(194r) Fe(III)-Induced Rapid Deposition and Polymerization of Dopamine on Microfiltration (MF) Membranes

Fe(III)-induced Rapid Deposition and Polymerization
of Dopamine on Microfiltration (MF) membranes

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

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

Corresponding Author Email: hgaohong@dlut.edu.cn

Polydopamine
deposition, a promising strategy for material surface modification, is widely
attempted to manufacture high-flux hydrophilic MF membranes. Nevertheless, the
prospect is subjected to the time-consuming and uneven deposition arisen in the
general coating routes. In this work, Fe(III) was employed to accelerate deposition
and avoid agglomeration. According to the coordination theory, one Fe(III) ion and
three dopamine molecules can be complexing together in the solution, which accelerates
the deposition effectually. Besides, the multivalent Fe(III)-Fe(II) redox system,
helpful to catalyze dopamine oxidization under dissolved oxygen, could promote
the polymerization. The mechanism is illustrated in Figure 1a. In this instance,
polydopamine coating layer can be yielded homogeneously and rapidly on the MF
membrane surface. As a result, the growth rate of PDA with Fe(III) is accelerated
by about 5 times, from 11.5 to 62.0 nm/h. The microstructure comparison between
modified PVDF MF membranes without Fe(III) for 12 h and with Fe(III) for 2 h is
shown in Figure 1b. PDA thickness coated on the former is about 139.5 nm, and
that on the latter is comparable to be 124.8 nm. Much more, the samples
modified in the PDA-Fe(III) solution possess the surface pore distribution
similar to the pristine membranes. In comparison with the membranes modified by
a general coating route, the PDA-Fe(III)-coated membranes behave excellently
with the water flux three times higher. On the whole, the Fe(III)-induced PDA
surface modification is a potential way to manufacture high-flux hydrophilic MF
membranes facilely and efficiently.

Acknowledgement:

The
authors are grateful to the financial support from National Natural Science
Foundation of China (No. 21606035, U1663223, 21527812), Education
Department of the Liaoning Province of China (LT2015007), and Changjiang
Scholars Program (T2012049).