Development of high performance nanofibrous composite membranes by optimizing polydimethylsiloxane architectures for phenol transport

• Main Authors: Jin, Meng-Yi, Liao, Yuan, Tan, Choon-Hong, Wang, Rong
• Other Authors: School of Civil and Environmental Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: Engineering::Civil engineering; Polydimethylsiloxane; Phenol Extraction
• Online Access: https://hdl.handle.net/10356/85497; http://hdl.handle.net/10220/50434
• Institution: Nanyang Technological University

Phenol removal and recovery from wastewaters are highly demanded in industries due to its high toxicity and industrial importance. It can transport through the silicon-based rubber polydimethylsiloxane (PDMS) via the solution-diffusion mechanism. To improve the phenol removal efficiency in extractive processes, dense PDMS membranes with different macromolecular structures have been developed and evaluated in this work. The condensation-cured PDMS membranes (PA) with network architecture exhibited higher phenol partition coefficients (K) than the hydrosilylation-cured PDMS membranes with linear and branch architectures. This was attributed to the four-armed quaternary-siloxy linkages formed in the three-dimensional network structure, increasing the free volume for phenol passage and hydrogen bonding between phenol and PDMS matrix. The K of PA was further enhanced by optimizing the PDMS precursor chain length and cross-linker amount, and the corresponding membrane mechanical properties and phenol overall mass transfer coefficients (k0) were examined. The optimal PA formulation was utilized to fabricate a highly effective nanofibrous composite membrane via spray coating. The resultant composite membrane exhibited a k0 of 18.3 ± 1.3 × 10−7 m/s in an aqueous-aqueous extractive process, significantly outperforming the commercial counterpart with 45% increment. This is the first demonstration of the importance of PDMS macromolecular structures on phenol extraction. The newly-developed condensation-cured PDMS could contribute to the fabrication of highly effective composite membranes for various extractive processes.