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In this work, studies on characterization and electrochemical treatment of kaolin from the municipality of Agua Blanca, Hidalgo, Mexico were carried out, in order to identify its properties and establish the operating conditions for an electrochemical purification treatment. Different characterization techniques were used in order to quantify this clay characteristics, such as X-ray diffraction, scanning electron microscopy, analysis of the whiteness index, particle size, FTIR, Induced Coupled Plasma Spectroscopy, Z potential, cyclic voltammetry, chronopotentiometry and chronoamperometry. This study shows that the tested clay had a high content of kaolinite, but also impurities, such as: quartz, iron oxides, and titanium oxides. These impurities have an influence on the surface charge of the kaolin particles and therefore on their properties. The clay with a heat treatment exhibited a thermal behavior characteristic of this type of clays. The particle size range was between 0.5 and 100 μm with an average particle size about 15 μm. The voltammetry study revealed that a reduction processes occur in a range of 0.07 to − 1.2 V (E vs. SCE) and, when a cell potential of 3.3 V for 24 h was imposed, there was a decrease of about 43% in the amount of iron oxides present in the ore. This reduction was of particular significance for the cleaning process.

How does a profit-maximizing manager form teams and compensate workers in the presence of both adverse selection and moral hazard? Under complete information, it is well known that any complementarity in characteristics implies that positive assortative matching is productively efficient. But, under asymmetric information, we uncover the problem of disassortative incentives: incentive costs may increase in assortativity. Profit maximization thus prescribes either random or negative assortative matching, both productively inefficient, when complementarities are weak and effort costs are high enough. When this is the case, the manager may instead prefer to delegate matching, allowing workers to sort themselves into teams. Our results shed light on recent empirical work documenting patterns of non-assortative matching inside of firms.

A series of Ph-m-SPEEKK/polysiloxanes organic-inorganic hybrid proton exchange membranes (HMs) were prepared. The Ph-m-SPEEKK was synthesized from 2-phenylhydroquinone and 1,3-bis(4-fluorobenzoyl)benzene, and sulphonated in a controlled way until a 1.60 meq g−1 ion exchange capacity was reached. The crosslinked polysiloxane phase (PSP) was prepared by the sol-gel route from PDMS as the linear fraction and phenyltrimethoxysilane (PTMS) as crosslinker, the non-crosslinked PSP contained only PDMS. The crosslinked PSP was characterized by FTIR and solid state 29Si NMR, which revealed that the PTMS is fully crosslinked in the PSP structure. SEM micrographs of the HMs showed no apparent macro phase separation of the organic-inorganic components. The macroscopic properties of the HMs investigated were water uptake, swelling, methanol permeability and proton conductivity. The methanol permeability of the crosslinked HMs decreased to a limiting value between 16.3 and 17.9 × 10−7 cm2 s−1 at 60 °C. A continuous increase of the proton ion conductivity (64.1–90.0 mS cm−1 at 80 °C and 95% RH) was achieved with the addition of increasing amounts of the crosslinked PSP content as compared with the non-crosslinked HM. The HM with a 20 wt% of PSP presented a proton conductivity of 90.0 mS cm−1 and an activation energy for proton transport of 17.2 kJ mol−1, both comparable to Nafion 117 and in a single DMFC test the electrode assembly fabricated with this HM reached a maximum power density of 38.0 and 30.5 mW cm−2 for 2 and 5 M methanol concentrations, respectively, higher than Nafion 117 and the pristine Ph-m-SPEEKK membranes.