(18c) Fe(III)-Induced Polydopamine Coating with "Deposition-Polymerization" Mechanism for Microfiltration Membrane Hydrophilization

Fe(III)-Induced
Polydopamine Coating with "Deposition-Polymerization" Mechanism
for Microfiltration Membrane Hydrophilization

Xuehua Ruan, Xuhang
Liao, Gaohong He^*, Yan Dai, Xiaobin Jiang

State
Key Laboratory of Fine Chemicals, School of Petroleum and Chemical Engineering,
Dalian University of Technology, Panjin, Liaoning, P.R. China, 124221

Corresponding
Author Email: hgaohong@dlut.edu.cn

Polydopamine
coating is widely attempted to fabricate high-flux hydrophilic membranes, but
subjected to the time-consuming and uneven deposition.  In this work, Fe(III)-induced
polydopamine coating with "deposition-polymerization" mechanism was
proposed for microfiltration membrane hydrophilization, with the intent to accelerate
deposition and reduce agglomeration simultaneously. According to the coordination
theory, Fe(III) ions could be complexing with threefold dopamine molecules and
accelerate deposition effectually. Besides, the multivalent Fe(III)-Fe(II)
redox system could activate dissolved oxygen to oxidize dopamine and promote
the polymerization. In this instance, the hydrophilic layer was yielded
homogeneously and rapidly on membrane surface. In comparison to the regular
route, the Fe(III)-induced route can accelerate polydopamine deposition by 5
times, with the rate increased from 11.5 to 62.0 nm/h. The hydrophilic layer
with requisite thickness close to 100 nm was constructed rapidly in 2 hours to
enhance water permeation flux. Moreover, membrane surface pores could be retained
substantially. The PDA-Fe(III)-coated membranes behaved excellent with water
flux three times higher than the membranes modified by general routes. Fe(III)-induced
polydopamine deposition is a potential way to manufacture high-flux hydrophilic
membranes facilely and efficiently.

Figure
1 Fe(III)-induced dopamine reaction mechanism, membrane microstructure and
performance.

Acknowledgement:

The authors are grateful to the
financial support from National Natural Science Foundation of China (No.
21606035, U1663223 and 21676043), the Fundamental Research Funds for the
Central Universities (DUT18JC24, DUT16TD19), Liaoning Province S&T
Department (Grant no. 201601037) and Education Department (LT2015007), and Changjiang
Scholars Program (T2012049).