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Introduction. Laboratories in the educational sector that offer analytical services and generate dangerous residues of Cr (VI) in their methods must adopt special measures for its elimination as it is a highly carcinogenic species of a negative environmental impact. Objective. Heterogeneous photocatalysis and bioadsorption environmental alternatives were evaluated in the removal of Cr (VI) in liquid waste generated in analytical services laboratories of the University of Nariño. Materials and methods. In both methods a factorial design 23 with high and low levels was applied, allowing to optimize the variables: pH = 1, amount of photocatalyst (TiO2) 0.5 g and 30 minutes of irradiation with UV light for the photocatalysis; and the variables: amount of bioadsorbent (green banana peel) 1g, pH = 1 and contact time of 60 minutes from Cr (VI) concentration of 100 mg / L for bioadsorption. The efficiency of the two methods was evaluated by comparing means and the assessment of technical and environmental feasibilitiy from matrices. Results. : From the liquid waste with a total chromium concentration of 2,116 mg / L, removal rates of 96.07 ± 0.65% were obtained for photocatalysis and 99.9% ± 0.01 for the bioadsorption process; the latter showing a better performance. Finally, the best technical and environmental feasibility was obtained for bioadsorption. Conclusion. Bioadsorption is shown as an eco-efficient process and is therefore presented as an environmentally sustainable option for the elimination of Cr (VI) in the management of hazardous waste. [ABSTRACT FROM AUTHOR]

Introduction. In this moment, an application of advanced oxidation processes (AOP) is being developed. They are based on technologies for the destruction of pollutants by the use of chemical substances known as hydroxyl free radicals, which have high oxidation properties. Those radicals react with the pollutant and transform it into environmentally harmless compounds. For the specific case of Mertect pesticide several advanced oxidation processes have been studied, among which chemical oxidation, photolysis and homogeneous and heterogeneous photocatalysis can be remarked. They aim to degrade this pollutant and thus reducing the negative impacts it can bring to the environment. Objective. To evaluate the degradation efficiency of the Mertect pesticide by the use of advanced oxidation processes (AOP). Materials and methods. For the experimental part of the project, a factorial 33 experimental design was proposed. For this design it was used a photo reactor that consisted on an ultra violet light lamp, a glass container to keep the solution of the pesticide to be degraded and a submersible pump that allowed the solution to recirculate through the treatment system. The degradation of the pesticide was measured by ultra violet/visible spectrophotometry. Results. Photochemical processes based on heterogeneous photocatalysis with titanium dioxide - TiO2- and homogeneous photocatalysis with iron (III) have significant removal rates of the Mertect pesticide, above 99.0% and 95.0%, respectively, for the aforementioned oxidation processes. Conclusion. Advanced oxidation processes are adequate for the removal and degradation of the Mertect pesticide. [ABSTRACT FROM AUTHOR]

Introduction. Textile dyes are very persistent in the environment and the classic methods to eliminate them are not useful because partial oxidations or reductions can create very toxic secondary products. Many of the dyes are not directly toxic for living organisms, but the strong coloring they bring to the aquatic environment can suppress photosynthesis in watercourses so their presence must be controlled. Objective. To select the optimal dose of photo sensitizer and oxidation agent to degrade novactive blue FHBRNS. Materials and methods. A synthetic sample with 300mg/L of novactive blue FHBRNS dye used in textiles was used. This is the most common concentration in effluents from the textile industries that use this dye. In the experiments, TiO2 and FeCl3 were used in 30 and 60 mg/L concentrations and as an oxidation agent H2O2 was used in concentrations between 0.5, 1.0 and 1.5 mg/L. Results.The dye is fastly degraded and mineralized with FeCL3. This happened in the test in which 60mg/L FeCL3 and 10 mL/L of H2O2 were used. Conclusion. Degradation percentages of 97.3% and 65.8%, respectively, were obtained. [ABSTRACT FROM AUTHOR]

