Top 10 Advancement in Surface and Colloid Chemistry.

Surface and colloid chemistry involves the
study of physical and chemical phenomena that occur at
the interface of two phases,
including solid–liquid interfaces, solid–gas interfaces,
solid–vacuum interfaces, and liquid–gas interfaces. It includes
the fields of surface chemistry and surface physics (Prutton,
Martin, 1994).

In everyday life, reactions and changes are observed
that are dependent on the structures of the involved matter (which may be
solids, liquids, or gases). However, in many industrial (chemical industry and
technology) and natural biological phenomena, it is found that some processes
require a more detailed definition of matter. Matter exists as Gas Liquid Solid
phases, as has been recognized by classical science.

Surface chemistry can be roughly defined as the
study of chemical reactions at interfaces. It is closely related
to surface engineering, which aims at modifying the chemical composition
of a surface by incorporation of selected elements or functional groups that
produce various desired effects or improvements in the properties of the
surface or interface. Surface science is of particular importance to the fields
of heterogeneous catalysis, electrochemistry, and geochemistry.

The science of surface and colloid chemistry is one
of the most important. Common examples of the principles at work  involves the following;  Rain drops , Combustion engines,  Soap bubbles Foam (in firefighting),  Food products (milk, cheese) , Air pollution
(fog, smog, sandstorms) , Wastewater treatment, 
Washing and cleaning Cosmetics, 
Paint and printing; adhesion; friction, 
Oil and gas production,  Oil
spill,  Plastics and polymers,  Biology and pharmaceutical,  Milk products Cement , Adhesive Coal (coal
slurry transport).

With the above been said, below are the 10
advancement in surface and colloid chemistry.

HETEROGENEOUS CATALYSIS: With catalyst supports, the reaction that occurs
often occurs on the surface of either the catalyst or the support.
In surface and colloid chemistry, heterogeneous catalysis refers
to the form of catalysis where the phase of
the catalyst differs from that of the reactants. Phase here
refers not only to solid, liquid, versus gas, but also immiscible
liquids, e.g. oil and water. The great majority of practical
heterogeneous catalysts are solids and the great majority of reactants are
gases or liquids (Gadi Rothenberg, 2001).  Heterogeneous catalysis is of
paramount importance in many areas of the chemical and energy industries.
Heterogeneous catalysis has attracted Nobel prizes for Fritz
Haber and Carl Bosch in 1918, Irving Langmuir in 1932,
and Gerhard Ertl in 2007 (Swathi and Sebastian, 2008). Good examples of
heterogeneous catalysis involve the following, the cracking, isomerisation and
re-forming of hydrocarbons to form appropriate and useful blends of
petrol, Ammonia synthesis (Haber–Bosch process), Sulfuric acid synthesis (Contact
process), and Nitric acid synthesis (Ostwald process).

2.
SEMICONDUCTOR DEVICE FABRICATION: This is the process
used to create the integrated circuits that are present in everyday electrical
and electronic devices. It is a multiple-step sequence of photo lithographic
and chemical processing steps during which electronic circuits are gradually
created on a wafer made of pure semi-conducting material. Silicon is
almost always used, but various compound semiconductors are used for
specialized applications.

The entire manufacturing process, from start to
packaged chips ready for shipment, takes six to eight weeks and is performed in
highly specialized facilities referred to as fabs.

3.
SURFACE TENSION: The role of surface tension of liquids
is found in many important systems. The capillary vise is found to play an
important role in many everyday processes (such as washing and cleaning,
plants, etc.). Surface tension is the elastic tendency of a fluid surface
which makes it acquire the least surface area possible. Surface
tension allows insects (e.g. water striders), usually denser than water,
to float and stride on a water surface. It is also this phenomenon that allows
ship which is denser than water to float on water.

At liquid-air interfaces, surface tension results
from the greater attraction of liquid molecules to each other (due to cohesion)
than to the molecules in the air (due to adhesion). The net effect is an inward
force at its surface that causes the liquid to behave as if its surface were
covered with a stretched elastic membrane. Thus, the surface becomes under
tension from the imbalanced forces, which is probably where the term
“surface tension” came from (US Geological Survey (July 2015) . Because
of the relatively high attraction of water molecules for each other through a
web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons
per meter at 20 °C) compared to that of most other liquids. Surface
tension is an important factor in the phenomenon of capillarity.

Surface tension has the dimension of force per
unit length or of energy per unit area. The two are equivalent,
but when referring to energy per unit of area, it is common to use the term surface
energy, which is a more general term in the sense that it applies also to solids.
Surface and colloid chemistry also finds immense application in the Separation
of oil and water (in this case, water and liquid wax) is caused by a tension in
the surface between dissimilar liquids. This type of surface tension is called
“interface tension”, but its chemistry is the same.

4.
FUEL CELL PRODUCTION: Fuel cell is a device that
converts the chemical energy from a fuel into electricity through a
chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing
agent (Nice et al, 2008). Fuel cells are different from batteries in
that they require a continuous source of fuel and oxygen or air to sustain the
chemical reaction, whereas in a battery the chemicals present in the battery
react with each other to generate an electromotive force (emf). Fuel
cells can produce electricity continuously for as long as these inputs are
supplied.

