The Synthesis And Experimental Research On A New Scale Inhibitor And Anti Corrosion-AADMP

In this paper, A new phosphonate corrosion and scale inhibitor —α-aminoadipic acid-N, N'-dimethylidenephosphonic acid (AADMP)was designed and synthesized according to optimized molecule structure theory.It had common feature and molecule structure of Phosphonate and Phosphonopoly carboxylic acid corrosion and scale inhibitors. Furthermore, it decreased phosphate content and increased amino acid structure. So its biodegradability was improved. it can replace low molecular. Phosphonate corrosion and scale inhibitors. It can solve high Phosphonate content and hard biodegradability in using Phosphonate and Phosphonopoly carboxylic acid corrosion and scale inhibitors. So it is accorded with the requirements of environmental protection. It can be extensively applied in circulating cooling water.α-aminoadipic acid-N, N'-dimethylidene-phosphonic acid is synthesized from the raw material of α- aminoadipic acid, formaldehyde and phosphorous acid by water as solvent in stated condition. This synthetic production was recrystallized by methanol as solvent and by ethanol as wash according to its physical and chemical properties. The product (AADMP) was purified by multi-times recrystallization, multi-times dehydrated, abraded, dried in vacuum. The character AADMP was characterized by IR, MS and NMR spectra.The effect of the monomer ratio, pH value of the reaction system, reaction temperature and reaction time were investigated by means of orthogonal experiments in this paper. The results prove that the optimum synthetic conditions of AADMP were as follows:n(C₆H₁₁NO₄):n(HCHO): n (H₃PO₃)=1:2.4:2.4;reaction temperature 100℃;reaction time 3h;H₃PO₃ was added in one time. AADMP product had most high scale inhibitory rate. The optimal scale inhibitory rate can be up to 90.08%.The antiscaling property of synthetic product was studied by using method of bubble, the effect of scale inhibitor concentration , Ca²⁺concentration, pH, as well aswater bath temperature on scale inhibiting performance were discussed. The results showed: increased AADMP concentration, pH and decreased Ca ^concentration, water bath temperature can add scale inhibiting performance. The results showed that AADMP is fit for conditions as follows: middle rigidity (calcium concentration 160-240mg/L), pH value 8.0-9.0, water temperature 60⁷0 °C. The synthetic product has favorable scale inhibiting properties for CaCC>3.A static weight losing method was used to measure the anticorrosion properties of the synthetic products. 30mg/L of AADMP shows 80% anticorrosion rate for A3 carbon steel. While increasing AADMP concentration, anticorrosion rate for brass decreases with AADMP 0¹0mg/L when using lOmg/L of AADMP , anticorrosion rate for brass reaches the minimum, then anticorrosion rate for brass rapidly increase while increasing AADMP concentration. 50mg/L of AADMP shows 96 % anticorrosion rate for brass.