Application of Functionalized DVB-co-GMA Polymeric Microspheres in the Enhanced Sorption Process of Hazardous Dyes from Dyeing Baths

Intensive development of many industries, including textile, paper, plastic or food, generate huge amounts of wastewaters containing not only toxic dyes but also harmful auxiliaries such as salts, acid, bases, surfactants, oxidants, heavy metal ions. The search for effective pollutant adsorbents is a huge challenge for scientists. Synthesis of divinylbenzene copolymer with glycidyl methacrylate functionalized with triethylenetetramine (DVB-co-GMA-TETA) resin was performed and the obtained microspheres were evaluated as a potential adsorbent for acid dye removal from dyeing effluents. The sorption capacities were equal to 142.4 mg/g for C.I. Acid Green 16 (AG16), 172 mg/g for C.I. Acid Violet 1 (AV1) and 216.3 mg/g for C.I. Acid Red 18 (AR18). Non-linear fitting of the Freundlich isotherm to experimental data was confirmed rather than the Langmuir, Temkin and Dubinin-Radushkevich. The kinetic studies revealed that intraparticle diffusion is the rate-limiting step during dye adsorption. Auxiliaries such as Na₂SO₄ (5–25 g/L), CH₃COOH (0.25–1.5 g/L) and anionic surfactant (0.1–0.5 g/L) present in the dyeing baths enhance the dye adsorption by the resin in most cases. Regeneration of DVB-co-GMA-TETA is possible using 1 M NaCl-50% v/v CH₃OH.     

Flammability Tests and Investigations of Properties of Lignin-Containing Polymer Composites Based on Acrylates

In this paper flammability tests and detailed investigations of lignin-containing polymer composites’ properties are presented. Composites were obtained using bisphenol A glycerolate (1 glycerol/phenol) diacrylate (BPA.GDA), ethylene glycol dimethacrylate (EGDMA), and kraft lignin (lignin alkali, L) during UV curing. In order to evaluate the influence of lignin modification and the addition of flame retardant compounds on the thermal resistance of the obtained biocomposites, flammability tests have been conducted. After the modification with phosphoric acid (V) lignin, as well as diethyl vinylphosphonate, were used as flame retardant additives. The changes in the chemical structures (ATR-FTIR), as well as the influence of the different additives on the hardness, thermal (TG) and mechanical properties were discussed in detail. The samples after the flammability test were also studied to assess their thermal destruction.     

New photoluminescent copolymers of naphthalene-2,7-diol dimethacrylate and N-vinyl-2-pyrrolidone

Syntheses of the new photoluminescent copolymers: 2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene with N-vinyl-2-pyrrolidone (NVP) are presented. The obtained compound was copolymerised with different ratios of active diluent (NVP). Thermo- and photo-polymerisations of the compositions with use of the initiators: α,α′-azoiso-bis-butyronitrile and 2,2-dimethoxy-2-phenyl-acetophenone were carried out. The following properties were determined: density, polymerisation shrinkage, glass transition temperature, Young’s modulus, hardness and tensile strength. Moreover, the dynamic-mechanical, thermal and photoluminescent properties were studied. These materials may have potential use as luminophores and coatings filtering harmful UV radiation.     

Electrocatalytic properties of platinum nanocenters electrogenerated at ultra-trace levels within zeolitic phosphododecatungstate cesium salt matrices

A unique preparation method of obtaining stable composite film (with ultra-low platinum content) highly active towards oxygen reduction and hydrogen oxidation is presented here. The matrix for platinum centers consists of high-surface-area zeolite-type acidic salt of cesium phosphododecatungstate (Cs_2.5H_0.5PW₁₂O₄₀) admixed with carbon (Vulcan XC-72) carriers. Platinum nanoparticles were deposited on the working electrode modified with matrix via corrosion of platinum counter electrode during cyclic voltammetry experiment conducted in acid electrolyte containing chloride ions. The results obtained from rotating disk voltammetry revealed that the composite film containing Pt nanoparticles at very low loadings (on the level of 2–5 μg cm^?2) demonstrated remarkable electrocatalytic activity towards both oxygen reduction and hydrogen oxidation, particularly, when compared to the performance of the Cs_2.5H_0.5PW₁₂O₄₀-free system (i.e., containing only Vulcan support) prepared and examined under analogous conditions. The phenomenon should be primarily ascribed to the mesoporous nature of the matrix enabling immobilization and stabilization of small catalytic nanoparticles (1–2 nm diameters) inside the pores as well as to high surface acidity of the polyoxometalate-based salt providing proton-rich environment at the electrocatalytic interface.     

Inverse gas chromatography as a source of physiochemical data

Inverse gas chromatography (IGC) is presented as a useful method for the examination of physicochemical properties of various materials. The advantages of IGC are presented. However, the uncertainties and sources of possible errors are also indicated and discussed.     

In vitro evaluation of the antioxidant and antimicrobial activity of DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one]

The aim of this study was to evaluate the in vitro antioxidant and antimicrobial properties of the natural cyclic hydroxamic acid: 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA). Antioxidant activity of the isolated DIMBOA was examined using DPPH, FRAP and ABTS tests. It was found that DIMBOA exhibits a potent free-radical scavenging activity and a weaker iron (III) ions reducing activity. Antimicrobial activity against selected G(+), G(–) bacterial strains and against yeasts-like reference strains of fungi was investigated using disk-diffusion method. It has been shown that DIMBOA possess growth inhibitory properties against many strains of studied bacteria and fungi, such as Staphylococcus aureus, Escherichia coli as well as against Saccharomyces cerevisiae.     

