Response surface optimization for simultaneous removal of Alizarin Red S and Alizarin Yellow dyes from aqueous solution using magnetic Zn-Al-Zr layered double hydroxide.

In this study, magnetic-zinc-aluminum-zirconium layered double hydroxide (Fe3O4/Zn-Al-Zr LDH) was synthesized by a simple and efficient co-precipitation method. This nanosorbent was employed as an innovative adsorbent for the removal of two anthraquinone dyes, namely Alizarin Red S (AR) and Alizarin Yellow (AY). The characteristic properties of Fe3O4/Zn-Al-Zr LDH were investigated by SEM, EDX, XRD, VSM and FTIR. The adsorption properties were studied by optimizing different variables such as contact time, initial dye concentration, pH, and adsorbent mass. Response surface methodology involving Box-Behnken design was also applied to offer an appropriate regression model for adsorption system and subsequently investigate the most influential variables. Furthermore, the experimental isotherm data and kinetic data revealed that the Langmuir isotherm and pseudo second-order model are acceptable, respectively. Maximum Langmuir adsorption capacities of Fe3O4/Zn-Al-Zr LDH were obtained 150.87 and 130.21 for AR and 166.85 and 145.35 mg/g for AY, in single and binary solutions, respectively. [ABSTRACT FROM AUTHOR]