Electro-driving Separation Performance And Integration With Microfluidic Chip Of Nanofiltration Membrane

Membrane technology is commonly used as laboratory and industrial separation technology and on-chip integrated in the membrane separation unit operation is an important issue in the area of lab-on-chip. This thesis is to investicate the electro-driving permeation performance of nanofiltration membrane outside the chip, and to integrate nanofiltration membrane in the glass microfluidic chip. The main work and results are summarized as follow:1. Polypiperazine - amide nanofiltration membranes and nylon 6,6 membranes were prepared by interfacial polymerization. Effects of trimesoyl chloride solution concentration on morphology and thickness of nanofiltration membranes were studied. Experimental results showed that the roughness and porosity of the oil phase surface of nanofiltration membranes increased with trimesoyl chloride solution concentration, but the water phase surface varied oppositely. The thickness of nanofiltration membranes increased with trimesoyl chloride solution concentration, and this membrane belongs to uniform membrane.2. The permeability of cation (Ca²⁺ and Na⁺) and anions (SO₄^2- and Cl^-) of different valence and retention property of buffer solution ion and FITC labeled amino acids of nanofiltration membrane under DC electric field driving were investigated. Effects of electric field and operation time on the ion permeability of nanofiltration membrane were studied. Experimental results showed that the permeation order of cation and anions of nanofiltration membrane by electro-driving were the same as the pressure-driven. The ion peameation percentage was increased with electric field strength and operation time, and the difference of permeation performance between ions was not significant. However, FITC labeled glycine and lysine were blocked totally, and buffer solution ions (Na⁺, B₄O₇^2-) could pass through the membrane.3. The SO₄^2- and Cl^- permeability and retention property of FITC labeled amino acids of nylon 6,6 membrane under DC electric field driving were first investigated. Nylon 6,6 membranes were prepared by interfacial polymerization, and the SO₄^2- and Cl^- and FITC labeled amino acids permeability of nylon 6,6 membrane were studied by electro-driving. And effects of electric field, operation time and temperature on the SO₄^2- and Cl^- permeability of nylon 6,6 membrane were studied. Experimental results showed that the permeation percentage of SO₄^2- and Cl^- is high and similar for nylon 6,6 membrane, but FITC labeled glycine and lysine were blocked totally, the molecular weight cutoff is around 500. So in a broader sense, the synthesized nylon 6,6 membrane is one kind of nanofiltration membrane.4. Set up the integration method of nanofiltration membrane in microfluidic chip, and design and fabricate glass microfluidic chip, and nanofiltration membranes were in-situ prepared by interfacial polymerization in micro-channel. The chip configuration and fluid flow rate on the stability of fluid interfaces were studied, and nanofiltration membranes integration was tried at the connection of the two micro-channel. Retention results showed that FITC could be completely blocked.