Quaternary branched polyethylenimine-based nanocomposite for removal of NO3− ions from aqueous solutions

This study synthesized a nanocomposite based on quaternary branched polyethyleneimine containing sodium alginate and graphene oxide and characterized by FE-SEM, EDX-MAP, XRD, FT-IR, and TGA and used as an efficient sorbent for the removal of nitrate ions. The maximum ion exchange in optimized conditions was discovered to be 75%. The experimental studies showed that nitrate removal follows the pseudo-first-order model due to more consonance. Also, Weber–Morris and Boyd models suggested that the nitrate ions adsorption on the surface of nanocomposite is not controlled only by the intraparticle diffusion step. Moreover, Langmuir, Redlich–Peterson, and Hill models exhibited high regression coefficients of 0.991, 0.993, and 0.992, respectively. Thermodynamic studies confirmed the adsorption system was spontaneous and exothermic. Recovery assay showed that more than 98% of the nitrate ion exchanged by the nanocomposite was regenerated and nanocomposite could be reused seven cycles without efficacy reducing significantly. The nanocomposite showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli cells, with minimum inhibitory concentrations of 62.5 and 125 μg mL⁻¹, and zone of growth inhibition of 17.5 ± 0.5 and 10.5 ± 0.5 mm, respectively. The results represented that the introduced nanocomposite is a useful material for the removal of nitrate ions from aqueous solution and has antibacterial properties.