Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan–magnetite nanocomposite strip. Magnetite nanoparticles (Fe₃O₄) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV–visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15–30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K₂Cr₂O₇ (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan–magnetite nanocomposite strip from aqueous solution was evaluated using UV–visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan–magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

A simple formulation of bactericidal cold cream using the biosynthesized silver nanoparticles (AgNPs) from Cassia auriculata flower extract and their antibacterial activity was tested against various clinical pathogens such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Staphylococcus epidermidis. An eco-friendly method was followed for the biosynthesis of AgNPs using C. auriculata flower extract as a reducing agent at room temperature. The effect of different concentrations of flower extract and the various pH conditions of the reaction medium toward the formation of NPs were studied. Surface plasmon resonance peaks were obtained from 403 nm to 428 nm. Further, the synthesized NPs were characterized by dynamic light scattering particle size analysis, Zeta potential analysis, atomic force microscope, and high-resolution transmission electron microscopic analysis.