Effect of combined fouling on desalination performance of membrane capacitive deionization (MCDI) during long-term operation

Abstract

The effect of combined fouling on desalination performance of membrane capacitive deionization (MCDI) process was investigated and bovine serum albumin (BSA) as well CaCl₂ were chosen as representative of organic and inorganic matter, respectively. Result showed that when calcium concentration was in the range of 0.5–3 mM, the removal efficiency for CaCl₂/BSA mixed solution displayed slower decline compared to the single solution indicating that the presence of BSA mitigated fouling degree. However, after the calcium concentration exceeded to 5 mM, the co-existence of BSA showed negative effect for the ion removal and the efficiency for the mixed solution declined more obviously compared to that in the single solution. Additionally, it was found that calcium concentration had an important effect on BSA absorption onto membrane surface and BSA deposition degree was intuitively distinguished by Scanning electron microscopy (SEM). Based on analysis of size distribution and zeta potential, the result showed that when calcium concentration was in the range of 0.5–3 mM, the adsorption amount for BSA onto the membrane surface decreased from 1.72 to 0.71 μg/cm² accordingly, while it increased to 1.02 μg/cm² when calcium concentration increased to 5 mM. These findings would offer deeper insights into the effect of combined fouling on MCDI performance, which was expected to provide a theoretical basis for further application.

Graphical Abstract

Keywords:

• Membrane capacitive deionization
• combined fouling
• bovine serum albumin
• removal efficiency

Acknowledgements

This study was mainly financially supported by National Natural Science Fund of China (grant number: 51508153), Natural Science Fund of Jiangsu (grant number: BK20150813), Fundamental Research Funds for the Central Universities (2018B15014) and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Additional information

Funding

This study was mainly financially supported by National Natural Science Fund of China (grant number: 51508153), Natural Science Fund of Jiangsu (grant number: BK20150813), Fundamental Research Funds for the Central Universities (2018B15014) and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.