Nanofiltration membranes with dually charged composite layer exhibiting super-high multivalent-salt rejection

Abstract

a b s t r a c tState-of-the-art nanofiltration (NF) membranes generally positively or negatively charged could not remove both multivalent cations and anions once and for all according to the Donnan Exclusion. Designing NF membranes with facile approach for effective removal of multivalent-salt without compromising the permeation is still a tough challenge. In this work, we demonstrate a sort of novel NF membrane consists of a positively charged interlayer sandwiched between substrate and negatively charged outermost surface. The restructured NF membranes with dually charged composite layer were fabricated via amination-interfacial polymerization (A-IP) on poly (vinyl chloride) (PVC) substrate. The resultant NF membranes exhibited super high salts rejection of up to 99.0% MgCl 2 , 99.0% MgSO 4 , 98.5% CaCl 2 , 95.7% Pb(NO 3 ) 2 , and 96.0% Na 2 SO 4 . Additionally, reasonably high flux (8.7 L m À 2 h À 1 bar À 1 , (pure water permeability (PWP))) approaching those of commercial NF membranes was obtained due to the relatively loose structure of the composite layer. Furthermore, the transport and separation mechanism of the restructured NF membranes reveals that the significant upgraded separation performance could be attributed to the synergistic effect of the dually charged layer. Moreover, the dually charged composite layer shown none unfavorable interaction and the resultant NF membranes possessed good interfacial stability.

A Strategy for Nonmigrating Plasticized PVC Modified with Mannich base of Waste Cooking Oil Methyl Ester

“…As seen from the Fig. 2(d) , it is clearly to observe that the signals at 1.25, 2.80, 3.58 and 5.29 ppm were attributed to the protons of -C H 2 -, O-C H 3 , -NH-C H 2 -C H 2 -NH- and -C H =C H -, respectively 31 , which appeared stronger with more displacement of chlorine with mannich base of WCOME, but the signal at 4.5 ppm corresponds to the protons of C H -Cl presented weaker gradually, which indicated that the self-plasticization PVC was obtained.…”

Internally plasticized PVC materials via covalent attachment of aminated tung oil methyl ester

“…30 In addition, the displacement of chlorine with amidation derivatives was usually to modify PVC surfaces for preparing functional ultraltration membranes with improved antifouling properties. [31][32][33] Covalent immobilization of trypsin and chymotrypsin onto aminated-PVC microspheres was also descried by Li et al 34 However, the displacement of chlorine with aminated derivatives via single reaction for plasticizing PVC materials has never reported.…”

Understanding the chlorination mechanism and the chlorine-induced separation performance evolution of polypiperazine-amide nanofiltration membrane

“…Charge properties of samples were detected using an electrokinetic analyser (SurPASS, Anton Paar, Austria) [24]. Fibres were immobilized in a module in advance to analyse the charge properties of membrane inner surface.…”

“…Furthermore, the solutes employed in membrane separation performance evaluation would also affect the research results. Unlike the dense RO membranes, the separation performance, particularly the salts rejection, of the relatively loose NFMs is significantly influenced by its charge properties, which are commonly determined by the content of -NH and -COOH groups in the separating layer [22][23][24].…”