Dissolution of barium sulfate scale using ethylenediaminetetraacetic acid (EDTA) / Izzati Syahirah Mohd Salikin

Barium sulfate (BaSO₄) scale is one of the major problems that cause equipment breakdown consequently decline the oil recovery. In order to remove the scale, a chelating agent ethylenediaminetetraacetic Acid (EDTA) is used as a scale remover. The objective of this experiment is to identify the effect of temperature and concentration of EDTA to the dissolution of (BaSO₄) scale. Different temperature and concentration of EDTA are varied to find the optimum effectiveness. Experiment was conducted at concentration of 0.5M, 0.05M, 0.01M, 0.005M, 0.001M and at temperature of 27 (room temperature), 40, 60 and 80 °C. Based on the results obtained from Inductively Coupled Plasma Mass Spectrometry (ICP-MS) 0.005M EDTA solution at 80°C is the most optimum condition as the solubility of barium sulfate was found to be 110.5 ppm. Further studies on infrared band changes, weight loss and surface structure of (BaSO₄) scale was carried out at the most optimum condition as acquired. Fourier Transform Infrared Spectroscopy (FTIR), Electronic Balance and Geology Microscope were used to study those parameters. From FTIR analysis, some bands disappeared after the dissolution as vibrational mode of sulfate take placed. Weight loss experiment showed 1.4256 g of barium sulfate was dissolved in EDTA solution after dissolution process occurred and the solubility is calculated to be 88%. Observation of barium sulfate scale using Geology Microscope displays the changes in surface structure after placed in EDTA solution. Result obtained complement each other as barium sulfate scale before and after dissolution showed a difference in studied parameter. This study showed that EDTA at high concentration and low temperatures are not potent for (BaSO₄) dissolution.