Electrodialytic removal of H2SO4 from its aqueous mixture with Na2SO4

The experimental results of the separation of sulfuric acid from sodium sulfate by the membrane electrolysis method have been presented. The anion-exchange membrane Neosepta ACM has been used. It has been found that the current efficiency of H2SO4 removal is similar for pure acid solution and for the mixture H2SO4-Na2SO4 if the initial acid concentrations are the same. For the same current density effectiveness of H2SO4 removal is higher for lower initial acid concentration (63% for 0.5 M and 56% for 1 M (j = 100 mA/cm2)

Applicability of molecular simulations for modelling the adsorption of the greenhouse gas CF4 on carbons

Tetrafluoromethane, CF4, is powerful greenhouse gas, and the possibility of storing it in microporous carbon has been widely studied. In this paper we show, for the first time, that the results of molecular simulations can be very helpful in the study of CF4 adsorption. Moreover, experimental data fit to the results collected from simulations. We explain the meaning of the empirical parameters of the supercritical Dubinin–Astakhov model proposed by Ozawa and finally the meaning of the parameter k of the empirical relation proposed by Amankwah and Schwarz

Highly Efficient Hydrophobic Titania Ceramic Membranes for Water Desalination

International audienc

Sorption and magnetic properties of oxalato-basedt trimetallic open framework stabilized by charge-assisted hydrogen bonds

We report a new structure of {[Co(bpy)(2)(ox)][{Cu(2)(bpy)(2)(ox)}Fe(ox)(3)]}(n)·8.5nH(2)O NCU-1 presenting a rare ladder topology among oxalate-based coordination polymers with anionic chains composed of alternately arranged [Cu(2)(bpy)(2)(ox)](2+) and [Fe(ox)(3)](3−) moieties. Along the a axis, they are separated by Co(III) units to give porous material with voids of 963.7 Å(3) (16.9% of cell volume). The stability of this structure is assured by a network of stacking interactions and charge-assisted C-H…O hydrogen bonds formed between adjacent chains, adjacent cobalt(III) units, and alternately arranged cobalt(III) and chain motifs. The soaking experiment with acetonitrile and bromobenzene showed that water molecules (8.5 water molecules dispersed over 15 positions) are bonded tightly, despite partial occupancy. Water adsorption experiments are described by a D’arcy and Watt model being the sum of Langmuir and Dubinin–Serpinski isotherms. The amount of primary adsorption sites calculated from this model is equal 8.2 mol H(2)O/mol, being very close to the value obtained from the XRD experiments and indicates that water was adsorbed mainly on the primary sites. The antiferromagnetic properties could be only approximately described with the simple Cu(II)-ox-Cu(II) dimer using H = −J·S(1)·S(2), thus, considering non-trivial topology of the whole Cu-Fe chain, we developed our own general approach, based on the semiclassical model (SC) and molecular field (MF) model, to describe precisely the magnetic superexchange interactions in NCU-1. We established that Cu(II)-Cu(II) coupling dominates over multiple Cu(II)-Fe(III) interactions, with J(CuCu) = −275(29) and J(CuFe) = −3.8(1.6) cm(−1) and discussed the obtained values against the literature data

Cellulose Acetate Membranes Modification by Aminosilane Grafting in Supercritical Carbon Dioxide towards Antibiofilm Properties

The study explores the grafting of cellulose acetate microfiltration membranes with an aminosilane to attain antibiofilm properties. The grafting reaction was performed in the supercritical carbon dioxide used as a transport and reaction medium. The FTIR analyses and dissolution tests confirmed the covalent bonding between the aminosilane and polymer. The membranes’ microstructure was investigated using a dual-beam SEM and ion microscopy, and no adverse effects of the processing were found. The modified membranes showed a more hydrophilic nature and larger water permeate flow rate than the neat cellulose acetate membranes. The tests in a cross-filtration unit showed that modified membranes were considerably less blocked after a week of exposure to Staphylococcus aureus and Escherichia coli than the original ones. Microbiological investigations revealed strong antibiofilm properties of the grafted membranes in experiments with Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella Enteritidis

Highly Efficient Hydrophobic Titania Ceramic Membranes for Water Desalination

Hydrophobic titania ceramic membranes (300 kD) were prepared by grafting of C₆F₁₃C₂H₄Si­(OC₂H₅)₃ and C₁₂F₂₅C₂H₄Si­(OC₂H₅)₃ molecules and thus applied in membrane distillation (MD) process of NaCl solutions. Grafting efficiency and hydrophobicity were evaluated by contact angle measurement, atomic force microscopy, scanning electron microscopy, nitrogen adsorption/desorption, and liquid entry pressure measurement of water. Desalination of NaCl solutions was performed using the modified hydrophobic membranes in air gap MD (AGMD) and direct contact MD (DCMD) processes in various operating conditions. High values of NaCl retention coefficient (>99%) were reached. The permeate fluxes were in the range 231–3692 g·h^–1·m^–2, depending on applied experimental conditions. AGMD mode appeared to be more efficient showing higher fluxes and selectivity in desalination. Overall mass transfer coefficients (K) for membranes tested in AGMD were constant over the investigated temperature range. However, <i>K</i> values in DCMD increased at elevated temperature. The hydrophobic layer was also stable after 4 years of exposure to open air