Immobilization of zero valent cobalt and tin nanoparticles in sodium alginate/graphitic carbon nitride beads for efficient reduction of organic pollutants

This study explores nano-remediation as an advanced strategy for the removal of organic pollutants , contributing to sustainable environmental management. Hydrogel nanocomposite beads composed of sodium alginate (Na-alg) and graphitic carbon nitride (g-C 3 N 4 ) were synthesized, utilizing Na-alg as a polymeric matrix and g-C₃N₄ as a mechanical support to enhance catalytic surface area and durability. These beads were further functionalized with zero-valent tin (Sn 0 ) and cobalt (Co 0 ) nanoparticles via a simple ion-immobilization process using metal salt solutions (0.2 M: SnCl 2 and CoCl 2 ). Characterization techniques, including FTIR , SEM, EDX , and ICP-OES, confirmed the structural integrity, morphology, elemental composition, and nanoparticle loading efficiency. ICP-OES revealed a remarkable 98.8 % decoration efficiency of Sn 0 on Na-alg/CNBs compared to 32.3 % for Co 0 . The catalytic performance of the synthesized nanocomposites was assessed in the reduction of various organic pollutants, including rhodamine B (Rh B), reactive black 5 (RB-5), methyl orange (MO), methylene blue (MB), 2-nitrophenol (2-NP), and 4-nitrophenol (4-NP). Sn 0 /Na-alg/CNBs exhibited superior catalytic activity, achieving the highest apparent rate constant (k app ) of 0.1444 min −1 for Rh B, attributed to the efficient nanoparticle distribution. Parameters such as k app , percentage reduction, reduction time, and half-life were systematically analyzed to evaluate and compare performance. This work highlights the potential of Sn 0 and Co 0 immobilized Na-alg/CNB nanocomposites as sustainable catalysts for environmental remediation. • Synthesis of Na-alg/CNBs via in-situ polymerization. • Immobilization of Zero-Valent metal NPs on Na-alg/CNBs. • Extensive studies are conducted to determine optimal parameters for superior catalysts. • Sn 0 /Na-alg/CNBs showcase promising potential towards RhB degradation. • Illustrate the effectiveness of the catalyst using a pseudo-first-order reaction.