Currently, proton exchange membrane fuel cells (PEMFC) are the focus of attention in the development of electrochemical devices called fuel cells. These devices, which are capable of transforming chemical energy into electrical energy, have shown high performance in the conversion of energy from fuels such as hydrogen and methanol [1]. The operation of a PEMFC is similar to that of a galvanic cell where the electrons produced travel through an external circuit while the protons are transported through a barrier called a proton exchange membrane (PEM) which, in turn, prevents the passage of electrons and fuel [2]. Today, the most popular materials for PEMs are the perfluorosulphonic materials, among which the most outstanding is Nafion ®. This is because the Nafion exhibits excellent mechanical properties, chemical stability, and high proton conductivity; however, its high cost and low operating temperature for proton transport are factors that influence the search for new proton conductive materials [3,4]. Sulfonation of polymers to produce, for example, sulfonated poly-ether-ether-ketone (SPEEK) seems to be a promising solution for the substitution of perfluorosulphonic materials because it has a proton conduction on the order of 10 −2 S cm −1 (above 80 °C), which is similar to the that of Nafion membranes [5]. However, the degree of sulfonation of

a b s t r a c tProcesses of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-tovolume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800 t of carbon dioxide per year, so the CO 2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476 kg of CO 2 could be captured with 1 t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15 nm wide and 200 nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50 m 2 /g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO 2 emissions.

Flat hybrid membranes composed of polyetherimide (PEI) as matrix and zeolitic imidazolate frameworks (ZIFs) as fillers at concentrations of 10 and 20 wt % were prepared. Apparent permeability coefficient and apparent diffusivity coefficient of gases (CO2 and N2) for these hybrid membranes (PZIFs) were determined by the "time-lag" method. The experimental conditions used were from 25 °C to 55 °C with pressures of 2, 3 and 5 bar. The PZIFs with fillers of ZIF-8 (PZ-Zn) and ZIF-67 (PZ-Co) showed apparent selectivities ( ( 2 ) ( 2 ) ⁄ ) of 39.6 and 27.5, respectively, higher than the( 2 ) ⁄ of the reference membrane PEI, while the membrane with filler of ZIF-Mix (PZ-Zn/Co) showed the lowest( 2 ) ⁄ selectivity of 10.3 in the membrane series (under conditions of 25 °C and 2 bar). It is proposed that the selectivity of the membrane series can be attributed to two critical factors: the particle size/distribution ratio in the polymer base and sorption of CO2 at local sites of the bimetallic mixture.On the other hand, gas permeation studies (O2, CO2 and CH4, and CO2/CH4 and CO2/C2H4 mixtures), were carried out in the series of PZIFs membranes. Permeability data were obtained by an isostatic method based on a permeation cell connected in series to a gas chromatograph where the rate of permeated gases was analyzed until a stationary state was reached. The complementary characterization techniques were: scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction, which support the existence of the amorphous/crystalline phases of the PZIFs.

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