Zero-valent aluminum for oxidative degradation of aqueous organic pollutants.
Oxidative degradation of aquatic organic contaminants using zero-valent aluminum (ZVAl) in the presence of dissolved oxygen (O2) was investigated. The metal corrosion process in acidic conditions (pH < 4) was accompanied by electron transfer from ZVAl to O2, which led to the simultaneous generation of Al3+ and hydrogen peroxide (H2O2). The oxidation of 4-chlorophenol (4-CP), a model substrate, was initiated by the generation of hydroxyl radicals (HO*) via electron transfer from Al0 to H2O2. Degradation was initiated after an induction period of about 2 h, during which the native oxide layer was dissoluted. The HO*(-) mediated oxidation reaction was completely quenched by adding methanol as a radical scavenger. Systematic studies on the effects of ZVAl loading, pH, and surface oxide content revealed that the oxide layer dissolution controlled the Al0-mediated oxidation of 4-CP. The proposed process is similarly compared with the zero-valent iron (ZVI) system, but the ZVAl/O2 system showed a higher oxidation capacity compared with ZVI/O2 because of the stability of aquo-complexed Al3+ ions over a wider pH range. The degradation of phenol, nitrobenzene, and dichloroacetate was also successfully achieved with ZVAl. The present study proposes the ZVAl/O2 process as a viable method of oxidative water treatment.
Bokare
Alok D
AD
School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
Choi
Wonyong
W
D000332:Aerobiosis; D000388:Air; D000535:Aluminum / Q000737:chemistry*; D000693:Anaerobiosis; D002733:Chlorophenols / Q000302:isolation & purification; D003999:Dichloroacetic Acid / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D009578:Nitrobenzenes / Q000302:isolation & purification; D009930:Organic Chemicals / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D019800:Phenol / Q000302:isolation & purification; D013499:Surface Properties; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
D002733:Chlorophenols; D009578:Nitrobenzenes; D009930:Organic Chemicals; D010087:Oxides; D014874:Water Pollutants, Chemical; D019800:Phenol; C029107:4-chlorophenol; D003999:Dichloroacetic Acid; D000535:Aluminum; C036077:nitrobenzene; D010100:Oxygen