摘要
The adsorption of Mn2＋ onto immobilized Mn-oxide and Fe-oxide adsorbent such as manganese oxide-coated sand 1 （MOCS1）, manganese oxide-coated sand2 （MOCS2）, iron oxide-coated sand2 （IOCS2）, and manganese and iron oxide-coated sand （MIOCS）was investigated. The effects of pH （5.5 to 8.0） and temperature （25 to45°C） on the equilibrium capacitywere examined. Equilibrium studies showed that there is a good fitwith both Freundlich and Langmuir isotherm,which indicates surface heterogeneity and monolayer adsorption of the adsorbents. Kineticdata showed high correlationwith the pseudo second-order model,which signifies a chemisorption-controlled mechanism. The activation energies, activation parameters （ΔG＊,ΔH＊,ΔS＊）, and thermodynamic parameters （ΔG0 , ΔH0 , ΔS0 ） confirmed that adsorptionwith MIOCSwas endothermic and more spontaneous at higher temperaturewhile an opposite trendwas observed for the other adsorbents. Thermodynamic studies showed that adsorption involved formation of activated complex,where MOCS1 and MIOCS follow a physical-chemical mechanism,while MOCS2 and IOCS2 follows purely chemical mechanism.
The adsorption of Mn2＋ onto immobilized Mn-oxide and Fe-oxide adsorbent such as manganese oxide-coated sand 1 （MOCS1）, manganese oxide-coated sand2 （MOCS2）, iron oxide-coated sand2 （IOCS2）, and manganese and iron oxide-coated sand （MIOCS）was investigated. The effects of pH （5.5 to 8.0） and temperature （25 to45°C） on the equilibrium capacitywere examined. Equilibrium studies showed that there is a good fitwith both Freundlich and Langmuir isotherm,which indicates surface heterogeneity and monolayer adsorption of the adsorbents. Kineticdata showed high correlationwith the pseudo second-order model,which signifies a chemisorption-controlled mechanism. The activation energies, activation parameters （ΔG＊,ΔH＊,ΔS＊）, and thermodynamic parameters （ΔG0 , ΔH0 , ΔS0 ） confirmed that adsorptionwith MIOCSwas endothermic and more spontaneous at higher temperaturewhile an opposite trendwas observed for the other adsorbents. Thermodynamic studies showed that adsorption involved formation of activated complex,where MOCS1 and MIOCS follow a physical-chemical mechanism,while MOCS2 and IOCS2 follows purely chemical mechanism.
基金
the Philippine ERDT scholarship and Taiwan National Science Council(NSC101-2221-E-041-007)for their financial support
