Abstract
Preparation of nonionic surfactants from cheap biomaterials such as rosin and application in the field of corrosion inhibitors are the main goal of the present work. In this respect, rosin acids reacted with poly (ethylene glycol) monomethyl ether has molecular weight 750 g/mol, MPEG 750, to produce rosin ester (RMPEG-750). On the other hand, modification of rosin acid with maleic anhydride using Diles Alder reaction produced adduct (RMA) which esterified with MPEG 750 to produce branched nonionic surfactants to study the effect of rosin modification on both surface activity and corrosion inhibition efficiency in 1 M HCl. The surface activity of the prepared surfactants evaluated in deionized water and 1 M HCl to measure the micellization and adsorption of the prepared surfactants at water/air interface. The surface tension, critical micelle concentration, and surface activities were determined. Surface parameters such as surface excess concentration (Gamma(max)), the area per molecule at interface (A(min)), and the effectiveness of surface tension reduction were determined from the adsorption isotherms of the prepared surfactants. The results of polarization measurements indicated that RMPEG750 acts as a mixed type inhibitor in acidic solution. The inhibition efficiency (IE) is dependent upon inhibitor concentration and increases with increasing inhibitor concentration. The charge transfer resistance of carbon steel increases with increasing inhibitor concentration and the corrosion process on CS surface is mainly controlled by charge transfer reaction.