Mautner Andreas, Kobkeatthawin Thawanrat, Mayer Florian, Plessl Christof, Gorgieva Selestina, Kokol Vanja, Bismarck Alexander
Polymer & Composite Engineering (PaCE) Group, Institute of Materials Chemistry & Research, University of Vienna, 1090 Vienna, Austria.
Polymer & Composite Engineering (PaCE) Group, Department of Chemical Engineering, Imperial College London, SW7 2AZ London, UK.
Nanomaterials (Basel). 2019 Jan 22;9(2):136. doi: 10.3390/nano9020136.
Water hardness not only constitutes a significant hazard for the functionality of water infrastructure but is also associated with health concerns. Commonly, water hardness is tackled with synthetic ion-exchange resins or membranes that have the drawbacks of requiring the awkward disposal of saturated materials and being based on fossil resources. In this work, we present a renewable nanopaper for the purpose of water softening prepared from phosphorylated TEMPO-oxidized cellulose nanofibrils (PT-CNF). Nanopapers were prepared from CNF suspensions in water (PT-CNF nanopapers) or low surface tension organic liquids (ethanol), named EPT-CNF nanopapers, respectively. Nanopaper preparation from ethanol resulted in a significantly increased porosity of the nanopapers enabling much higher permeances: more than 10,000× higher as compared to nanopapers from aqueous suspensions. The adsorption capacity for Ca of nanopapers from aqueous suspensions was 17 mg g and 5 mg g for Mg; however, EPT-CNF nanopapers adsorbed more than 90 mg g Ca and almost 70 mg g Mg. The higher adsorption capacity was a result of the increased accessibility of functional groups in the bulk of the nanopapers caused by the higher porosity of nanopapers prepared from ethanol. The combination of very high permeance and adsorption capacity constitutes a high overall performance of these nanopapers in water softening applications.
水的硬度不仅对水基础设施的功能构成重大危害，还与健康问题相关。通常，水的硬度是通过合成离子交换树脂或膜来解决的，这些方法存在需要妥善处理饱和材料以及基于化石资源等缺点。在这项工作中，我们展示了一种用于水软化的可再生纳米纸，它由磷酸化的TEMPO氧化纤维素纳米纤维（PT-CNF）制备而成。纳米纸分别由水中的CNF悬浮液（PT-CNF纳米纸）或低表面张力有机液体（乙醇）制备，后者命名为EPT-CNF纳米纸。由乙醇制备纳米纸导致纳米纸的孔隙率显著增加，从而实现更高的渗透率：与水悬浮液制备的纳米纸相比，渗透率高出10000倍以上。水悬浮液制备的纳米纸对钙的吸附容量为17 mg/g，对镁为5 mg/g；然而，EPT-CNF纳米纸吸附的钙超过90 mg/g，镁接近70 mg/g。较高的吸附容量是由于乙醇制备的纳米纸孔隙率较高，使得纳米纸本体中官能团更容易接触所致。极高的渗透率和吸附容量相结合，使得这些纳米纸在水软化应用中具有很高的整体性能。
