Contents lists available at ScienceDirect Separation and Purifcation Technology journal homepage: www.elsevier.com/locate/seppur Study of synergetic efect and comparison of novel sulfonated and carboxylated bulky diamine-diol and piperazine in preparation of negative charge NF membrane Hamidreza (Jafar) Rezania a , Vahid Vatanpour b, ⁎ , Abbas Shockravi a, ⁎⁎ , Mortez Ehsani c a Department of Organic Chemistry, Faculty of Chemistry, Kharazmi University, P.O. Box 15719-14911, Tehran, Iran b Department of Applied Chemistry, Faculty of Chemistry, Kharazmi University, P.O. Box 15719-14911, Tehran, Iran c Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran, Iran ARTICLEINFO Keywords: Desalination New monomers Thin flm composite Nanofltration Interfacial polymerization Polyamide ABSTRACT Two new sulfonated (SDA) and carboxylated (CDA) aromatic diamine-diol monomers were synthesized and applied to prepare thin-flm composite (TFC) nanofltration (NF) membranes with improved antifouling and performance properties. The interfacial polymerization method was used to make sulfonated and carboxylated TFC-NF membranes with reaction of trimesoyl chloride (TMC) in the organic phase with amine and hydroxyl agents in the aqueous phase. Herein, for the frst time, a comparison between carboxylated and sulfonated TFC wascarriedout.Moreover,theprobabilityofsynergeticefectbetweenthesetwosyntheticmonomers(CDAand SDA)andpiperazinemonomerwasstudied(thesulfonatedmonomerandpiperazineshowedasynergeticefect). The outcomes of fux recovery ratio (FRR), fux and contact angle showed that in the presence of newly syn- thesized monomers, membrane hydrophilicity considerably improved. The salt retention sequence for all membranes was Na 2 SO 4 ≫ NaCl > CaCl 2 , which means all membranes had a negative charge. Among the fve prepared TFC membranes (SDA, CDA, PIP, SDA/PIP, and CDA/PIP), the SDA/PIP showed the best salt rejection (97% Na 2 SO 4 ) with fux (50Lm −2 h −1 ) and 91% FRR, at operating pressure of 10 bars. Although the SDA showed the highest permeability (62Lm −2 h −1 )andFRRof92%,itpresentedthelowestNa 2 SO 4 rejection. The results indicated that mixing carboxylated monomers with PIP caused deterioration in properties, while mixing sulfonated monomer with PIP enhanced the performances of the related TFC. Better permeability of the mem- brane made by newly synthesized monomers is ascribed to the existence of strong hydrophilic sulfonic acid, carboxylic acid and terminal hydroxyls, and amine groups at polyamide top layer producing enhanced mem- brane antifouling properties. 1. Introduction The World Economic Forum listed water scarcity as the largest global risk in terms of potential efect over the next decade in 2015. Nowadays,almosttwo-billionpeopleintheworld,(approximately25% oftheworld'spopulation)donothaveaccesstosafedrinkingwater [1]. Desalinationofsaltywaterbythin flmcomposite(TFC)membranei.e., reverse osmosis (RO) and nanofltration (NF) might be economically and technically feasible to manage water scarcity and overwhelmed water defcit specially in countries with shoreline [1]. The NF, due to higher fux rates and lower energy consumption, has replaced RO in numerous applications [2]. Besides wastewater and water treatment, the NF has also shown signifcant penetration into other industrial sectors such as food and beverage processing [3], pharmaceutical and biomedical processes [4], and chemical and petrochemical applications [5]. Although TFC membrane has been studied for quite a long time, exploring efective TFC NF membranes with good rejection, high fux and low fouling still facing challenges [6,7]. Moreover, there are many methods available to modify polymeric NF membranes. For example: developingnewtypesofmembranematerials [8],modifyingmembrane surfaces (UV-initiated grafting, plasma grafting and ion implantation) [9], coating of hydrophilic polymers [10] as well as incorporating na- nomaterials into selective layer of the membranes [11,12]. However, some of these methods are not commercially feasible as the equipment involved may be too costly for large scale membrane production [13]. https://doi.org/10.1016/j.seppur.2019.04.043 Received 10 September 2018; Received in revised form 9 April 2019; Accepted 14 April 2019 ⁎ Corresponding author. ⁎⁎ Corresponding author. E-mail addresses: vahidvatanpour@khu.ac.ir (V. Vatanpour), abbas_shockravi@yahoo.co.uk, shockravi@khu.ac.ir (A. Shockravi). Separation and Purification Technology 222 (2019) 284–296 Available online 15 April 2019 1383-5866/ © 2019 Elsevier B.V. All rights reserved. T