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The Science Behind
Activated Carbon Water Filters
Also called “activated
charcoal,” activated carbon is a form of carbon that has been processed to have
an incredibly large surface area
by CB Tech
Why
is the same active ingredient useful in teeth whitening, water filtration, and
outer space life support systems?
Activated
carbon has swept through the modern world and become an essential component in
an enormous range of industries, including medical, cosmetic, and agricultural
applications.
This
versatile ingredient is also a crucial component for the best water filtration
systems.
But
what makes activated carbon so widely effective? Let’s explore the unique
characteristics of activated carbon along with why it’s the best choice for
water filtration.
What
Is Activated Carbon?
Also
called “activated charcoal,” activated carbon is a form of carbon that has been
processed to have an incredibly large surface area.
Tiny,
low-volume pores provide a surface for either adsorption or chemical reactions.
One
gram of activated carbon has over 32,000 square feet (3,000 square meters) of
surface area — and one teaspoon has roughly the area of a football field.
This
enormous area alone makes activated carbon extremely useful for a wide range of
applications, but activated carbon can undergo further chemical treatment to
increase its adsorption properties.
.
Activated carbon is derived from a carbonaceous source material. Examples include wood, bamboo, sawdust, willow peat, coconut shell, peach pits, coir, petroleum pitch, and a variety of coal.
.
Activated carbon is derived from a carbonaceous source material. Examples include wood, bamboo, sawdust, willow peat, coconut shell, peach pits, coir, petroleum pitch, and a variety of coal.
But
regular carbon isn’t the same as activated carbon. To form millions of tiny
pores across its surface, carbon must first be “activated.”
This
is produced by one of two methods: thermal or chemical activation.
1. Thermal Activation
In thermal
activation, the source material is formed into activated carbon utilizing hot
gases. After being exposed to heat, steam is usually introduced to help open
the pores.
Thermal
activation is typically done through a process involving reduction of moisture,
reduction of volatiles, carbonization, and a steam treatment. This process is
carried out in an inert atmosphere using gases such as carbon dioxide, nitrogen
or argon.
2. Chemical Activation
In chemical
activation, chemicals are added to the raw source material before the
carbonization process. Typically, the chemical used is a strong base, acid, or
salt. The material is then exposed to heat, and it activates quickly.
.
Classifying Activated Carbon
.
Classifying Activated Carbon
Complex
and varied, activated carbon is broadly categorized by size, method of
preparation, and industrial application.
Manufacturers
have produced as many as 150 different kinds of activated carbon, but we’ve
listed the seven most common types below:
Granular Activated Carbon (GAC) — Granular activated carbon particles are
large, but they have a smaller external surface area than other types of
activated carbon. GAC particles are well suited for the adsorption of vapors
and gases because they diffuse quickly, and they are often used in water
treatment.
Powdered Activated Carbon (PAC) — Powdered activated carbon has incredibly fine
particles made up of ground or crushed carbon. Generally, PAC particles are
added directly to other process units, including rapid mix basins, raw water
intakes, and clarifiers. They are the particle of choice for carbon block
filters.
Extruded Activated Carbon (EAC) — Extruded activated carbon particles fuse PAC
with a binding agent, producing a tough, cylindrical or spherical particle. Due
to its low-pressure drop, low dust content, and good mechanical strength, EAC
is primarily used in gas phase application. EAC particles are used in CTO
filters, which remove chlorine, taste, and odor.
Impregnated Carbon — These porous carbon particles contain several types of inorganic
impregnated compounds such as silver and iodine. Silver loaded activated carbon
is often used as an adsorbent in water purification and may inhibit the growth
of microbes.
Bead Activated Carbon (BAC) — BAC is formed from petroleum pitch. Similar
to EAC particles, BAC is valued for its low dust content and mechanical
strength. Its spherical shape makes it ideal for applications such as water
treatment.
Woven Carbon
— Activated carbon can be woven into technical rayon fiber to create activated
carbon cloth. The finished material has carbon filtering properties and is used
in many applications such as odor absorption and defense.
Polymer Activated Carbon — With polymer activated carbon, the porous carbon
particle is coated with a biocompatible polymer. This gives the finished carbon
a smooth, permeable outer shell that doesn’t block its pores. Polymer activated
carbon is largely used in hemoperfusion, a kind of medical treatment.
In
water purification, activated carbon removes impurities and contaminants
through the chemical process of adsorption.
But
it is used in a wide range of applications besides water filtration. In fact,
activated carbon is an essential component in many different industries.
Uses
of Activated Carbon
Activated
carbon is used in a vast range of applications from gold purification to sewage
treatment.
Some
of the common uses include air purification, hydrogen and methane storage,
metal extraction, teeth whitening and other cosmetic products, and air filters
in respirators and gas masks.
