New functionalized magnetite chitosan–heterocyclic nanocomposites excelling in Cd2+ removal from aqueous solution with biological activity

Abstract

Abstract Newly modified magnetic chitosan nanoparticles were synthesized for the high-efficiency removal of cadmium ions from aquatic environments. The structure and morphology of the composites were confirmed using FTIR, TGA, XRD, BET, SEM, TEM, SAED pattern analysis, and zeta potential. Under optimal conditions (pH = 6.0, contact time = 120 min, and sorbent dosage = 0.005 g/100 mL), the maximum removal of Cd (II) by synthesized samples MC, SA, and SB was 90.8%, 95%, and 95.15%, respectively. The kinetic data at optimal pH = 6 could be accurately described using a pseudo-second-order equation, while the Langmuir isotherm model best represented the sorption process. The Langmuir Qmax values for the synthesized nanocomposites S*, S3, S4, S*t, S3t, and S4t were 243.90, 250, 270.27, 212.76, 237.09, and 238.09, respectively. The thermodynamic analysis of these samples shows that the sorption process was exothermic (negative ∆H°) − 15.148, − 13.60, − 13.18, − 18.163, − 16.820, and − 16.06 kJmol−1, respectively. This implies that the diffusion of Cd(II) on the sorbent decreased with the temperature rise. The positive values of ΔS⁰ were 152.37, 147.80, 146.83, 160.94, 157.08, and 154.93 kJmol−1, respectively. The antimicrobial properties of the functionalized sorbents SA and SB were evaluated by measuring the zone of inhibition (ZOI) against Staphylococcus aureus and Klebsiella pneumoniae, representing Gram-negative and Gram-positive bacteria, respectively. SA and SB showed promising activity, demonstrating clear zones of (20 ± 0.2 and 18 ± 0.4 mm), and (22 ± 0.2 and 20 ± 0.4 mm) for S. aureus and K. pneumoniae, respectively. Additionally, these sorbents demonstrated moderate antioxidant activity, with the highest scavenging percentages of 94.20% and 96.63%, respectively, at a concentration of 1000 µg/mL, as assessed by the DPPH method.

Keywords

• Functionalization
• Magnetic chitosan
• Cadmium remediation, uptake kinetics, and isotherms
• Tannery wastewater
• Antimicrobial and antioxidant activities