Ayrton F. Martins

Photo-degradation of the antimicrobial ciprofloxacin at high pH: identification and biodegradability assessment of the primary by-products.

Photo-treatment for the removal of pharmaceuticals in effluents is a topic currently under discussion. In some countries effluents from hospitals are directly emitted into open ditches without any further treatment and with very little dilution. Under such circumstances photo-degradation in the environment can occur. However, photo-degradation does not necessarily end up with the complete mineralization of a chemical. Therefore, photo-product biodegradability and toxicity against environmental bacteria is of interest. Hospital effluents have often a pH around 9. Therefore, photo-oxidation (150W medium-pressure Hg-lamp, batch reactor) of ciprofloxacin (CIP) was studied at pH 9. The primary elimination of CIP was monitored and structures of photo-products were assessed by liquid chromatography ion trap mass spectrometry (LC-MS/MS). Five compounds were identified as probable products of photo-defluorination, -decarboxylation and loss of the piperazine moiety. These photo-products were not biodegradable in the Closed Bottle test - OECD 301D. They did not affect Vibrio fisheri in the applied concentrations.

Ciprofloxacin in hospital effluent: degradation by ozone and photoprocesses.

There are several papers in the literature that have recorded satisfactory results for the degradation of different pharmaceuticals in aqueous solutions by means of oxidation processes; however, only a few of them relied on real samples in carrying out their investigations. This study examines the results of the performance of photo-induced oxidation, heterogeneous photocatalysis, ozonation and peroxone in degrading the fluoroquinolone antimicrobial ciprofloxacin (CIP) in a hospital effluent. The real samples were collected from the treatment system of the University Hospital of Santa Maria (HUSM). Liquid chromatography with fluorescence detection (LC-FLD) was used to monitor the decrease of the CIP concentration. As expected, photo-induced oxidation was much slower than the other processes in bringing about total CIP degradation. Both heterogeneous photocatalysis and peroxone led to almost complete CIP degradation after 60 min treatment. Ozonation showed the best performance: total degradation after 30 min treatment. This was an unexpected result in view of the greater capacity of the other two processes to generate hydroxyl radicals. However, this finding supports a result in the literature that has tended to be overlooked. The by-products formed during the application of the processes were found to be very similar. Moreover, on the basis of the data obtained from the literature, there is some evidence to suggest that the by-products are derived from the oxidation of the piperazine group.

Effects of Cadmium, Lead, Mercury and Zinc on °-Aminolevulinic Acid Dehydratase Activity from Radish Leaves

The purpose of the present study was to investigate the in vitro and the in vivo effects of cadmium, zinc, mercury and lead on δ-aminolevulinic acid dehydratase (ALA-D) activity from radish leaves. The in vivo effect of these metals on growth, DNA and protein content was also evaluated. The results demonstrated that among the elements studied Cd2+ presented the highest toxicity for radish. 50% inhibition of ALA-D activity (IC50) in vitro was at 0.39, 2.39, 2.29, and 1.38 mM Cd2+, Zn2+, Hg2+ and Pb2+, respectively. After in vivo exposure Cd2+, Zn2+, Hg2+ and Pb2+ inhibited ALA-D by about 40, 26, 34 and 15%, respectively. Growth was inhibited by about 40, 10, 25, and 5% by Cd2+, Zn2+, Hg2+, and Pb2+, respectively. DNA content was reduced about 35, 30, 20, and 10% for Cd2+, Zn2+, Hg2+, and Pb2+, respectively. The metal concentration in radish leaves exposed to Cd2+, Zn2+, Hg2+, and Pb2+ was 18, 13, 6, and 7 μmol g−1, respectively. The marked ability of radish to accumulate Cd2+ and Zn2+ raises the possibility of using this vegetable as a biomonitor of environmental contamination by these metals.

Oxidation-coagulation of β-blockers by K2FeVIO4 in hospital wastewater: assessment of degradation products and biodegradability.

This study investigated the degradation of atenolol, metoprolol and propranolol beta-blockers by ferrate (K2FeO4) in hospital wastewater and in aqueous solution. In the case of hospital wastewater, the effect of the independent variables pH and [Fe(VI)] was evaluated by means of response surface methodology. The results showed that Fe(VI) plays an important role in the oxidation-coagulation process, and the treatment of the hospital wastewater led to degradations above 90% for all the three β-blockers, and to reductions of aromaticity that were close to 60%. In addition, only 17% of the organic load was removed. In aqueous solution, the degradation of the β-blockers atenolol, metoprolol and propranolol was 71.7%, 24.7% and 96.5%, respectively, when a ratio of 1:10 [β-blocker]:[Fe(VI)] was used. No mineralization was achieved, which suggests that there was a conversion of the β-blockers to degradation products identified by liquid chromatography/mass spectrometry tandem. Degradation pathways were proposed, which took account of the role of Fe(VI). Furthermore, the ready biodegradability of the post-process samples was evaluated by using the closed bottle test, and showed an increase in biodegradability. The use of the ferrate advanced oxidation technology seems to be a useful means of ensuring the remediation of hospital and similar wastewater.

