What is Bentonite?

Long before human civilization was equipped with the advanced technology of healing, our ancestors relied upon Earth to have beneficial impacts on the body. Maybe nowadays, it is more familiar to call it clays. For a long time, clays were trusted for their therapeutic benefits. Moreover, scientists found it as a way for humans to adapt to surrounding nature and utilize it for their own good. And one of the clays that have been no stranger to humans is bentonite.

Bentonite itself got its own name after Fort Benton, the largest bentonite source, which lies in the county seat of Chouteau County, Montana. The place is still part of the upstream navigable port on the Mississippi River System. Another nickname for Bentonite, Montmorillonite clay, also arises from Montmorillon, a region of France where it was first found. Since then, it has been consumed to repairing damaged body functions.

The Properties of Bentonite

As an absorbent aluminum phyllosilicate clay, bentonite has a chemical formula of Al2H2O6Si. The material with molecular weight of 180.1 gr/moles, is mostly available in white to gray powder. Based on its chemical formula, we can predict there is a basic substance of aluminum, Hydrogen, and Silica contained. With all of the atoms being negatively charged, it attracts positive ions the most such as magnesium, iron, Calcium, and sodium. However, so far, there are two types of bentonite available, and the uses of each one depend on its physical properties. The first type is known as Sodium Bentonite which is the type of swelling clay. It is covered with a single water layer of particles that contain natrium ions. On the other hand, the non-swelling clay is called Calcium Bentonite, and as its name implies, it is covered with a double water layer containing Calcium ions.

Through thousands of years of utilization, bentonite began to be taken advantage of in many industries and applications that depend so much on its type. For example, sodium bentonite which has the ability to clump particles together, is used most as cat litter. More applications from this type is for lubrication during the mud drilling process. And with the ability to absorb impurities, calcium bentonite is mostly found as a basic cleansing agent. Moreover, as an efficient absorbent, the chemical compound is also heavily used as a water purifier. But how does it work? Let’s talk more about it.

How is Bentonite Made?

Tracing back to how it was made briefly, bentonite belongs to the smectite class of clays, which are types of minerals with approximately less than 2 micrometers for the largest dimension. Despite its rare existence in large quantities, bentonite is mostly found in the earth’s surface sediments. The material stemmed from the modification of glassy material derived from volcanoes or rocks with the presence of silica such as basalt or granite, through some geological time periods. It was predicted that most bentonite deposits first existed in the Tertiary and Mesozoic periods (circa 200 million years ago).

Bentonite as a Water Purifier

There are several considerations to use bentonite to help purify the water. Aside from its well-known absorption property and ion exchange capability, it should be noted that bentonite itself presents no harm to human health. With the addition that it is non-combustible and non-toxic unlike chemical based coagulants used for water treatment. More benefits come from the economic perspective where clay minerals such as bentonite are cheaper and locally available.

However, due to the hydrophilic nature of bentonite, it is not quite effective in absorbing organic compounds. Therefore, the absorption capacity has been developed more by surface modification through chemical or physical processes. In chemical processes, the absorption capacity is increased by treatment with strong inorganic acids under high-temperature conditions or by grafting clay surfaces with organic molecules. During the physical process, the clay surface is impregnated by organic molecules. After the transformation, the bentonite itself is more commonly known as organo-bentonite, which has a higher absorption capacity in contrast to the original bentonite.

As stated before, bentonite works as a water purifier by becoming coagulant. So what does coagulant exactly do? Coagulant is a material agent with the ability to do coagulation. The coagulation process itself is important for treatment of both household or industrial wastewater. If mixed in a solution, coagulant will provide ionic charges opposite to those of particles that are present in the water. Moreover, it neutralizes the charges and creates a jelly-like substance called a flock. Then, flocculation causes an increase in the size and mass of the coagulated particles until at one point, the particles are big enough to settle in the bottom of the container, making it easier to be eliminated from the water. The aim of using coagulants is, of course, to get rid of physical pollutants such as turbidity or solids and chemical pollutants such as BOD or COD, as well.

How to Use Bentonite as Water Purifier

Now, another question emerges; how to use bentonite as a water purifier? So, first of all, bentonite powder needs to be concentrated in paste form. Once it is already served as bentonite paste, prepare the concentration of 20% in hot water (around 90 degrees celsius). Rest the mixture for about 16 to 20 hours. When it is all set, treat the contaminated water with this paste at the rate of 10 to 40 kg of bentonite for every 1 meter cubic of the polluted water mixture. The last process is to stir it for about 30 minutes and leave it for maturation. During this maturation process, the bentonite will absorb the contaminants and furthermore, it will flocculate and settle to the bottom of the container.


With two types of bentonite recognized, its applications vary in many industries from cat litter in the animal feed industry to coagulant for water treatment. Bentonite is indeed equipped with an excellent absorbing feature as it is proven to be more environmentally friendly compared to other chemical-based coagulants. An easy-to-use application of bentonite adds to the list of benefits of using it as a water purifier. As it is also safer to have no combustible property, bentonite is definitely a must-try for industries that have had struggles in treating their wastewater.

Tradeasia International is a renowned chemical provider company known for its expertise in sourcing and supplying various chemical products, including Bentonite and other chemical offerings. If you have a specific business requirement for Bentonite and other products, please feel free to get in touch with us.