羟基铝柱撑膨润土对水中Cr(Ⅵ)的吸附性能研究

Adsorption peroperty of hydroxyl-Al pillared bentonite for Cr(Ⅵ)in aqueous solution

为了提高膨润土的吸附性能,采用羟基铝离子改性制成羟基铝柱撑膨润土。在利用红外光谱、BET&BJH、扫描电镜及Zeta电位表征其物理化学特性的基础上,考察吸附Cr(Ⅵ)的主要因素,通过吸附动力学、等温吸附过程、吸附热力学探讨作用机理。结果表明:羟基铝离子进入膨润土层间;片状结构出现剥裂现象,表面变得粗糙和疏松、孔洞增多;BET比表面积与微孔面积分别由49.56m^(2)/g增至247.52m^(2)/g、11.35m^(2)/g增至181.61m^(2)/g,孔体积增大,平均孔径变小。经过改性后对Cr(Ⅵ)的吸附能力明显增强;在40℃与pH=4条件下,用10g/L吸附剂处理30mg/L含Cr(Ⅵ)废水,去除率达到95.50%。吸附作用机理包括化学吸附和离子交换;吸附属于吸热反应,升温促进吸附反应。

In order to improve the adsorption performance of sodium bentonite,hydroxyl-Al pillared bentonite was prepared with hydroxyl aluminium cations.The physical and chemical properties were characterized by using FT-IR,BET&BJH,SEM and Zeta potential.The effects of several processing variables on the adsorption performance were studied in detail.The adsorption mechanism was discussed with respect to a number of kinetic/adsorption isotherm models and thermodynamic analysis.The characterization results indicated that hydroxyl-Al cations intercalated to the layers of bentonite.The layers were separated with larger spacing after modification,and the porosity and roughness of the surface increased.The BET specific surface area increased from 49.56 m^(2)/g to 247.52 m^(2)/g,and micropore area increased from 11.35 m^(2)/g to 181.61 m^(2)/g.The pore volume increased and the average pore size decreased.At pH 4,temperature 40℃ with adsorbent dosage of 10 g/L,the treatment to 30 mg/L of Cr(Ⅵ)reached the highest removal rate of 95.50% after contacting 60 min.The adsorption process mainly corresponded to chemical adsorption and ionic exchange.The adsorption process was endothermic and spontaneous,and increasing temperature promoted the adsorption.