To
fully explain every application of activated carbon would take volumes, so
we’ve condensed its many uses into several broad categories:
Medical Applications — Activated carbon is widely used in the medical community to treat
overdoses and poisoning. Additionally, activated carbon capsules or tablets can
be purchased around the world to alleviate problems like indigestion and
diarrhea.
Industrial Applications — Activated carbon is used in a broad range of
industrial and manufacturing contexts. One common industrial application is in
metal finishing. Activated carbon is the primary purification agent for
removing impurities from metals like nickel.
Analytical Chemistry Applications — Because of its high adsorption, activated carbon is
often used to purify solutions of organic molecules and chemicals. When
combined with diatomaceous earth, activated carbon acts as a stationary phase
in the low-pressure separation of carbohydrates.
Agricultural Applications — Activated carbon has risen in popularity with
organic farmers and vintners. In livestock production, activated carbon serves
as an additive to animal feed, a natural pesticide, a processing aid, and a
disinfectant. For winemaking, it is a processing agent that absorbs odor and
undesirable color pigments.
Environmental Applications — Because of its high surface area and adsorption
potential, activated carbon serves a wide range of environmental uses. It is
useful in groundwater remediation and spill cleanup.
Cosmetic Applications — Activated carbon is now a popular ingredient in
shampoos, toothpaste, and face masks. The same properties that make activated
carbon a wonderful filter make it excellent in cosmetic contexts. It traps
toxins and contaminants so they can be washed away.
Distilled Beverage Purification — In the manufacturing of whiskey and vodka,
activated carbon filters are sometimes used to remove organic impurities from
the beverage. Activated carbon filters out impurities that affect taste, color,
and odor without reducing the alcohol content of the drinks.
Water Purification — Water purification is a major use of activated carbon. Activated
carbon filters are used in both large- and small-scale products. They can
remove impurities from large-scale, community-wide water systems as well as
smaller scale, residential applications.
Air and Gas Purification — Activated carbon filters out odors, pollutants, and
volatile organic compounds (VOCs) from the air by trapping gas molecules and removing
them efficiently from circulation. Also, activated carbon can be used to detect
and adsorb radon in the air. In gas purification, activated carbon filters
remove odors, hydrocarbons, and oil vapors from the air.
Mercury removal
— Mercury is a common and hazardous emission of coal-fired power plants or
industries. When infused with halogens or sulfur, activated carbon traps
mercury gas and removes it from the air.
Gas storage
— Activated carbon’s porous surface acts like a sponge for many types of gases.
Research suggests activated carbon can store fuel gases efficiently in low
mass, low volume, and low-pressure environments.
Space Technology — Activated carbon is an essential component in the life support
systems of spacesuits. The activated carbon filter removes trace contaminants
from the flow of oxygen to the astronaut, including body odors.
This
is only a sampling of activated carbon’s versatility. Because it is such a
useful material, researchers are constantly discovering new applications for
activated carbon.
How
Activated Carbon Filters Work
Carbon’s
effectiveness is largely thanks to its incredible surface area.
Physical
adsorption is the main way in which activated carbon filters out a given
substance. As liquid or air comes into contact with activated carbon,
intermolecular forces draw molecules into the millions of pores and pockets on
the surface of activated carbon.
Beyond
physical adsorption, activated carbon also facilitates chemical reactions. A
common example involves chlorine molecules. When chlorine comes into contact
with activated carbon, both molecules react to form chloride ions, effectively
removing chlorine from water.
The
amount of contamination that activated carbon removes from the air or water
depends on many different factors, including the type and amount of pollution,
the acidity and temperature of the water or air, and how long the water or air
spends in contact with the activated carbon.
The
specific type of activated carbon also determines the level of filtration
provided. Carbon molecules with large holes trap big and heavy molecules such
as the ones found in organic chemicals.
Small,
fine pores pick up smaller and lighter contaminants. Manufacturers of activated
carbon often label their products by their adsorption potential.
While
activated carbon is safe to ingest, no trace of carbon is left in drinking
water after it has been properly and thoroughly treated.
Types
of Activated Carbon Filters
Currently,
two types of carbon are most often used for water filtration: powdered
activated carbon (PAC) and granular activated carbon (GAC).
PAC
has a smaller particle size than GAC and is typically more efficient at
removing a wide range of impurities from the water.
In
most filters, the activated carbon is combined with a secondary element or
media such as silver. The added components give the filter additional
bacteriostatic properties.
1. GAC
Filters
Also
known as “fixed-bed carbon filters,” GAC filters are typically cylindrical
containers that hold particles of GAC.
Water
is added to the container and as the water flows through the system, the loose
carbon particles filter out impurities.
