New rapid test for evaluation of scale inhibitors

A new method of evaluation of scale inhibitors efficiency has been developed and tested. This method is based upon solution conductivity measurement. It consists of determining a supersaturation level of any scale forming compound in a given water, at defined conditions, in the presence of a specified amount of scale inhibitor and also without inhibitor. This method allows the stabilizing features of compounds under investigation to be differentiated. With this method the efficiency of preventing CaCO3 precipitation from aqueous solutions was determined for three phosphonate compounds which are effective as corrosion inhibitors of mild steel in neutral water: 2-phosphonobutane-1,2,4-tricarboxylic acid (TBTC), ethylenediaminetetramethylenephosphonic acid (EDTMP) and phosphono-N-methylenephosphonic derivative of polycaproamide (PMPP). It was ascertained that the above compounds are effective in preventing CaCO3 crystallization from water. EDTMP showed the best stabilizing properties and PBTC what poorer ones.