Detergency

An educational slide for science or engineering students. It's about detergency. That containing detergent, its classification, working principle etc.

1. WELCOME

2. D etergency Created by : MANAS MANDAL RUPOM Registration No : J201713017 Session : 2016-17 Department : Wet Process Engineering Sheikh K amal Textile Engineering College, Jhenaidah.

3. Detergency is a process to remove oil or dirt from fabric surface using surface active agents(surfactants/ detergent). In other word detergency is the ability of a detergent to detach(remove) soil (dirt and grease) from a surface by displacing it with chemicals(called surfactants) which adhere more readily to the surface being cleaned than to the soil . Detergency ?

4. C LEANING P ROCESS : The process by which detergent remove dirt and oil is detergency. When a fabric adhered with oil and dirt is immersed in a bath of surface active agent (detergent), then the detergent remove the oil or dirt from the fabric surface. The main function of the detergents is to break down the surface tension between dirt/oil and the fabric. Then the oil/dirt can easily be washed out finely by using some mechanical stress to the fabric. 1 2 3

5. Mechanism

6. M ECHANISM: Fabric Oil ɵ Stage: 1 Stage: 2 Stage: 3 For each type of fabric and dirt there is a certain angel between fabric and oil or dirt which depends on the surface tension between them. But detergent or surfactant can reduce the surface tension. And by reducing the surface tension, the dirt or oil is being converted from horizontal shape to spherical shape. Then the contact angel between fabric and dirt or oil increased and the area of contact reduce the most. So, then the oil or dirt can easily be removed from fabric surface by some physical stress. ɵ ɵ

7. M ECHANISM: ɵ T s T LS T L At the adhering situation of dirt, its actual shape will be detached by the interaction of the following forces: T L = Surface tension between oil and surrounding. T S = Surface tension between fibre and water. T LS = Surface tension between fibre and oil. ɵ = Contact angel. From Young’s equation we get, T S = T LS + T L cosƟ cosƟ T L = T S - T LS [When Ɵ=0, cosƟ= 1] T S = T LS + T L T LS = T S – T L  

8. ɵ T s T LS T L M ECHANISM: Any increase in T LS + T L in relation to T S will decrease the area of contact between the oil and fibre. Then oil drop will more spherical and easy to detach. If Ɵ = 0°, then T L = T S - T LS If Ɵ < 90 °, A ttaching face. If Ɵ > 90°, Detaching face. ɵ Attaching Phase D e taching Phase

9. M ICELLE F ORMATION: Fig: 02 Fig: 03 Fig: 01 When detergent molecules are added to pure water, firstly few molecules aligned to the air/ water surface. Hydrophilic heads are on to touch of water and hydrophobic tail oriented towards air. When additional molecules are added, surface are pecked fully then molecules are forced into bulk. Then detergent molecules form a spherical shape named ‘MICELLE’. Hydrophilic head Hydrophobic tail Fig: Detergent Molecule In micelle, hydrophobic tail of molecules are situated inner side of the spherical shape which are insoluble in water. And hydrophilic heads surrounded outside.

10. M ICELLE F ORMATION: Oil or dirt of fabric surface that are hydrophobic, collapsed in the micelle. That means hydrophobic dirt is bounded by the tail part which are also hydrophobic. And this micelle covered by the hydrophilic head on the outer side. In this situation, dirt or oil is free (loose) from fabric surface. Then this can be easily removed by applying some mechanical stress to the fabric.

11. C LASSIFICATION: Ionic detergency: Anionic Cationic Amphoteric 2. Non ionic detergency Anionic Detergency : When detergent ionizes & produces anion as dominating part that’s known as anionic detergency. Example: C 17 H 35 COO Na C 17 H 35 COO - + Na + Sodium stearate Large anion portion dominating (Dominating part)

12. C LASSIFICATION: b) Cationic D etergency : W hen detergent ionizes & produces cation as dominating part that’s known as cationic detergency. N CH 2 (CH 2 ) 14 CH 3 Cl Catylpyridinium Chloride N CH 2 (CH 2 ) 14 CH 3 + + Cl - Dominating Cation Portion Example:

13. C LASSIFICATION: c) Amphoteric Detergency : It produces both cations & anions in large segments ( zwitter ions ). Example: H 2 N - ( CH 2 ) n - COOH H 2 N - (CH 2 ) n - COO + H In alkaline ( OH ) it shows anionic detergency, in acetic ( H ) it shows cationic and in neutral it is nonionic. It has lubricating properties - + - + 2) Nonionic detergency : When detergent doesn’t not ionized but gets oriented at surface & reduces surface tension its known as nonionic detergency. Example: C 17 H 35 COOH + CH 2 -CH 2 C 17 H 35 COO(CH 2 -CH 2 -O ) O Stearic acid E thylene glycol Ester It consists of sufficient hydrophilic heads and hydrophobic tails.

14. Thanks to all.