Green synthesis and characterization of alginate nanoparticles and its role as a biosorbent for Cr(VI) ions

•A new protocol is employed for the synthesis of calcium alginate nanoparticles using natural honey as the stabilizing agent.•1% aqueous honey solution is used as the solvent medium.•Sodium alginate solution is cross-linked with 1% calcium chloride solution.•Spherical calcium alginate nanoparticles with size in the range of 10–100 nm were obtained.•More than 93% of Cr (VI) ions are removed at pH 4 in 180 min.

Green synthesis of nanoparticles has attained considerable attention in recent years because of its myriad of applications including drug delivery, tissue engineering and water purification. In the present study, alginate nanoparticles stabilized by honey were prepared by cross-linking aqueous solution of alginate with calcium ions. Honey mediated synthesis has been reported earlier for the production of metal nanoparticles. However no literature is available on the use of this technique for polymeric nanoparticles. Highly stable nanoparticles of 10–100 nm size were generated by this technique. The synthesised nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopic techniques. Potential of using these nanoparticles for heavy metal removal was studied by using Cr(VI) from aqueous solution, where a maximum removal efficiency of 93.5% was obtained. This method was also successfully employed for the production of other polymeric nanoparticles like casein, chitosan and albumin.

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