Dušan G. Antonović

Characterization of chitosan/montmorillonite membranes as adsorbents for Bezactiv Orange V-3R dye

The synthesis, characterization and environmental application of chitosan/montmorillonite membrane for adsorption Bezactiv Orange V-3R were investigated. Chitosan/montmorillonite membranes were synthesized in different ratios, containing 10-50% of montmorillonite (MMT) in membrane. These membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM). The adsorption kinetics were investigated using three different concentrations of Bezactiv Orange dye (30, 50 and 80 mg/L). The adsorption capacity increases with increasing amount of MMT in membranes. These membranes show the highest adsorption capacity when the initial dye concentration was 80 mg/L. The results show that the optimum condition for adsorption of Bezactiv Orange is pH 6. A comparison of kinetic models was evaluated for the pseudo-first and pseudo-second order and intra-particle diffusion. The experimental data were fitted to the pseudo-second order kinetic model, and also followed by intra-particle diffusion. Intra-particle diffusion is not the only rate-controlling step. The Langmuir and Freundlich adsorption isotherms were applied to experimental equilibrium data at different concentration of dye solution. The results indicated the competency of chitosan/MMT membranes adsorbent for Bezactiv Orange adsorption.

Comparative study of differently treated animal bones for Co2+ removal

The objective of the present study was the evaluation of differently treated bovine bones for Co(2+) removal from aqueous media. Powdered bones (B), as well as samples prepared by H(2)O(2) oxidation (BH(2)O(2)) and annealing at 400-1000 degrees C (B400-B1000), were tested as sorbent materials. A combination of XRD, FTIR spectroscopies, DTA/TGA analyses, specific surface area (S(p)) and point of zero charge (pH(PZC)) measurements was utilized for physicochemical characterization of sorbents. Sorption of Co(2+) was studied in batch conditions as a function of pH, contact time and Co(2+) concentration. Initial pH values in the range 4-8 were found optimal for sorption experiments. Equilibrium time of 24h was required in all investigated systems. The maximum sorption capacities differ significantly from 0.078 to 0.495mmol/g, whereas the affinity towards Co(2+) decreased in the order: B400>BH(2)O(2)>B600>B>B800>B1000. The pseudo-second-order model and Langmuir theoretical equation were used for fitting the kinetic and equilibrium data, respectively. Ion-exchange with Ca(2+) and specific cation sorption were identified as main removal mechanisms. The amounts of Co(2+) desorbed from loaded bone sorbents increased with the decrease of pH as well as with the increase of Ca(2+) concentration. Heating at 400 degrees C was found to be an optimal treatment for the production of the Co(2+) removal agent.

Distribution of Heavy Metals and Arsenic in Soils of Belgrade (Serbia and Montenegro) 1

Soils of the urban and suburban area of Belgrade have been hardly studied, especially concerning their concentrations of potentially toxic metals. The present paper is aimed at determining the possible pollution in soils. The total acid soluble concentrations of heavy metals and As in the samples were determined. It was found that they were arranged in the order Zn > Ni > Pb > Cr > Cu > As > Hg > Cd in samples collected in the examined area (the order of the elements is based on their arithmetic mean concentrations). In all the samples collected at 0–10 and 40–50 cm depths from 46 selected sites, the contents of Pb and Zn were lower at the depth 40-50 cm. Using target values given by the Dutch Ministry of Housing, Spatial Planning and Environment, it may be concluded that Belgrade soil can, for the most part, be regarded as unpolluted. Traffic seems to be one of the main sources of these metals, but the influence of other factors cannot be excluded. 1Serbia and Montenegro was the name of the country at the time this paper was accepted; the name was changed to Serbia as of May 21, 2006.

Hydrogen bonding of N-monosubstituted amides. IR study of N-butylacetamides

Abstract The self-association through hydrogen bonding of four isomeric N-butylacetamides has been studied by infrared spectroscopy in carbon tetrachloride, chloroform and benzene. The spectroscopic and thermodynamic parameters for the self-association have been determined. It was found that self-association decreases in the order: N-n-butylacetamide〉N-isobutylacetamide〉N-sec-butylacetamide〉N-tert-butylacetamide. The equilibrium constants and enthalpies of self-association for chloroform and benzene solutions are significantly smaller than in carbon tetrachloride.

