Making Process Al2(SO4)3. xH2O.

Alum is a chemical compound made of molecules of water and two types of salt, one of which usually Al2 (SO4) 3. Potassium alum, also commonly known as alum, which has the formula K2SO4.Al2 (SO4) 3.24H2O. Alum potassium alum is the most important types. Potassium alum is a compound that is colorless and has a crystalline form octahedral or cube when potassium sulfate and aluminum sulfate are both dissolved and cooled. Solution of potassium alum is acidic. Potassium alum is very soluble in hot water. When crystalline potassium alum is heated by chemical separation occurs, and partly dehydrated salt dissolves in water. Potassium alum has a melting point of 900 º C.Another type of alum is aluminum sulfate which includes sodium alum, ammonium alum, and alum silver. Alum is used for the manufacture of fire-resistant textile materials, medicines, etc. (http://encarta.com).Aluminum sulfate solid by another name: alum, alum solid, aluminum alum, cake alum, or aluminum salts are the products made in the form of powders, granules, or chunks, with the chemical formula Al2 (SO4) 3. xH2O.Turbidity in water can be removed through the addition of a type of chemical called a coagulant. In general, materials such as aluminum sulfate [Al2 (SO4) 3.18H2O] or commonly called alum or alum, ferrous sulfate, poly aluminum chloride (PAC) and poly organic electrolytes can be used as a coagulant. To determine the optimal dose, coagulant and pH suitable to be used in water purification process, it can simply be done in the laboratory using a simple test (Alearts & Santika, 1984).Principle of water purification is to use the stability of pollutant particles in colloidal form. The stability of these particles is due to pollutants:
a. These tiny particles are too light to settle in a short time (several hours).b. These particles can not be fused, join and become larger particles and heavy, because the electrical charge on the surface, electrostatic between particle charge and the other one.The stability of particle-particle pollutants can be plagued by affixing coagulant.In the process of water purification chemicals involves two processes of coagulation and flocculation (Alearts & Santika, 1984).Coagulation process is a process of growth and the mixing is done right from a process of coagulant, and stabilization of colloidal particles suspended, and the initial aggregation of particles stabilized (Reynolds, 1982).Colloidal particles are formed generally too difficult to remove if it is only with the deposition by gravity. But if the colloid-colloid is stabilized by aggregation or coagulation into larger particles then the colloid-colloid can be removed quickly (Metcalf & Eddy, 1978).There are three components of the coagulation mechanism of the double layer (layer doeble compression), adsorption (adsorbtion) and absorption by the polymer (absorption by the polymer).Coagulation is the process of adding chemicals (coagulant) that has the ability to make the colloidal particles are not stable so that the particles are ready to form flocks.Flocculation is a process of flock formation and incorporation of the particles that make the larger size and weight making it easy to settle. Flocculants are used for water purification that is NaOH. This is because many contain impurities so that the positive ions with the addition of polymers that can bind to negative flocks are larger and faster deposition process (Soeparman & Suparmin, 2002).DISCUSSIONWater is one component that is essential for life in addition to the air. Living things that exist can not be separated from the use of water in his life. But in the recent issue of clean water availability becomes a problem because the amount of water that has been kerkotori by contaminants. Contaminants derived from household and industrial waste. So in quality, water resources has declined. Similarly in terms of quantity, which is not able to meet the growing need.One way to overcome this problem is by water treatment. There are three important stages in the process of water treatment with the addition of chemicals such as alum, namely: the establishment phase of core deposits, stage flocculation, phase separation with liquid flock.Coagulation and flocculation is a process that is commonly done in industrial wastewater treatment. Coagulation is the process of adding a chemical coagulant into the water or waste which aims to reduce power between colloidal particles repel, so the particles can be merged into a flock of small-flock. Flocculation is the process of merging small flock flock-flock-flock to become larger so it will be easy to settle.Usually the water treatment using alum, conducted at the beginning of the process of sewage treatment. Alum is added to water, causing suspended particles to settle and then the water can be processed further. One of them with the filtration process. Then disinfected and can be consumed.Alum is aluminum sulfate which can be used as a water purifier such as sedimentation (water treatment) because of alum dissolved in water is able to bind impurities and precipitate impurities in the water making the water becomes clear. Known alum as a coagulant in wastewater treatment. As a coagulant alum is very effective to precipitate particles floating in the form of colloid or suspension. Besides being used as a water purifier, alum can also be used as additives for antiperspirant (deodorant).At this time the lab will be the production of alum (alum). Alum itself is a group of hydrated double salt crystals form and are isomorphous. Alum is known as aluminum potassium sulfate dodekahidrat or Kal (SO4) 2:12 H2O is known to many as a coagulant in water treatment and waste. As a very effective coagulant alum sulfate to precipitate particles floating in the form of colloid or suspension. Tawas is the market divided into two types based on shape, namely alum and alum muddy nodes. Alum or alum is made in two ways:1. Bauxite ProcessWith this process bauxite alum made directly from bauxite and sulfuric acid. Where the bauxite contains approximately 50% Al (OH) 3.2. The process of Al (OH) 3With the process of Al (OH) 3 is alum made of Al (OH) 3 is reacted with sulfuric acid to form sulfate alum.While on practicum was conducted alum manufacture of Al (OH) 3 is reacted with sulfuric acid. In the first procedure done is to weigh the Al (OH) 3 as much as 100 grams with 300 mL of water. This water used to dilute alum alum so it changes from solid to solution, because the alum in solid form would be difficult to react with dilute sulfuric acid. Then added 200 mL of 98% concentrated sulfuric acid slowly and gently stirred for approximately 60 minutes until homogeneous. The use of sulfuric acid here serves as a reactant. Mixing process is carried out in the hood, this is done because one ingredient maker alum is concentrated sulfuric acid which is a hazardous chemical which when inhaled can damage the health and the mixing process produces an exothermic reaction (heat release) so explosive and can explode. After all ingredients are mixed, then stirred to homogeneous. After that, wait a minute, then print on the container that has been provided. At the time packed into a container, alum should not be too cold. If too cold, alum would crystallize and precipitate due to low solubility in cold atmosphere, consequently alum difficult to print. To test the alum who has made can be done using waste water (water that is no longer clear) is a way of alum is added with the coagulant, coagulant has the ability to make the colloidal particles are not stable so that the particles are ready to form flocks. After it is added flocculants made of polymers, flocculants are used for water purification that is NaOH. This is because many contain impurities so that the positive ions with the addition of polymers that can bind to negative flocks are larger and faster deposition process. Then the mixture was stirred and allowed a few moments until the impurities contained in the water settles everything. Alum alum good is capable of binding many mengendapkannya dirt and water so clear.REFERENCES
Alaerts, G and Santika, S.S. 1984. Water Research Methods. Surabaya: BusinessThe National.Anonymous. 2001. Alum. Retrieved from http://www.encarta.com (accessed March2007).Metcalf & Eddy. 1991. Waste Water Treatment and Engineering. Graw Hill.Reynold, T.D. 1982. Unit Operation and Process in Environmental Engineering.California: Broks / Cole Engineering.Soeparman & Suparmin. 2002. Feces and Liquid Waste Disposal. New York:Medical books EGC.