[Mechanism and promotion effect of K+ on yield of Fe(VI)].
The mechanism and promotion effects of K+ on the yield of Fe(VI) were studied during the reaction of forming ferrate. The experiment results showed that K+ is far better than Na+ for the preparation of Fe(VI) at temperatures higher than 50 degrees C. The optimal temperature for the preparation of Fe(VI) with K+ is 65 degrees C. During the reaction, the yield of ferrate increases with the concentration of K+, and the promotion effect of K+ is obviously with ferric nitrate dosage increase. The Fe(VI) concentration prepared with 4.4 mol/L KOH is 0.05 mol/L at 85 g/L ferric nitrate; and which achieves 0.15 mol/L when added 2 mol/L K+. The promotion effect of K+ on the yield of ferrate is remarkable when ferric nitrate dosage is higher than 75 g/L, reaction temperature is below 55 degrees C and ClO(-) concentration is lower than 1.16 mol/L. The K+ can substitute for partly alkalinity and reduce the concentration of OH(-) in the reaction solution. During the reaction, the K+ can enwrap around FeO4(2-) that can reduce the contact between Fe(3+) and FeO4(2-), and decrease the catalysis effect of Fe(3+) on FeO4(2-). At the same time, K+ can react with FeO4(2-) to form solid K4FeO4, whichwill lower the Fe(VI) concentration, decrease the decomposition rate of Fe(VI), enhance the stability and improve the yield of Fe(VI).
Zhang
Yan-Ping
YP
School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. zyphit@163.com
Xu
Guo-Ren
GR
Li
Gui-Bai
GB
D007501:Iron / Q000032:analysis / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D011188:Potassium / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D058085:Iron Compounds; D016877:Oxidants; D017680:Potassium Compounds; C017311:ferrate ion; C044384:potassium ferrate; D007501:Iron; D011188:Potassium