利用商用凝胶型离子交换树脂实现超微纳米颗粒的大规模生产与高效水处理

Commercial Gel-Type Ion Exchange Resin Enables Large-Scale Production of Ultrasmall Nanoparticles for Highly Efficient Water Decontamination

纳米技术为深度水处理提供了新的机遇。然而,高活性超微(<5 nm)纳米颗粒材料的大规模生产仍存在挑战,且超微材料在实际水处理中也存在操作困难等问题,阻碍了纳米技术在水污染控制领域的推广应用。针对这些问题,我们提出了一种简便的解决方法,即以商用凝胶型离子交换树脂N201为载体合成超微纳米颗粒。N201是一种季铵化的毫米级聚(苯乙烯二乙烯基苯共聚)小球。在N2O1中通过简单的浸渍-沉淀获得了水合氧化铁(HFO)、水合氧化锰(HMO)、硫化镉(CdS)和零价铁(ZVI)等纳米颗粒,所有纳米颗粒的尺寸都小于5 nm。中试生产表明该合成方法可方便放大,并制备了大量亚5 nm HFO颗粒。关于超微纳米颗粒的合成机理,我们认为在每个在水中溶胀的N201小球内都包含连续均匀水相,使反应物可快速地扩散到树脂球内部(7 s内从小球表面扩散到中心),从而实现纳米颗粒的爆发成核,形成超窄尺寸分布的晶核。此外,交联聚合物链间还可形成狭窄的孔隙(直径<5 nm),可防止在其中形成的纳米颗粒过度生长。由于N201载体具有毫米级尺寸,所制备复合的纳米材料可方便用于连续流装置中。批次实验和柱吸附测试表明,超微HFO颗粒对As(Ⅲ/Ⅴ)的吸附性能比约17 nm的HFO显著增强。本研究有望进一步促进纳米技术在实际水处理中的推广应用。

Nanotechnology presents innovative solutions in advanced water treatment;however,its application is limited by the challenging large-scale production of ultrasmall(<5 nm)nanoparticles(NPs)with extraordinary decontamination reactivity and the difficulty of handling such tiny NPs in engineering.To address these challenges,we propose a straightforward route for synthesizing ultrasmall NPs using the commercial gel-type anion exchange resin N201 as the host.N201 is a millimeter-scale poly(styrene-codivinylbenzene)bead modified with quaternary ammonium groups.Nanoparticles of hydrated ferric oxide(HFO),hydrated manganese oxide(HMO),cadmium sulfide(CdS),and zero-valent iron(ZVI)were obtained through simple impregnation-precipitation in N201,and all of the NPs possessed an ultrasmall size of sub-5 nm.A pilot-scale production assay indicated that the synthetic system could be enlarged proportionally to prepare massive sub-5 nm HFO.Regarding the underlying mechanism,each N201 bead contained a continuous water phase,allowing the rapid diffusion of the reactants(7 s for diffusion from the bead surface to the center),resulting in burst nucleation to produce ultrasmall NPs with a narrow size distribution.Moreover,the crosslinked polymer chains provided a confined space(<5 nm diameter)to prevent the excessive growth of the formed NPs.Owing to the millimetric N201 host,the resultant nanocomposite can be applied in flow-through systems.The batch and column adsorption assays demonstrate the dramatically enhanced adsorption performance of the ultrasmall HFO toward As(Ⅲ/Ⅴ)than the
17 nm analogs.This study can advance the widespread use of nanotechnology in practical water treatment.