Characteristics and defluoridation performance of granular activated carbons coated with manganese oxides.
Using a redox process, granular activated carbon (GAC) was coated with manganese oxides to enhance its ability to adsorb fluoride from an aqueous solution. Compared with plain GAC, the fluoride adsorption capacity of this new adsorbent was improved and at least three times greater than that of uncoated GAC. The surface characteristics of coated GAC were observed with scanning electron microscopy. The surface area of the new adsorbent was calculated using the Brunauer-Emmett-Teller method. X-ray diffraction revealed that manganese oxides are amorphous. X-ray photoelectron spectroscopy demonstrated that manganese existed primarily in the oxidation state +IV. Kinetic and equilibrium adsorption data showed that the adsorption process follows the pseudo-second order kinetic and Freundlich equation models. The sorption data also indicated that the removal of fluoride by adsorption is a highly complex process, involving both boundary layer diffusion and intra-particle diffusion. The pH value of solution influences fluoride removal, and the optimum equilibrium pH value of fluoride adsorption is 3.0.
School of Environmental Science and Engineering, Shandong University, 27 Shanda Nanlu, Jinan 250100, China. wsg@sdu.edu.cn
Yue
Y
Ma
Shu-Guang
SG
Wang
Maohong
M
Fan
Wen-Xin
WX
Gong
Bao-Yu
BY
Gao
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis / Q000379:methods; D014867:Water; D014965:X-Rays
D017895:Manganese Compounds; D010087:Oxides; D012996:Solutions; D014867:Water; C027424:manganese oxide; D002244:Carbon; D005459:Fluorides