Barite Removal Using Macropa: Simulation and Solubility Investigations

We describe an in-depth study of the performance of the macrocyclic descaling agent `macropa' for barite (BaSO4) removal. Macropa outcompetes known chelating agents such as DTPA, HEDTA, and EDTA at moderate pH. The solubility studies showed that macropa has a promising performance in removing the barite minerals at a pH of 8. Around 11.4 g of barite can be dissolved in 1 L of the macropa solution while using EDTA and DTPA solutions can dissolve around 5 and 8 g/L of the barite particles, respectively, all at the same pH of 8. Insight into the mode of action of macropa was sought using a DFT-based computational method, and this reveals that the binding energies are sensitive to the orientation of the OH groups of the acids and acid groups themselves in the 3D structural orientation. The calculated binding energies correlate well with the experimentally observed dissolution behavior. There are several indications that macropa binds K+ as well, and some care has to be taken with designing descaling experiments properly.