Navegando por Autor "Cañizares, Pablo Canizares"

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Application of electrokinetic soil flushing to four herbicides: a comparison
(Elsevier, 2016-06) Santos, Elisama Vieira dos; Souza, Fernanda L.; Sáez, Cristina; Cañizares, Pablo Canizares; Lanza, Marcos R. V.; Martinez-Huitle, Carmem A.; Rodrigo, Manuel Andres
In this work, four bench-scale plants containing soil spiked with four herbicides (2,4-Dichlorophenoxyacetic acid (2,4-D), oxyfluorfen, chlorsulfuron and atrazine) undergo treatment consisting of an electrokinetic soil flushing (EKSF). Results clearly demonstrate that efficiency of EKSF depends on the chemical characteristic of the pesticide used. The amount of pesticide collected in the anode well is more significant than that collected in the cathode wells, indicating that the electromigration is much more important than drainage by electro-osmotic flux for this application. After 15 d of treatment, the 2,4-D is the pesticide most efficiently removed (95% of removal), while chlorsulfuron is the pesticide more resilient to the treatment. Additionally, volatilization was found to be a process of the major significance in the application of electrokinetic techniques to soil polluted with herbicides and because of that it should always be taken into account in the future design of full-scale processes
Removal of oxyfluorfen from ex-situ soil washing fluids using electrolysis with diamond anodes
(Elsevier, 2016-04-15) Santos, Elisama Vieira dos; Sáez, Cristina; Martínez-Huitle, Carlos Alberto; Cañizares, Pablo Canizares; Rodrigo, Manuel Andres
In this research, firstly, the treatment of soil spiked with oxyfluorfen was studied using a surfactant-aided soil-washing (SASW) process. After that, the electrochemical treatment of the washing liquid using boron doped diamond (BDD) anodes was performed. Results clearly demonstrate that SASW is a very efficient approach in the treatment of soil, removing the pesticide completely by using dosages below 5 g of sodium dodecyl sulfate (SDS) per Kg of soil. After that, complete mineralization of organic matter (oxyflourfen, SDS and by-products) was attained (100% of total organic carbon and chemical oxygen demand removals) when the washing liquids were electrolyzed using BDD anodes, but the removal rate depends on the size of the particles in solution. Electrolysis of soil washing fluids occurs via the reduction in size of micelles until their complete depletion. Lower concentrations of intermediates are produced (sulfate, chlorine, 4-(trifluoromethyl)-phenol and ortho-nitrophenol) during BDD-electrolyzes. Finally, it is important to indicate that, sulfate (coming from SDS) and chlorine (coming from oxyfluorfen) ions play an important role during the electrochemical organic matter removal
Reversible electrokinetic adsorption barriers for the removal of atrazine and oxyfluorfen from spiked soils
(Elsevier, 2017-01-15) Santos, Elisama Vieira dos; Sáez, Cristina; Cañizares, Pablo Canizares; Martínez-Huitle, Carlos Alberto; Rodrigo, Manuel Andres
This study demonstrates the application of reversible electrokinetic adsorption barrier (REKAB) technology to soils spiked with low-solubility pollutants. A permeable reactive barrier (PRB) of granular activated carbon (GAC) was placed between the anode and cathode of an electrokinetic (EK) soil remediation bench-scale setup with the aim of enhancing the removal of two low-solubility herbicides (atrazine and oxyfluorfen) using a surfactant solution (sodium dodecyl sulfate) as the flushing fluid. This innovative study focused on evaluating the interaction between the EK system and the GAC-PRB, attempting to obtain insights into the primary mechanisms involved. The obtained results highlighted the successful treatment of atrazine and oxyfluorfen in contaminated soils. The results obtained from the tests after 15 days of treatment were compared with those obtained using the more conventional electrokinetic soil flushing (EKSF) technology, and very important differences were observed. Although both technologies are efficient for removing the herbicides from soils, REKAB outperforms EKSF. After the 15-day treatment tests, only approximately 10% of atrazine and oxyfluorfen remained in the soil, and adsorption onto the GAC bed was an important removal mechanism (15–17% of herbicide retained). The evaporation loses in REKAB were lower than those obtained in EKSF (45–50% compared to 60–65%)
Treating soil-washing fluids polluted with oxyfluorfen by sono-electrolysis with diamond anodes
(Elsevier, 2017-01) Santos, Elisama Vieira dos; Sáez, Cristina; Cañizares, Pablo Canizares; Martínez-Huitle, Carmem A.; Rodrigo, Manuel Andres
