BR13 dye removal using sodium dodecyl sulfate modified montmorillonite: Equilibrium, thermodynamic, kinetic and reusability studies

Abstract

In this study, Montmorillonite(MMT) samples obtained from Erzurum in Turkey were modified with sodium dodecyl sulfate(SDS) and used for the removal of Basic Red13(BR13) dye. According to equilibrium, kinetic and thermodynamic studies BR13 adsorption was found endothermic, fitted best the pseudo-second-order model and complied with the Langmuir isotherm. The max. adsorption capacity and max. removal yield were calculated as 1111.11 mg/g from the Langmuir model and observed as % 98.24 for BR13, respectively. The best regeneration eluent was found as ethanol and regenerated MMT-SDS can be reused at least three adsorption/desorption cycles. Binary system studies showed that the MMT-SDS was not selective for BR13 adsorption and over 80 % removal observed for BR13, Methyl Orange and Reactive Orange16. A comparative adsorption study between MMT and MMT-SDS showed that although the BET surface area decreased after the modification(46.87 m²/g to 22.47 m²/g) the removal efficiency for MMT-SDS was 68 %, while 45 % for MMT. The modification showed that the target of increasing negative surface charge was reached at −105.25 mV compared to the pre-modification which was -49.62 mV. The intercalation of SDS was observed from the XRD, EDX and FTIR results with a typical reflection of SDS, sulfur presence of 2.83 % and the specific peaks of SDS, respectively.