氨基改性SiO_(2)气凝胶去除Cu(Ⅱ)的性能与机制  

Performance and mechanism of the amine-modified silica aerogel for the removal of Cu(Ⅱ)

作　　者：翟红侠[1] 赵越 李超凡 孔维丽 谢发之[1,2] 李海斌 ZHAI Hongxia;ZHAO Yue;LI Chaofan;KONG Weili;XIE Fazhi;LI Haibin(School of Materials and Chemical Engineering,Anhui Jianzhu University,Hefei 230601,China;Anhui Key Laboratory of Water Pollution Control and Wastewater Resource,Hefei 230601,China)

机构地区：[1]安徽建筑大学材料科学与工程学院,合肥230601 [2]水污染控制与废水资源化安徽省重点实验室,合肥230601

出　　处：《复合材料学报》2023年第8期4613-4624,共12页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(52003003);安徽省矿山生态修复工程实验室开放课题(KS-2022-003);安徽省先进建筑材料国际联合研究中心基金(JZCL014 ZZ)。

摘　　要：为有效去除液相中重金属Cu(Ⅱ),以正硅酸乙酯为原料、3-氨丙基三乙氧基硅烷为氨基化试剂,通过共缩聚法合成氨基改性SiO2气凝胶(NG)。系统考察pH、离子强度、时间、温度等因素对NG去除Cu(Ⅱ)的影响,结合吸附动力学模型、吸附等温模型、吸附热力学、位点能量分布理论分析其吸附机制。研究结果表明:p H在3.00~6.00条件下,Cu(Ⅱ)吸附量随pH升高而增大。离子强度由0 mol/L增至0.08 mol/L时,Cu(Ⅱ)吸附量受抑制作用呈逐渐降低趋势,FTIR分析显示NG与Cu(Ⅱ)主要形成外层络合物。NG吸附Cu(Ⅱ)时间在8 h内基本达到平衡,其吸附主要经过边界层扩散、颗粒内扩散与化学吸附等过程,且该吸附过程最符合准二级动力学模型与Freundlich模型。温度升高有利于促进吸附反应发生,Cu(Ⅱ)最大吸附量达到130.45 mg/g,其吸附过程属吸热、熵增加的自发反应。位点能量分布显示随吸附反应进行,Cu(Ⅱ)优先占据NG上高能量吸附位点,再占据低能量吸附位点,NG吸附Cu(Ⅱ)的主要机制是外层络合与静电作用。In order to remove Cu(Ⅱ)from the liquid phase efficiently,the amine-modified silica aerogel(NG)was prepared by co-condensation method using tetraethyl orthosilicate as raw material and 3-aminopropyltriethoxysilane as amino agent.The effects of pH,ionic strength,time,temperature and other factors on the removal of Cu(Ⅱ)by NG were systematically investigated.The adsorption mechanism of Cu(Ⅱ)on the NG was analyzed by combining adsorption kinetics model,adsorption isotherm model,adsorption thermodynamics and site energy distribution theory.The results demonstrate that the adsorption capacity of Cu(Ⅱ)increase with pH value from 3.00-6.00,and the adsorption is inhibited by the addition of ionic strength at the range of 0-0.08 mol/L.The outer-sphere complexes formed by Cu(Ⅱ)and NG are confirmed by using FTIR analysis.Furthermore,the adsorption equilibrium is achieved within 8 h,and the adsorption process mainly go through boundary layer diffusion,intra-particle diffusion and chemisorption.The adsorption process is best fitted with the pseudo-second-order model and Freundlich model.The increase of temperature is beneficial to promote the adsorption reaction of Cu(Ⅱ),and the maximum adsorption capacity reaches to 130.45 mg/g.The adsorption process is endothermic and entropy increasing spontaneous reaction.The energy distribution show that Cu(Ⅱ)is preferentially adsorbed on the high-energy adsorption sites on NG and then occupied low-energy adsorption sites.Overall,the adsorption mechanism is mainly attributed to the electrostatic interaction and the outer-sphere complexation.

关 键 词：气凝胶 吸附 Cu(Ⅱ) 动力学 模型 位点能量分布 

分 类 号：TQ352[化学工程] TB332[一般工业技术—材料科学与工程]