Experimental and theoretical study of dyes adsorption process on chitosan-based cryogel

In this research, the adsorption of three synthetic dyes dissolved in an aqueous solution on chitosan cryogel beads (Q-C-EGDE) was compared. The effect of the pH of the solution on the adsorption capacity of each dyes was analyzed. Furthermore, the kinetics and adsorption isotherms were compared, at temperatures of 283.15 K, 303.15 K and 323.15 K, and the kinetic and adsorption equilibrium data were fitted to three mathematical models, respectively. The biosorbent was characterized by scanning electron microscopy (SEM), the nitrogen physisorption BET method and Fourier transform infrared spectroscopy (FTIR). The characterization results show that the cryogel is composed of low-surface, macroporous, porous grooved walls. The functional groups that took part in the adsorption were mainly amino groups (NH₃⁺). When comparing the adsorption capacities, it was found that the dyes adsorb in the following order Blue 1 > Red 2 > Yellow 5 reaching capacities from 1600 mg/L to 850 mg/L. The results of the adsorption and mathematical modelling suggest that the process is regulated mainly by physisorption and is largely limited by mass transfer mechanisms within the cryogel, where the electrostatic charges present affect adsorption. The latter was corroborated by the Monte Carlo simulation.

Development of standardized method for the quantification of azo dyes by UV-Vis in binary mixtures

The azo dyes, Yellow 5 (Y5), Red 2 (R2) and Blue 1 (B1), quantified in solutions and in mixtures of binary dyes, were studied by means of UV-Vis spectroscopy. In this work was used a CIE algorithm developed in Visual Basic for Applications (VBA). The CIE algorithm is based on the tristimulus chromaticity diagram, as an alternative to the shielding effect that arises in dye mixtures, and it can also be applied to complex quantification methods such as HPLC (High Performance Liquid Chromatography). The results obtained through of the algorithm, showed a higher accuracy from 97 to 99% in relation with similar UV-Vis quantification methods. In contrast, linear methods only managed to reach an accuracy from 78 to 98%. Additionally, the algorithm yielded significant similar values to the UHPLC reference method. The results showed that the method CIE algorithm was accessible and reliable to quantify binary mixtures of the dyes used which suggests the possibility to apply this method on other dyes, within the limits of quantification obtained in this study (0.076-24.56 mg/L) and the pH values from 2 to 10.

Adsorption mechanisms of hexavalent chromium from aqueous solutions on modified activated carbons

Functional groups of the activated carbon play the major role in metals removal from aqueous solutions and, for this reason, different treatments can be used to modify the adsorbent surface improving the adsorption capacity for a particular pollutant. In this research, oxidation with nitric acid, heating under an inert atmosphere, and ammonia treatment were applied to modify the activated carbon surface. The modified adsorbents were used for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions at different concentrations (10-500 mg L^-1), pH 6, and 25 °C. Adsorption mechanisms of Cr(VI) on the activated carbon were proposed based on the surface chemistry, adsorption/reduction, and desorption experiments. Findings demonstrate that acid functional groups of the activated carbon had an important effect on the hexavalent chromium removal. For instance, a high reduction of Cr(VI) to Cr(III) (50%) was obtained by the oxidized adsorbents, whereas the heat treated adsorbents achieved a low reduction (35%), but the ammonia-treated activated carbon achieved the lowest reduction (20%). The heat-treated adsorbent showed the best Cr(VI) adsorption capacity (48 mg g^-1), especially at equilibrium Cr(VI) concentration lower than 200 mg L^-1, and the fastest adsorption kinetics among the studied adsorbents. Furthermore, the highest Cr(VI) desorption (90%) was achieved with 0.1 N NaOH-NaCl solutions. In summary, an anionic/reduction coupled adsorption mechanism of Cr(VI) seems to be feasible, and the heat-treated activated carbon is an interesting option for sequestering Cr(VI) species from aqueous effluents.

Superoxide dismutase and Naproxen in the very late phase of carrageenan induced edema in rats

BACKGROUND

Rat hind-foot carrageenan induced edema (CIE) is a widely used model to evaluate anti-inflammatory drugs. It shows two well-defined phases, however a third not fully characterized phase has been observed. Superoxide dismutase (SOD) is a free radical-scavenger with anti-inflammatory activity. In our country there is not a specifically designed instrument to evaluate edema in CIE.

METHODS

Edema was induced by intraplantar injection of carraageenan. Fours groups were evaluated: placebo, two different doses of SOD, and Naproxen. Edema was evaluated by a specially designed mercury plethismograph. Intensity of the inflammatory reaction was determined during the classical early and late phases and during the third very late phase.

RESULTS

All treatments, but higher dose of SOD, showed good anti-inflammatory activity throughout early, late, and very late phases. Naproxen was more effective than SOD during first and second phase, however this difference disappeared during the third phase. In terms of equimolar basis the enzyme appeared 1,800 time more potent than Naproxen. Mercury plethysmometer performance was fine.

CONCLUSIONS

The anti-inflammatory activity of SOD and Naproxen is extended until the very late phase in the CIE model. In this bioassay, this long lasting activity of the enzyme should be ascribed to a mechanism supplementary to its free radical-scavenger property. SOD may be indeed an alternative treatment in inflammatory diseases.

