In this report, synthesis, growth and formation kinetics of silver nanoparticles mediated by various plant extracts in their biodiversity have been monitored using UV-Vis spectrophotometer by sampling at time intervals during bioreduction process. Plasmon band resonance of the silver nanoparticles was observed as the reaction progresses indicating nucleation and particle formation. There were cases of red shifting indicating particle size increase. In the bioreduction process, onset of nanoparticle nucleation and growth were observed within 2, 5, 10 or 30 min and eventual formation of spherical or quazi-spherical amidst twinned morphology as determined by transmission electron microscope (TEM). The nanosilver growth kinetics mechanism has been probed using a time-resolved UV-Vis in conjunction with TEM following existing Lifshitz-Slyozov-Wagner theory. For some biological extractmediated synthesis, a single-stage mechanism that is diffusion controlled following Ostwald ripening (OR) is proposed. Whereas, for other bioreduction process, a double stage involving (1) initial OR followed by (2) surface adsorption-oriented attachment is proposed for temporal evolution of the nanosilver in green environment.

We report the synthesis of various shaped silver nanoparticles mediated by ZnCl 2 salt. It has been demonstrated that the salt, PVP/AgNO 3 mole ratio, and the type of polyol (EG, DEG,and GL) significantly determined twinning probability, which is an index of silver seed growth origin. High twining probability arising from low PVP/Ag + ratio and 50 mole% salt favours 1D grown nanowires and nanorods, whereas low twining amidst high mole% salt (150) in DEG offered 2D grown nanoflakes and nanosheets. Other shaped silver nanoparticles have been found. Accidentally, we arrived at a core-shell heterostructure of Ag-ZnO nanocomposite with Ag core enrichment when mole% of the salt was made up to 300. Growth kinetic of nanosphere obtained was monitored, and effect of salt mediation was found crucial. Structural evolution of shaped Ag nanoparticles and nanocomposites have been monitored using XRD, SEM, EDX, TEM, and UV/vis.

The base hydrolysis of Malachite green (MG ? ) was studied in aqueous solution of mixed surfactants of sodium dodecyl sulfate (SDS) and Triton X-100 (TX-100) at 25°C. The results show that the SDS/TX-100 system compositions has relatively significant influence on the rate constant of the base hydrolysis of MG ? when compared with the reaction in the respective single surfactant systems.

The interaction of eosin B dye from aqueous solution with MIL-100(Fe) and functionalized MIL-100(Fe) metal–organic frameworks (MOFs) is reported in this study. MIL-100(Fe) was prepared and functionalized with thioglycolic acid (TH) and ethylenediammine (ED) separately by incorporating the thiol (–SH) and the amine (–NH2) group of the functionalizing agents into the open metal sites of the MIL-100(Fe) to obtain the acidic (TH-MIL-100) and basic (ED-MIL-100) forms of the MOF respectively. Characterization of the MOFs was done by melting point analysis, elemental analysis, spectroscopic techniques, scanning electron microscopy (SEM), and powdered X-ray diffraction (PXRD) analysis. The adsorption experiments were carried out at different conditions such as pH, adsorbent dosage, contact time, temperature, and initial concentration of the dye to estimate the optimum conditions and the maximum adsorption capacities. Adsorption capacities were observed to increase in the order of ED-MIL-100 < MIL-100 < TH-MIL-100, while the TH-MIL-100 was the most effective in the removal process due to acid–base interaction between the acidic thiol group (–SH) and the alkaline medium of eosin B dye solution. The Langmuir Isotherm was seen to fit well to adsorption data obtained for all three adsorbent materials studied, and adsorption processes followed the pseudo-second order kinetics. This study, therefore, indicates the suitability of functionalization of MIL-100(Fe) towards improving its adsorption capacity.

The inhibitive effect of ocimum gratissimum by seed extract on the corrosion of zincaluminium (ZA) alloy in 2 M hydrochloric acid (HCl) solution has been studied using gravimetric methods. Inhibition increases with concentration of extract but decreases with temperature. This observation implies that ocimum gratissimum seed extract is an effective and non toxic inhibitor of the corrosion of zinc-aluminium alloy. Adsorption of the extract on the surface obeyed the Freundlich adsorption isotherm. The calculated rate constant (k) shows a first order kinetics in the absence and presence of the inhibitor. The kinetic parameter B, measured for the reaction has a high negative value which implies that ocimum gratissimum becomes more effective as the temperature increases. Synergistic effect of halide additives shows an increase in the efficiency of the extract. However synergism parameter shows that synergism of halide additives decreases with increased concentration of inhibitor.