Kinetic Study of Sr2+ Sorption by Bone Char

Abstract The effect of particle size, bone char mass, initial pH, and metal concentration on the kinetics of Sr2+ sorption by bone char was studied and discussed. Considering the sorbed amounts of Sr2+, solution pH changes, changes of Ca2+ concentrations and Ca/Sr molar ratios, with time, it was concluded that surface complexation reactions are dominant in the first, more rapid stage of the sorption process, while the contribution of the ion-exchange mechanism increases with time and becomes more significant in the second, slower phase. Under all investigated experimental conditions, the pseudo-second-order model was found to provide high correlation coefficients and the equilibrium amounts of Sr2+ sorbed comparable to the values obtained experimentally.

NH…π hydrogen bonding: FTIR study of N-butylpropionamides-aromatic donor systems

Abstract The present paper reports the results of a FT infrared study in the region of the fundamental NH stretching vibration for N-n-butyl, N-iso-butyl, N-sec-butyl and N-tert-butylpropionamide-aromatic donor systems. The spectroscopic and thermodynamic characteristics for 1:1 amide-aromatic donor complexes are given.

Novel composite films based on amidated pectin for cationic dye adsorption.

Pectin, with its tendency to gel in the presence of metal ions has become a widely used material for capturing the metal ions from wastewaters. Its dye-capturing properties have been much less investigated, and this paper is the first to show how films based on amidated pectin can be used for cationic dye adsorption. In the present study amidated pectin/montmorillonite composite films were synthesized by membrane casting, and they are stable in aqueous solution both below and above pectin pKa. FTIR, thermogravimetry and SEM-EDAX have confirmed the presence of montmorillonite in the cast films and the interactions between the two constituents. In order to evaluate the cationic dye adsorption of these films Basic Yellow 28 was used, showing that the films have higher adsorption capacity compared to the others reported in the literature. The results were fitted into Langmuir, Freundlich and Temkin isotherms indicating an exothermic process and setting the optimum amount of montmorillonite in the films to 30% of pectin mass. According to the Langmuir isotherm the maximum adsorption capacity is 571.4 mg/g.

Complexation of amidated pectin with poly(itaconic acid) as a polycarboxylic polymer model compound

Complexes based on amidated pectin (AP) and poly(itaconic acid) (PIA) were prepared by casting films from solutions of AP and PIA in different ratios with the pectin amount ranging from 10% to 90% by mass. The complexes were investigated by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG). In all investigated ratios of AP/PIA glassy transparent films with a uniform structure were obtained. The results of elemental analysis confirmed the composition of the complexes, and FTIR spectroscopy has shown carboxylic and amide peak shifting, indicating complex formation between AP and PIA. Comparison of thermograms of AP/PIA films with different ratios of AP indicated that the increase of the amount of AP increases the thermal stability of the films by retarding the onset of the main degradation processes.

Synthesis and FTIR spectroscopic study of some N-monosubstituted propanamides

Abstract In the present work we investigated the conformations of some N -mono-substituted propanamides of general formula CH 3 CH 2 CONHR, wherein R is chosen from n -(C 1 C 9 )alkyl, cyclo(C 3 C 6 )alkyl, some branched (C 3 C 6 )alkyl or phenyl. The amides were synthesised by the well known Schotten-Baumann reaction—acylation of the corresponding amines with propionyl chloride. On the basis of FTIR data for diluted solutions (concentrations below 10 −3 mol dm −3 ) of N -mono-substituted propanamides in carbon tetrachloride, chloroform, dichloromethane, or a 1:1.5 mixture of benzene and carbon tetrachloride the exact position of the N-H stretching band was established. For spectroscopic data the different conformational isomers were assigned and its structures unequivocally proven. These results are in good accordance with 1 H NMR and MS data.

Synthesis and spectroscopic study of some new rigid N-bicyclo substituted 2-phenylacetamides

Abstract In a continuation of our previous works the conformations of some new rigid N-bicyclo substituted 2-phenylacetamides, PhCH 2 CONHR, were investigated by vibrational, 1 H n.m.r. and mass spectra. N-monosubstituted 2-phenylacetamides were obtained by using the known Schotten-Baumann reaction of acylation of amines with phenylacetyl chloride. From spectroscopic data, the different conformational isomers were assigned and its structure undoubtly proven. On the other hand it can be concluded that the bulkiest substituent on the nitrogen atom have led only to the trans form.