Rapid Ti(III) reduction of perchlorate in the presence of beta-alanine: kinetics, pH effect, complex formation, and beta-alanine effect.
Ti(III) reduction of perchlorate might be a useful method for the treatment of highly perchlorate-contaminated water. Though the reaction rate was usually low, we observed that beta-alanine (HOOCCH(2)CH(2)NH(2)) could significantly promote the reaction. A complete (>99.9%) perchlorate removal was obtained in a solution containing [ClO(4)(-)]=1.0mM, [Ti(III)]=40 mM, and [beta-alanine]=120 mM after 2.5h of reaction under 50 degrees C. The effects of both pH and complex formation on the reaction were then studied. The results showed that without beta-alanine the optimal pH was 2.3. When pH increased from 1.6 to 2.3, the reduction rate increased remarkably. In the pH range >2.3, however, the reduction was significantly inhibited, attributed to the formation of Ti(III) precipitate. The presence of beta-alanine at a molar ratio of [beta-alanine]:[Ti(III)]=3:1 significantly increased the reduction rate of perchlorate even at near neutral pH. This is because beta-alanine formed complexes with Ti(III), which greatly improved the total soluble [Ti(III)] in the pH range between 3.5 and 6. The findings may lead to the development of rapid treatment methods for intermittent and small stream of highly perchlorate-contaminated water, which are resulted from the manufacturing, storage, handling, use and/or disposal of large quantities of perchlorate salts.
Wang
Chao
C
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Huang
Zhengdao
Z
Lippincott
Lee
L
Meng
Xiaoguang
X
D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010472:Perchlorates / Q000737:chemistry / Q000302:isolation & purification*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*; D015091:beta-Alanine / Q000737:chemistry* / Q000302:isolation & purification
D010472:Perchlorates; D014874:Water Pollutants, Chemical; D015091:beta-Alanine; D014025:Titanium; C494474:perchlorate