Multifunctional magnetic pectin-GO/Cu-Co-LDH nanocomposite for rapid Congo Red removal and antibacterial activity

A multifunctional magnetic Pectin-GO/Cu-Co-LDH@Fe₃O₄ nanocomposite was fabricated by Ca²⁺ ionic crosslinking of a pectin-GO matrix incorporating Cu-Co-LDH@Fe₃O₄. Unlike previously reported similar adsorbents, this material uniquely combines Cu-Co-LDH anion-exchange sites, GO aromatic domains, a biodegradable pectin network, and superparamagnetic Fe₃O₄ in a single magnetically recoverable hybrid for simultaneous dye removal and antibacterial activity. FE-SEM showed a rough, porous morphology favourable for rapid mass transfer. Using a four-factor central composite design, CR adsorption was optimized with a robust quadratic model (F = 44.40, p < 0.0001, R² = 0.981). Under the optimum conditions (pH 4, 10 min, 10 mg L^-1 CR, 0.6 g L^-1 dosage), ~98.1% removal was achieved. Equilibrium data fitted the Sips isotherm best (R² = 0.995), with a Langmuir maximum capacity of 120.3 mg g^-1. Uptake occurs through the synergistic action of electrostatic attraction, LDH anion exchange, π-π stacking with GO, and hydrogen bonding. Kinetics followed the double-exponential model (R² = 0.991). The process was spontaneous and exothermic. Magnetic recovery enabled reuse for six cycles with <5% mass loss, while inhibition zones of 17.6 ± 0.6 mm (E. coli) and 20.2 ± 0.8 mm (S. aureus) at 5.0 mg/disc confirmed antibacterial activity. These features make the nanocomposite a practical candidate for dye-contaminated wastewater treatment.