N octanol

Magnolol and honokiol (98% purity) were acquired from New Natural Biotechnology (Shanghai, China). Phosphotungstic acid solution, sodium phosphate monobasic and potassium phosphate monobasic were purchased from Sigma-Aldrich (Madrid, Spain). N-octanol, acetonitrile, ethyl alcohol, and potassium chloride were obtained from VWR chemicals (Barcelona, Spain). Hydrochloric acid 37% and sodium hydroxide were purchased from Scharlab (Barcelona, Spain). Hydrogen peroxide 30% and boric acid were obtained from Merck (Barcelona, Spain). Phospholipon 90 G was provided by Lipoid GmbH (Ludwigshafen, Germany).

Alkyltrimethylammonium
bromides (C_nTAB, where n is the number of carbon atoms in the alkyl chain), i.e., octyltrimethylammonium
bromide (n = 8), dodecyltrimethylammonium bromide
(n = 12), cetyltrimethylammonium bromide (n = 16), and octadecyltrimethylammonium bromide (n = 18) of highest purity (≥98%, Sigma-Aldrich),
were used as cationic surfactants, while n-octanol
(≥98%, VWR) was used as a nonionic surfactant.
Particles
of high-purity quartz (>98% SiO₂) of size 50–100
μm were used in floatability tests.
Milli-Q water (18.2
MΩ·cm) was used for cleaning all
parts of the experimental setup and preparation of pure solutions
of cationic surfactants and their mixtures with a nonionic surface-active
substance used in the experiments.
The experiment was designed
in such a way that the concentration
of C_nTAB, as the solution main component,
was changed in a quite broad range, while the concentration of n-octanol (nonionic additive) was kept constant and equal
to 5 × 10^–4 M. This particular concentration
was chosen as the lowest, having a significant and easily measurable
synergistic influence on the measured parameters.^{12 (link)}