粉煤灰基层状金属氧化物对水中活性红X-3B的吸附

以粉煤灰(FA)为原料,采用共沉淀法制备了层状双金属氢氧化物(LDH)和层状金属氧化物(LMO,也称LDO),并采用XRD和BET技术进行了表征。比较了FA、LDH、LMO对活性红X-3B染料(X-3B)的吸附效果;考察了LMO吸附X-3B的影响因素,并探讨了吸附机理。XRD表征结果表明,LMO在吸附X-3B后重新恢复LDH层状结构。BET表征结果表明,LMO的比表面积大于LDH。吸附实验结果表明,3种吸附剂对X-3B吸附效果的优劣顺序为:LMOLDHFA;在初始X-3B质量浓度为50 mg/L、LMO投加量为2.0 g/L、吸附温度为25℃、吸附pH为7、吸附时间为30 min的条件下,X-3B去除率可达98.1%;LMO对X-3B的吸附符合Langmuir等温吸附方程,饱和吸附量为129.53 mg/g,且吸附过程可用准二级动力学方程描述。

Adsorption of reactive red X-3B from water by layered metal oxides based on fly ash

Layered double hydroxide（LDH）and layered metal oxides（LMO,or LDO）were prepared using fly ash（FA）as the raw material by co-precipitation method,and characterized using XRD and BET. The adsorption effects of reactive red X-3B dye（X-3B）on FA,LDH and LMO were compared. The factors affecting adsorption of X-3B on LMO were investigated,and the adsorption mechanism was discussed. The XRD results demonstrated that LMO could restore the layered structure of LDH after adsorption of X-3B. The BET results showed that the specific surface area of LMO was larger than that of LDH. The X-3B adsorption effects of the 3 adsorbents decreased in the order of LMO>LDH>FA. The optimal adsorption conditions were as follows：LMO dosage of 2.0 g/L,adsorption temperature of 25 ℃,adsorption time of 30 min,adsorption pH of 7,with the highest X-3B removal rate as 98.1%. The adsorption of X-3B on LMO fitted the Langmuir isothermal adsorption equation well and the saturated adsorption capacity was 129.53 mg/g. The adsorption process could be best described by the pseudo-second-order kinetic model.