改性绿沸石的制备及其吸附氨氮的性能研究

摘要

为了进一步提高绿沸石吸附材料的氨氮吸附性能, 通过氢氧化钠预处理、热改性等手段制备了碱热改性绿沸石;采用静态试验的方法, 考察了热改性时间、热改性温度、改性碱液用量、吸附水温等因素对改性绿沸石吸附氨氮性能的影响, 并通过吸附动力学、吸附等温线、SEM、XRF等手段分析其吸附机理.结果表明:绿沸石的最佳改性条件是在35℃下以2 mol/L碱液改性后再于400℃下焙烧2.5 h;当氨氮废水质量浓度为25 mg/L时, 此改性绿沸石的最佳吸附条件为温度30℃、振荡速度200 r/min, 最大氨氮吸附量为9.21 mg/g, 它比未改性绿沸石的最大氨氮吸附量4.36 mg/g提高了111.2％;用Freundlich和Langmuir等温模型、准一级、二级动力学对吸附过程拟合, 结果表明绿沸石对氨氮的吸附是单层化学吸附和多层物理吸附共同作用的吸附-还原过程.%In order to further improve the ammonia nitrogen adsorption performance of the green zeolite, the alkali heat-modified green zeolite was prepared by means of sodium hydroxide pretreatment and thermal modification.The effects of thermal modification time, thermal modification temperature, modified lye dosage and adsorption water temperature on the adsorption of ammonia nitrogen on modified green zeolite were investigated by static test. The adsorption mechanism was analyzed by adsorption kinetics, adsorption isotherms, SEM, XRF. The results showed that the best modification condition of green zeolite was pretreated by 2.0 mol/L NaOH solution at 35℃ and roasting at 400 ℃ for 2.5 h. The best adsorption conditions of green zeolite was prepared by 25 mg/L ammonia nitrogen at 30 ℃ and shaking at 200 r/min. The maximum ammonia nitrogen adsorption amount was 9.21 mg/g, which was the largest than unmodified green zeolite. Ammonia nitrogen adsorption amount of 4.36 mg/g increased by 111.2％.The Freundlich and Langmuir isothermal models, quasi-first-order and second-order kinetics were used to fit the adsorption process. The adsorption of ammonia nitrogen by smectite was the adsorption-reduction process of single-layer chemical adsorption and multi-layer physical adsorption.