Degradation of chlordecone and beta-hexachlorocyclohexane by photolysis, (photo-)fenton oxidation and ozonation.

Intensive use of chlorinated pesticides from the 1960s to the 1990s has resulted in a diffuse contamination of soils and surface waters in the banana-producing areas of the French West Indies. The purpose of this research was, for the first time, to examine the degradation of two of these persistent pollutants - chlordecone (CLD) and beta-hexachlorocyclohexane (ß-HCH) in 1 mg L-1 synthetic aqueous solutions by means of photolysis, (photo-) Fenton oxidation and ozonation processes. Fenton oxidation is not efficient for CLD and yields less than 15% reduction of ß-HCH concentration in 5 h. Conversely, both molecules can be quantitatively converted under UV-Vis irradiation reaching 100% of degradation in 5 h, while combination with hydrogen peroxide and ferrous iron does not show any significant improvement except in high wavelength range (>280 nm). Ozonation exhibits comparable but lower degradation rates than UV processes. Preliminary identification of degradation products indicated that hydrochlordecone was formed during photo-Fenton oxidation of CLD, while for ß-HCH the major product peak exhibited C3H3Cl2 as most abundant fragment.

Improving degradation of paracetamol by integrating gamma radiation and Fenton processes.

Degradation of paracetamol (N-(4-hydroxiphenyl)acetamide) in aqueous solution by gamma radiation, gamma radiation/H2O2 and gamma radiation/Fenton processes was studied. Parameters affecting the radiolysis of paracetamol such as radiation dose, initial concentration of pollutant, pH and initial oxidant concentration were investigated. Gamma radiation was performed using a (60)Co source irradiator. Paracetamol degradation and mineralization increased with increasing absorbed radiation dose, but decreased with increasing initial concentration of the drug in aqueous solution. The addition of H2O2 resulted in an increased effect on irradiation-driven paracetamol degradation in comparison with the performance of the irradiation-driven process alone: paracetamol removal increased from 48.9% in the absence of H2O2 to 95.2% for H2O2 concentration of 41.7 mmol/L. However, the best results were obtained with gamma radiation/Fenton process with 100% of the drug removal at 5 kGy, for optimal H2O2 and Fe(2+) concentrations at 13.9 and 2.3 mmol/L, respectively, with a high mineralization of 63.7%. These results suggest gamma radiation/H2O2 and gamma radiation/Fenton processes as promising methods for paracetamol degradation in polluted wastewaters.

[Laparoscopic management of symptomatic urachal anomalies]. / Manejo laparoscópico de las anomalías sintomáticas del uraco.

INTRODUCTION: Acquired urachal anomalies are a rare pathology. Gold-standard treatment for this clinical situation remains the resection of the urachus in its entire tract with or without partial resection of the bladder. Our aim is to up-date authors's experience in the minimally invasive surgical treatment of acquired urachal disease. METHODS: From 2001 to 2007, 14 patients were operated for acquired urachal disease at our institution. A three portal technique previously described by the authors was employed. The diagnosis of acquired uracal disease was confirmed in all cases and the resection of the urachus in its entire tract performed in cephalocaudal direction onto the bladder. Operative and demographic data was prospectively collected and analysis retrospectively performed. RESULTS: Mean operative time was 63 minutes (45,110), minimal blood loss, and no conversions to open surgery or perioperative complications were verified. The majority of the patients were discharged in the first 24 hours. At a follow-up of 22 months no recurrences of urachal pathology recurrences have been verified. CONCLUSIONS: Laparoscopy plays a significant role in the management of symptomatic urachus anomalies. It allows objective confirmation of clinical diagnosis and adequate resection of the urachus in a safe and efficient fashion, while providing the well-known advantages of minimally acces surgery. Preoperative evaluation work-up has minimal impact of therapeutical decision.

Ultrasonic degradation of sulfadiazine in aqueous solutions.

Advanced oxidation methods, like ultrasound (US), are a promising technology for the degradation of emerging pollutants in water matrices, such as sulfonamide antibiotics. Nevertheless, few authors report the degradation of sulfonamides by high-frequency US (>100 kHz), and limited information exist concerning the use of ultrasonic-driven processes in the case of sulfadiazine (SDZ). In this study, SDZ degradation was investigated with the aim to evaluate the influence of initial concentration, pH and US frequency, and power. Ultrasonic frequencies of 580, 862, and 1,142 kHz at different power values and SDZ initial concentrations of 25, 50, and 70 mg L(-1) were used. The results show that SDZ degradation followed pseudo first-order reaction kinetics with k values and percent removals decreasing for increasing solute initial concentration. Higher SDZ percent removals and removal rates were observed for the lowest operating frequency (580 kHz), higher dissipated power, and in slightly acidic solution (pH 5.5). Addition of the radical scavenger n-butanol confirmed that hydroxyl radical-mediated reactions at the interface of the cavitation bubbles are the prevailing degradation mechanism, which is directly related to the pKa-dependent speciation of SDZ molecules. Finally, addition of H2O2 had a detrimental effect on SDZ degradation, whereas the addition of the Fenton reagent showed a positive effect, revealing to be a promising alternative for the removal of sulfadiazine.