Electrokinetic mobility, pH and conductance/conductivity data for aqueous silica and PTFE suspension of controlled composition for selected temperature ranges

The Data in Brief contains data on the electrokinetic mobility of PTFE and silica particles in aqueous suspensions as a function of pH and temperature. Furthermore, the concomitant conductivities and pH values are reported both for systems in the absence and presence of PTFE particles as a function of temperature and are compatible with the associated research paper “The influence of temperature on the charging of Polytetrafluoroethylene surfaces in electrolyte solutions” (Barisic et al.). The trend of the electrokinetic charging with temperature can be inferred from this for both kinds of particles. The data on the evolution of the pH and the measured conductivities are valuable input for future models that simulate the charge of inert surfaces at variable temperature.


Data
The shared data involve the pH, electrophoretic mobility, the conductivity and the conductance of solutions and suspensions (containing particles of interest, i.e. PTFE or silica particles) as a function of temperature. In the experiments, we vary the initial pH of the solution and the salt composition. Tables 1e3, 6, 7, 11 and 12 present data on the electrophoretic mobilities and the conductance of the respective suspension for negative, uncharged, and positive surfaces. Tables 4, 5, 8e10, 13 and 14 include the corresponding conductivities and pH values. Table 8 a and b show the reproducibility in terms of pH measurements. Table 10 a, b, c, and d show reproducibility in terms of conductivity measurements. Fig. 1a shows an example pertaining to Table 2 for a negatively charged surface, while Fig. 1b shows the same kind of data for the positively charged surface (Table 11). The tables include the relevant experimental error estimates.
The trends in electrophoretic mobility are inversed based on the average values.

Experimental design, materials, and methods
The electrokinetic mobilities were measured using the Brookhaven Zeta-PALS equipment. This setup also measures conductance. The settings in most cases were such that the temperature was varied from room temperature down to low temperatures. In some cases, it was also chosen to start an experiment directly at a lower temperature to observe whether the starting point would affect the results. These experiments were done both with PTFE particles and AEROSIL380 particles.
Separate pH and conductivity measurements were obtained using the SurPass equipment. The pH and conductivity were measured starting at low temperature and letting the temperature slowly increase to room temperature. This was done for defined solutions in terms of salt and acid composition Specifications table   Subject area  Chemistry  More specific subject area  Physical and colloid chemistry  Type of data  Tables  How data was acquired Laser-Doppler (PALS) device for electrokinetic mobility and conductance (Nanobrook 90 plus PALS, Brookhaven), pH and conductivity electrodes.

Data format
Raw data.

Experimental factors
Silica and PTFE particles were used as received. Suspensions and solutions were prepared at room temperature with the respective salts and acids. No specific treatment.

Experimental features
The Brookhaven PALS device was used to measure the electrokinetic mobility and conductance as a funcition of temperature for a given suspension over a range of temperatures (from room temperature, where the suspension was prepared to lower temperature). The pH and conductivity of suspensions of given salt, acid and particle concentration and solutions containing salt and acid identical to those of the suspensions were measured as a function of temperature starting from low temperature.

Data source location
Karlsruhe, Germany Data accessibility Data is with this article.

Value of the data
The experimental data in combination with each other can be used to infer the variation of the isoelectric point of PTFE particles and silica particles (AEROSIL380) as a function of temperature [1]. Conductivity data of suspensions and concomitant solutions can be used as quantitative tests of models to describe the charging of PTFE particles as a function of pH and temperature [1]. The data involve a more comprehensive data set than the currently available one [2] for hydrophobic surfaces. The data can be used to construct charging models for a range of temperatures and modelers can benefit from the temperature-dependent data. The data can help to unravel the origin of the charging of inert surfaces in electrolyte solutions, which is currently under debate, and to inspire even more comprehensive experimentation on the effect of temperature.
both with and without PTFE particles of known mass. In some experiments, a known mass PTFE particles were added to a solution with known volume (at room temperature) that had reached a given temperature. PTFE particles were Microdispers-200 obtained from Polysciences Europe (Hirschberg, Germany). AEROSIL380 particles were obtained from EVONIK (Germany). All chemicals were reagent grade. Solutions were made using MilliQ water.
The pH and conductivity electrode of the SurPass equipment were calibrated as described in the manual of the set-up. The data were collected in the premeasurement option "record".
The data are all presented as the raw data in terms of tables.  Table 2 Electrophoretic mobility (and standard deviation) and conductance of a PTFE suspension in 10 mM NaCl as a function of temperature. At room temperature the pH of the PTFE suspension was 5.  Table 3 Electrophoretic mobility (and standard deviation) and conductance of an Aerosil380 suspension in 10 mM NaCl as a function of temperature. At room temperature the pH of the Aerosil380 suspension was 4.8.          Table 14 pH and conductivity of a solution (a) and pH and conductivity of a PTFE suspension (b) containing 0.1 mM KNO 3 as a function of temperature in lower temperature ranges. The experiment was started at 17 C and measurements were stopped at room temperature. At room temperature the pH of the PTFE suspension was 1.65. The mass concentration in the PTFE suspension was 0.5 g/L.