沸石的改性及其对氨氮吸附特征

为研究不同改性方法及其组合顺序对天然沸石吸附NH₄+效率的影响及其吸附特征,选择盐、高温、酸3种改性方法进行不同组合. 结果显示,改性组合顺序对天然沸石的吸附性能影响较明显,最佳改性组合顺序为“盐+酸+高温”,其改性后的沸石在初始ρ(NH₄+)为15、30和50 mg/L下对NH₄+的去除率分别为87%、92%和94%. 采用Langmuir和Freundlich 2种方程来拟合“盐+酸+高温”改性后沸石的吸附行为,表明其更符合Langmuir模型,R2为0.998 5,其最大吸附量(q_max)为8.23 mg/g,并且其吸附过程符合一级动力学方程, R 2为0.998 1. 扫描电子显微镜(SEM)和比表面积(BET)分析结果表明,沸石经最优组合改性后表面形态明显变化,比表面积增大. 

Modification of Natural Zeolites and their Ammonia Adsorption Characteristics

In order to investigate the impact of different modification methods and the combination of those methods on clinoptilolite adsorption of ammonia in aqueous solutions,three modification methods– salt,calcination and acid – were chosen,and they were combined in different orders.The results showed that the combination sequences clearly affected the adsorption performance of the modified zeolites.The optimal modification sequence was salt first,acid second and calcination last.With the optimal modified zeolites,the removal rates reached 87%,92% and 94% in 15,30 and 50 mg/L ammonium solutions,respectively.The Langmuir and Freundlich equations were used to fit the adsorption behaviors of the zeolites modified by the optimal combination sequence.The results demonstrated that the Langmuir equation was better to fit the experimental data,and its maximum adsorption capacity was 8.23 mg/g with a regression coefficient(R2) of 0.9985.The adsorption kinetic result was fitted to the first-order equation,of which the regression coefficient(R2) reached 0.9981.Further investigation by SEM(scanning electron microscope) and BET(brunauer,emmett and teller) showed that the zeolites modified by the optimal sequence had a rougher surface and larger specific surface area compared with the natural ones.