Reduction and conversion of 2,4,6-trinitrotoluene (TNT) by sulfide under simulated anaerobic conditions.
To account for the fast disappearance of TNT in anaerobic fermentative liquid, we investigated TNT (TNT(0)=50 mg/L) reduction by Na(2)S at 30+/-1 degrees C in two types of buffer systems, a phosphate buffer (PB, system A) and a CH(3)COOH-NaHCO(3) buffer (system B). The effects of pH, sulfide concentration and buffer system on the conversion and reaction rate of TNT were investigated. The effect of different variables on the conversion of TNT decreased in the following order: Na(2)S concentration>pH>buffer system. A kinetics study showed that TNT reduction by Na(2)S occurred in two stages separated by a change point. The observed rate constants of the first stage K(obs-1) were 1 order of magnitude lower than those of the second stage. The TNT conversion rate increased and the time to reach the change point became shorter with increasing Na(2)S concentration and pH. A 5-fold increase in Na(2)S concentration above the theoretical stoichiometric concentration was optimum. Observed rate constants of the first stage K(obs-1) were proportional to the hydrosulfide ion concentration and the conversion rate of TNT was greater and faster in buffer system B than in system A.
Qiao
Hua
H
Department of Environmental Engineering, Zhejiang University, Hangzhou 310029, China.
Wang
He-ling
HL
Feng
Hua-jun
HJ
Yao
Jun
J
Shen
Dong-sheng
DS
Tang
Zhi-jian
ZJ
D000693:Anaerobiosis; D000704:Analysis of Variance; D002021:Buffers; D003627:Data Interpretation, Statistical; D053834:Explosive Agents / Q000737:chemistry*; D005240:Feasibility Studies; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013440:Sulfides / Q000737:chemistry*; D014303:Trinitrotoluene / Q000737:chemistry*
D002021:Buffers; D053834:Explosive Agents; D013440:Sulfides; D014303:Trinitrotoluene