We explore the optical birefringence of the nematic binary mixtures 6CB1−x7CBx (0 ≤ x ≤ 1) imbibed into parallel-aligned nanochannels of mesoporous alumina and silica membranes for channel radii of 3.4 ≤ R ≤ 21.0 nm. The results are compared with the bulk behavior and analyzed with a Landau-de-Gennes model. Depending on the channel radius the nematic ordering in the cylindrical nanochannels evolves either discontinuously (subcritical regime, nematic ordering field σ < 1/2) or continuously (overcritical regime, σ > 1/2), but in both cases with a characteristic paranematic precursor behavior. The strength of the ordering field, imposed by the channel walls, and the magnitude of quenched disorder varies linearly with the mole fraction x and scales inversely proportional with R for channel radii larger than 4 nm. The critical pore radius, Rc, separating a continuous from a discontinuous paranematic-to-nematic evolution, varies linearly with x and differs negligibly between the silica and alumina membranes. We find no hints of preferred adsorption of one species at the channels walls. By contrast, a linear variation of the nematic-to-paranematic transition point TPN and of the nematic ordering field σ vs. x suggest that the binary mixtures of cyanobiphenyls 6CB and 7CB keep their homogeneous bulk stoichiometry also in nanoconfinement, at least for channel diameters larger than ∼7 nm.

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Waste incineration is one of the paths of implementation of the European Union’s strategy aimed at reducing the amount of waste deposited in landfills. Along with the development of methods for processing and recycling various wastes, new waste is generated. One example is waste from polyethylene terephthalate (PET) bottles washed during their recycling. In this paper, physical and chemical properties of such wastes are analyzed in terms of their use in the power industry. This research is part of the search for new sources and new technologies for energy production. The study has taken into account the energy properties of waste intended for combustion (calorific value, water content, chemical composition, volatile substances, combustible and non-flammable content). Thermogravimetric analysis of the material tested indicated that the waste is a good source of energy. It was found that the elemental composition (C, H, N, S, O) of the waste investigated is similar to that for biomass materials, and the calorific value of 13.2 MJ/kg qualifies the waste for combustion, provided that its initial moisture is reduced, for example, for co-combustion in the cement industry. Another possibility is mixing the waste with other kinds of waste to obtain a new fuel with more satisfactory parameters.

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Lignite mining results in a significant amount of waste clayey materials—the so-called Pliocene clays, which are often considered useless mineral waste. One method of management is to use them as inexpensive adsorbents in water and wastewater treatment, or as permeable barriers in groundwater remediation. The study is an attempt to use the raw Pliocene clays to remove Pb(II), Ni(II), and Zn(II) ions from wastewaters. The mineralogical composition, physicochemical, granulometric, structural, and surface properties were examined. The value of the point of zero charge pH of the adsorbent was found to be 7.1. To determine the optimal adsorption conditions, the central composite design (CCD) method was used with the pH of the solution, metal ion concentration, and the adsorbent mass as independent variables, and the percentage removal as the response variable. The determined optimal values of the adsorbent mass and the solution pH turned out to be similar for all three metals, with a pH of 6–7 and an adsorbent dose of 18–24 g/dm3. In further tests, the pH was established slightly lower than it would appear from the CCD method in order to avoid the possible precipitation of metals in the form of hydroxides. The kinetics of sorption were investigated and it was found that the sorption process ran for several minutes. The effect of temperature showed that the adsorption was spontaneous and thermodynamically favored. The leachability of the metals indicated that Pb(II) and Zn(II) were strongly bound in the adsorbent, whereas Ni(II) manifested a larger mobility. It was found that the tested clays had quite good sorption properties in relation to the tested metal ions and could be used for water and wastewater treatment.

The structural and surface properties of natural and modified Pliocene clays from lignite mining are investigated in the paper. Chemical modifications are made using hydrofluoric acid (HF), sulfuric acid (H2SO4), hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), and hydrogen peroxide (H2O2), at a concentration of 1 mol/dm3. Scanning electron microscopy is used to detect the morphology of the samples. Nitrogen adsorption isotherms were recorded to determine the specific surface area (SSA), mesoporosity, microporosity, and fractal dimensions. The raw clay has an SSA of 66 m2/g. The most promising changes in the structural properties are caused by modifications with HF or H2SO4 (e.g., the SSA increased by about 60%). In addition, the raw and modified clays are used in preliminary tests with Cu(II) sorption, which were performed in batch static method at initial Cu(II) concentrations of 25, 50, 80, 100, 200, 300, and 500 mg/dm3 in 1% aqueous suspensions of the clayey material. The maximum sorption of Cu(II) on the raw material was 15 mg/g. The structural changes after the modifications roughly reflect the capabilities of the adsorbents for Cu(II) adsorption. The modifications with HF and H2SO4 bring a similar improvement in Cu(II) adsorption, which is around 20–25% greater than for the raw material. The structural properties of investigated clays and their adsorptive capabilities indicate they could be used as low-cost adsorbents (e.g., for industrial water pretreatment).