Data from: Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas-liquid membrane contactor system

The wetting of hollow fiber membranes decreases performance of the liquid-gas membrane contactor for CO2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid-gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre sized roughness on the surface of the PVDF membrane, which was achieved with a SiO2 concentration of 4.44 mg ml-1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155±3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid-gas membrane absorption.在沼气提质的CO₂捕集工艺中，中空纤维膜的润湿现象会降低液气膜接触器的运行性能。为解决该问题，本研究采用喷雾沉积法，以疏水型二氧化硅（SiO₂）纳米颗粒与聚二甲基硅氧烷（polydimethylsiloxane, PDMS）复配制备的超疏水涂层，对用于液气膜接触器的聚偏氟乙烯（poly(vinylidene fluoride), PVDF）中空纤维膜进行了改性处理。沉积于PVDF膜表面的SiO₂粗糙层可有效提升膜面疏水性；原始PVDF的表面结构对所生成SiO₂涂层的均匀性具有显著影响。当涂层溶液中SiO₂浓度为4.44 mg·ml⁻¹（0.2 g/45 ml）时，PVDF膜表面可形成微米-纳米级复合粗糙结构，进而实现PVDF表层的均匀涂层改性。经改性后的膜面水接触角可达155±3°，显著高于原始PVDF膜表面。较高的水接触角有助于缓解膜润湿现象，但超疏水涂层的引入会额外增加传质阻力。此外，本研究以单乙醇胺（monoethanolamine, MEA）溶液为吸收剂，分别在原始与改性PVDF中空纤维膜接触器中开展了连续CO₂吸收实验。长期稳定性测试结果表明，改性PVDF膜接触器的性能优于原始膜接触器，且具备优异的长期运行稳定性，这表明喷雾沉积法是制备用于液气膜吸收过程的超疏水PVDF膜的极具潜力的技术路径。