Affiliation:
1. School of Chemistry and Chemical Engineering Qinghai Normal University Xining 810008 China
2. Academy of Plateau Science and Sustainability People's Government of Qinghai Province & Beijing Normal University Xining 810016 China
3. Qinghai Institute of Salt Lakes Department Chinese Academy of Sciences Institution Xining 810008 China
4. Institute Co. LTD of Science and Technology Information of Qinghai Province Xining 810008 China
Abstract
AbstractManganese dioxide nanomaterials with high crystallinity and purity was prepared quickly by a simple hydrothermal reaction, and the effect of hexadecyl trimethyl ammonium chloride (CTAC) on crystal form, morphology and pore structure of manganese dioxide was investigated. Removal of methylene blue from aqueous solution by adsorption onto two manganese dioxide adsorbents was studied. The material characterization results showed that manganese dioxides have (2×2) tunnel structure and nanowires morphology. BET surface area and pore volume of ɑ‐MnO2 (CTAC) was 58.99 m2/g and 0.2081 cm3/g, respectively. The adsorption results showed that pH value had a certain effect on the removal of methylene blue. The adsorption kinetics results indicated that the adsorption rate of ɑ‐MnO2 and ɑ‐MnO2 (CTAC) to methylene blue was very fast, most adsorption was completed within 5 minutes, and the adsorption equilibrium was reached after 2 hours. The removal efficiency of ɑ‐MnO2 and ɑ‐MnO2 (CTAC) was 71.27 % and 78.92 %, respectively. Pseudo‐second‐order kinetic model was better fitted with adsorption data than pseudo‐first‐order model, suggesting adsorption behavior is controlled by chemical processes. Additionally, the free energy change (ΔGΘ) was determined by Van′t Hoff equation is negative, which confirms the adsorption process is spontaneous and feasible. The adsorption mechanism involves a complex process of electrostatic attraction, charge‐independent adsorption, physical adsorption, hydrogen bonding and redox.