Desalination is the process of removing salt from seawater to make fresh water safe for drinking. (Aintablian, X. W., 2014) Many countries are using desalination as a way of creating a more reliable water supply that doesn't depend on rain. Desalination produces drinking water and concentrate (the water that contains the salts that were removed in the desalination process, which is sometimes called brine). As such, we have decided to research on how different variables affect the amount of clean water collected. Using distillation, we are able to adjust the variables and find the prime conditions for the most amount of clean water to be collected.
1.1 Background Research
Desalination (desal) is the process of removing dissolved salts and minerals from seawater or brackish water. It is also called desalting or by its shortened name, desal. Desalination produces drinking water and concentrate (the water that contains the salts that were removed in the desalination process, which is sometimes called brine). The dominant technology used in desalination today is reverse osmosis, which involves forcing water through semi-permeable membranes to remove salts and other impurities. (athirstyplanet, 2014)
Distillation is the oldest and most commonly used method of desalination. Distillation is a phase separation method whereby saline water is heated to produce water vapor, which is then condensed to produce freshwater. The various distillation processes used to produce potable water, including MSF, MED, VC, and waste-heat evaporators, all generally operate on the principle of reducing the vapor pressure of water within the unit to permit boiling to occur at lower temperatures, without the use of additional heat. Distillation units routinely use designs that conserve as much thermal energy as possible by interchanging the heat of condensation and heat of vaporization within the units. The major energy requirement in the distillation process thus becomes providing the heat for vaporization to the feedwater.In a salt solution of water and sodium chloride, when water evaporates, the sodium chloride is left behind, because water forms a gas much more easily than sodium chloride does. (Barrans, R., 2014)
Normal Simple Distillation Setup
Our Distillation Setup
Due to the lack of a proper simple distillation setup, we had to make our own with the resources we could obtain. The setup we made is quite similar other than the fact that the Normal Simple Distillation setup is more enclosed and prevents most of the steam from escaping.
Salinity is just one of the factors affecting the quality of water. There are many other factors that will influence the quality of water: such as pH, alkalinity, hardness, chloride, nutrients, heavy metals, odour and turbidity. A salinometer/salinity meter is a machine that is capable of measuring the table salt (NaCl) content, known as salinity, of a solution. A salinometer generally works by passing an electric current through any known mass of water. Since salt water conducts electricity much more easily than pure water the salinity content of water can be easily calculated. Because of this salinometers are also known as conductivity meters. Most conductivity meters give readings in microSiemens per cm (µS/cm). (Leonhard, L. D., n.d.)
1.2 Research Question
1) How does the angle of the pipes affect the amount of water collected?
2) How does the flow rate of the water (In) through the pipes affect the amount of water collected?
3) How does the amount of heat applied to the salt water affect the amount of water collected?
4) Why is the salinity level of the water collected lower than that of the water evaporated?
5) If the round-bottom flask were to be replaced by a container of another material, would that affect the results of the experiment?
6) Why is distillation not used by countries as a form of desalination?
- Hypothesis 1: A 40º-50º angle will be the optimum range of angles that will affect the condensation of the water vapour and allow for the most efficient water collection
- Hypothesis 2:The higher the flow rate of water through the hollow copper pipes, the faster the rate of condensation, resulting in a greater amount of water.
- Hypothesis 3: The greater the amount of heat used to boil the water, the faster the rate of evaporation, which will result in a faster amount of time for the water to be collected in the beaker.
1.3.1 Independent variable(s)
Angle of the pipes
Amount of heat(Temperature)
- The amount of heat that is going to be applied to the beaker (from the heating mantle)
- The amount of water passing through the copper pipes varied
- We will be adjusting the tap to determine the amount of water flowing through.
- Turning the tap in anti-clockwise direction according to length.
← Flow rate (#1,#2,#3)
- Angle that the copper pipes are going to be slanted at
1.3.2 Dependent variable
- Amount of water collected in the beaker
- The amount of water wasted
- Salinity of saltwater ~3.5% (35 g/L, or 599 mM)
- Amount of time it takes to collect the water- 30 minutes
- Material of the pipes
- Amount of water in the round-bottom flask
- Length of the rubber tubes
- Environment in which the tests were conducted