the fabric makes it easy to damage the fabric during storage. It is seen that the pH value of textile products is closely related not only to the health of consumers but also to the quality of textile products.

pH testing procedure

Method: ISO 3071 2005 (E)

A. Equipment/ Apparatus

i. Scissors

ii. Scale

iii. Stoppard glass or propylene flasks

iv. Mechanical shaker

v. Beakers are chemically resistant with a capacity of 150 ml.

vi. Rods chemically resistance

vii. pH Meter with a glass electrode capable of measuring to at least 0,1 pH units.

viii. Balance accurate to 0,001 g.

B. Reagent: For pH Meter calibration

i. pH 4 Potassium hydrogen phthalate solution 10.21 g/l.

ii. pH 6.9

iii. Potassium hydrogen orthophosphate (Na2Hp04) 3.9 g/l.

iv. Potassium chloride solution 0.1 ml/l prepared using distilled or deionized water.

v. Distilled or Deionized water at least grade 3.

C. Sampling

i. Cut the specimen at least 150 mm away from the selvage of the fabric

ii. Specimen Size 5 mm Squire.

iii. Specimen weight 2 grams.

D. Working Procedure

i. Take 100 ml distilled water in the Stoppard glass.

ii. Sample put on the Stoppard glass.

iii. Shaker for two hours.

iv. Measurements of the pH of the aqueous extract.

v. Immerse the electrode time in the same solution used to prepare the extract until the indicated pH value stabilizes.

vi. Immediately immerse the first exhaust in a beaker at a depth of at least 10 nm and stir gently with a rod until the pH value is fixed.

vii. 1st reading steers 2nd 30 seconds does not steer 3rd not steer 30 seconds.

viii. Result record 2nd and 3rd average.

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