This works is focused on the treatment by sono-electrolysis of the liquid effluents produced during the Surfactant-Aided Soil-Washing (SASW) of soils spiked with herbicide oxyfluorfen. Results show that this combined technology is very efficient and attains the complete mineralization of the waste, regardless of the surfactant/soil radio applied in the SASW process (which is the main parameter of the soil remediation process and leads to very different wastes). Both the surfactant and the herbicide are completely degraded, even when single electrolysis is used; and only two intermediates are detected by HPLC in very low concentrations. Conversely, the efficiency of single sonolysis approach, for the oxidation of pollutant, is very low and just small changes in the herbicides and surfactant concentrations are observed during the tests carried out. Sono-electrolysis with diamond electrodes achieved higher degradation rates than those obtained by single sonolysis and/or single electrolysis with diamond anodes. A key role of sulfate is developed, when it is released after the electrochemical degradation of surfactant. The efficient catalytic effect observed which can be explained by the anodic formation of persulfate and the later, a sono-activation is attained to produce highly efficient sulfate radicals. The effect of irradiating US is more importantly observed in the pesticide than in the surfactant, in agreement with the well-known behavior of these radicals which are known to oxidize more efficiently aromatic compounds than aliphatic species
Treatment of ex-situ soil-washing fluids polluted with petroleum by anodic oxidation, photolysis, sonolysis and combined approaches
(Elsevier, 2017-02-15) Santos, Elisama Vieira dos; Sáez, Cristina; Cañizares, Pablo Canizares; Silva, Djalma Ribeiro da; Martínez-Huitle, Carlos Alberto; Rodrigo, Manuel Andres
In this research, the treatment of soil spiked with petroleum was studied using a surfactant-aided soil-washing (SASW) process followed by sonolysis (US), photolysis and boron doped diamond electrolysis (BDD-electrolysis) for washing liquid treatment. Results clearly demonstrate that SASW is a very efficient approach in the treatment of soil, removing completely the petrochemical compounds by using dosages about 5 g of extracting surfactant (sodium dodecyl sulfate (SDS)) per kg of soil. The main characteristics of the effluents produced in this soil remediation technology as well as the efficiency of the treatment (US, photolysis and BDD-electrolysis) depend on the dosage of SDS. Depollution of the effluents (degradation and mineralization of the organic matter) is related to the reduction in size of micelles formed by SDS and petroleum, and it depends on the treatment used. US and photolysis were inefficient decontamination processes, while BDD-electrolysis favors the complete depletion of micelles. However, the intensification of the efficiency was attained by synergic degradation effects when UV light irradiation and US were coupled with BDD-electrolysis, US/BDD-electrolysis and photo/BDD-electrolysis, respectively. Sulfate (coming from SDS) ions play an important role during the BDD-electrolysis, US/BDD-electrolysis and photo/BDD-electrolysis because persulfate and persulfate radicals are produced (by sulfate activation applying US or photolysis), improving the efficiency of the processes
UV assisted electrochemical technologies for the removal of oxyfluorfen from soil washing wastes
(Elsevier, 2017-06-15) Santos, Elisama Vieira dos; Sáez, Cristina; Cañizares, Pablo Canizares; Martínez-Huitle, Carlos Alberto; Rodrigo, Manuel Andres
In this work, it is studied the treatment of soil polluted with oxyfluorfen by Surfactant-Aided Soil-Washing (SASW) and after that, photo-electrolysis was used for the treatment of the soil-washing fluid produced. This liquid waste is characterized by the high concentration of micelles of pesticide and surfactant (sodium dodecyl sulfate, SDS), whose initial size depends on the ratio soil-surfactant used in the soil washing treatment. The waste treatment is studied in terms of the decrease in size of the particles and the depletion of the pollutants. Results clearly demonstrate that photo-electrolysis with diamond electrodes is a very effective treatment technology with results that overcome those obtained by single photolysis and/or single electrolysis with diamond electrodes. The greater improvements attained by combining UV irradiation to the electrolysis were observed in the removal of the pesticide while the removal of the surfactant was little affected. Electrolysis does not only deplete the complete concentration of pesticide but it also shows to be very efficient in the depletion of the surfactant, preventing its potential recycle. The significant concentration of sulfate released during the attack to the surfactant and the effect of the peroxosulfate anions that are formed from the anodic oxidation of that anion, explain the improved performance of the technology in the treatment of washing fluids with higher concentrations of SDS

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Navegando por Autor "Cañizares, Pablo Canizares"