The Study Of The Synthesis And Application Of A New Scale Inhibitor And Anticorrosion DPAA

In this paper, A new phosphonate corrosion and scale inhibitor 2,5-diphosphonic acid—adipic acid (DPAA)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 significantly reduced the volume of phosphorus less than the current use of the organic acid. So its biodegradability was improved.and can replace existing phosphonate corrosion and scale inhibitors,which could be extensively applied in circulating cooling water and chemical cleaning drug.2,5-diphosphonic acid-adipic acid is synthesized through three reactive steps by using adipic acid, bromine and phosphite as raw material. The product (DPAA) was purified by multi-times recrystallization, multi-times dehydrated, dried in vacuum. The character of DPAA was characterized by IR and NMR spectra.The antiscaling property of synthetic product was studied by using method of bubble, the effect of scale inhibitor concentration, [Ca²⁺], pH, as well as reaction time on DPAA performance were discussed. The results showed: in the condition of [Ca²⁺]240mg/L,scaling reaction time 6h and pH 7.0, increased DPAA concentration can add scale inhibiting performance; In the water condition of DPAA scale inhibiting performance, acidity is better than alkalescence. According to the experiment ,the optimal scale inhibiting performance condition is that [Ca²⁺] 120 mg/L, pH 8.5 ,temperature 30℃,DPAA 15mg/L,and the optimal scale inhibition ratio can be up to 90%.Contrast results showed that the DPAA scale inhibiting performance better than PBTCA,DTPMP and EDTMP at the condition of middling Ca²⁺ concentration,but in High calcium water, the performance not better than PBTCA,DTPMP and EDTMP. A rotary hanged weight losing method was used to measure the anticorrosion properties of the synthetic products in different dosages. The result indicate:in the stimulant water quality, anticorrosion reaction 72 h, 60mg/L of DPAA shows well effect of anticorrosion rate for A₃ carbon steel and anticorrosion rate reach to 72.28%;If it is used in pretreatment film, Use 160mg/L of DPAA Pre-film Treatment 24h,then reaction 48 h,15 mg/L of DPAA was enough to reach 89.17%. Furthermore, Zn²⁺ greatly enhanced the anticorossion effect of DPAA. When it is used in pretreatment film, 10 mg/L of DPAA and 6 mg/L of Zn²⁺ , that anticorossion ratio be up to 96.10%. at the same condition, copper material anti-corrosion ratio could be up to 96.18%.