焙烧水滑石去除水中溴酸盐的试验研究

Study on Bromate Removal by Calcined Layered Double Hydroxides

采用共沉淀法和焙烧处理制备了三种不同的焙烧水滑石(CLDH):Zn-Al-CLDH、Mg-Al-CLDH和Fe-Al-CLDH,对其进行了X射线衍射、比表面积和扫描电镜表征,并将其用作吸附剂去除水中的溴酸盐。结果表明,Zn-Al-CLDH对溴酸盐的去除效果最好,而Fe-AlCLDH对溴酸盐的去除效果最差;当p H值为7、温度为20℃、振荡速度为200 r/min、溴酸盐初始浓度为100μg/L时,1 g/L的Zn-Al-CLDH在0.5 h内可吸附去除92.8%的溴酸盐,经2.5 h达到吸附平衡,此时对溴酸盐的去除率为98%;在相同条件下Mg-Al-CLDH和Fe-Al-CLDH的吸附平衡时间分别为14和1.5 h,去除率分别为96%和49.6%;另外,CLDH对溴酸盐的吸附是放热反应,且吸附性能易受空气的影响。

Zn-Al-CLDH, Mg-Al-CLDH and Fe-Al-CLDH were synthesized by the co-precipitation method and subsequent calcination treatment, and the samples were characterized by XRD, BET and SEM. Taking them as adsorbents, the removal performance of bromate in water was studied. The results showed that Zn-Al-CLDH had the best bromate removal effect while Fe-Al-CLDH had the worst bromate removal effect. When pH = 7, T = 20 ℃ , shock speed = 200 r/min, and initial bromate concentration = 100 μg/L, 1 g/L Zn-Al-CLDH showed abromate removal rate of 92.8% within 0.5 h and the adsorption equilibrium was achieved in 2.5 h with a removal rate of 98%. Under the same condition, the equilibrium time and the bromate removal rate for Mg-Al-CLDH and Fe-Al-CLDH were 14 h, 96% and 1.5 h, 49.6% respectively. In addition, experiments showed that adsorption of bromate on CLDH was exothermic reaction, and adsorption capacity of CLDH was sensitive to air.