Volume 66, Issue 4

Batch experiments aimed at the sorption of Pb(II) onto peat were performed from an aqueous solution in both the absence and presence of common complexing agents (acetate or citrate). The influence of the initial pH of the solution, metal ion concentration and contact time on the sorption efficiency of Pb(II) was examined at ambient temperature (18 ± 0.5) °C for each experiment. The results showed that the presence of acetate improved the efficiency of the sorption process, while the presence of citrate in the aqueous solution decreased the efficiency of the Pb(II) sorption onto peat. The equilibrium data fitted well with the Langmuir isotherm model and confirmed the monolayer sorption of uncomplexed and complexed Pb(II) species onto peat. The values of maximum sorption capacities (q max) were 135.13 mg g−1 for Pb(II) complexed with acetate, q > 79.36 mg g−1 for uncomplexed Pb, q > 38.46 mg g−1 for Pb(II) complexed with citrate. The kinetics of Pb(II) sorption onto peat, in both the absence and presence of complexing agents, indicated a pseudosecond order mechanism. Analysis of IR spectra showed that carboxylic and hydroxyl groups had an important role in the binding process of Pb(II) species onto peat.

Preliminary results of research focused on the utilisation of specific waste from metallurgical and mining activities to obtain ferrite pigments are presented. As a source of iron in the spinel-type ferrites with the general structure MFe2O4 (where M is a bivalent metal such as Ca and Zn), three types of industrial wastes were used: metallurgical slag from the production of non-ferrous metals and two types of AMD (acid mine drainage) sludge: one of natural origin (Fe-sediment) and the second one synthetically prepared from AMD (Fe-precipitate). This waste was homogenised by ZnO and CaCO3 in various stoichiometric ratios n(Ca): n(Zn): n(Fe) and calcined at the temperature of 1000–1095°C. Mineralogical (XRD) analysis of the metallurgical slag pigments confirmed the formation of zinc ferrite and hematite only (Ca from reaction components entered into other phases). The ferric component of the AMD sludge (Fe-precipitate and Fe-sediment) formed a mixture of zinc ferrite, calcium ferrite, and hematite while increased calcination temperature supported the ferritic structure formation. Prepared pigments have no considerable colour differences; they were in brown colour tones. Pigments from the AMD sludge were more dark brown coloured than those from slag. Pigments were applied in an alkyd-resin paint and consequently basic anticorrosive tests were performed. Pigments obtained from metallurgical slag showed better anticorrosive properties than those from AMD. However, because of high Pb content in pigments from the slag (0.67–1.10 mass % Pb in pigments), utilisation of these pigments in coatings is problematic. Ferrite pigments from the AMD sludge, mainly that with zinc ferrite, have promising application in anticorrosive paints but optimisation of the preparation process is required.

Phenolic acids and derivatives of quercetin in Indian (amla) and European gooseberry were determined by high-performance liquid chromatography with diode array detector. The calibration curves were constructed using phenolic compounds standards (the coefficient of determination (R 2) was 0.9990–0.9997 for phenolic acids and 0.9989–0.9994 for flavonols, respectively). The lowest detection limit was 0.28 mg L−1 and 0.35 mg L−1 for hyperoside and gallic acid, respectively, whereas the highest was 1.80 mg L−1 and 7.98 mg L−1 for quercetin and chlorogenic acid, respectively. The quantification limits calculated were 0.85–24.04 mg L−1 for hyperoside and chlorogenic acid, respectively. The predominant phenolic acid in amla and gooseberry is gallic acid: (5.37 ± 0.04) mg per 100 g of dry mass (d.m.) and (3.21 ± 0.03) mg per 100 g of d.m., respectively. The next one was caffeic acid, 0.65–1.22 mg per 100 g of d.m., followed by p-coumaric acid, 0.84–1.17 mg per 100 g of d.m. Out of the flavonols, rutin is predominant: (3.11 ± 0.13) mg per 100 g of d.m. and (2.12 ± 0.03) mg per 100 g of d.m., respectively. Anti-oxidant activity was also determined.

Mesoporous organosilica-porphyrin composites were obtained by entrapment of 5,10,15,20-tetraphenylporphyrin (TPP) and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP) into three polysilsesquioxanes prepared by the sol-gel method from 1,2-bis(triethoxysilyl)ethane, 1,6-bis(triethoxysilyl)hexane, and 1,8-bis(triethoxysilyl)octane. The materials were characterised by their texture and optical properties (fluorescence and absorbance) and by light-induced antimicrobial activity against E. coli BL21(DE3) (pET16bDsRed) strain.

