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Chemically modified Lagenaria vulgaris shell (ccLVB) was tested as a new sorbent for the removal of Ni(II) from aqueous solution, in batch conditions. The sorption process was very fast reaching equilibrium in about 20 min. Ni(II) sorption is almost invariant in the pH range from 3 to 6. Sorption kinetics followed pseudo-second order, intraparticle diffusion and Chrastil’s models, which suggest that both surface reaction and diffusion were the rate-limiting steps. Equilibria experimental results are well fitted by Langmuir and Temkin sorption isotherm models, indicating mixed adsorption process. The maximum biosorption capacity of ccLVB for Ni(II) was found to be 84.51 mg g-1. The calculated thermodynamic parameters showed that the biosorption of nickel on ccLVB was feasible, spontaneous and exothermic at 25-45ºC. The desorption experiments showed that the ccLVB could be reused for five cycles without significant loss in sorption capacity. Release of Na+ ions from the biosorbent during sorption of Ni(II) reveals that the main sorption mechanism is ion exchange. Presented study suggests that ccLVB can be used effectively for the removal of Ni(II) ions from aqueous solution.

The effectivness of UV/H2O2 process, Fenton and photo-Fenton process at decolorization of commercially important textile dyes Reactive Orange 4 (RO4) and Reactive Blue 19 (RB19) was evaluated. The effect of operational condition such as initial pH, initial H2O2 concentration, initial Fe2+ concentration and initial dye concentration on decolorization of RO4 and RB19 was studied. The photo-Fenton process is found to be more efficient than UV/H2O2 and Fenton process for decolorization of simulated dye bath effluent and solutions of the dyes in water alone under optimum conditions. In simulated dye bath the removal efficiency was slightly lower than for the solutions of the dyes in water alone for both dyes types. The results revealed that the tested advanced oxidation processes were very effective for decolorization of RO4 and RB19 in aqueous solution. [Projekat Ministarstva nauke Republike Srbije, br. TR34008]

The Bi2O3 films-based anodes were synthesized by electrodeposition of Bi on stainless steel substrate at constant current density and during different deposition times, fallowed by calcination, forming Bi2O3. The thickness of the films was determined by two methods: the observation under the microscope and by calculation from mass difference. Electrochemical proceses at the anodes were ivestigated by linear sweep voltammetry. At the anodes obtained within 2, 5, 10 and 15 minutes of deposition, two dyes, namely: Reactive Blue 19 and Crystal Violet, were decolorized by oxidation with •OH radical, generated from H2O2 decomposition at the anodes. Decoloration times of the anodes varied, and the shortest one was achieved with the anode obtained during 5 minutes of deposition, with the film thickness of 2.5±0.3 μm. The optimal H2O2 concentration for the dyes degradation was found to be 10 mmol dm-3. [Projekat Ministarstva nauke Republike Srbije, br. ТR 34008]

In present study a low cost biosorbent derived from Lagenaria vulgaris plant by xanthation, was tested for its ability to remove copper from aqueous solution. The effect of contact time, initial pH, initial concentration of copper(II) ions and adsorbent dosage on the removal efficiency were studied in a batch process mode. The optimal pH for investigated metal was 5. A dosage of 4 g dm-3 of xanthated Lagenaria vulgaris biosorbent (xLVB) was found to be effective for maximum uptake of copper(II). The kinetic of sorption of metal was fast, reaching at equilibrium in 50 min. The kinetic data were found to follow closely the pseudo-second-order model. The adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 23.18 mg g-1 copper(II) ions on xLVB. The presence of sulfur groups on xLVB were identified by FTIR spectroscopic study. Copper removal efficiency was achieved at 81.35% from copper plating industry wastevater.

The photodegradation of textile dye Reactive Blue 19, an anionic anthraquinone dye of reactive class, was investigated using UV radiation in the presence of H2O2 in UV reactor with low-pressure mercury lamps, with maximum energy output at the wavelength 254 nm. The effects of experimental variables, namely initial pH, initial dye concentration and concentration of peroxide were studied. The change of concentration of RB19 was followed by UV/vis spectrophotometric measurement of absorbance at 592 nm. The increase of the initial pH resulted in the efficiency increase of dye decolorization. The total decolorization was achieved in about 15 min. Results show that with the increase of dye concentration from 10 to 100 mg dm-3 the efficiency of process decreases. With the increase of the initial concentration of H2O2 from 10 to 30 mmol dm-3, the decolorization rate constant increased from 0.083 to 0.120 min1, with the decrease of process rate at the concentrations above. The highest decolorization rates were achieved at peroxide concentration of approx. 30 mmol dm-3, above which decolorization was inhibited by scavenging effect of peroxide. This study shows that UV/H2O2 process is promising treatment for dye RB 19 degradation in water and wastewater.

