Desalination ( IF 7.098 ) Pub Date : 2020-01-09 , DOI: 10.1016/j.desal.2019.114307 Mohammad Reza Shirzad Kebria; Ahmad Rahimpour; Saeed Khoshhal Salestan; S. Fatemeh Seyedpour; Arman Jafari; Fatemeh Banisheykholeslami; Naser Tavajohi Hassan Kiadeh
Dendrimers are a new class of polymeric materials owning unique properties such as hydrophobicity. In this study, hydrophobic hyper-branched dendritic (HB-Den) structures were synthesized via a polycondensation reaction between hydroxyl groups of boehmite and carboxylic groups of nitrilotriacetic acid (NTA) and was used to improve the hydrophobicity of electrospun nanofibrous membranes (ENMs). Effects of the different contents of HB-Den structures on membrane morphology, elemental properties, surface hydrophobicity, desalination performance and antifouling properties were assessed by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), water contact angle measurements and air gap membrane distillation (AGMD) experiments. Digital microscopy images showed monodisperse dendrimers with a tree-like structure. The water contact angle and liquid entry pressure (LEP) increased from around 129.3° and 101 ± 3.1 kPa for a neat PVDF membrane to 138.3° and 121 ± 2.2 kPa upon loading with 0.075 wt% HB-Den structures. FTIR analysis of the HB-Den containing ENMs confirmed the presence of carboxylic groups of NTA on the membrane surface. After desalination experiments, the 0.075 wt% HB-Den ENM showed a stable flux of 10.7 kg/m2 h and 99.9% NaCl rejection over 15 h filtration of a 3.5 g/l NaCl solution. The anti-fouling properties of the ENMs were also enhanced by incorporation of the dendritic structures. The 0.075 wt% HB-Den ENM showed flux recovery of about 94% after 20 h desalination experiment using real seawater as a feed solution.