Study the Corrosive Effect of Greenhouse Gases on Metallic and Non-metallic Materials

Abstract

Carbon dioxide is a major corrosive pollutant for building materials. It enters inside materials by diffusion or osmosis process and in presence of moisture it produces H2CO3 which decrease the pH value and accelerates chemical and electrochemical reaction with building materials. The carbonation reaction produces deterioration inside and outside of building materials. It produces corrosion reaction with metallic bar and disbanding with concrete. CO2 reacts with Ca (OH)2 and Mg(OH)2 to form voluminous compound CaCO3.MgCO3.H2O. This compound is increased the size of building components thus crack is developed. It also generates swelling and dissolving effect in building
materials. H2CO3 creates acidic environment for reinforced iron bar in concrete and it forms corrosion cell with iron bar thus corrosion reaction starts on their surface. This reaction produces disbonding between set cement and iron bar. Metallic bar exhibits various forms of corrosion like galvanic, pitting,crevice and stress. The moist environment carbon dioxide generates swelling and dissolving corrosion with nonmetallic materials. The acid rain also develops swelling and dissolving corrosion. In carbon dioxide environment, octahydrodibenzo[a,d][8]annulene-5,12-diphenyhydrazone and CoS are used to mitigate the corrosion of building materials. The organic compound octahydrodibenzo[a,d][8]annulene-5,12-diphenyhydrazone is used as coating whereas CoS as filler. The coating and filler compounds are boned by chemical bonding to form a composite barrier on the interface of building materials to minimize the process of diffusion or osmosis of CO2. This barrier deactivates the attack of CO2 and stop decarboxylation reaction with concrete. The corrosion rates of metallic and nonmetallic materials were calculated by weight loss method and potentiostatic polarization technique. Octahydrodibenzo[a,d][8]annulene-5,12 diphenyhydrazone was synthesized in laboratory and it used for corrosion protection at different temperatures and concentration coating and filler compounds in 10 ml H2CO3. The coating and filler compounds were developed protective passive composite barrier on the surface metallic bar and these compounds enhanced bonding between metal and concrete. These phenomena were studied by the Langmuir, Temkin isotherm and Arrhenius equation, heat of adsorption, activation energy, free energy, enthalpy and entropy.