Removal of dexamethasone from aqueous solution and hospital wastewater by electrocoagulation

This study is concerned with the removal of the anti-inflammatory dexamethasone from aqueous solution and hospital wastewater by electrocoagulation. The variation of the toxicity during the electrocoagulation was also studied through experiments that were designed and optimized by means of response surface methodology. The coagulation efficiency was evaluated by measuring the dexamethasone concentration by high performance liquid chromatography coupled to a diode array detector. In addition, variation was evaluated through a Vibrio fischeri test. The results showed an increase in the removal of dexamethasone (up to 38.1%) with a rise of the current applied and a decrease of the inter-electrode distance, in aqueous solutions. The application to hospital effluent showed similar results for the removal of dexamethasone. The main effect of the electrocoagulation was that it removed colloids and reduced the organic load of the hospital wastewater. Regarding the current applied, the calculated energy efficiency was 100%. Without pH adjustment of the aqueous solution or hospital wastewater, the residual aluminum concentration always remained lower than 10 mg L(-1), and, with adjustment (to pH 6.5), lower than 0.30 mg L(-1), at the final stage. No toxicity variation was observed during the electrocoagulation process in aqueous solution, either in the presence or absence of dexamethasone.

Use of chromium oxide in digestibility studies: variations of the results as a function of the measurement method

The objective of the present study was to evaluate the agreement of two methods for the determination of chromium oxide in feed, duodenal contents and faeces in the investigation of feed digestibility. Four Holstein steers fitted with permanent ruminal and duodenal cannulae were used in a 4×4 Latin square design experiment. Steers were fed diets varying in urea content three times daily, restricted at a level equivalent to 2·5% of live body weight (dry matter basis). Faecal and duodenal fluxes of dry matter and nitrogen were estimated using chromium oxide (Cr2O3) as a indigestible marker. The equivalent Cr2O3 concentration in the solution resulting from acid digestion of the samples was measured by chromium determination by simple photometry at 350 nm and by flame atomic absorption spectrometry. Chromium concentrations in feed, duodenal contents and faeces and ruminal and total digestibilities of dry matter and nitrogen were affected by the chromium determination methods used. Despite the fact that the AAS method is more precise and sensible, sometimes its utilisation is limited by availability of equipment. In this situation, the chromium determination by photometric method can be a feasible alternative, since proper corrections in optical density readings are done.

Development and validation of a high-performance liquid chromatographic method for the determination of clomazone residues in surface water.

A method is described for the determination of clomazone residues in surface water by high-performance liquid chromatography with UV detection. The method involves solid-phase extraction with C18 extraction tubes. Clomazone was separated on a C18 column with a mobile phase of methanol-water (65:35, v/v) at pH 4.0 and a flow-rate of 1.0 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method developed can be used for determination of clomazone in surface water, at the limit of 0.1 mcirog/l set by the European Union drinking water directive, with a 400-fold preconcentration.

Photocatalytic Degradation of Brilliant Red Dye and Textile Wastewater

The degradation of textile wastewater and brilliant red dye solutions in a coil photoreactor provided with recirculation, assisted by powdered TiO2 and medium-pressure mercury lamp irradiation, was investigated. Factorial design was used for the attainment of the best conditions for COD and color abatement. pH and TiO2 loading showed to be critical variables for the photocatalytic degradation process for both textile wastewater and aqueous reactive dye solutions (25 mg L−1). For both substrates, the optimized process conditions by factorial design were almost the same (pH 2–3, 444 mg TiO2 L−1 loading, 5 L h−1 recirculation flow-rate). A 41% COD abatement for textile wastewater was obtained with a 120 min treatment. For the Brilliant Red dye solutions, a 20 min treatment resulted in about 90% decolorization (517 nm, pH 5), as well as in a reduction of 66% of the integrated absorbance (200–600 nm, pH 5).

Comparison of advanced processes on the oxidation of acid orange 7 dye.

ABSTRACT The degradation of acid orange 7 dye (AO7) was studied using a 1 L semi-batch tank stirred glass reactor for performing three different photochemical processes (photoperoxidation, Fenton, photo-Fenton). A commercial low pressure lamp was used for irradiation of samples. The advancement of degradation was monitored by measurement of color reduction, UV-spectra, HPLC-UV and COD. The obtained results showed that the photo-Fenton treatment was the most effective for the degradation of AO7.

Cadmium determination in biological samples by direct solid sampling flame atomic absorption spectrometry

Abstract A direct solid sampling flame atomic absorption spectrometric procedure for trace determination of cadmium in biological samples has been developed. Test samples (0.05–2.00 mg) were ground and weighed into small polyethylene vials, which were connected to the device for solid sample introduction into a conventional air/acetylene flame. Test samples were carried as a dry aerosol to a quartz cell, placed between the burner and the optical path, which had a perpendicular entrance and a slit in the upper part. The atomic vapor generated in the flame produced a transient signal that was totally integrated within 1 s. The effect of operating conditions and the extent of grinding on the analytical signal were evaluated. Background signals were always low and a characteristic mass of 0.29 ng Cd was obtained. Calibration was performed using different masses of solid certified reference materials. Results obtained for certified and in-house reference materials were typically within the 95% confidence interval of the certified and/or reference value, and the precision, expressed as relative standard deviation, was between 3.8 and 6.7%. The proposed system is simple and it might be adapted to conventional atomic absorption spectrometers allowing the determination of Cd in more than 80 test samples per hour, excluding weighing.