(449x) A Novel Membrane Distillation Response Technology for Nucleation Detection and Crystallization Process Control

A Novel Membrane Distillation Response Technology for
Nucleation Detection and Crystallization Process Control

Xiaobin Jiang*, Gaohong He*, Wu Xiao, Xuehua Ruan,
Dapeng Lu

State Key Laboratory of Fine
Chemicals, Research and Development Center of Membrane Science and Technology,
School of Chemical Engineering, Dalian University of Technology, Dalian, P. R.
China

*Corresponding author: Email: xbjiang@dlut.edu.cn,
hgaohong@dlut.edu.cn

Abstract

Most of
researchers considered the mass transfer flux decline and the crystallization
on the membrane interface as a fouling behavior. The research was focused on
the strategy of avoiding and reducing the crystallization, non-attention had
been paid on applying this sensitive nucleation response phenomenon to the
crystallization research [1,2]. The inevitable crystallization on the membrane
interface under certain operational conditions and solution concentration
inspired us that the membrane interface performed as the response medium of the
nucleation detection. The responding mechanism is constructed base on the chain
effect of ¡®solution concentrated & metastable zone
uplimit reached-nucleation on
the pores of the porous membrane interface-transmembrane
flux sharply decrease¡¯. The inflection point of the transmembrane flux
confirms the nucleation timing on the membrane interface. The accurate
recording of the transmembrane flux data can be utilized to calculate the
solution concentration to determine the metastable zone width (MSZW), which is
key dynamic data for the effective control strategy of
crystal nucleation and growth [3,4].

Without relying on the optical signal, MDC based nucleation
response method would be easy and more meaningful in the case of opaque
solutions that laser intensity response (LIR) method is invalid [5]. This
advantage will improve the controlling accuracy and flexibility during MSZW
measurement. Moreover, with the proposed method, it would be easy to enhance
control over the process so that to select the real working conditions to
simulate different evaporation rates for the concentrating rate in the isothermal
membrane distillation process can be adjusted by the membrane permeability, the
partial vapor pressure difference and the membrane area, etc.

While, a strict requirement on the membrane
interface structure is obvious to enhance the detection accuracy of this
proposed method. With conducted effective work of Trout and Diao, the developed
Nanoparticle Imprint Lithography (NpIL) method had successfully prepared the
polymer films with nanopores of various, uniform shapes that can hinder
nucleation or promoted it [6]. In addition, the had reported the significant
impact of polymer interface with nanometer scale pores on inducing
crystallization and polymorphism control [7,8]. These foundational work can
promote the theoretical research and application of the MDC based nucleation response
and crystallization control by providing the qualified microporous membrane as
desired nucleation detection and response interface.

Fig. 1 Schematic
diagram of nucleation response and metastable zone width (MSZW) measurement
with MDC technology (compared with the laser detection technology)

Acknowledgment

This work is supported by National Natural
Science Foundation of China (Grant No. 21306017, 21527812), Program for
Changjiang Scholars and Support Project of the China Petroleum and Chemical
Corporation (X514001).

References

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