Removal of basic dyes in binary system by adsorption using rarasaponin–bentonite: Revisited of extended Langmuir model

摘要

The preparation of organo-bentonite via microwave radiation\udusing natural surfactant (i.e.rarasaponin) from the\udtropical soapfruit pericarps of Sapindus rarak was\udconducted in this work. The adsorption per-formance of bentonite and its modified form was studied for the removal of two dyes (i.e.methylene blue and malachite green) in single and binary systems. Langmuir and Freundlich models\udwere applied to evaluate adsorption equilibrium data in\udsingle systems. From physical meaning interpretation of\udthe model parameters, it was found that Langmuir model gave the best representation. A new approach in representing binary experimental isotherms with extended Langmuir\udmodel incorporating fractional surface coverage\udin 3D mesh plot was also verified. The results show that recently proposed modification of extended Langmuir model could be used to evaluate binary adsorption data well with\udreasonable fitted parameter value.