Adsorption kinetics and thermodynamics of vat dye onto nano zero-valent iron

Abstract

<span style="font-size:9.0pt; mso-bidi-font-size:12.0pt;mso-bidi-font-family:" times="" new="" roman""="" lang="EN-US">Nano zero-valent iron (NZVI) particles have been synthesized by the aqueous phase borohydride reduction method, and the synthesized NZVI particles are used for the removal of Vat green 1 dye in aqueous solution. The effect of parameters like initial dye concentration, <i style="mso-bidi-font-style:normal">p</i>H, adsorbent dose, temperature and contact time on the adsorption process are investigated. The studied adsorbent exhibits high efficiency for vat green 1 adsorption and the equilibrium state is achieved in 1 min. For equilibrium studies, three isotherm models, namely Langmuir, Freundlich and Temkin are used. It is found that Freundlich is fitted very well with the experimental data. In the kinetics studies, pseudo-first order, pseudo-second order and intra-particle diffusion model are tested. The pseudo-first order equation provides the best correlation with the obtained data. Different thermodynamic parameters, like Gibb’s free energy enthalpy and entropy of the adsorption process have also been evaluated. Observed thermodynamic parameters indicate that the process is spontaneous and endothermic.

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