V20 volumetric karl fischer titrator

The moisture contents of the PSO samples were determined using a V20 Volumetric Karl Fischer Titrator (Mettler-Toledo, Columbus, OH, USA), following the method described by Zhou et al. [16 (link)] and were expressed as percentage. The acid values in the oil samples were tested following the AOCS official method, Cd 5a-40, and were expressed as mg KOH/g oil. The peroxide values were determined using AOCS method Cc 13k-13 and were expressed as mmol/kg. The Iodine values in the oil samples were measured following the AOCS official method, Cd 1d-92, and were expressed as mg I₂/g oil. The saponification values of the oil samples were detected following the AOCS official method, Cd 3-25, and were expressed as mg KOH/g oil.

All pretreatment experiments were conducted in a N,N,N-dimethyl butylammonium hydrogen sulfate {[DMBA][HSO₄]} with an acid: a base ratio of 1:1 (mol/mol) was synthesized according to the method published by Gschwend et al.^{43 (link)}. The water content of the synthesized [DMBA][HSO₄] was adjusted to 20 wt% using a V20 Volumetric Karl-Fischer titrator (Mettler-Toledo, USA).

Using a dropping funnel, acid was added dropwise to a round bottomed
flask containing the corresponding amine, magnetically stirred, and
chilled to 0 °C using an ice bath. IL water content was reduced
to below 20 wt % by rotary evaporation and measured using a V20 Volumetric
Karl Fischer Titrator (Mettler-Toledo). Acid–base ratios of
[HSO₄]⁻ ILs were determined by titration
by 0.1 M NaOH, using a G20S Compact Titrator (Mettler-Toledo), standardized
using potassium hydrogen phthalate purchased from Sigma-Aldrich. Acid–base
ratios of [HCOO]⁻, [Cl]⁻, and
[OAc]⁻ ILs were determined through calibration curves
of acid–base ratio vs pH for dilute solutions (0.5 wt %). ¹H-NMR and ¹³C-NMR spectra were recorded on a Bruker
400 MHz spectrometer (Supporting Information).