A new biosorbent, abbreviated as LVB-ZrO2,was synthesized by chemically modifying Lagenaria vulgaris shell with ZrO2. The removal of textile dye RB19 from aqueous solution by LVB-ZrO2 was studied. Characterization by SEM, FTIR and XRD confirmed the chemical modification of the biomaterial, which showed significant improvement of removal efficiency compared with unmodified Lagenaria vulgaris shell. LVB-ZrO2 point of zero charge is 5.49. The biosorption process is highly pH dependent and the optimal pH is 2.0, at which complete dye removal was attained. The results are the best by a pseudo-second order kinetic model. The optimal adsorbent dosage is 4 mg/dm³. The RB19 biosorption follows the Langmuir isotherm model (R²=0.9978), with the maximum sorption capacity of 75.12 mg/g. LVB-ZrO2 is a mechanically stable, easy to synthesize, cost-effective, biocompatible and environmentally-friendly biosorbent with the high potential for the removal of RB19 from aqueous solution. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stainless steel/Bi2O3 anode was synthesised by electrodeposition from acidic Bi (III) solution on stainless steel substrate and calcination at 500°C. Characterisation by SEM, EDX, XRD and TGA revealed that the anode surface was fully covered with pure α-Bi2O3, which formed a inhomogeneous and porous coat. Three dyes with different chromophores, namely: Reactive Blue 19, Methylene blue and Reactive Orange 4 were completely decolourised by electrochemical oxidation at the synthesised anode in the presence of hydrogen peroxide. Decolourisation followed the pseudo-first order kinetics model for all the three dyes. Decolourisation rates are sorted in descending order: Reactive Orange 4 > Reactive Blue 19 > Methylene Blue. For all the three dyes, an increase of the initial dye concentration caused the decrease of the reaction rate constants. At higher initial dye concentrations, the decolourisation times were significantly prolonged for all the three dyes, however, the complete decolourisation was done as well. [ABSTRACT FROM AUTHOR]

Degradation of azo dye Reactive Orange 16, a widely used textile dye, was carried out with UV light in the presence of H2O2. The experiments were conducted in the batch mode using low-pressure mercury lamps, emitting at 253.7 nm. Liquid-chromatography tandem mass spectrometry (LC/MS/MS) and high resolution mass spectrometry (FT-ICR) were employed in order to identify some of degradation products as well as to suggest possible degradation pathways. According to the mass spectrum characterization of RO16 dye and MSnfragmentation (up to MS4), its possible fragmentation pattern was proposed. The results revealed that degradation occurred mainly via hydroxylation, cleavage of the C‒S bond between the aromatic ring and the sulfonate group, cleavage of the azo bond, cleavage of the C‒N bond between azo group and naphthalene ring and aromatic ring opening. Toxicity test with marine photobacteriumVibrio Fisheriwas performed to consider whether or not the UV/H2O2treatment of RO16 dye results in the products with enhanced toxicity for aquatic life. [ABSTRACT FROM PUBLISHER]

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new biosorbent, abbreviated as LVB-ZrO₂, was synthesized by chemically modifying Lagenaria vulgaris shell with ZrO₂. The removal of textile dye RB19 from aqueous solution by LVB-ZrO₂was studied. Characterization by SEM, FTIR and XRD confirmed the chemical modification of the biomaterial, which showed significant improvement of removal efficiency compared with unmodified Lagenaria vulgaris shell. LVB-ZrO₂point of zero charge is 5.49. The biosorption process is highly pH dependent and the optimal pH is 2.0, at which complete dye removal was attained. The results are the best by a pseudo-second order kinetic model. The optimal adsorbent dosage is 4 mg/dm³.The RB19 biosorption follows the Langmuir isotherm model (R² = 0.9978), with the maximum sorption capacity of 75.12 mg/g. LVB-ZrO₂is a mechanically stable, easy to synthesize, cost-effective, biocompatible and environmentally-friendly biosorbent with the high potential for the removal of RB19 from aqueous solution.