镍盐溶液活化海绵铁加速三氯乙酸降解的研究

Improvement in the degradation of trichloroacetic acid by sponge iron through its surface modification by nickel

海绵铁经酸浸活化处理或外加镍盐溶液活化处理,可以显著提高其降解水中三氯乙酸(TCAA)的反应速率。实验结果表明,海绵铁降解TCAA反应属于一级反应,酸浸活化和镍盐活化处理都没有改变海绵铁降解三氯乙酸的反应级数,对反应活化能的影响也不大,但都可以显著提高其表观反应速率常数kobs,经酸浸处理和经镍盐活化处理后海绵铁降解TCAA表观反应速率常数分别提高了3倍和8倍。此外,减小海绵铁粒径,提高单位水体海绵铁用量(mFe/VTCAA)也有利于提高海绵铁对三氯乙酸的降解速率。对于20℃,海绵铁用量为mFe/VTCAA=50 g/L时,经镍盐活化处理的海绵铁降解TCAA表观反应速率常数kobs可达到0.855 h-1。

When sponge iron was activated by immersion in acid or nickel salt solutions,its activity for the degradation of trichloroacetic acid（TCAA） in water was significantly increased.The experimental results showed that the degradation of TCAA by sponge iron is a first order reaction,and being activated by immersion in acid or nickel salts neither changed the order of the degradation reaction nor greatly affected the activation energy,but did significantly increase the apparent rate constant of the reaction,kobs,by factors of three and eight,respectively.Moreover,a decrease in the radius of the sponge iron and an increase in the amount of sponge iron acting on a fixed volume of TCAA（mFe/VTCAA） both resulted in an increase in the degradation rate.The apparent rate constant of the degradation of TCAA by sponge iron activated by nickel salts reached 0.855 h^-1 when the reaction was carried out at 20 ℃ with mFe/VTCAA equal to 50 g/L.