A Novel Technique for Water Hardness Removal by Using Polystyrene

Abstract

In the year 2006, Egypt generated a total of 16 million tons of municipal solid waste which was predicted to grow at a rate of 3.4 percent year-by-year. Plastics amount reach about 970 thousand MT/year (Ministry of Trade and Industry 2008). The Egyptian Styrene and Polystyrene Production Company '' E-STYRENICS'' is The Only Source for Producing Polystyrene in Egypt. The Company Produces 200,000 MTA Polystyrene. In the study, the usage of waste polystyrene is assessed whether it can remove the water hardness. Polystyrene, a solid or foamed synthetic aromatic polymer which is made from a number of monomer styrene. When it is used for general purposes, it seems to be hard, clear and usually brittle in nature. In terms of resin per unit weight, it is a cheap polymer that do not easily permits oxygen and water vapour inside it. Polystyrenes has relative low melting point (Billmeyer 1984). Polystyrene was first commercially produced by BASF in 1931. The inventors of this mass polymerization process had to resolve two conflicting problems. Heat removal from high-viscosity melts and development of an appropriate workup scheme Heat removal was accomplished by heat-exchange tubes in the polymer melts. Polystyrene was obtained after exit of the melt from a high-temperature polymerization zone, using an extrusion screw. Today's processes are characterized by a fully continuous polymerization with heat removal by evaporation of the styrene and solvent. The main advantage consistent temperature results in a high product quality with a narrow molecular weight distribution and high transparency (Huang 2001). The white coffee cups usually contains waste polystyrene which can be converted to adsorbent through the process of heterogenous sulfonation and in order to confirm its completion, IR technique is used (i.e., Infra-Red technique). Through titration methods, the cation exchange capacity and the degree of sulfonation can be confirmed. In distilled water, Magnesium or Calcium salts are dissolved in order to prepare the hard water. When compared to conventional adsorbent, the hard water is highly purified by the modified polymer (Kaminsky et al 2004). Structurally, polystyrene is considered as a cheap, hard plastic which is nothing, but a phenyl group attached at every carbon atom in the lengthy chain of hydrocarbons. When the styrene undergoes free radical vinyl polymerization, the polystyrene is produced. According to the literature (Hossain and Mehedi 2002) the polystyrene production is highly contributed as packaging materials such as meat trays, cups, trays, plates, bowls and yogurt. Though it is a sad truth that recycling of waste polystyrene occur rarely, it can be recycled throu gh three main ways such as material recycling, chemical recycling and thermal recycling. Polystyrene is an odorless, tasteless, rigid thermoplastic. As in (figure. 1) pure polystyrene has the following structure, which is produced from the polymerization of styrene monomer (Benning 1969). EquationNo.1 shows the polymerization reaction of polystyr...