Protolytic dissociation of cyanoanilines in the ground and excited state in water and methanol solutions

The effect of cyano substituents on the photoacidity of mono- and dicyanoanilines has been investigated. It was demonstrated that the cyano substitution increases significantly the acidity of aniline derivatives in the excited state in comparison to the ground state. 3,5-Dicyanoaniline is the strongest acid in the lowest excited singlet state, while 4-cyanoaniline is the weakest one. The derivatives of aniline with two cyano groups in o,o'-position show different properties from those characteristic for aniline and other investigated cyanoanilines. In the methanol solution with sodium methanolate the anions of 2,6-dicyano-3,5-dimethylaniline and 2,6-dicyano-3,5-diphenylaniline appear already in the ground state. The electronic ground and excited state charge distributions and dipole moments of all investigated cyanoanilines have been evaluated by ab initio calculations using the GAMESS program.     

Coordination behaviour and two‐dimensional‐network formation in poly[[μ‐aqua‐diaqua(μ5‐propane‐1,3‐diyldinitrilotetraacetato)dilithium(I)cobalt(II)] dihydrate]: the first example of an MII–1,3‐pdta complex with a monovalent metal counter‐ion

The title compound, {[CoLi₂(C₁₁H₁₄N₂O₈)(H₂O)₃]·2H₂O}_n, constitutes the first example of a salt of the [M^II(1,3‐pdta)]²⁻ complex (1,3‐pdta is propane‐1,3‐diyldinitrilotetraacetate) with a monopositive cation as counter‐ion. Insertion of the Li⁺ cation could only be achieved through application of the ion‐exchange column technique which, however, appeared unsuccessful with other alkali metals and the ammonium cation. The structure contains two tetrahedrally coordinated Li⁺ cations, an octahedral [Co(1,3‐pdta)]²⁻ anion and five water molecules, two of which are uncoordinated, and is built of two‐dimensional layers extending parallel to the (010) lattice plane, the constituents of which are connected by the coordinate bonds. O—H_water...O hydrogen bonds operate both within and between these layers. The crystal investigated belongs to the enantiomeric space group P2₁ with only one (Λ) of two possible optical isomers of the [Co(1,3‐pdta)]²⁻ complex. A possible cause of enantiomer separation during crystallization might be the rigidification and polarization of the [M(1,3‐pdta)]²⁻ core, resulting from direct coordination of Li⁺ cations to three out of four carboxylate groups constituting the 1,3‐pdta ligand. The structure of (I) differs considerably from those of the other [M^II(1,3‐pdta)]²⁻ complexes, in which the charge compensation is realized by means of divalent hexaaqua complex cations. This finding demonstrates a significant structure‐determining role of the counter‐ions.     

Complexation of metal ions in Langmuir films formed with two amphiphilic dioxadithia crown ethers

The two new crown ethers presented in this study were synthesized in order to investigate two important features of ionophores, namely metal cation complexation and interfacial properties, and the way in which they interrelate. The two derivatives were conceived as analogs of membrane phospholipids with respect to their amphiphilicity and geometry. They contain a hydrophilic 1,1'-dioxo-3,3'-dithio-14-crown ether headgroup and bear two myristoyl or stearoyl lateral chains. The length of the myristoyl and stearoyl derivatives in an extended conformation is comparable with the thickness of the individual leaflets of cell membranes. The membrane-related and complexation properties of the two crown ether derivatives were studied in monomolecular films spread on pure water and on aqueous solutions of mono-, di-, and trivalent metal salts. The properties of the monolayers are described quantitatively using thermodynamic models. The compression isotherms of the monolayers formed on different subphases show a clear-cut differentiation of the monovalent and di- or trivalent cations with both ligands. This differentiation was interpreted in terms of conformational changes occurring in the crown ether derivatives upon complexation. Molecular modeling indicates that the mono- and divalent cations are coordinated differently by the ligands, yielding complexes with different conformations. The differences of the conformations of the mono- and di- or trivalent cation complexes may be important from the point of view of the interactions with lipid membranes and the biological activity of these potential ionophores.     

A Novel Method of High Sensitive Determination of Prednisolone on Renewable Mercury Film Silver Based Electrode

Fast and sensitive method of prednisolone determination at renewable mercury film electrode using differential pulse adsorptive stripping voltammetry (DPAdSV) was successfully developed. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition were optimized. A linear voltammetric response for analyte was obtained in the concentration range from 0.05 µmol L⁻¹ (18 µg L⁻¹) to 2.25 µmol L⁻¹ (0.81 mg L⁻¹), with a detection limit of 0.01 µmol L⁻¹ for preconcentration time of 20 s. Repeatability of method was determined as RSD % for prednisolone concentration of 0.04 µmol L⁻¹ as 1.6 % (n=9). The proposed method was successfully applied and validated by recovery parameter of prednisolone in simulated sample and pharmaceutical product.