Adsorption performance and mechanism of methylene blue by H3PO4- modified corn stalks

Abstract

Abstract A novel bio-adsorbent based on H3PO4-modified corn stalks (P-CSs) was synthesized and used to adsorb methylene blue (MB) from aqueous solution. The successful modification of corn stalks by H3PO4 was verified by using XPS, FT-IR, respectively. Meanwhile, the adsorption performance and the adsorption mechanism of P-CSs were investigated. This novel bio-adsorbent performed stably over a considerably wide pH range of 6.0∼9.0. And electrostatic attraction and ion exchange were involved in adsorption of MB on P-CSs. Furthermore, the adsorption of MB by P-CSs perfectly fitted the Langmuir isotherm model (R2 = 0.997–0.999) and pseudo second order kinetic model (R2= 0.999). The qe of MB on P-CSs was 129 mg/g at 308 K by Langmuir model, and thermodynamic study showed that MB adsorption is a spontaneous exothermic process. The regeneration and re-adsorption experiments indicated P-CSs’s merit of regeneration with the recovery efficient of 91% after 4 adsorption-desorption cycles. This novel bio-adsorbent prepared in this work could achieve effective removal of MB and could be reused for 4 and more adsorption-desorption cycles for MB removal.