Novel Schiff Base Fe(III) and Cu(II) Complexes: Synthesis, Characterization, Analytical, and Antimicrobial Applications

Metal speciation is essential in environmental and biological systems due to the varied toxicity and reactivity of various oxidation states. In the present study, parahydroxy benzaldehyde reacts with thiosemicarbazide to yield an orange colored parahydroxy thiosemicarbazide (P-HTC) Schiff base. The P-HTC Schiff base reacts with Fe(III) and Cu(II) to produce dark brown and dark green complexes, respectively. The P-HTC ligand and Cu(II)-P-HTC and Fe(III)-P-HTC complexes were characterized utilizing UV-visible, CHNS, and FTIR techniques, which suggested the formation of stable complexes. The hydrophobic Cu(II)-P-HTC and Fe(III)-P-HTC complexes were successfully floated into the scum layer using an oleic acid (HOL) surfactant. Temperature, sample volume, pH, P-HTC concentration, Effect of interferences, HOL concentration, and other factors influencing flotation performance were optimized. The concentration of Cu(II) and Fe(III) was determined in the mother liquor using FAAS. The analytical detection limits were 0.0396 and 0.1155 ng/L for Cu(II) and Fe(III), respectively. The recoveries of Cu(II) and Fe(III) from wastewater were 99.83 and 99.96 for Cu(II) and Fe(III), respectively, and for tap water were 99.78 and 99.55 for Cu(II) and Fe(III), respectively. The relative standard deviations (RSD) were below 3.8%. The proposed method was successfully applied to determine Cu(II) and Fe(III) in pharmaceutical and environmental water samples. The antimicrobial activity of the P-HTC, Cu(II)-P-HTC, and Fe(III)-P-HTC complexes was thoroughly studied. The mechanism of flotation of Cu(II)-P-HTC and Fe(III)-P-HTC complexes was proposed.