Facile preparation of thin and nanodisperse ZIF-8/PDMDES hybrid membrane for efficient alcohol recovery via pervaporation

Membrane-based separation technology has emerged as a focal point of research in the realm of renewable energy. In this investigation, nano-sized ZIF-8 particles were synthesized and then embedded into a poly-dimethyldiethoxysilane (PDMDES) matrix through a facile method, thereby creating an ultra-thin ZIF-8/PDMDES hybrid membrane specifically designed for alcohol permselective pervaporation. The successful synthesis of ZIF-8 nanoparticles was corroborated by the XRD, SEM, and FTIR characterization approaches. The addition of ZIF-8 nanoparticles into the hybrid membranes markedly augmented their hydrophobicity, thermal stability, and affinity toward alcohols, surpassing the attributes of the unmodified PDMDES membrane. The utilization of low-viscosity PDMDES led to an actual ZIF-8 loading that exceeded the theoretical one, resulting in unique membrane morphologies: dense layer and loosely-packed layer. The newly prepared hybrid membrane exhibited an improved separation factor and simultaneously increased permeation flux in the alcohol recovery via pervaporation, showcasing preferable anti-tradeoff achievements. Accordingly, the obtained hybrid membrane with a ZIF-8 loading of 6.5 wt% displayed an outstanding pervaporation performance for recovering ethanol from a 5 wt% ethanol/water mixture at 40 ℃, achieving a remarkable total flux of 6.67 kg∙m⁻²h⁻¹, a distinguished ethanol permeability of 14.36 × 10⁴ Barrer, and a competitive separation factor of 7.68.