Fabrication of a Mixed Matrix Membrane Using Nitrogen-Enriched Nanoporous Polytriazine for Removal of Pb<sup>2+</sup> from Aqueous Solution
Jasasmita Das, Anuj Rawat, Monika Chaudhary, Paritosh Mohanty
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.