Osmosis: Safe Drinking Water

Water is one of the many things that all human being need in order to survive. Considering the vast amount of water that is on the planet, it is reasonable to believe that there is more than enough water for everyone to have their fair share and more. Yet this sadly is not the case, as the majority of the water on Earth is unsuitable to drink due to the fact that it is tainted with a numerous amount of contaminants, such as bacteria and salt. The amount of safe drinking water is decreasing more and more each year and will soon become one of the more scarce resources on the planet. Over the years, many different people all over the world have tried to create and refine a water purification process that is both effective and efficient. The
It was first discovered in 1748 by the French physicist, Jean-Antoine Nollet and later thoroughly studied in 1877 by German plant physiologist, Wilhelm Pfeffer. Ten years prior, Moritz Traube prepared the first recorded synthetic membrane that was made from a precipitated film of copper ferrocyanide. It was not until almost two hundred years later that the process of osmosis was revisited and extensively reviewed by researchers from the University of California at Los Angeles. In 1959, Sidney Loeb and Srinivasa Sourirajan developed a membrane made from cellulose acetate, which removed at least ninety percent of salts from the water, but not at the expense of speed and efficiency. Their design was later refined by John Cadotte in a way that improved both flow rates and salt rejection. The membrane Cadotte developed, known as thin film composite membranes, also had a high refusal for salts as well as high refusal for organic contaminants. With the constant development and improvement of reverse osmosis membranes, they were able to take a step towards the commercial market first in 1965 with a water filtration pilot program utilizing the method in Coalinga, California under the leadership of Joseph W. McCutchan and pioneer Sidney Loeb. In 1977, Cape Coral, Florida started to use reverse osmosis on a citywide
The reaction would be cellulose with acetic anhydride in the presence of a catalyst, such as sulfuric acid. This would result in the formation of acetylated cellulose, the main component of the membrane, and acetic acid, a byproduct. The cellulose based membranes were easy to make and are more resistant to chlorine than other reverse osmosis membranes. But they are sensitive to changes in pH and temperature, and they also tend to break down in the presence of water over time. Then came along the thin film composite membranes, first synthesized by John Cadotte. This membrane was composed of a polyamide coating made through the reaction between m-phenylenediamine and trimesoyl chloride. This new membrane allowed for higher salt rejection and water flow, while allowing for a reduced pressure to be applied to counteract the osmotic pressure. But when the polyamide comes into contact with chlorine, it disrupts the hydrogen bonding breaking down the polymer and greatly reducing salt