材料期刊网

以粉煤灰(fly ash,FA)为原料,通过酸改性和沉淀焙烧法制备的粉煤灰基复合材料(CeO2/Fe2O3/FA)用于直接湖蓝5B (Direct sky blue 5B,DSB 5B)染料的吸附,考察了最佳吸附条件和吸附性能,探讨了吸附机理及复合吸附剂的再生.结果表明,水体pH、染料起始浓度、接触时间和振荡频率均对CeO2/Fe2OJFA吸附DSB 5B有影响;吸附30 min即可达到动态平衡,吸附量比FA增大近11倍.在不同温度和不同起始染料浓度下的吸附过程均能用准二级吸附速率方程精确描述.等温吸附数据符合Langmuir模型,所得饱和吸附量为263.16 mg·g-1,同时也较好地符合Dubinin-Radushkevich(D-R)模型,由此获得的平均吸附能(E)及由Arrhenius方程求得的表观活化能(Ea)值均表明吸附过程是由物理吸附、氢键作用和化学吸附共同控制,但化学吸附起主要作用.热力学参数△G°、△H°和△S°的结果表明复合材料对DSB 5B的吸附具有界面上混乱度增加的自发吸热性质.复合吸附剂能用很稀的NaOH溶液再生,且可至少重复使用3次.作为一种低值高效的新型吸附剂,CeO2/Fe2O3/FA能用于高浓度染料废水中DSB 5B的有效去除.

CeO2/Fe2O3/FA composite prepared by acid treatment and chemical precipitation method was used for the adsorption of Direct Sky Blue 5B (DSB 5B) dye from aqueous solution.The optimum adsorption conditions and adsorption properties were investigated,and the adsorption mechanism and the regeneration of the composite adsorbent were also discussed.The results show that the adsorption of DSB 5B on CeO2/Fe2O3/FA is affected by the solution pH,initial dye concentration,contact time and oscillation frequency,and can achieve dynamic equilibrium in 30 min.The adsorption capacity of CeO2/Fe2O3/FA for DSB 5B is nearly 11 times larger than that of FA.The adsorption process can be accurately described by the pseudo-second-order adsorption model at different temperatures and different initial dye concentrations.The experimental isotherm data were analyzed by using three isotherm models,namely Langmuir,Freundlich and Dubinin-Radushkevich,and found to well follow the Langmuir isotherm with the saturated adsorption capacity of 263.16 mg · g-1(25 ℃).The adsorption data are also in good agreement with the D-R model,and the obtained average adsorption energy (E) and the apparent activation energy (Ea) values calculated by Arrhenius equation indicate that the adsorption may be the dual nature of physisorption,ydrogen bonding and chemisorption,but is predominant on the chemisorption process.The thermodynamic parameters,the negative values of adsorption gibbs free energy changes (AG°) and the positive values of adsorption enthalpy changes (AH°) and adsorption entropy changes (AS°) show that the adsorption is the process of spontaneous and exothermic nature with the increase of the interfacial disorder.The CeO2/Fe2O3/FA adsorbent can be regenerated by a very dilute NaOH solution,and reused at least 3 times for dye removal from the wastewater.As a novel low-cost and high-efficiency adsorbent,CeO2/Fe2O3/FA composite can be used to effectively remove DSB 5B in high-concentration dye wastewater.