Preparation Of Fluorescent Poly (Aspartic Acid) And Evaluation Of Its Scale Inhibition

Reform and opening up, industrial water consumption has been presenting a trend of sharp growth with the rapid development of economy. The reasonable use of water resources has an extremely important role in modern industry and agriculture. The circulating cooling water system will foul in heating process because of its high hardness and alkalinity. And the phenomenon could cause a serious of technical problems, such as reducing heat transfer efficiency and blocking the pipeline.On the control of scale deposit, the general method is to add inhibitors in the circulating cooling water. Polyaspartic acid?PASP?, which is of high biodegradability and restraining high concentration "Ca" crystallization, was discussed in this paper. The concentration of inhibitors will affect the rate of scale inhibition. Lacking of the dosage, the scale inhibition efficiency is not ideal;however,the high dosage result in a waste of raw materials, and the inhibition rate even decreases instead of increasing. So it is particularly important that how to control PASP addition automatically by determining the concentration in situ. This study aims to combine fluorescence with anti-scale to achieve the scale inhibitors dosage accurately addition. Details are as follows,1. Polysuccinimide?PSI? was synthesized by using maleic anhydride and urea with the mixed acids added, the polymerization was carried out for 50 min, then purified. PASP was successfully preparated by alkaline hydrolysis of the PSI above. The products were characterized by FTIR, 1H NMR and TGA respectively.2. Preparation and evaluation of naphthalene-polyaspartic acid. 1-naphthalene was selected as ring-opened agent to prepare modified Naphthalene-polyaspartic Acid. FL analysis shows that the relationship between the concentration of 6¹2 mg/L and fluorescence intensity with the excitation wavelength of 366 nm and 422 nm, and R2 was 0.9980. The static scale inhibition results showed a good scale inhibition properties with a scale inhibition rate of 78% achieved for CaCO₃ with a dosage of 14 mg/L, and a better scale inhibition effect for Ca SO₄ achieving an inhibition rate of 80%.3.Preparation and evaluation of PASP-SEA-Try. PASP-SEA-Try was synthesized by incoprating PSI with 2-aminoethanesulfonic acid and tryptophan. The results showed that the fluorescent chromophoreindolyl groups had been successfully grafted on PSI. The fluorescence intensity and the concentration of PASP-SEA-Try followed a linear relationship. As for CaCO₃, when the dosage was 9 mg/L, FPASP showed excellent scale inhibition properties with a rate of 78%. And when it refered to Ca SO₄, even significantly enhanced scale inhibition effiency achieved, reaching up to 98%. These rates above were determined by using the static scale inhibition method. When PASP-SEA-Try was added to the solution, CaCO₃ and Ca SO₄ deposits showed flower patterns with floppy accumulation by scanning electron microscopy?SEM?.