【作者】 李勇；

【导师】 冉瑾；

【作者基本信息】 合肥工业大学 ， 化学工程与技术， 2024， 硕士

【摘要】 随着工业化进程的推进和新能源行业的大力发展,高浓度工业废水的处理和合理开发利用锂资源已然成为急需解决的问题。现有的分离技术中,膜分离技术因其具有低能耗、高效、经济、绿色的优点,在废水处理、有机溶剂纳滤、能量收集和离子分离等领域均有应用。膜分离技术中膜材料的组成、结构和稳定性直接决定着分离效果。研究人员发现氧化石墨烯（GO）膜具有有序的通道和提供功能化的反应位点被广泛应用于离子分离,但是原始GO膜在水溶液极易溶胀导致离子在通道内无差别地透过从而表现出低的离子选择性。基于此,本文通过向GO层间通道中引入带有离子功能基团的分子来制备具有高通量和高选择性的二维阳离子交换膜。具体内容如下:（1）为了抑制原始GO膜在水溶液中溶胀以及解决碱回收分离过程中渗透通量和离子筛分性能低的问题,本文提出离子化工程策略以设计具有二维受限通道的阳离子交换膜。首先在GO纳米片上共价接枝1,2-二氨基苯磺酸（1,2-diaminobenzene sulfonic acid,PDASA）和氨基磺酸（Sulfanilic acid,SA）分子并通过真空辅助过滤法制备出PDASA@GO和SA@GO膜。PDASA@GO和SA@GO膜不仅具备与GO类似的规则有序的传输通道同时离子功能化基团促进反离子运输（Na⁺）,为保持溶液电中性更小水合尺寸和低荷电量的OH^-能过透过膜而WO₄^2-被阻隔,使得PDASA@GO和SA@GO膜能够协同提高OH^-渗析系数和分离因子。在原始GO膜中,OH^-的渗析系数(U_OH^-)为0.92×10^-3 m h^-1,分离因子（S）达到8.5。相比之下,PDASA@GO和SA@GO膜的U_OH^-分别提高到7.5×10^-3 m h^-1和5.6×10^-3 m h^-1,S提高到147和195,成功打破了渗透通量与选择性间的权衡效应。（2）为了解决GO膜在不同一/二价阳离子分离体系中单价离子运输速率低和选择性差的问题,本文继续沿用上述所提出的策略,选用具有不同分子结构和不同离子功能基团的接枝分子,包括氨基甲磺酸（Aminomethanesulfonic acid,AMSA）、3-氨基丙磺酸（3-amino-1-propanesulfonic acid,APSA）、对氨基苯磺酸（p-aminobenzenesulfonic acid,ABSA）、苯胺-2,5-二磺酸（2-amino-1,4-benzenedisulfonic acid,ADSA）、3-氨基丙基膦酸（3-aminopropylphosphonic acid,APPA）和4-氨基丁酸（4-aminobutyric acid,ABA）,通过形成共价键的方式将上述的分子引入至纳米片上作为离子交换位点以促进反离子的运输,所制备的膜分别记作AMSA@GO、APSA@GO、ABSA@GO、ADSA@GO、APPA@GO、和ABA@GO膜。在选择性电渗析分离过程中,离子化通道的形成不仅加快了单价阳离子的运输速率而且同步提升了一/二价阳离子的选择性。由于不同分子间存在不同的结构导致所制备的离子功能化还原氧化石墨烯（I-r GO）膜其通道的尺寸以及通道内的化学环境发生改变,进而表现出对一/二价阳离子的选择性筛分性能的差异。另外,本研究将从通道尺寸和通道内的微化学环境两个角度,包括调节阳离子与不同离子交换基团相互作用和调节层间距,引入阳离子-π相互作用力,以及增强离子交换基团密度这四种调控策略,进一步强化分离效果并研究离子功能化膜结构与分离效果间的构效关系。在选择性电渗析分离过程中,APSA@GO膜的Li⁺运输速率达到1.09 mol m^-2 h^-1,Li⁺/Mg²⁺选择性达到86.7,其性能远高于原始r GO膜、其他二维膜和聚合物杂化膜。此外,通过不同调控策略进一步强化了对一/二价阳离子的分离,离子选择性范围在37.34～198.22。更多还原

