Dendritic amine sheltered membrane for simultaneous ammonia selection and fouling mitigation in forward osmosis
2019
Bao, Xian | Wu, Qinglian | Shi, Wenxin | Wang, Wei | Zhu, Zhigao | Zhang, Zhiqiang | Zhang, Ruijun | Zhang, Bing | Guo, Yuan | Cui, Fuyi
Tailoring a compatible membrane with simultaneous resistance to ammonia and fouling is fundamental to the application of forward osmosis (FO)-based technologies in resources recovery from domestic wastewater but challenging. Herein, polyamidoamine dendrimer, with an open interior cavity and abundant terminal primary amines, was grafted on a nascent thin film composite (TFC)-FO membrane surface to provide an energetic barrier for ammonia passage and foulants absorption. Benefiting from the repulsive force imposed by the protonated primary amines, the resultant membrane exhibited superior selectivity towards ammonia (98.81% rejection rate). The hydrophilic dendritic primary amines also generated a protective hydration layer over membrane surface for foulants isolation, thus endowing the grafted membrane with robust fouling resistance and fouling reversibility and further maintaining outstanding average water flux of 29.81 Lh⁻¹m⁻² in concentrating domestic wastewater with 80% water reduction. Meanwhile, the grafted membrane possessed a significantly higher ammonia nitrogen rejection of 86.08% than the pristine membrane (40.51%) due to the simultaneously enhanced membrane selectivity to ammonia and anti-fouling capacity. Besides, the robust resistance to organic foulants significantly delayed the initiation of microorganism growth and thus effectively suppressed the formation of biofouling on membrane surface during the long-term domestic wastewater concentration. The developed ammonia-selective and anti-fouling TFC-FO membrane has great potential in facilitating the application of FO-based technologies in resources recovery from domestic wastewater.
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