Phosphorus modified graphitic carbon nitride activated by guanidine phosphate enables fast, efficient and selective immobilization of aquatic lead

With the assistance of preinstalled silica templates, polymeric graphitic carbon nitride with enhanced porosity suffers from complicated procedures and by-product wastes. Besides, it is still difficult to achieve the incorporation of phosphate groups with high contents on carbon-based materials (mostly < 1.0 at.% of P) via a one-step preparation since phosphate species on the surfaces of sorbents could complex heavy metals strongly from wastewaters. Given the porosity engineering of guanidine phosphate (GP) for carbonaceous materials, GP activated graphitic carbon nitrides (GPCNs) with developed surface area (4.2- 4.8 fold of enhancement than inactivated one) and abundant phosphate groups (9.9-16.7 at.% of P) were fabricated via a one-step pyrolysis at 450, 500, and 550 degrees C. On this basis, the sorption of Pb(II) on GPCNs were studied under geochemical conditions including contact time, solution pH, ionic strength, humic acid concentration, interfering cations and anions, and temperature. GPCN pyrolyzed at 500 degrees C could cap-ture Pb(II) rapidly (20.0 min) with superior maximum capacities (81.8-217.1 mg/g at pH 5.0, T 298 K), excellent selectivity coefficients (8.10-16.54) and favorable reusability (81.4% of capacity remained). The formation of minerals was dominant for the selectivity rather than ion exchange or surface coordi-nation, etc. This work starts up the facile activation of carbon nitride with developed porosity and surface functionality to manage aquatic pollutants.(c) 2023 Elsevier B.V. All rights reserved.