Experimental study of using Ca-DTPMP nanoparticles in inhibition of CaCO3 scaling in a bulk water process

• The nano-Ca-DTPMP inhibitor is prepared by a surfactant-assisted method.
• The inhibition efficiency of the nano-Ca-DTPMP for CaCO3 precipitation is investigated.
• An electrochemical method is used to obtain the precipitation/inhibition curves.
• The inhibition efficiency is increased by varying the nano-Ca-DTPMP concentration from 5.6 to 11.2 ppm.
• The nano-structured Ca-DTPMP inhibitor can act more efficiently than micro-sized and commercial DTPMP solutions.

Nano-metal-phosphonates are used as an inhibitor to prevent scale formation in water processes such as water desalination and in porous media inhibition processes using sea water. The use of such inhibitors in all mineral scale inhibition applications is proposed because of their better inhibitory effects. The nano-Ca-DTPMP (nano-calcium-diethylenetriamine penta(methylenephosphonate)) particles are synthesized and utilized in CaCO3 scaling inhibition experiments. The precipitation/inhibition curves were obtained through the online electrochemical measurement of Ca2 + concentration and pH against time. Moreover, the Field Emission Electron Microscopy (FESEM) analysis of the CaCO3 formation precipitates is carried out to study the crystal shape and morphology changes. The results show that nano-Ca-DTPMP inhibitors delay the precipitation of CaCO3, decelerate the Ca2 + and pH reduction and increase the final Ca2 + concentration in the bulk solution. This occurred because of inhibitor particles interfering into the calcite crystals and significantly changing the shape and morphology that is confirmed by the FESEM images of the precipitate formation. The inhibition effect enhances by increasing inhibitor concentration from 5.6 to 11.2 ppm. It is found that at the same concentrations, the inhibition influence of the nano-Ca-DTPMP on the calcite precipitation is effectively more than that of both micro-Ca-DTPMP and the commercial DTPMP.