文档介绍：Chapter 9. Detergency of Surfactants
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§1. Introduction
Cleaning process is a plex process;
No surfactants by self can clean a surface;
Detergency (洗涤作用) – this term, when applied to a surfactants, means the special property it has of enhancing the cleaning power of a liquid.
Detergency – bination of effects involving adsorption at interface, alteration of interfacial tension, solubilization, emulsification, and the formation and dissipation of surface charges;
Detergency – involving mechanical action, biochemical action, and fabric softening.
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§2. Mechanisms of the cleaning process
Three elements in cleaning process
The substrate (the surface that is to be cleaned)
Hard surface – glass , metals, and etc
Soft surface – fabric , fiber
The soil (the material that is to be removed from the substrate in the cleaning process)
Liquid soils – oil or fat
Solid soils – black carbon, dust, and etc
(3) The bath or cleaning solution.
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2. Force between substrates and soils
Mechanical force – soft & porous substrates, particle diameter r of the particles , then force,
r < 100nm, then difficult to wash off
(2) Electrostatic force – surface potentail
wool/water= - 48mV
cotton/water= - 38mV
silk/water= - 1mV
cation bridge (阳离子桥) - polyvalency ions
Soil---
++
- - - - - - - - - - - - - - - -
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2. Force between substrates and soils
Mechanical force – soft & porous substrates, particle diameter r of the particles , then force,
r < 100nm, then difficult to wash off
(2) Electrostatic force – surface potentail
wool/water= - 48mV
cotton/water= - 38mV
silk/water= - 1mV
cation bridge (阳离子桥) - polyvalency ions
Electrostatic force > Mechanical force
Soil---
- - - - - - - - - - - - - - -
++++
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(3) Chemical force – polar soils prote