Microcystin-leucine arginine (MC-LR) is the most abundant and toxic secondary metabolite produced by freshwater cyanobacteria. This toxin has a high potential hazard health due to potential interactions with liver, kidney and the nervous system. The aim of this work was the design of a simple and environmentally friendly electrochemical system based on highly efficient nanostructured electrodes for the removal of MC-LR in tap water. Titania nanoparticles were deposited on carbon (graphite) under a simple and efficient microwave assisted approach for the design of the electrode, further utilized in the electrochemical remediation assays. Parameters including the applied voltage, time of removal and pH (natural tap water or alkaline condition) were investigated in the process, with results pointing to a high removal efficiency for MC-LR (60% in tap water and 90% in alkaline media experiments, under optimized conditions).
The elimination of residual drugs from pharmaceutical and domestic sources is a growing concern, as they are able to reach water and soil resources and can present environmental and health risks even in very low concentrations. Traditional water and wastewater treatment systems have not been efficient in the removal of these compounds, evidencing the importance of the development of new remediation methods. In view of the applicability and versatility of electrocoagulation techniques in the removal of pollutants, the aim of this work is to evaluate the parameters: biochemical oxygen demand (BOD), chemical oxygen demand (COD), color, turbidity, algestone acetophenide (AAc) and estradiol enanthate (EEn) using a pilot treatment system, as well as phytotoxicity and Brine shrimp toxicity. The study showed good removal efficiency, comprising remarkable remediation performance assayed through BOD (61.5%), COD (58.6%), color (83.1%), turbidity (96.7%), AAc (77.0%) and EEn (56.7%) after 30 minutes. For toxicity, raw effluent was considered more phytotoxic for lettuce and cucumber seeds when compared to treated effluent. The results suggest that the pilot prototype was promising, providing an increase in both the germination potential and the root growth of the seeds (Lactuca sativa and Cucumis sativus) and a significant decrease in the acute toxicity to Artemia salina.
A new approach using paper spray ionization mass spectrometry (PSI−MS) for the analysis of steroid hormones in wastewater samples has been demonstrated. Triangular papers containing paraffin barriers as microfluidic channels were used to direct the sample solution to the paper tip, preventing the sample from spreading over the corners of the paper. The method was used to analyze the hormones levonorgestrel and algestone acetophenide in industrial wastewaters. Analytical curves presented a correlation coefficient (R 2 ) above 0.99. Limits of quantification were below 2.3 ppm and limits of detection below 0.7 ppm. Values of precision (coefficient of variation) and accuracy (relative error) were less than 15% for all analyses. Recovery results ranged from 82% to 102%. Levonorgestrel was also analyzed by high-performance liquid chromatography coupled to mass spectrometry in order to compare the analytical performance with PSI−MS. No statistically significant differences were found between both methods. This study demonstrates the usefulness of PSI−MS for rapid analysis of hormones in industrial wastewater samples and also indicates its potential to be employed as a simple and reliable analytical method in environmental sciences.
One of the most prominent fields of environmental chemistry is the study and the removal of micro-pollutants from aqueous matrices. Analytical techniques for their identification and quantification are becoming more sensitive and comprehensive and, as a result, an increasing number of drugs have been detected in environmental samples. However, the literature shows that conventional treatments for drinking water and wastewater are not sufficient for remove these compounds. This study aims to check whether the process of hydrothermal carbonization (CHT) is effective in removing the synthetic sex hormones: ethinyl estradiol, gestodene and cyproterone acetate from aqueous samples. The system used in CHT basically consists of a pressurized reactor made of stainless steel and solutions of compounds of interest, both individual and mixed, with a concentration of 1.0 μg.L-1 and a pH range of 2.0 to 3.0. The maximum surface temperature in the reactor was about 180 °C, the internal pressure was 20 bar with 90 minutes for the reaction. Four experiments were conducted, one for each hormone and one with the three hormones together. In individual tests removal of the compounds was found to be 99.8% for ethinyl estradiol, 99.3% for gestodene and 100% for cyproterone acetate. For a mixture of the hormones treated under the same conditions, the mean values of CHT-removal of Ethinylestradiol, Gestodene and Cyproterone Acetate were 99.60%, 96.80% and 68.90%, respectively. The impact of the matrix effect may have affected the efficiency of the hormone removal process by CHT.
Contaminants removal from industrial effluent is a major environmental concern. In this context, Algestone Acetophenide and Estradiol Enanthate are synthetic sex hormones widely used in the manufacture of contraceptives, whose presence in waterbodies may lead to environmental hazard. Given that so far, the methods employed in the removal of these drugs have presented limited efficiency or high implementation costs, the present work presented an electrochemical reactor composed by 32 carbon steel electrodes (1728 cm 2), which was employed in a real scale model to remove these synthetic hormones in an industrial pharmaceutical effluent. After 60 minutes the removal efficiency of the hormones Algestone Acetophenide and Estradiol Enanthate was of 88.9% and of 91.8% respectively, with low energy consumption (< 0.742 kWh.m-3). Physicochemical parameters such as color, turbidity, Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) also showed good removal efficiency too (> 50%), which implicates that the method herein depicted may be a valuable alternative to promote the removal of these contaminants in industrial wastewater.
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