32
tained or restored, disease occurs. So, the changes in environment in which we live
is important as any change in environment can change homeostasis affecting
our health
1.8 Colloid Chemistry
Colloid chemistry is a specialization of chemistry that deals with material dispersions (e.g., particulates) in solids, liquids, and gases. Table 1.5 gives some examples
of colloidal suspensions. Dispersion of microscopically insoluble particles in
another substance is called colloid and term colloidal suspension is used to refer to
the overall mixture. To qualify as a colloid, the particles should not settle or should
take a very long time to settle.
The size of colloidal particles varies between about 1 and 1000 nanometers.
Some colloids are known to be translucent due to Tyndall effect, which is the
scattering of light by particles in suspension.
The following forces are responsible for suspension of colloid particles:
• Excluded volume repulsion (not able to overlap among hard particles).
• Electrostatic interactions (repulsion of colloidal particles due to electrical charges
possessed by them).
• Van der Waals forces (interaction between two dipoles that are permanent or
induced).
• Entropic forces (force resulting from the tendency of a thermodynamic system to
maximize its entropy).
• Steric repulsion (repulsion due to overlapping electron clouds around atoms/
molecules).
Unstable colloidal dispersions can form flocs and the phenomenon is widely
used by environmental professionals for removal of turbidity by following means:
• Removal of the electrostatic barrier accomplished by the addition of salt to a
suspension.
• Changing the pH of a suspension to neutralize the surface charge of the particles
in suspension.
• Addition of polymer flocculant to bridge individual colloidal particles or by
causing aggregation due to entropic effects.
Colloids are present in everybody’s cells, in the blood, and in all body fluids. Any
disturbance to colloidal nature would lead to disease. Particulate air pollution is
likely to contribute to their cardiovascular mortality and morbidity due to thrombotic (formation of a blood clot obstructing the flow of blood inside a blood vessel)
effects (Brook et al. 2010; Robertson and Miller 2018).
1 Fundamentals of Chemistry for Environmental and Medical Professionals
tained or restored, disease occurs. So, the changes in environment in which we live
is important as any change in environment can change homeostasis affecting
our health
1.8 Colloid Chemistry
Colloid chemistry is a specialization of chemistry that deals with material dispersions (e.g., particulates) in solids, liquids, and gases. Table 1.5 gives some examples
of colloidal suspensions. Dispersion of microscopically insoluble particles in
another substance is called colloid and term colloidal suspension is used to refer to
the overall mixture. To qualify as a colloid, the particles should not settle or should
take a very long time to settle.
The size of colloidal particles varies between about 1 and 1000 nanometers.
Some colloids are known to be translucent due to Tyndall effect, which is the
scattering of light by particles in suspension.
The following forces are responsible for suspension of colloid particles:
• Excluded volume repulsion (not able to overlap among hard particles).
• Electrostatic interactions (repulsion of colloidal particles due to electrical charges
possessed by them).
• Van der Waals forces (interaction between two dipoles that are permanent or
induced).
• Entropic forces (force resulting from the tendency of a thermodynamic system to
maximize its entropy).
• Steric repulsion (repulsion due to overlapping electron clouds around atoms/
molecules).
Unstable colloidal dispersions can form flocs and the phenomenon is widely
used by environmental professionals for removal of turbidity by following means:
• Removal of the electrostatic barrier accomplished by the addition of salt to a
suspension.
• Changing the pH of a suspension to neutralize the surface charge of the particles
in suspension.
• Addition of polymer flocculant to bridge individual colloidal particles or by
causing aggregation due to entropic effects.
Colloids are present in everybody’s cells, in the blood, and in all body fluids. Any
disturbance to colloidal nature would lead to disease. Particulate air pollution is
likely to contribute to their cardiovascular mortality and morbidity due to thrombotic (formation of a blood clot obstructing the flow of blood inside a blood vessel)
effects (Brook et al. 2010; Robertson and Miller 2018).
1 Fundamentals of Chemistry for Environmental and Medical Professionals