Two-dimensional Co ultrathin metal–organic framework nanosheets (Co-UMOFNs) were synthesized and blended into poly (ether block amide) (PEBA) to prepare composite mixed matrix membranes on PVDF supports for the pervaporation of phenol aqueous solution. The membranes were characterized by XRD, ATR-IR, TGA, CA and SEM measurements. Effects of the Co-UMOFNs loading, feed temperature and feed concentration on phenol separation performance were investigated. The results showed that Co-UMOFNs have a two-dimensional layered morphology and have good compatibility with the PEBA. A “brick and mortar” architecture morphology was achieved after incorporating Co-UMOFNs into the PEBA membrane. The amorphous PE segments in the PEBA were turned into a crystalline structure, restricting the motion of PE segments. The filling of Co-UMOFNs slightly improved the thermal stability and hydrophobicity as well. With the increase of the Co-UMOFNs loading from 0% to 40%, the phenol separation factor increased from 27 to 45, and the total flux decreased from 1.2 kg m -2 h - 1 to 0.42 kg m -2 h - 1 , when separation of 1000 ppm phenol solution at 70 °C. The interlayer galleries induced by the Co-UMOFNs stacking increased the tortuosity, and the crystalline structure of the Co-UMOFNs-PEBA improved the energy barriers of water penetration. Therefore the water flux was inhibited and the phenol separation factor increased. Depression of water permeation can be another protocol to prepare high-performance organophilic pervaporation membranes.
The recovering of phenolic compounds from waste waters is of vital significance owing to their strong toxicity, carcinogenicity and potential biological accumulation. Herein, different organic ligands-functionalized MIL-101 particles were synthesized and introduced into the polyether block amide (PEBA) matrix to construct excellent mixed matrix membranes (MMMs) for the permselective pervaporation of phenol. A range of characterization techniques were employed to investigate the physicochemical properties of these MIL-101 based particles and the resultant membranes. It was found that the incorporation of ligand-modified MIL-101 demonstrated better interfacial compatibility and hydrophobicity than the unmodified MIL-101. The BMIL-101/PEBA-3 membrane exhibited optimum separation factor of 12.47 and corresponding total flux of 1711.71 g·m −2 ·h −1 at 50 °C for a 1000 ppm phenol solution. The separation factor increased by 4.83 % versus FMIL-101/PEBA-3 membrane. However, in comparison to the original PEBA polymer membrane, the total flux and separation factor climbed by 16.96 % and 10.95 %, respectively, whereas the MMMs introducing unfunctionalized MIL-101 (3 wt%) exhibited a reduction in the phenol separation factor. Effects of polymer solution concentration, casting solution thickness, filler content, operating temperature, and phenol concentration on membrane separation performance were explored systematically. What’s more, the BMIL-101/PEBA-3 membrane also presented outstanding long-term stability for 84 h, which also provides novel guidelines to develop high-performance membranes for phenol recovery.
Yan Zhuang,Zhihao Si,Siyu Pang,Hanzhu Wu,Jan Baeyens,Xinmiao Zhang,Peiyong Qin
Despite much progress in the development of photo-initiators (PIs) for many advanced applications, their high migration and weak thermal stability are still challenging. Especially, it easily results in an incomplete curing and sacrificial separation performance in the use of polymeric membranes . PI 2-hydroxy-2-methylpropiophenone (1173) has been most frequently used in photocuring owing to its high reactivity and universal applicability. Herein, we reported a series of alkyl chain engineered PI 1173 with different chain lengths for fabricating polydimethylsiloxane (PDMS) membranes. The dodecyl isocyanate functionalized PI 1173 displayed a lower migration ratio of 1.42% from the PDMS matrix compared with 2.99% for PI 1173. Its degradation temperature was also improved where the weight loss was only 10% as the temperature was raised to 241.1 °C. Importantly, the fabricated PDMS membranes initiated by alkyl chain engineered PIs showed an excellent n -butanol permselective pervaporation (PV) with separation factor of 38–54 and total flux of 818–1396 g m −2 h −1 when feeding 1.5 wt% n -butanol aqueous solution at 60 °C. It provides a general method for fabricating high-quality separation membranes .
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