The first fuel cells were invented in 1838. The
first commercial use of fuel cells came more than a century later in NASA space
programs to generate power for satellites and space capsule.

5.
CLEANING AND DETERGENCY: One of the most important applications
of surface and colloid chemistry principles in everyday life is in the systems
where cleaning and detergency is involved. These are some of the most important
phenomena for humans (as regards health and welfare and technology), and it has
been regarded as such for many centuries. For example, the effect of clean
wings of airplanes is of utmost concern in flight security. Humans have been
aware of the role of cleanliness on health and disease for many thousands of
years. Many critical diseases, such as AIDS or similar infections, are found to
be lesser in incidence in those areas of the world where cleanliness is
highest. The term detergency is used for such processes as washing clothes, or
drycleaning, or cleaning. The substances used are designated as detergents
(Zoller, 2008). In all these processes, the object is to remove dirt from
fabrics or solid surfaces (floors or walls or other surfaces of all kinds).

6.
SELF-ASSEMBLY MONOLAYERS (SAMS): lipid-like substances
(almost insoluble in water) formed self-assembly monolayers (SAMs) on the
surface of water (Gaines, 1966; Adamson and Gast, 1997; Birdi, 1989, 1999,
2002; Chattoraj and Birdi, 1984).

Self-assembled monolayers (SAM) of organic
molecules are molecular assemblies formed spontaneously on surfaces by
adsorption and are organized into more or less large ordered domains (Love; et
al. (2005). In some cases molecules that form the monolayer do not interact
strongly with the substrate. This is the case for instance of the
two-dimensional supramolecular networks of e.g. Perylene-tetracarboxylicacid-dianhydride (PTCDA) on gold or
of e.g. porphyrins on highly
oriented pyrolitic graphite (HOPG).

7.
PRODUCTION OF ADHESSIVES: Adhesive may be used
interchangeably with glue, cement, mucilage, or paste (Pike,
Roscoe, 2013), and is any substance applied to one surface, or both surfaces,
of two separate items that binds them together and resists their separation. Adjectives
may be used in conjunction with the word “adhesive” to describe properties
based on the substance’s physical or chemical form, the type of materials
joined, or conditions under which it is applied.

The use of adhesives offers many advantages over
binding techniques such as sewing, mechanical fastening, thermal
bonding, etc. These include the ability to bind different materials together,
to distribute stress more efficiently across the joint, the cost effectiveness
of an easily mechanized process, an improvement in aesthetic design, and
increased design flexibility.

8.
DRUG DELIVERY:  Drugs
are applied in various ways to treat illness. A drug designed to cure liver or
lung must reach its target with a suitable concentration. The main object is to
treat the illness in any particular organ, and the drug dosage is determined
accordingly. However, if the drug breaks down in the process of transport
through the stomach, etc., then other innovations are needed. In the following
text, an example is given where drug delivery is designed through the nasal
pathway. Inhalable drug delivery: At present, there are many drugs that are
applied through the nasal pathway (inhalable drug delivery [IDD]). Besides
small molecules (such as hormones), even much larger molecules (such as insulin
and other proteins) have been reported as useful IDD systems. However, they
need to meet certain critical demands: Deliver the drug effectively and reach
the lung The particles (in the form of aerosols) need to be designed to achieve
consistent delivery Surface-active substances, which are known to enhance
penetration through the skin barrier, also needs to be added. These should, of
course, not cause any irritation in the nose and other air pathways. Insulin is
currently being marketed commercially for IDD.

9.
DIAGNOSTICS (IMMOBILIZED ENZYMES ON SOLID SURFACES):
In the past decade, extensive diagnostic instruments have become available to
determine the state of illness control. For instance, the concentration of
glucose (in the case of diabetes control) in blood can be easily measured today
by using a strip (size: 1 mm × 1 mm) covered with a suitable enzyme (glucose
oxidase), which, in contact with the blood sample, reacts (within 30 s) to
produce degraded substances of glucose (hydrogen peroxide). This enzyme is very
specific to the degradation of glucose. The reaction is calibrated to produce
an electrical signal, and millimole per liter (from 3 to 30 mmol/L) or
milligram per liter glucose from a small drop of blood can be safely measured.
The preparation of the diagnostic strip requires an even layer of the enzyme
(or any other suitable chemical) on the test strip. It can be controlled using
the following surface chemistry principles: Contact angle Surface tension of
the applied solution Use of AFM to make image analyses

10.
SOLID SURFACE ADSORPTION: In a large variety of
applications, the surface of a solid plays an important role (e.g., active
charcoal, talc, cement, sand, catalysis). Solids are rigid structures and
resist any stress effects. Many such considerations in the case of solid
surfaces will be somewhat different for liquids. The surface chemistry of
solids is extensively described in the literature (Adamson and Gast, 1997;
Birdi, 2002). Mirror-polished surfaces are widely applied with metals, where
the adsorption at the surface is much more important. Further, the corrosion of
metals initiates at the surfaces, thus requiring treatments based on surface
properties. As described in the case of liquid surfaces, analogous analyses of
solid surfaces can be carried out. The molecules at the solid surfaces are not
under the same force field as in the bulk phase. Adsorption studies have been
widely involve in water treatment, corrosion inhibition, environmental
purification etc. 

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