γ-Valerolactone as Bio-Based Solvent for Nanofiltration Membrane Preparation

Abstract

γ-Valerolactone (GVL) was selected as a renewable green solvent to prepare membranes via the process of phase inversion. Water and ethanol were screened as sustainable non-solvents to prepare membranes for nanofiltration (NF). Scanning electron microscopy was applied to check the membrane morphology, while aqueous rose Bengal (RB) and magnesium sulphate (MgSO4) feed solutions were used to screen performance. Cellulose acetate (CA), polyimide (PI), cellulose triacetate (CTA), polyethersulfone (PES) and polysulfone (PSU) membranes were fine-tuned as materials for preparation of NF-membranes, either by selecting a suitable non-solvent for phase inversion or by increasing the polymer concentration in the casting solution. The best membranes were prepared with CTA in GVL using water as non-solvent: with increasing CTA concentration (10 wt% to 17.5 wt%) in the casting solution, permeance decreased from 15.9 to 5.5 L/m2·h·bar while RB rejection remained higher than 94%. The polymer solubilities in GVL were rationalized using Hansen solubility parameters, while membrane performances and morphologies were linked to viscosity measurements and cloudpoint determination of the casting solutions to better understand the kinetic and thermodynamic aspects of the phase inversion process.

Spray coating polymer substrates from a green solvent to enhance desalination performances of thin film composites

“…This has been achieved using benign, bio-based solvents with strong polarity such as γ-valerolactone (GVL), dimethyl isosorbide (DMI) and dihydrolevoglucosenone (Cyrene TM ) 28 . PES dope solutions prepared with γ-valerolactone yielded sponge-like membranes with no macrovoids after NIPS 29 , while replacing NMP with Cyrene TM typically yield membranes with dense structures and hence lower water fluxes after NIPS 30,31 . Alternatively, PES dope solutions prepared with dimethyl isosorbide can produce membranes with pure water permeance of 6300 L•m -2 •h -1 •bar -1 32 .…”

Grüne Chemie mit γ‐Valerolacton

“…γ‐Valerolacton gehört demnach zur Gruppe der polaren aprotischen Lösemittel und könnte die bei der Toxizitätsbewertung als Vergleichssubstanzen genutzten klassischen Lösemittel mit Ausnahme von Tetrahydrofuran ersetzen (Abbildung 1a). Anwendungsoptionen als Lösemittel im Bereich der organischen Synthese sind Metall‐katalysierte Arylierungen und Alkenylierungen sowie die Synthese von Polymeren [4] oder Block‐Kopolymeren, im industriellen Bereich die Synthese von Membranen [5], Fasern oder Oberflächenbeschichtungen sowie pharmazeutisch relevanter Substanzen. Anwendungen als Lösemittel für Endverbraucherprodukte wie Abbeizmittel oder Nagellackentferner sind bereits patentiert.…”

Grüne Chemie: Mit Gamma‐Valerolacton lösen

“…9) Ebenso lassen sich Filter und Membranen zur Nanofiltration auf Basis von Celluloseacetat, Polyimiden oder Poly(ether)sulfonen mit GVL als Lösungsmittel darstellen. 10) GVL eignet sich darüber hinaus als Reinigungsmittel zum (Ab-)Lösen von Beschichtungen. 5) Es entfernt Farbe und Klebstoffe.…”