Xunke Zhao,Kaihuan Nie,Fuyi Sun,Cheng Xie,Yanran Cheng,Yuanyuan Che
Nanofiltration holds promise for treating dyeing and printing wastewater on account of its key merits: low consumption, easy manipulation, and absence of secondary contamination. In this study, the fabrication of a uniform permselective ZIF-8@GO composite membrane in the alumina ceramic tube by the continuous flow combined with in situ self-assembly way was investigated. Subsequently, the properties of ZIF-8@GO membrane were examined in relation to reaction time, reaction temperature, flow rate, and GO concentration. Furthermore, the durability of the membrane was tested. It was observed that under optimal conditions, the rejection rate and permeation flux of methyl blue solutions remained essentially constant during 24 hours of continuous operation, with values of 98.39% and 38.27 L/(m 2 ·h·bar), respectively. This work aims to simplify and smoothly implement the industrialized production of MOF-based composite membranes and offers a potential solution for the low-cost and efficient treatment of organic dye wastewater in the printing and dyeing industry.
Yumeng Zhao,Guoshu Gao,Peng Zhu,Cun Liu,Xiongfu Zhang,Feichao Wu,Guohui Yang
Metal-organic framework (MOF) membranes hold great potential for acetic acid dehydration by pervaporation. However, it remains challenging to develop stable MOF membranes suitable for this application due to the corrosion of membranes by acetic acid. Herein, we report a robust aluminum (Al)-based MIL-96 membrane on porous ceramic tubes for acetic acid pervaporation dehydration. It is prepared by an induction strategy with Al-Sol@MIL-96-C layer, obtained by calcining an Al-based sol layer containing small MIL-96 seeds. The induced layer possesses a sponge-like structure and high reactivity, favoring the uniform growth of MIL-96 crystals and establishing a strong connection between the membrane layer and the support. The achieved MIL-96 membrane, with a thickness of ∼2 μm, exhibits excellent performance in separating 90 wt% acetic acid/water mixtures by pervaporation, showing a high separation factor of ∼3000 with a permeation flux of 1.54 kg/(m 2 ·h). Notably, due to the connectivity of the Al-Sol@MIL-96-C layer, these membranes show long-term operational stability for over 200 h, as well as great tolerance to ultrasonic treatment, highlighting the enormous potential for applications. This work provides a feasible approach to fabricate robust MOF membranes for pervaporation separation of acetic acid/water mixtures.
Yali Zhao,Xiayi Yang,Jiayu Luo,Yanying Wei,Haihui Wang
MOF membranes are very promising in molecular separation, but it is still a challenge for industrial applications due to the complex and time-consuming synthesis. We use the fast current-driven synthesis (FCDS) method to achieve controlled growth of ZIF-8 membranes on porous graphite-coated ceramic tubes by controlling the growth time and current density. Grown for 30 min at a current density of 0.74 mA/cm 2 , the ZIF-8 membrane exhibits selectivity for C 3 H 6 /C 3 H 8 up to 63 with C 3 H 6 permeance of 6 × 10 −9 mol/(m 2 s Pa). Furthermore, the ZIF-8 membrane exhibits a pressure resistance of up to 3 bar and good stability of ~96 h. This work realizes the breakthrough of the MOF membrane synthesis via FCDS method from the frequently-used expensive and fragile anodic aluminum oxide (AAO) disc substrate to the tough ceramic tubular substrate, which broadens the road for the industrialization of MOF membranes in gas separation fields.
Due to their rationally controlled pore size and easy functionalization, metal-organic frameworks (MOFs) are a promising candidate for membrane separation . As one of the most stable MOFs, UiO-66 has attracted intense attention for the preparation of molecular sieving membranes. A new post-synthesis modification (PSM) strategy was developed to enhance the separation selectivity of supported UiO-66-NH 2 membranes on porous ceramic tubes called UiO-66-NH 2 @SA by using salicylaldehyde (SA) modification. The mixed gas separation factors of H 2 /CO 2 and H 2 /CH 4 can be improved due to constrictions of the pore size through reaction of –NH 2 with SA giving iminophenol moieties. Notably, SA-modified UiO-66-NH 2 membranes are rather stable, at a high operation temperature of 200 °C and 1 bar, mixture separation factors of 11.3 for H 2 /CO 2 and 22 for H 2 /CH 4 can be obtained. Further, no obvious performance degradation has been observed after 3 months storing in air. This high stability of UiO-66-NH 2 @SA membrane could provide possibility for the industrial applications of hydrogen separation and purification.
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