Seawater desalination using distillation method based on convex lens and Ag doped ZnO thin film to improve freshwater productivity and quality

Abstract

Water is the most important need to support human life. Potentially, seawater is an alternative solution to solve water crisis problem especially in coastal areas. However, seawater have 3,5% salinity level. Water with high salinity is certainly not consumable. One effort that can be done to overcome the clean water crisis in the coastal areas is through desalination of seawater to produce water with low salinity. Some of the desalination methods that ever existed were MSF (Multi Stage Flash Distillation) and Reverse Osmosis. But both of these methods have high investment cost. Therefore, a cheaper and easier method to apply such as distillation is required. Distillation is done by drying the seawater under the sun which triggers the evaporation of water that evaporates and condenses to obtain freshwater. In this research, distillation system is combined with convex lens and Ag doped ZnO thin film. The convex lens is a lens that can focus heat and sunlight after passing through the lens. The use of the convex lens in the distillation system can speed up the evaporation process of seawater. The distillation system is made of glass and aluminum. Ag doped ZnO thin film was synthesized from AgNO3 and ZnCH3COOH by sol-gel method. Based on photocatalyst activity, when the Ag doped ZnO thin film is exposed with visible light, it will form a superoxide compound that can degrade pollutant such as heavy metals, eliminating harmful microbes and bacteria. This material also has a hydrophilicity that makes the water absorbed by the material coated with the thin film. With this characteristic, it can make the water more easily move on the glass due to the influence of gravity. Tests carried out include characterization of a thin layer of Ag doped ZnO, evaporation rate and water quality. From this technology, it can increase the production of freshwater and quality from the seawater desalination process with distillation method.