Facile Synthesis of Silver Nanoparticles Decorated Magnetic-Chitosan Microsphere for Efficient Removal of Dyes and Microbial Contaminants

A facile and rapid synthesis of core-shell type magnetite-chitosan microsphere decorated with silver nanoparticles (MCSM) is described. The composition and structure of the as-synthesized microsphere characterized by various spectroscopic and microscopic techniques demonstrated formation of 3.63 +/- 0.76 ym MCSM with decoration of silver nanoparticles (AgNPs) having 16 +/- 2.5 nm size. The thermogravimetric analysis (TGA) data showed good thermal stability, whereas vibrating sample magnetometry (VSM) analysis indicated the superparamagnetic behavior of the as-synthesized microsphere. The adsorptive removal and antimicrobial property of MCSM was explored for eco-friendly and cost-effective water purification. The MCSM removed 99.99% microbial contaminants and 99.5% of dyes from single as well as multicomponent systems from water bodies efficiently. Furthermore, the dye removal capacity of MCSM (q(e) = 271.2 +/- 14.5 mg/g) was found to be higher compared to the other nanoadsorbents attributing to the high effective surface area of the microsphere and plenty of functional groups of shell structure of chitosan favored binding of dyes on MCSM. Moreover, the adsorbed dyes were desorbed from MCSM at higher pH values and regenerated MCSM was used for next cycle of dye removal. The magnetic behavior of MCSM facilitated easy separation using external magnetic field leading to recycling and reuse, whereas decoration of AgNPs on the microsphere inhibited the bacterial growth. The long-term antibacterial activity of MCSM significantly improved the antifouling property to inhibit the biofilm formation on MCSM. The proposed core-shell type MCSM thus provides a promising opportunity for cost-effective water purification.