Silver nanoparticle incorporated calcium crosslinked hydrogel composite for reduction of methylene blue dye and nitrite sensing

Abstract

The dissipative convective procedure was used, followed by the freeze-drying technique to successfully fabricate self-organized alginate/xantham gum (Alg/XG) composite materials encapsulating silver nanoparticles (AgNPs) and without nanoparticles and cross-linked with CaCl2 and prepared Alg/XG/AgNPs/Dex/Ca nanocomposite. The synthesized nanocomposite was thoroughly characterized by techniques such as Fourier transform infrared spectroscopy (FT-IR), N2 adsorption Study (BET), X-ray diffraction (XRD), Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDAX), and Transmission electron microscopy (TEM). The results revealed that Alg/XG/AgNPs/Dex/Ca composites showed remarkably porous structures with ordered capillaries. These nanocomposites were assessed for catalytic reduction of methylene blue (MB) dye. The Alg/XG/AgNPs/Dex/Ca composite competently reduced the MB dye within 50 s in the presence of NaBH4 with a rate constant of 0.31907 min−1 and also showed 98 % degradation. It was established that the reduction reaction follows pseudo-first-order kinetics. The value of △H0 is −113.85 kJ mol−1 confirmed the exothermic nature and the positive values of △S0 (259.96 J k−1mol−1) suggested good affinity of the MB dye molecules toward the absorbent. The Activation energy of the reaction is 11.65 kJ mol−1. Furthermore, as-prepared Alg/XG/Dex/AgNPs/Ca was tested for the electrochemical oxidation of nitrite, which also gave good results. It sensed the nitrite with LOD and LOQ values of 0.10 ng mL−1 and 0.36 ng mL−1, respectively, and a sensitivity of 276.4451 μA/μM/cm2 was calculated. The results reveal that synthesized nanocomposite is a promising nano-catalyst in the degradation of MB dye and the electrochemical investigation of nitrite.The use of nanoparticles-incorporated composites as catalysts opens a range of new possibilities for applications in the area of catalysis.