One‐Walled Phthalimide Extended Calix[4]Pyrrole‐Based Supramolecular Adsorbent for Alleviating Nitrate From Simulated Water

Abstract In this investigation, meso ‐substituted one‐walled phthalimide appended calix[4]pyrrole ( m Pth–C4P) was prepared from pthalimide functionalized dipyrromethane (DPM, 4 ), acetone, and freshly distilled pyrrole via both conventional as well as green protocols utilizing the deep eutectic solvent (DES) of N,N' ‐dimethyl urea (DMU) & l ‐(+)‐tartaric acid (TA) in an appropriate ratio of 7:3. In order to lessen the nitrate (NO 3 − ) ion endowed eutrophication peril, the m Pth–C4P was effectively employed as a supramolecular adsorbent for the sequestration of NO 3 − ion from aquatic phase. The m Pth–C4P was extensively characterized by FTIR, 1 H‐NMR, SEM–EDX, and elemental mapping to corroborate the synthesis and adsorption of NO 3 − ion. The surface area was found to be 11.465 m 2 g −1 and the pore size of 3.2 nm, pointed out to the mesoporous nature of m Pth–C4P. Batch methodology was exploited for detailing the influence of process parameters on %efficiency and adsorption capacity. The m Pth–C4P demonstrated excellent adsorption competence (> 91%) within 16 min from a [NO 3 − ] of 20 mg L −1 , which translates into a good pseudo‐second order rate constant value of 0.026 g mg −1 min −1 . Freundlich model was the best‐fit model pointing out multilayer adsorption. The maximum saturation capacity was 239.03 mg g ‒1 at 298 K, which is far better than most of the reported adsorbents indicating the potential of m Pth–C4P to confiscate NO 3 − . The dynamics appraisal elucidated pseudo‐second order to favor the uptake with both intraparticle and liquid film diffusion models governing the rate of reaction. Thermodynamic parameters suggested that the uptake of NO 3 − was spontaneous, favorable, and exothermic which is in harmony with the isotherm studies. The m Pth–C4P can be used consecutively up to 4 cycles along with good potential in real water > 80% uptake. All these results established m Pth–C4P as an efficacious scavenger for NO 3 − from simulated water.