TY - JOUR
T1 - The role of inorganic ions in the calcium carbonate scaling of seawater reverse osmosis systems
AU - Waly, Tarek
AU - Kennedy, Maria Dolores
AU - Witkamp, Geert-Jan
AU - Amy, Gary L.
AU - Schippers, Jan Cornelis
N1 - KAUST Repository Item: Exported on 2020-10-01
PY - 2012/1
Y1 - 2012/1
N2 - In supersaturated solutions the period preceding the start of 'measurable' crystallization is normally referred to as the 'induction time'. This research project aimed to investigate the induction times of CaCO 3 in the presence of Mg 2+ and SO 4 2-. The prepared synthetic solutions have the same ionic strength values found in the Gulf of Oman SWRO concentrates at 30% and 50% recovery. The results showed a significant increase in the induction time by 1140%, 2820%, and 3880% for a recovery of 50%, when adding SO 4 2- only, Mg 2+ only, or both Mg 2+ and SO 4 2-, respectively, to synthetic SWRO concentrate compared to that obtained in the absence of Mg 2+ and SO 4 2- at an initial pH of 8.3. The increase in the induction time in the presence of SO 4 2- was more than likely to be due to nucleation and growth inhibition while the presence of Mg 2+ affected the nucleation and growth through both complexation and inhibition. After a 5-month solution stabilization period, ESEM and XRD analyses showed aragonite in solutions containing Mg 2+. On the contrary, calcite was the final crystal phase formed in solutions with no Mg 2+. This suggests that magnesium may play an important role in inhibiting the formation of calcite. © 2011 Elsevier B.V..
AB - In supersaturated solutions the period preceding the start of 'measurable' crystallization is normally referred to as the 'induction time'. This research project aimed to investigate the induction times of CaCO 3 in the presence of Mg 2+ and SO 4 2-. The prepared synthetic solutions have the same ionic strength values found in the Gulf of Oman SWRO concentrates at 30% and 50% recovery. The results showed a significant increase in the induction time by 1140%, 2820%, and 3880% for a recovery of 50%, when adding SO 4 2- only, Mg 2+ only, or both Mg 2+ and SO 4 2-, respectively, to synthetic SWRO concentrate compared to that obtained in the absence of Mg 2+ and SO 4 2- at an initial pH of 8.3. The increase in the induction time in the presence of SO 4 2- was more than likely to be due to nucleation and growth inhibition while the presence of Mg 2+ affected the nucleation and growth through both complexation and inhibition. After a 5-month solution stabilization period, ESEM and XRD analyses showed aragonite in solutions containing Mg 2+. On the contrary, calcite was the final crystal phase formed in solutions with no Mg 2+. This suggests that magnesium may play an important role in inhibiting the formation of calcite. © 2011 Elsevier B.V..
UR - http://hdl.handle.net/10754/562042
UR - https://linkinghub.elsevier.com/retrieve/pii/S0011916411007934
UR - http://www.scopus.com/inward/record.url?scp=83255185102&partnerID=8YFLogxK
U2 - 10.1016/j.desal.2011.09.012
DO - 10.1016/j.desal.2011.09.012
M3 - Article
SN - 0011-9164
VL - 284
SP - 279
EP - 287
JO - Desalination
JF - Desalination
ER -