Effect of superoxide dismutase from bovine erythrocytes on different activity parameters in adjuvant-induced arthritis

BACKGROUND

The purpose of this work was to evaluate the effect of superoxide dismutase (SOD) on primary swelling, lipoperoxidation, body thymus, and spleen weight in the adjuvant-induced arthritis (AIA) model in rats.

METHODS

Orally and intraperitoneally administered SOD (100 U/kg) from bovine erythrocytes, as well as naproxen (40 mg/kg) and dexamethasone (25 mg/kg), were evaluated against placebo.

RESULTS

Primary edema was not decreased by SOD; in contrast, naproxen and dexamethasone showed good anti-inflammatory activity. Lipoperoxidation increased 1.8, 2.5, and 2.8 times with intraperitoneal SOD, naproxen, and dexamethasone administration, respectively, while oral SOD decreased lipoperoxidation levels to approximately one-half of that found in the control group. Body weight increased with SOD but decreased with dexamethasone. Naproxen did not change the animal weight. Thymus weight remained unchanged with SOD and naproxen, while it decreased with dexamethasone. Spleen weight remained the same with SOD, but increased with naproxen and decreased with dexamethasone. No side effects were observed in the SOD group, whereas 20% of the rats in the naproxen group died of gastrointestinal hemorrhage, and 50% of the rats in the dexamethasone group, of pulmonary infection.

CONCLUSIONS

In conclusion, SOD showed no anti-inflammatory activity but decreased lipoperoxidation when administered orally. No deleterious effects in primary and secondary immunologic organs were observed with this agent.

Anti-inflammatory activity of Debaryomyces hansenii Cu,Zn-SOD

BACKGROUND

Cu,Zn-superoxide-dismutase, Cu,Zn-SOD, can be obtained from different sources with different anti-inflammatory activities. In this study we compared the anti-inflammatory capacity of the marine yeast Debaryomyces hanseii Cu,Zn-SOD (Dh-SOD) with that of bovine erythrocytes (Be-SOD) in a preventive and a therapeutic fashion.

METHODS

Edema was induced by carrageenan injection into the rat hind paw and was evaluated using a mercury plethysmograph. Development of the inflammatory process was followed by volume displacement at time 0 (carrageenan injection), 1, 2, 3, 4, 5, 6, 9, 12, and 24 h thereafter. Three different SOD doses were used in preliminary experiments to prevent edema: 10, 100, and 1,000 U/kg.

RESULTS

The results indicate that, at the lowest dose (10 U/kg), both SOD samples are effective in reducing inflammation in both the prostaglandin and amplification phases (-24.8% and -17.5% in the case of Be-SOD, and 11.8% and -18.7% in the case of Dh-SOD, respectively) (p < 0.05). At 100 U/kg, Be-SOD also shows good anti-inflammatory activity in all edema phase (-27.1% in the serotonin phase; -19.4% in the prostaglandin phase; and -20% in the amplification phase) (p < 0.05), but Dh-SOD was less effective (-10.9%, -9.1%, and -5.7%). At the highest dose tested (1000 U/kg), Dh-SOD was, again, more effective than Be-SOD in all three edema phases (-33.1% and -1.5%; -17.9% and -2.6%; and -13.8% and 6.7%, respectively) (p < 0.05). When evaluated as a therapeutic alternative, single doses of Dh-SOD at 1,000 U/kg, and Be-SOD at 100 U/kg, both showed good anti-inflammatory activities (-31.7% and -23.5%, respectively) (p < 0.05).

CONCLUSION

For therapy purposes alone, Dh-SOD appears to be a better anti-inflammatory agent than Be-SOD in carrageenan-induced edema.

[Usefulness of physical examination at school]

OBJECTIVE

To evaluate the utility of school health examinations performed at four years of age.

DESIGN

Evaluation of the results of school health examinations performed on 5,709 children are presented, with the follow up of selected problems found (overweight, growth failure, strabismus, reduced uncorrected visual acuity, hearing loss, psychomotor development and speech development impairment, hydrocele, cryptorchism, haematuria, dental caries and heart murmur).

SETTING

4-year old kindergarten children assessed in the school health program in the city of Barcelona (Catalonia, Spain).

MAIN RESULTS

The examination identified 1,177 suspected defects in 960 children. Through a telephone interview with the families of 745 of these children, it was found that only 34.1% were previously unknown to families. The most frequently unknown problem was dental caries. Professional help was sought for 54.3% of the suspected defects. Only 10.5% of the suspected problems began any sort of treatment. The most frequently treated problems wer previously uncorrected refractive defects of the vision. Families report that 8.2% of the suspected problems improve.

CONCLUSIONS

These results suggest that the current health output of school health examinations in our city is modest, and that their cost-opportunity should be reviewed.

[Evaluation of a project of primary prevention of smoking: the Barcelona PASE project]

The results of the short-term evaluation of a program to prevent the use of tobacco and other substances among schoolchildren of sixth and seventh grade are presented. Schoolchildren who participated in the project show significant differences when compared to a reference group through a matched analysis in the regular use of tobacco and having bought tobacco, but not in the experimentation nor in the intention to smoke. The results suggest the program is useful to prevent the onset of smoking, although longer term evaluation data are needed. The results and their implications for a comprehensive smoking prevention approach in schools are discussed.