Contents lists available at ScienceDirect Journal of Water Process Engineering journal homepage: www.elsevier.com/locate/jwpe Surface modification of forward osmosis membrane using polyoxometalate based open frameworks for hydrophilicity and water flux improvement Alireza Shakeri a, ⁎ , Hossein Mighani b , Narges Salari b , Hasan Salehi a a School of Chemistry, College of Science, University of Tehran, P.O. Box, 14155-6619, Tehran, Iran b Department of Chemistry, Faculty of Science, Golestan University, P.O. Box 155, Gorgan, Iran ARTICLE INFO Keywords: Forward osmosis Thin film composite membrane Wastewater treatment Polyoxometalate Hydrophilicity ABSTRACT Forward osmosis (FO) has emerged as a novel membrane-based separation method for application for waste- water treatment, seawater desalination,and sustainable energy. A major challenge in the development of forward osmosis process is the lack of a high-efficiency membrane. In this study, a next-generation membrane for FO process was investigated by integrating nanotechnology with membrane science. Incorporation of poly- oxometalate based open frameworks (POM-OFs) within the polyamide (PA) active layer of thin film composite (TFC) membrane has generated a new type of thin film nanocomposite (TFN) membrane with significantly enhanced hydrophilicity and permeability properties. The successful incorporation of the POM-OFs in the membranes active layer was investigated through Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) methods. The water flux of POM-OFs modified membrane (TFN w3 , containing 500 ppm of POM-OFs) in FO and PRO modes was 29.9 and 41.7 LMH, the value of which was about two times those of TFC membrane. In conclusion, we report a novel forward osmosis membrane for wastewater treatment. 1. Introduction As society develops, the accessibility to clean water becomes an important global issue [1]. To address the water scarcity crisis an- dproviding fresh and clean water to the general populace membrane- based water treatmentis apromising solution [2,3].Forward osmosis (FO) is a membrane-based separation process, which in the osmotic- pressure gradientbetween two solutionswith different concentration act as a natural driving force [4–6]. Based on this osmotic pressur- edifference, water can be driven across the semi-permeable membra- newhile contaminants and unwanted elements retaining in the feed solution [7,8]. In spite of lower water flux, as compared to conventional pressure-driven membrane processeswhich uses high hydraulic pres- sure at the feed side, FO benefits from low operation energy, low membrane foulingtendencyand high water recovery [9–11]. But achieving these advantages heavily relies on the performance of the FO membrane. In the last decade, thin film composite (TFC) membranes have been used predominantly as osmotic membranes in water and energy ap- plications, because each layer in the composite membrane can be in- dependently optimized with the proper choice of materials and pre- paration methods [12,13].Introducing nanomaterials in the selective layer of composite membranesis a promising modification approach to further improve the TFC membrane performancein membrane separ- ationprocesses [14].Up to date, a range of nanoparticles including in- organic salts [15,16], zeolite [17], carbon nanotube (CNT) [18], gra- phene oxide (GO) [12], silica nanoparticles [19], cellulose nanocrystals [20], graphene quantum dot [21], copper-1,4-benzene dicarbox- ylatenanosheets (CuBDC-NS) [22]and metal-organic frameworks (MOF) [23] have beenused in the modification of separation performance of composite membranes in FO process. Despite this progress, there is still a major problem, the poor compatibility between hardinorganic na- noparticles and the soft polymer matrixcan cause detrimental effects on the membrane selectivity [24]. Surface modification of these nanoma- terials with organic ligands is one of the strategies can be used to solve the above-mentioned issues [25]. In addition, TFN membrane fabri- cated by these nanomaterials has higher surface water permeability and hydrophilicity in comparison to the conventional nanomaterials without surface modification [26]. The design and synthesis of porous materials are of increasing in- terest because of the unique properties these materials have in sorption, separation, and catalysis.Polyoxometalate-based open frameworks (POM-OFs) are a new type of hybrid material consisting of poly- oxometalate clusters as inorganic building blocks coordinated by https://doi.org/10.1016/j.jwpe.2019.02.002 Received 10 September 2018; Received in revised form 21 January 2019; Accepted 4 February 2019 ⁎ Corresponding author. E-mail address: alireza.shakeri@ut.ac.ir (A. Shakeri). Journal of Water Process Engineering 29 (2019) 100762 2214-7144/ © 2019 Published by Elsevier Ltd. T