However,
channeling is a common problem with GAC filters. As water enters the chamber,
it automatically flows through the container by the path that presents the
least resistance.
This
means carbon particles bypassed by the water are underutilized, reducing the
overall efficiency of the filtering system.
.
GAC filters are also known for growing bacteria. As water flows down frequently traveled “channels” through the activated carbon, pockets of carbon and stationary water remain behind.
.
GAC filters are also known for growing bacteria. As water flows down frequently traveled “channels” through the activated carbon, pockets of carbon and stationary water remain behind.
These
areas of relatively stagnant and contaminated water are ideal settings for
bacterial growth.
2. Carbon
Block Filters
Solid
carbon block filters are densely packed blocks of PAC and GAC particles of
varying sizes.
Water
is forced through the pores of the carbon block, and as it travels through the
filter, the tiny carbon particles remove a wide range of contaminants.
The
primary advantage of block filters over GAC filters is the elimination of
channeling. With carbon block filters, the carbon particles are stationary and
every particle is used to maximum effectiveness.
A
wide range of contaminants is removed from the water — small pollutants are
adsorbed by the carbon, while larger impurities are too big to pass through the
pores of the block and are left behind.
.
More efficient and effective than GAC filters, carbon block filters do have one drawback — it takes more time for water to pass through solid block filters than through carbon bed filters, which means it isn’t practical for situations where you need a huge quantity of water filtered quickly, such as in municipal water systems.
.
More efficient and effective than GAC filters, carbon block filters do have one drawback — it takes more time for water to pass through solid block filters than through carbon bed filters, which means it isn’t practical for situations where you need a huge quantity of water filtered quickly, such as in municipal water systems.
For
many households, however, a carbon block filter provides more than enough
filtered drinking water every day.
What
Carbon Filters Reduce From Your Water
Activated
carbon is an excellent filter and reduces a vast number of impurities from
drinking water. But what specific contaminants are eliminated by activated
carbon filters?
In
general, carbon filters remove at least 81 chemicals and are effective at
reducing another 52.
According
to the EPA, activated carbon is the only filtering material that removes all 12
identified herbicides and 14 pesticides, along with all 32 identified organic
contaminants.
Activated
carbon also removes chemicals, such as chlorine, that affect the aesthetic
quality of your drinking water. Most public water systems in the United States
contain chlorine as a disinfectant. However, chlorine can lead to an unpleasant
taste and smell in tap water as well as create potentially carcinogenic
byproducts. Activated carbon filters out chlorine byproducts and VOCs, to
produce clean water.
Note
that on its own, activated carbon doesn’t remove every contaminant. Certain
minerals, salts, and metals can slip through the filter.
However,
much of this is only true for GAC filters. Carbon block filters are capable of
removing many more pollutants, including metals such as lead.
Carbon
block filters also remove microbiological contaminants from drinking water,
including waterborne pathogens. The best carbon block filters reduce pollutants
like arsenic, asbestos, mercury, and radon.
While
no filter is capable of removing every contaminant from water, carbon block
filters come close.
Additionally,
carbon filtration systems target pollution without stripping water of
beneficial compounds like minerals, making your water as safe and healthy as
possible.
Carbon
Block Filters You Can Trust
Activated
carbon has revolutionized a wide range of industries, including water
filtration and purification. Multipure has revolutionized activated carbon.
Multipure
was the first company to develop the carbon block filter. Our signature carbon
block filters are capable of treating heavy metals, pathogenic cysts, and toxic
chemicals from your home’s water without stripping it of its beneficial salts
and minerals. With third-party testing and NSF International certifications,
you can trust the quality, performance, and reliability of our filters.
We
are passionate about improving health and quality of life for people all around
the world. Browse our collection of carbon block filters and find the perfect
fit for your home today!
CB
Tech brand drinking water carbon block
filtration systems are world-renowned for their cost-efficiency and efficacy,
effectively reducing the quantities of most drinking water contaminants with
minimal energy expenditure. Arsenic V, pesticides, herbicides, disinfection
by-products, heavy metals, cysts, particulates, chloramine and chlorine are
just a few examples of what CB Tech’s carbon block water
filters can handle.
The
system works by using multiple filtration technologies to target the broadest
range of contaminants. While a simple filtration system using a single
filtration method can effectively target one type of contamination, it fails to
filter other contamination types. By combining electrokinetic adsorption and
physical adsorption with mechanical filtration in a compact carbon structure,
CB Tech carbon block water filters can reduce the quantity of most contaminants
with minimal water waste and electricity usage.
CB
Tech further reinforces the efficacy of our products with over 45 years of
manufacturing experience, rigorous NSF testing and certification, and a
continuing commitment
to the highest quality standards. Our company will continue to develop
industry-leading solutions to new water contamination concerns well into the
future.
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