Introduction. The use of sunlight energy to eliminate pollutants in waste water, by the use of an appropriate catalyst, uses the sunlight that arrives directly to the Earth to produce several chemical reactions which allow the elimination of organic compounds in the water from urban, industrial and agropecuary effluents and change the oxidation state of heavy metals in a way that they pass from being soluble to an insoluble form. Objective. To evaluate the water degradation with methylene blue used to analyze some tests in chemicals laboratories by the use of a photosensitizer, using sunlight. Materials and methods. The degradation and mineralization of waste water with methylene blue by means of the sunlight was made. Different tests were made with the hydrogen peroxide, titanium dioxide and air combination. The degradation of this waste water was followed by the color reduction at a 650nm wavelength and the COD technique was used for the mineralization. Results. The optimal concentration of photo catalyst and oxidation agent for the degradation of waste water with methylene blue in a 30 mg/L concentration rate in the water found in this research work are: L20 mg/L of TiO2 and 2 mL H2O2/L with an air injection. Conclusion. Very good results in color degradation and lower mineralization percentages were found in an eight hour time of sunlight irradiation. [ABSTRACT FROM AUTHOR]

Introduction. Photocatalysis made with sun light appears as a simple and economic alternative to treat wastewater, colored with dyes from the textile industry. The use of this technology for the degradation and mineralization the 84 Orange Reactive dyes can open a new route different from the traditional oxidation processes. Objective. To study the photocatalysis with TiO2 in colored wastewater using a sunlight collector. Materials and Methods. A sunlight collector made up by three modules (each one made up by eight glass Schott-Duran pipes) was used. Each glass pipe is 48 cm of external diameter and 150 cm long and also contains an aluminum sheet, which allows the reflection of sunlight. The whole device had a re-circulation bomb and a tank. The sunlight collector had an inclination of 6 degrees in comparison with the floor and was facing North because it must be located according to the geographic position of the place. Only one condition was modified for each experiment with the objective of studying its influence in the dye's degradation. In this research work we show different combinations of hydrogen peroxide, titanium dioxide and air, used in the photocatalysis of the 84 orange reactive and waste water samples from textile industry. Results. The optimal concentrations found for 84 Orange Reactive in a 340 mg/lL concentration are: 40 mg/L of titanium dioxide and 2 mg/L of hydrogen peroxide with no air injection. Conclusion. With an appropriate quantity of titanium dioxide and a well calculated concentration of hydrogen peroxide, very good concentration percentages of the 84 Orange Reactive and colored waste waters are obtained, besides of high mineralization percentages. [ABSTRACT FROM AUTHOR]

Introduction. In textile industry there is a big production of waste water coming from all processes and it is difficult to be treated worldwide. Currently, research works are being made, applying advanced oxidation processes among which we have homogeneous and heterogeneous photo catalysis. This term is understood as the process that uses ultra violet light and an inorganic and semi conductive solid material, to provoke a chemical transformation. Objective. To evaluate the photo degradation sensitized with titanium dioxide for the recoltive red dye, by using an ultra violet light lamp. Materials and Methods. Several rehearsals were made with a 100 mgL-1 concentrations of the recoltive red dye used in the textile industry. It was also put under photo catalysis processes with an ultra violet lamp. Using TiO2 as a catalyst and H2O2 as an oxidant, we aim to identify the conditions under which this process is most effective. The rehearsals were made three times each, always with a joint pH control. The parameters measured were the dye degradation percentage and the mineralization, keeping in mind that the substances produced must be those less polluting. A two level experimental factorial design was applied to the data obtained, with interaction between the photo catalyst and the oxidant agent. Results. The rehearsals with a higher degradation percentage and a faster reaction are for the titanium dioxide with hydrogen peroxide under the following concentrations: 100 mgL-1 TiO2 and 2% of H2O2 for a 96% degradation and 0 of TiO2 and 2% v/v of H2O2 for a final degradation of 93%. Conclusions. The effect, when the titanium dioxide concentration is increased, is a higher degradation of the recoltive red dye. This ratifies the fact that the increase of the TiO2 allows that more active points exist to generate hydroxyl radicals and, therefore, a higher possibility of augmenting the degradation and mineralization percentages. [ABSTRACT FROM AUTHOR]