Comparative study of the synergistic effect of ATMP and DTPMPA on CaSO4 scale inhibition and evaluation of induction time effect

The performance and calcium sulfate inhibition ratio (CSI%) of five scale inhibition mixtures consisting of aminotris(methylenephosphonic acid) (ATMP), diethylenetriamine penta(methylene phosphonic acid) (DTPMPA) and poly(acrylic acid) (PAA) were studied at three elevated saturation indexes (SI). The induction time effect was studied for 40 min for each mixture. The results revealed that the best inhibitive performance was achieved by Mixture 3 at a 2-ppm dose on 3.76 SI, 4 ppm on 5.80 SI and 10 ppm on 8.00 SI. In addition, the induction time study confirmed that Mixture 3 had the longest induction time at the two saturation indexes and different concentrations. This high performance can be attributed to the synergistic effect of ATMP and DTPMPA in the calcium sulfate inhibitive mechanism. This mixture showed better scale inhibition kinetics compared to polyacrylate inhibitors.