【Abstract】 As industrialization progresses and the new energy sector undergoes rapid development,addressing the challenges of treating high-concentration industrial wastewater and sustainably harnessing lithium resources has emerged as an imperative.Membrane separation technology,characterized by its minimal energy consumption,efficiency,cost-effectiveness,and environmental sustainability,has found widespread application across numerous domains,including wastewater treatment,organic solvent nanofiltration,energy harvesting,and ion separation.The performance of membrane separation technologies is intrinsically linked to the properties of the membrane materials used,namely their composition,structure,and stability,which is crucial determinants of the separation efficacy.Notably,graphene oxide（GO）membrane,with its order channels and reaction sites for functionalization,has been extensively employed for ion separation.Nonetheless,the propensity of pristine GO membranes to swell in aqueous solutions undermines their ion selectivity,leading to non-selective ion transport.To address this limitation,this study introduces a novel approach by incorporating molecules endowed with ionic functional groups into the interstitial channels of GO,thereby fabricating two-dimensional cation separation membranes distinguished by their enhanced flux and selectivity.The specific contents are as follows:（1）To mitigate the swelling of pristine graphene oxide（GO）membranes in aqueous environments and to tackle the challenge of low permeate flux and ion selectivity in the process of alkali recovery separation,this study introduces an ionization-engineered strategy for the development of cation exchange membranes featuring two-dimensional restricted channels.The approach involves the covalent grafting of 1,2-diaminobenzene sulfonic acid（PDASA）and sulfanilic acid（SA）to GO nanosheets,followed by the fabrication of PDASA@GO and SA@GO membranes through a vacuum-assisted filtration technique.The PDASA@GO and SA@GO membranes exhibit not only structured and orderly channels akin to those in GO membrane but also enhance the transport of counter ion（Na⁺）via ionic functional groups,facilitating the passage of smaller,less charged OH^-ions while blocking WO₄^2-ions.This process synergistically improves the OH^-permeation coefficient and separation factor for the PDASA@GO and SA@GO membranes.Compared to OH^-permeation coefficient(U_OH^-)of 0.92×10^-3 m h^-1 and a separation factor（S）of 8.5 in pristine GO membranes,the PDASA@GO and SA@GO membranes demonstrate elevated U_OH^- values of 7.5×10^-3 m h^-1 and 5.6×10^-3 m h^-1,respectively,with S values reaching 147 and 195,which successfully broke the"trade-off"effect between penetration and selectivity.（2）To mitigate the challenges associated with low transport rates of monovalent ions and low selectivity in the separation of mono-and divalent cations through graphene oxide（GO）membranes.This study uses the strategy previously outlined,which involves the selection of molecules for grafting that exhibit diverse molecular structures and ionic functional groups,including aminomethanesulfonic acid（AMSA）,3-amino-1-propanesulfonic acid（APSA）,p-aminobenzenesulfonic acid（ABSA）,2-amino-1,4-benzenedisulfonic acid（ADSA）,3-aminopropylphosphonic acid（APPA）,and 4-aminobutyric acid（ABA）.These molecules are covalently bonded to nanosheets,serving as ion exchange sites to facilitate counterion transport.The resultant membranes,designated as AMSA@GO,APSA@GO,ABSA@GO,ADSA@GO,APPA@GO,and ABA@GO,are examined within the device of selective electrodialysis separation.This process leverages ionized channels to enhance both the rate of monovalent cation transport and the discrimination between mono-and divalent cations.Variations in molecular architecture contribute to differences in channel dimensions and the internal chemical milieu of the ion-functionalized reduced graphene oxide（I-r GO）membranes,resulting in distinct selectivity profiles for mono-and divalent cations.This research further delves into optimizing the separation efficacy and elucidating the correlation between the structural features of ion-functionalized membranes and their separation capabilities.It involves four modulation strategies:tuning interactions between cations and various ion exchange groups,adjusting interlayer spacing,introducing cation-πinteractions,and amplifying the density of ion exchange groups.In selective electrodialysis experiments,the APSA@GO membrane demonstrated a lithium ion transport rate of 1.09 mol m^-2 h^-1 and a Li⁺/Mg²⁺selectivity of 86.7,markedly outperforming original reduced graphene oxide membranes,other two-dimensional membranes,and polymer hybrid membranes.Moreover,the application of diverse regulatory strategies has significantly improved the differentiation between mono-and divalent cations,achieving ion selectivity metrics ranging from 37.34 to 198.22.更多还原