title: Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites.
abstract: A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.
authors.affiliation: School of Environmental Science and Engineering, Donghua University, Shanghai, PR China.
authors.forename: Gang
authors.initials: G
authors.lastname: Xue
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Liu
authors.forename: Quanyuan
authors.initials: Q
authors.lastname: Chen
authors.forename: Colin
authors.initials: C
authors.lastname: Hills
authors.forename: Mark
authors.initials: M
authors.lastname: Tyrer
authors.forename: Francis
authors.initials: F
authors.lastname: Innocent
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles; D008855:Microscopy, Electron, Scanning; D010777:Photochemistry; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D006812:Humic Substances; C009495:titanium dioxide; D002244:Carbon; D014025:Titanium