Corrosion inhibition of mild steel in 1 M HCl using water soluble chitosan derivative of vanillin.

The water-soluble chitosan derivative (WSCD) was made by mixing chitosan with sodium hydroxide, treating the mixture with chloroacetic acid, and then forming a Schiff base with vanillin in an acidic medium. In this study, we examined the corrosion-inhibiting ability of a WSCD on mild steel surfaces in acidic environments. Weight loss, EIS, PDP, LPS, and OCP measurements were used to study the corrosion resistance on mild steel surfaces in 1 M HCl solutions with known concentrations of WSCD. The results show that WSCD functions effectively as a mixed-type anodic and cathodic inhibitor, providing 87 % corrosion inhibition efficiency at 75 ppm. Using SEM to investigate the morphology of corroded mild steel with and without varying amounts of WSCD, impedance measurements show the development of a thin film of inhibitor on the metal surface, the extent of which increases as the inhibitor concentration rises. The WSCD molecule first adsorbs on mild steel and follows Langmuir adsorption isotherm. It is found that the (∆Gads0)adsorption's free energy is -17.473 kJ/mol. The contact angle measurements confirm that the hydrophobicity of the metal surface has increased as a result of the inhibitor's thin film development.

Assessment of antioxidant, antibacterial and anti-proliferative (lung cancer cell line A549) activities of green synthesized silver nanoparticles from Derris trifoliata.

In this work, silver nanoparticles (AgNP-DTa) were prepared using an aqueous seed extract of D. trifoliata. The importance of the present piece of work is viewed specially with respect to ascertaining the potential of a widely distributed under-utilized mangrove associated plant, Derris trifoliata (DT), as medicine. The as-prepared AgNP-DTa were well dispersed and stabilised in aqueous solution through biological ligands extracted from the seeds of DT. The functional groups present in the bio-ligands of DT act as reducing and stabilising agents in the formation of nanoparticles. Besides, in the present work, sunlight could induce and catalyse the reduction process of Ag+ to its corresponding silver atoms of nanoscale dimensions. The size of AgNP-DTa decreased with an increase in the duration of sunlight irradiation. Bio-augmented nanoparticles were characterized by UV-vis spectroscopy, XRD, HR-TEM, DLS, AFM and photoluminescence measurements. Preliminary phytochemical studies and FTIR analysis confirmed the presence of secondary metabolites with hydroxyl, amine and carbonyl groups as reducing/capping agents. AgNP-DTa demonstrated high DPPH scavenging activity with an IC 50 value of 8.25 µg ml-1. Greater antioxidant activity of AgNP-DTa was also confirmed from total antioxidant capacity (TAC) assay where it was found that the reducing power of 1 g of AgNP-DTa is almost equivalent to that of 1.3 g of Trolox. In addition, highly stable AgNP-DTa showed antibacterial activities against Gram positive and Gram negative bacteria. The as-prepared AgNP-DTa were observed to inhibit the growth of Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli and no clear zone was obtained for Pseudomonas aeruginosa. With reference to the anti-proliferative activities, AgNP-DTa exhibited moderate activity on A549 lung cancer cell lines with a median effective concentration of 86.23 ± 0.22 µg ml-1.