Oxidized multiwalled carbon nanotubes as adsorbent for the removal of manganese from aqueous solution

摘要

A batch adsorption process was applied to inves tigate the removal of manganese from aqueous solution by oxidized multiwalled carbon nanotubes (MWCNTs). In do ing so, the thermodynamic, adsorption isotherm, and kinetic studies were also carried out. MWCNT with 5-10-nm outer diameter, surface area of 40-600 m~2/g, and purity above 95 % was used as an adsorbent. A systematic study of the adsorption process was performed by varying pH, ionic strength, and temperature. Manganese-adsorbed MWCNT was characterized by Raman, FTIR, X-ray diffraction, XPS, SEM, and TEM. The adsorption efficiency could reach 96.82 %, suggesting that MWCNT is an excellent adsorbent for manganese removal from water. The results indicate that second-order kinetics model was well suitable to model the kinetic adsorption of manganese. Equilibrium data were well described by the typical Langmuir adsorption isotherm. Thermodynamic studies revealed that the adsorption reac tion was spontaneous and endothermic process. The exper imental results showed that MWCNT is an excellent manganese adsorbent. The MWCNTs removed the manga nese present in the water and reduced it to a permissible level making it drinkable.