###### Abstract  
A novel anion exchange resin AEE-3 was synthesized by N-alkylation of a weakly basic polyacrylic anion exchanger D311 with 1-bromopropane to effectively remove nitrate (NO3-N) from aqueous solution. The related finding revealed that its adsorption isotherm obeyed the Langmuir model well, and the second-order model was more validated for the NO3-N adsorption kinetics study. Compared to commercially-available polystyrene-based nitrate specialty resin Purolite A 520E (A520E), AEE-3 resin has a higher adsorbed amount and better regeneration performance toward NO3-N in the existence of dissolved organic matter (DOM) using static and dynamic methods. Notably, a real secondary treated wastewater (STWW) obtained from a local municipal wastewater treatment plant was also assessed for NO3-N removal in fixed-bed columns. Observations from this study indicated that AEE-3 could effectively remove NO3-N from contaminated surface water.  
nitrate; dissolved organic matter; ion exchange; selectivity +
Footnote †: journal: Applied  
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and can engender a strong affinity for resins via electrostatic attraction, hydrophobic interaction and so on [12; 13; 14]. Hence, AERs are more sensitive to fouling with DOMs, which would compete with NO3\({}^{-}\)-N for the active sites and cause the decrease in NO3\({}^{-}\)-N adsorption. More seriously, coexisting DOM could lead to an irreversible fixation to anion exchangers. Polyacrylic AERs with hydrophilic structures reveal a stronger resistance to organic fouling performance than polystyrene AERs [15]. Moreover, acrylic-based resins possess unique physiochemical properties, rapid adsorption rates and high ion-exchange capacities [16; 17]. Accordingly, polyacrylic AERs could serve as a promising absorbent to effectively remove NO3\({}^{-}\)-N from polluted water in the presence of DOMs. Nevertheless, few works have shown the feasibility of polyacrylic resins for NO3\({}^{-}\)-N removal in real STWW containing NO3\({}^{-}\)-N at high levels.  
However, competitive anions such as chloride (CI\({}^{-}\)) or sulfate (SO4\({}^{2-}\)) exist widely in water, which can weaken NO3\({}^{-}\)-N uptake efficacy of AERs [18]. To circumvent this limitation, studies have been devoted to preparing a novel anion exchanger with prominent selectivity toward NO3\({}^{-}\)-N. The long alkyl chain addition at the exchange sites of resins could be of great benefit for the preferable selectivity toward monovalent anions because of its steric hindrance and hydrophobic effect [19; 20]. Hence, it is intriguing for us to modify the weakly basic resin by introducing long alkyl groups around the active amine groups, which can easily form strongly basic functional groups (quaternary ammonium) which interact with NO3\({}^{-}\)-N through strong electrostatic attraction.  
Herein, a weakly basic polyacrylic anion exchanger D311 was modified with 1-bromopropane (C3H7 Br) to prepare a strongly basic anion exchanger AEE-3 with high efficiency and brilliant selectivity for NO3\({}^{-}\)-N uptake. The adsorption kinetics, isotherms, influence of pH value and competitive anions were investigated. In addition, commercial nitrate-selective polystyrene resin Purolite A 520E (A520E) was chosen to make a comparison with AEE-3 in both batch and fixed-bed column experiments, further demonstrating that AEE-3 is more resistant to fouling by DOMs (humic acid, tannic acid and sodium dodecyl benzene sulfonate). Also, a dynamic experiment was studied to evaluate the adsorption performance of AEE-3 toward NO3\({}^{-}\)-N in real STWW.