Adsorption and photocatalytic degradation behaviours of cationic dye BV16 in ZnO-<em>Ghezeljeh </em>nanoclay composite/UV-C system: Equilibrium, kinetic and thermodynamic studies

Abstract

<em>Ghezeljeh </em>montmorillonite nanoclay or “<em>Geleh-Sar-Shoor</em>” (means head-washing clay) has been used as a natural adsorbent to photocatalytic decolorization of BV16 dye under UV radiation. The results of XRD, FT-IR, CEC, Specific surface area and Zeta potential of the <em>Ghezeljeh</em> clay confirm that montmorillonite is the dominant mineral phase. Based on SEM images, it can be understood that the distance between the plates is in nm level. Adsorption of BV16 on to different clays might inhibit its photodegradation has been investigated. The photocatalytic decolorization of BV16 dye under UV radiation in aqueous ZnO-natural <em>Ghezeljeh </em>nanoclay composite suspension compared to the behavior of the dye on <em>Ghezeljeh </em>nanoclay, ZnO-<em>Ghezeljeh </em>nanoclay (shell-core), Cloisite Na⁺nanoclay, ZnO-Cloisite Na⁺nanoclay composite, ZnO-Cloisite Na⁺nanoclay (shell-core). The linearity of the plots (R²) demonstrates that pseudo-second order kinetic model play a significant role in the uptake of the dye. The R² values show that the dye removal isotherm using ZnO-natural <em>Ghezeljeh </em>nanoclay composite follows the Langmuir isotherm at natural temperature and Dubinin–Radushkevich isotherm at upper temperature. Calculation of ΔG⁰, ΔH⁰ and ΔS⁰ showed that the procedure is feasible, spontaneous and endothermic.