Rapid Water Softening with TEMPO-Oxidized/Phosphorylated Nanopapers

Abstract

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 Ca2+ of nanopapers from aqueous suspensions was 17 mg g−1 and 5 mg g−1 for Mg2+; however, EPT-CNF nanopapers adsorbed more than 90 mg g−1 Ca2+ and almost 70 mg g−1 Mg2+. 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.

Hydrothermally Reduced Graphene Hydrogel Intercalated with Divalent Ions for Dye Adsorption Studies

“…The increase in the lateral size of the GO and also the increase in zeta potential value after the inclusion of the divalent ion in the GO suspension indicated that Mg 2+ and Ca 2+ showed good affinity towards the oxygen functional groups GO sheets are highly negative charged which is attributed to the ionization of oxygen-containing functional groups present at the basal and planar plane. We posit that the higher particle diameter obtained for rGH-Ca is attributed to the larger ionic size of Ca 2+ for easier chelation with the oxygenated group of the GO [48]. The higher hydration energy of MgCl 2 led to the greater volumetric dimension of its hydrated ion which may limit their interactions via ionic cross-linking with the negatively charged GO sheets [49].…”

Retain strength, gain ductility: tough and transparent nanopapers by mercerisation

“…Thin nanocellulose lms, also called nanopapers, show great potential in a myriad of possible applications such as substrates for printable electronics, (Koga et al 2013(Koga et al , 2014Fujisaki et al 2014;Zhu et al 2014) water treatment membranes, (Mautner et al 2015(Mautner et al , 2016(Mautner et al , 2019Mautner 2020;Fijoł et al 2023) and interleaves in composite reinforcements (Mautner et al 2017(Mautner et al , 2020) amongst many others. These applications pose different requirements on nanopapers, rendering the tuneability of the mechanical, optical and morphological properties a necessity.…”

Zeolite-based monoliths for water softening by ion exchange/precipitation process

“…Direct feed of hard water to the boiler reduces the steam production due to the presence of metal ions, which, forming scale and sludge, priming and foaming, can greatly reduce the heat transfer efficiency 1 . Moreover, the scale formation during industrial activities produces boiler corrosion and blokage of membranes and pipes 2 . Hence the necessity to soften the water prior to use in such applications.…”