氢氧化钠预处理和盐热复合改性对沸石氨氮吸附性能的影响
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摘要
对天然斜发沸石进行碱液预处理、盐热复合改性,并进行挤压制粒,研究了改性及制粒对斜发沸石氨氮吸附性能的影响。结果表明:天然斜发沸石经1.0 mol/L NaOH溶液预处理2 h,再经2.0 mol/L NaCl溶液处理2 h及400℃焙烧热处理0.5 h后,氨氮去除率从54.4%提高到98.3%。在复合改性后的沸石中添加6%硅酸钠黏结剂,经400℃热处理,制成粒径为?1.5 mm×2.5 mm的短柱状改性沸石颗粒,其氨氮去除率为83.3%,散失率为1.1%。采用NaCl+NaOH溶液作为再生剂,1次再生后氨氮去除率为75.2%,5次再生后,氨氮去除率为67.8%。改性沸石及其颗粒对氨氮吸附过程符合准二级反应动力学公式,属于化学吸附(离子交换)。沸石粉体及其颗粒对氨氮的吸附是以膜扩散和内扩散为共同控制步骤,为自发和吸热过程,温度升高,吸附量增加。另外,熵效应是吸附反应过程的主要驱动力。
Natural clinoptilolite was pretreated by NaOH solution and compound modified by NaCl solution and roasting,as well as squeezed into granules after modification.Effects of modification and granulation on the properties of ammonia-nitrogen removal were investigated.The results show that ammonia-nitrogen removal rate of clinoptilolite(after pretreated by 1.0 mol/L NaOH solution and modified by 2.0 mol/L NaCl and roasting at 400 for 0.5 h)℃ increases from 54.4% to 98.3%,and the ammonia-nitrogen removal rate of the zeolite granules with the size of ?1.5 mm×2.5 mm prepared at 6% sodium silicate content and 400 is 83.3% and the loss ℃rate is 1.1%.The ammonia-nitrogen removal rate is 75.2% after regeneration for 1 time with NaCl and NaOH solutions,and 67.8% after regeneration for 5 times.The adsorption kinetics of ammonia-nitrogen of zeolite and granules follows a pseudo-second order adsorption dynamic model,which describes the adsorption of ammonia-nitrogen in aqueous solution mainly as a chemical adsorption.The ammonia-nitrogen adsorption process is mainly controlled by membrane diffusion and internal diffusion process.Besides,the process is a spontaneous and endothermic process,the adsorption capacity increases with increasing the temperature,and the entropy is the main effect of the adsorption process.
Natural clinoptilolite was pretreated by NaOH solution and compound modified by NaCl solution and roasting,as well as squeezed into granules after modification.Effects of modification and granulation on the properties of ammonia-nitrogen removal were investigated.The results show that ammonia-nitrogen removal rate of clinoptilolite(after pretreated by 1.0 mol/L NaOH solution and modified by 2.0 mol/L NaCl and roasting at 400 for 0.5 h)℃ increases from 54.4% to 98.3%,and the ammonia-nitrogen removal rate of the zeolite granules with the size of ?1.5 mm×2.5 mm prepared at 6% sodium silicate content and 400 is 83.3% and the loss ℃rate is 1.1%.The ammonia-nitrogen removal rate is 75.2% after regeneration for 1 time with NaCl and NaOH solutions,and 67.8% after regeneration for 5 times.The adsorption kinetics of ammonia-nitrogen of zeolite and granules follows a pseudo-second order adsorption dynamic model,which describes the adsorption of ammonia-nitrogen in aqueous solution mainly as a chemical adsorption.The ammonia-nitrogen adsorption process is mainly controlled by membrane diffusion and internal diffusion process.Besides,the process is a spontaneous and endothermic process,the adsorption capacity increases with increasing the temperature,and the entropy is the main effect of the adsorption process.
引文
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[4]LIN L,LEI Z F,WANG L,et al.Adsorption mechanisms of high-levels of ammonium onto natural and Na Cl-modified zeolites[J].Sep Purif Technol,2013,103(15):15–20.
[5]袁俊生,叶海彬,石林.斜发沸石Na+/K+交换过程的分子动力学模拟[J].硅酸盐学报,2009,37(10):1724–1729.YUAN Junsheng,YE Haibin,SHI Lin.J Chin Ceram Soc,2009,37(10):1724–1729.
[6]刘泉利,林海,董颖博,等.不同价态阳离子盐改性沸石吸附氨氮能力差异[J].湖南大学学报:自然科学版,2016,43(6):143–148.LIU Quanli,LIN Hai,DONG Yingbo,et al.J Hunan Univ Nat Sci(in Chinese),2016,43(6):143–148.
[7]YANG H,NING H L,PEI L.Properties study on ammonia nitrogen adsorption of attapulgite[J].Chin J Environ Eng,2011,5(2):343–346.
[8]李圣品,刘菲,陈鸿汉,等.法库沸石对氨氮的吸附特性和阳离子交互过程[J].环境工程学报,2015,9(1):157–163.LI Shengpin,LIU Fei,CHEN Honghan,et al.Chin J Environ Eng,2015,9(1):157–163.
[9]王文华,赵瑾,张晓青,等.天然沸石对海水中氨氮的吸附特性[J].环境工程学报,2015,9(9):4281–4286.WANG Whenhua,ZHAO Jin,ZHANG Xiaoqing,et al.Chin J Environ Eng(in Chinese),2015,9(9):4281–4286.
[10]TIAN J,GUAN J,YAN C,et al.Study on treatment of ammonia nitrogen waste water by zeolite-granule-adsorbent[J].Adv Mater Res,2013,668:211–215.
[11]FAUHIHIAN H,KABIRI T M.Removal of zirconium from aqueous solution by modified clinoptilolite[J].J Hazard Mater,2010,178:66–73.
[12]杨苏.微波改造提高天然沸石脱氮性能及机理研究[D].北京:北京科技大学,2013.YANG Su.Study on ammonia nitrogen removal from wastewater by microwave assisted zeolite(in Chinese,dissertation).Beijing:University of Science and Technology Beijing(in Chinese,Dissatation),2013.
[13]王萌,房春生,颜昌宙,等.沸石的改性及其对氨氮吸附特征[J].环境科学研究,2012,25(9):1024–1029.WANG Meng,FANG Chunsheng,YAN Changzhou,et al.Res Environ Sci(in Chinese),2012,25(9):1024–1029.
[14]钱吉彬,杨朗,张华,等.镇江斜发沸石对氨氮的吸附动力学及热力学研究[J].环境工程学报,2011,5(2):327-330.QIAN Jibin,YANG Lang,ZHANG Hua,et al.Chin J Environ Eng(in Chinese),2011,5(2):327–330.
[15]NIBOU D,MEKATEL H,AMOKRANE S,et al.Adsorption of Zn2+ions onto Na A and Na X zeolites:kinetic,equilibrium and thermodynamic studies[J].J Hazard Mater,2011,173(1/3):637–646.
[16]吕宪俊,陈平.长碳链烷基铵在蒙脱石层间的吸附热力学[J].硅酸盐学报,2011,39(10):1553–1558.LV Xianjun,CHEN Ping.J Chin Ceram Soc,2011,39(10):1553–1558.