Multimedia fate and transport simulation for green synthesized zero valent iron nanoparticles using SimpleBox4nano

Abstract

Green synthesized zero valent iron nanoparticles (nZVI) are promoted as environmentally benign alternatives to chemically synthesized ones. Simulation models are used to predict nZVI transport and transformation during environmental remediation. The objective of this study was to simulate the environmental fate and transport of nZVI synthesized using Cape gooseberry biomass. Cape gooseberry fruit, leaf, and husk extracts were used as reducing and capping agents for 0.5 M iron (III) chloride precursor in a 2:1 ratio and the nZVI synthesis done under sonication. The physiochemical properties of the synthesized nanoparticles (size, density and hamaker constant) and functional assays (attachment efficiencies with natural particles, dissolution rate constant, degradation and transformation rate constants and emission rates) were fed into SimpleBox4nano. The simulation showed low mobility and high concentrations of the nZVI in soils as compared to water, sediment and air compartments. Over 95% accumulated in agricultural soils and none existed in fresh water and seawater. The predicted environmental concentrations were highest in soil at the regional scale and highest in water at the global scale. At regional scale, nZVI mostly heterroaggregated to natural colloids and few freely dispersed. However, the freely dispersed nZVI became negligible in the continental and global scales. The tropics accumulated the most nZVI, followed by the moderate and arctic. Overall, the concentrations of nanoparticles heteroaggregated on natural colloids, heteroaggregated on natural particulates, freely dispersed nanoparticles and those dissolved did not differ significantly between the fruit based nZVI and the husk/leaf based nZVI.