CPAM插层膨润土复合材料的制备及对磷吸附行为

Preparation and Phosphorus Adsorption Property of Cationic Polyacrylamide Intercalated Bentonite Composite

摘要:

采用十六烷基三甲基溴化铵（CTMAB）、阳离子聚丙烯酰胺（CPAM）两步湿法首次成功制备出CPAM插层钠基膨润土（Bent）复合材料，利用XRD、FESEM、IR、BET以及TG-DTG-DSC等分析材料的组成、形貌以及结构特征，并进行模拟含磷废水的吸附研究。结果表明，CPAM已稳定插层在Bent的片层结构中，其层间距显著增大，红外光谱出现明显的羰基吸收峰，比表面积减小而表面疏水性增强。含磷废水处理表明，吸附性能大小的顺序为：CPAM/Bent > CTMAB/Bent > Bent，随着反应温度升高、含磷废水初始浓度增加以及pH值降低，CPAM/Bent对磷的去除率逐渐增大，当含磷废水初始浓度为3.5 mg/L、pH≈5、温度为35 ℃、投加量0.5 g/100 mL，20 min去除率达75%。CPAM/Bent经过5次吸附和再生后，其吸附磷的能力显著下降。吸附等温线均符合Langmuir和Freundlich方程，吸附过程更好地满足准二级动力学方程。

Abstract:

The composite material was first synthesized by Na-bentonite（Bent） intercalated with hexadecyl trimethyl ammonium bromide(CTMAB)、cationic polyacrylamide(CPAM) through two-step wet method. The composition、morphology and structure characteristics were analysed by XRD、FESEM、IR、BET and TG-DTG-DSC，and it was used to absorb simulated phosphorous wastewater. The results indicated that CPAM was intercalated into the lamellar structure of Na-bentonites steadily, the layer spacing was significantly increased，the infrared spectrum showed obvious carbonyl absorption peaks, the specific surface area of the sample decreased and surface hydrophobicity was enhanced after intercalation. The results of adsorption of phosphorous wastewater showed that the order of adsorbability was: CPAM/Bent > CTMAB/Bent > Bent, with the increase in reaction temperature、the initial concentration of phosphorous wastewater and the decrease of pH value, the removal rate of phosphorus with CPAM/Bent was gradually increased. While in the condition of initial concentration of 3.5 mg/L、pH of about 5、temperature of 35 ℃、adding amount of 0.5 g/100 mL, the removal rate of phosphorus were 75 % after twenty minutes. After five times adsorption and regeneration, the adsorption ability of CPAM/Bent to phosphorus decreased significantly. The adsorption isotherms could be described by Langmuir and Freundlich equations, The adsorption process could be better satisfied with the pseudo-second order kinetic equation.