Water is one of the most important gifts of nature to humanity. It is useful for a variety of activities from washing to drinking and industrial purposes. It is trite knowledge that water is the most used of all natural resources. Because of the importance of water, when challenges concerning water arises, it calls for a lot of concern. This is because as humans, we have to be conscious enough to stand against threat to our perpetual existence. For this reason, concern for water pollution has called for a lot of response from people from all over the world. This is necessary because water pollution is one of the most threatening forms of pollution to the environment.
Many years of increased industrial, agricultural and domestic activities has led to an increase in water pollution. In simple terms, water pollution is the release of harmful and toxic materials into water in a manner that is harmful to health. The use of fertilizer for agricultural production has contributed immensely to water pollution. Another source of water pollution is factory waste dump into water. As a result of pollution, the quantity of freshwater available for human use is declining at an alarming rate. This means that very soon, the human race would suffer water scarcity than it has ever done.
In order to control and manage water pollution, a variety of methods have been discovered and used. Some of these methods involve foam floatation, ion exchange, coagulation, sedimentation, filtration, electrolysis, disinfection chemicals, membrane processes, etc. These methods have their limitations. For instance, the methods based on chemical oxidation, solvent extraction, etc have shown only little effectiveness for the removal of trace levels of pollutants or contaminants. Coagulation, on the other hand, needs pH control and causes more problem of sludge disposal.
Among the various pollution removers from water, adsorption is deemed to be better than all other methods of pollutant removal. This is because the adsorption process is convenient, simple and easily operated. This process also removes different types of pollution. A good adsorbent is expected to have high porosity and large surface area. It is also expected to take less time for adsorption equilibrium.
One type of adsorption is silica gel. Silica gel is the most widely used adsorbent for moisture. Because it has large adsorption capacity for water. One quality of silica gel that makes it outstanding is that it has weak bond with water. It also has large pore volume and mesoporosity. Silica is also widely used because of its ease in regeneration.
Activated Carbon is another well-known adsorbent. It has been discovered as an adsorbent which can remove various kinds of pollutants such as dyes, phenols, metal ions and other organic and inorganic compounds. Activated carbon is effective for the removal of dyes and coloring materials in water. It is recorded that one activated carbon filtrasorb type (size 1.4-2.8mm) has the ability to remove a range of dyestuffs (acid, base and direct dyes) from water.
Natural clay minerals are also adsorbents that are well known since the start of modern civilization. One attractive characteristic of natural clay is that they are cost effective, they are cheap. Natural clays also have high surface area, which is a quality of any good adsorbent. They have high porosity and are abundant in most continents. There are many types of natural clay. Examples are kaolinite, pylophylite, (talc), smectites (montmorillonite, saponite), serpentine, mica, etc. the rate of adsorption of natural clay relies on negative charge on the surface. This gives it the ability to adsorb species that are positively charged.
There are other types of adsorbents. Others are chitin and chitosan, which are both naturally occurring adsorbents for the removal of water pollutants. No matter the number of adsorbent, the point remains that adsorbents are effective for removing water contaminants or pollutants. Other effective methods of pollutants removal should be researched and used in order to reduce the rate of water scarcity. With this, our fears for future water scarcity are mitigated.