Tubular hydrophobic ceramic membrane with asymmetric structure for water desalination via vacuum membrane distillation process

A porous ceramic membrane without water wetting is essential for the application of water desalination in membrane distillation. In this study, we report a hydrophobic tubular asymmetric alumina membrane that was modified by grafting hexadecyltrimethoxysilane (C16) molecules. The grafting efficiency and hydrophobicity of the grafted membrane were characterized by its morphology, contact angle and FTIR spectrum, as well as the changes in terms of nitrogen permeance and pure water flux over various pressures. Four kinds of tubular asymmetric alumina membranes were employed in the vacuum membrane distillation (VMD) process. The effects of membrane thickness and pore size on the water flux or salt retention were investigated. The mass transport resistance in substrate was non-negligible and sometimes could be the main contributor to the total mass transport resistance. The membrane with a top layer thickness of 20 urn, pore size of 150 nm and support pore size of 3.2 mu m was appropriate in the VMD process. After > 1000 min desalination, the permeate flux and salt rejection were maintained as high as at the beginning, i.e., approximately 30 kg-m(-2).h(-1) and 99.9%, respectively.

在膜蒸馏海水淡化应用中，一种不被水润湿的多孔陶瓷膜至关重要。在本研究中，我们报道了一种通过接枝十六烷基三甲氧基硅烷（C16）分子改性的疏水性管状非对称氧化铝膜。通过其形貌、接触角和傅里叶变换红外光谱，以及在不同压力下氮气渗透率和纯水通量的变化，对接枝膜的接枝效率和疏水性进行了表征。四种管状非对称氧化铝膜被用于真空膜蒸馏（VMD）过程。研究了膜厚度和孔径对水通量或盐截留率的影响。基底中的传质阻力不可忽视，有时可能是总传质阻力的主要贡献因素。顶层厚度为20μm、孔径为150nm且支撑体孔径为3.2μm的膜在VMD过程中是合适的。经过>1000分钟的脱盐后，渗透通量和盐截留率仍保持在初始的较高水平，即分别约为30kg·m⁻²·h⁻¹和99.9%。