Mg—Al水滑石对偶氮染料活性艳红X-3B的脱色性能研究

采用共沉淀法合成出一系列镁铝摩尔比不同的碳酸根型水滑石（LDHs），经500℃高温煅烧制备出镁铝复合氧化物CLDH，并用X-射线、红外光谱对它们进行表征。考查了吸附剂投加量、反应时间、初始pH值等因素对LDHs和CLDH处理阴离子染料活性艳红X-3B模拟废水效果的影响，并对吸附机理进行探讨。实验结果表明：以镁铝摩尔比为3：1时制得的水滑石对活性艳红X-3B溶液的脱色效果最好。水滑石LDHs及其焙烧产物CLDH对活性艳红X-3B染料均具有较好的吸附性能，最佳反应时间分别为60min和30min；在较宽的pH范围内二者的脱色性能稳定，且CLDH对该染料的吸附效果要优于LDHs。LDHs及CLDH对活性艳红X-3B的吸附结果符合Langmuir吸附等温式，25℃下饱和吸附量分别为263．77mg／g和875．23mg／g。LDHs及CLDH的吸附机理分别为离子交换和层状结构重建。饱和吸附后的CLDH用高温热解法再生，吸附性能良好，随再生次数增多，脱色率下降。

Study on decoloration of wastewater containing active red X-3B by Mg-AI layered double hydroxides

A series of CO3^2- -type Mg-Al layered double hydroxides（LDHs） with different Mg/Al molar rati- os were synthesized by co-precipitation,and parts of the synthesized clays were calcined at 500 ℃ to obtain the corresponding Mg-Al-O mixed oxides（CLDH）. The Mg-Al layered double hydroxides and Mg-Al-O mixed oxides were charaterized by XRD and FT-IR, respectively. The effects of adsorption time, sorbent dosage,initial pH val- ue on decoloration efficiency of simulated active red X-3B dye wastewater were investigated, and the adsorption mechanism was discussed. The results showed that the decolorization effect was the best when molar ratio of Mg2 ＋ to Al3＋ was 3： 1. Mg-Al layered double hydroxides or calcined Mg-Al layered double hydroxides had an excellent performance in decoloration of wastewater;the optimal reaction time was 60 min and 30 min, respectively;both were good with a wider pH and the latter possessed more advantages. The adsorption results of active red X-3B on LDHs and CLDH were conformed to the Langmuir isotherm equation, and the saturated adsorption of active red X-3B were 263.77 mg/g and 875.23 mg/g, respectively. It were found that LDHs and CLDH absorbed anions from solution through the ion exchange and reconstruction of the layered structure because of their special structure memory effect respectively. Thermal regeneration for re-use of CLDH after active red X-3B adsorption were feasible. The adsorption capacities of the regenerated materials decreased with increasing of cycles.