In this paper, we report on the preparation of momordica-like CuO nanostructures by the hydrothermal method using freshly extracted egg white protein (ovalbumin) in an aqueous medium. These momordica-like CuO nanostructures were characterised by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). XRD patterns showed that these nanostructures had a polycrystalline nature with a monoclinic structure. FE-SEM images indicated that the momordica-like CuO nanostructures obtained at 180°C for 15 h were composed of CuO nanorods with a length of less than 100 nm and a width ranging from 30 nm to 50 nm. Finally, a possible growth mechanism for the momordica-like CuO nanostructures is proposed and discussed.

Since many estrane and androstane derivatives exhibit cytotoxic, anti-oxidant, or anti-hormone activity, new steroidal derivatives were synthesised from appropriate estrogen or androgen precursors in order to obtain potential therapeutics for the treatment of steroid-dependent diseases. Starting from estradiol (I), 6-oxo derivatives V and VII were prepared. 17β-Salicyloyl-6-oxo derivatives VI and VIII were synthesised by the reaction of compounds V or VII with methyl salicylate in the presence of sodium. 17β-Salicyloyloxy estradiol IX was prepared from estradiol. Beckmann fragmentation of 16-oxyimino alcohols XII and XIII with methyl salicylate yielded corresponding D-seco derivatives XIV and XV. Simultaneous fragmentation and acylation of compound XII resulted in 3β-salicyloyl-D-seco derivative XVI which was also obtained from compound XIV. Anti-oxidant assays of the newly synthesised compounds V-IX, XIV, and XVI indicated a stronger capacity for hydroxyl radical scavenging, and a weaker capacity for DPPH radical scavenging, compared with the standard anti-oxidants BHA and BHT. Compounds V, XIV, and XVI showed higher or the same activity as BHT. The cytotoxicity of new compounds was evaluated against human breast and prostate carcinoma cells. Compound VI exhibited strong cytotoxicity against MDA-MB-231 cells; compound XIV exhibited strong cytotoxicity against PC-3 cell line, while compound VII moderately inhibited the growth of PC-3 cells.

The reaction of (substituted) alkenylidene-hydrazinecarbothioamides with 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile led to the formation of 1,3-dioxospiroindene[1,3]-thiazine and thioxoindeno[2,1-d]imidazolone derivatives in modest yields. In addition, 1,3-dihydroxyindan-2-ylidenepropanedinitrile was found. Explanations of these conversions involving nucleophilic reactions and condensations are presented.

A simple method for N-alkylation of 1,2-diaminoethane with different alcohols in a fixed-bed reactor using cheap CuO-NiO/γ-Al2O3 as the catalyst has been developed. The present catalytic system was applicable in the N-alkylation of 1,2-diaminoethane with both primary and secondary alcohols. Mono-N-alkylation of 1,2-diaminoethane with low-carbon alcohols resulted in high yields; the yields of tetra-N-alkylation of 1,2-diaminoethane with low-carbon alcohols declined markedly with the increase of the molecular volume of alcohols.

A highly stereoselective synthesis of E-isomer of aldoximes was developed through a base-catalysed domino aza-Michael/retro-Michael reaction of hydroxylamine and 2-(R-benzylidene)malononitrile. This reaction generates (E)-aldoxime diastereomer in high yields (eight examples, isolated yields of 82-93 %), excellent diastereomeric purity (diastereomeric ratio higher than 95: 5 by 1H NMR), and proceeds under mild reaction conditions (aqueous NaOH, pH 12, room temperature, 4 h).

An alternative method has been developed for the anomeric deacetylation of fully acetylated carbohydrate derivatives using zinc acetate dihydrate as a catalyst in methanol under mild conditions. The experimental simplicity, low cost, acceptable yield, use of a readily handled acidic catalyst, and the environmentally benign nature are some of the advantages of this method.

Solubility of methane in octane + ethanol was measured at temperatures ranging from 303.15 K to 333.15 K and pressures ranging from 2.60 MPa to 12.01 MPa. Experimental data were analyzed using the Soave-Redlich-Kwong equation of state with three types of mixing rules, and the estimated average deviation from the experimental solubility data was less than 3.5 %.