Fabrication of a Mixed Matrix Membrane Using Nitrogen-Enriched Nanoporous Polytriazine for Removal of Pb²⁺ from Aqueous Solution

Abstract

An important concern for the environment is the toxicity of lead ions in aqueous solutions. In the present research, a nitrogen-enriched nanoporous polytriazine (NENP) is synthesized (SA BET ∼ 700 m 2 g –1 ), which works well as an adsorbent to remove Pb 2+ from water bodies. In batch adsorption mode, 5 mg of NENP having a high nitrogen content (∼52%) is capable of reducing the concentration of Pb 2+ from 1.6 ppm to <10 ppb within 10 min, at 298 K and a pH of 7. The maximum adsorption capacity of 537 mg g –1 is estimated in 10 min for 600 ppm of Pb 2+ solution having a pH of 7. Meanwhile, a mixed matrix membrane designated as N-MMM was fabricated using NENP as the active adsorbent and characterized by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and N 2 sorption analysis. In a cross-flow membrane setup, N-MMM with the flux of 16.2 L m –2 h –1 can treat 5 L of an aqueous solution containing 1.6 ppm of Pb 2+ and provide safe drinking water (<10 ppb by WHO) for 300 min within the permissible limit (WHO) at 2 bar transmembrane pressure and a cross-flow velocity of 1L/M. N-MMM exhibits a remarkably high removal efficiency of 99.4% and good retention ability up to 3 consecutive cycles. These findings will be beneficial for the cost-effective production of metal-free heteroatom-enriched nanoporous materials for efficient removal of Pb 2+ ions from water bodies.