National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190, China; Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; Beijing Engineering Research Center of Process Pollution Control, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China.
National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190, China; Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; Beijing Engineering Research Center of Process Pollution Control, Beijing 100190, China.
J Environ Sci (China). 2014 Oct 1;26(10):2095-105. doi: 10.1016/j.jes.2014.08.009. Epub 2014 Aug 11.
Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon (AC) in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals (HO) in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol (tBA) with low dosages of AC, while it was hardly affected by tBA when the AC dosage was greater than 0.3g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05g/L, but it did not work when the AC dosage was no less than 0.1g/L. These observations indicate that HO in bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HO oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HO oxidation in basic bulk solution. A mechanism involving both HO oxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.
在这项工作中，使用商业活性炭（AC）在水相中对草酸盐进行了臭氧化处理。研究了 AC 剂量和溶液 pH 值对溶液主体中羟基自由基（HO）和 AC 表面氧化对草酸盐去除的影响。我们发现，当 AC 剂量小于 0.3g/L 时，草酸盐的去除率会受到叔丁醇（tBA）的抑制，但当 AC 剂量大于 0.3g/L 时，tBA 几乎不会影响草酸盐的去除率。tBA 还抑制了臭氧分解，当 AC 剂量不超过 0.05g/L 时，但当 AC 剂量不低于 0.1g/L 时，它就不起作用了。这些观察结果表明，溶液主体中的 HO 和 AC 表面的氧化都有助于草酸盐的去除。当 AC 剂量较低时，溶液主体中的 HO 氧化作用显著，而当 AC 剂量较高时，表面氧化作用占主导地位。当 AC 剂量为 0.5g/L 时，随着溶液 pH 值的升高，草酸盐的去除率下降。草酸盐的降解主要通过在酸性和中性溶液中的表面氧化发生，但在碱性溶液的主体中则通过 HO 氧化发生。提出了一种涉及溶液主体中的 HO 氧化和表面氧化的机制，用于 AC 增强的草酸盐臭氧化。
