Abstract
Present study was conducted to investigate the adsorption and ultrasound-assisted adsorption potential of silver nanoparticles (AgNPs) and silver nanoparticles loaded on chitosan (AgCS composite) as nano-adsorbents for methylene blue (MB) removal. AgNPs were synthesized using leaf extract of Ligustrum lucidum, which were incorporated on the chitosan’s surface for modification. UV–Vis Spectroscopy, FTIR, XRD, SEM, and EDX techniques were used to confirm the synthesis and characterization of nanomaterials. Batch adsorption and sono-adsorption experiments for the removal of MB were executed under optimal conditions; for fitting the experimental equilibrium data, Langmuir and Freundlich’s isotherm models were adopted. In addition, the antimicrobial potential of the AgNPs and AgCS were examined against selected bacterial and fungal strains. UV–Vis spectroscopy confirmed AgNPs synthesis from the leaf extract of L. lucidum used as a reducer, which was spherical as exposed in the SEM analysis. The FTIR spectrum illustrated phytochemicals in the leaf extract of L. lucidum functioning as stabilizing agents around AgNPs and AgCS. Whereas, corresponding crystalline peaks of nanomaterial, including a signal peak at 3 keV indicating the presence of silver, were confirmed by XRD and EDX. The Langmuir model was chosen as an efficient model for adsorption and sono-adsorption, which exposed that under optimum conditions (pH = 6, dye initial concentration = 5 mg L−1, adsorbents dosage = 0.005 g, time = 120 min, US power 80 W), MB removal efficiency of AgNPs was >70%, using ultrasound-assisted adsorption compared to the non-sonicated adsorption. Furthermore, AgNPs exhibited promising antibacterial potential against Staphylococcus aureus with the maximum zone of inhibition (14.67 ± 0.47 mm). It was concluded that the green synthesis approach for the large-scale production of metallic nanoparticles is quite effective and can be recommended for efficient and cost-effective way to eradicate dyes, particularly from textile wastewater.
Highlights
Synthetic dyes are extensively used in different industries, including textiles, leather, food, paper, and pulp
The color change was noticed during the formation of Ag-loaded chitosan (AgCS) composites, i.e., particles, and this color change might be due to the excitation of the surface plasmon vibrations/resonance in AgNPs
The composition and characteristics of nanoparticles and composite were confirmed by scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR), EDX, and X-ray Diffraction Analysis (XRD)
Summary
Synthetic dyes are extensively used in different industries, including textiles, leather, food, paper, and pulp. Though many conventional techniques have been employed to remove the harmful toxins from the effluents like reverse osmosis, ion exchange, micro- and ultra-filtration, oxidation, solvent extraction, and electrodialysis, but these methods are exorbitant and tedious [11,12], whereas treatment of colored compounds through adsorption was found to be most effective [13,14], as it has emerged as a promising and versatile water purification technique that can balance high pollutant removal efficiency and the possibility to treat large quantities of water as reported elsewhere [15,16,17] It is an excellent method because of its simple operation, easy use, immense pollution holding capacity, extensive scalability of adsorbents, and high-performance efficiency operations. Functional groups of chitosan (i.e., amino (–NH2 ) and hydroxyl (–OH)) are mainly responsible for its reactivity as an excellent natural adsorbent with an overall adsorptive capacity [22]
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