Three‐dimensional electric resistivity tomography surveys carried out on heavily urbanized areas represent a cumbersome task since buildings, houses, or other types of obstacles do not allow parallel electric resistivity tomography lines to be deployed. This paper proposes applying any four‐electrode configuration to provide subsurface information in complex urban areas. Such a procedure allows acquiring information beneath a construction by simply surrounding the structure of interest by a series of electric resistivity tomography profiles. Apparent resistivity is obtained from ‘L’‐ and ‘Corner’‐shaped profiles, where alternations between current and potential electrodes are carried out in an automatic way. Four ‘L’‐arrays and four ‘Corner’‐arrays are employed in a square geometry that allows surrounding the studied target to cover the subsurface. The first mentioned array will provide deep information. The second array will cover more of the shallow subsurface information. For the ‘L‐’ and ‘Corner’‐arrays, a mixture of traditional arrays are employed, like the Wenner–Schlumberger, axial, equatorial, azimuthal, and perpendicular dipole arrays.
Two synthetic examples are presented to demonstrate the possibilities of the proposed electric arrays. A resistive cube set at the centre of a working cube is modelled. The ‘L‐’ and ‘Corner‐’ arrays are capable to detect such a model; however, dimensions are exaggerated. Later on, an extended wall model is dealt with. Similar results as in the first synthetic example are obtained in terms of geometry and resistivity. However, depth to the top of the wall model is not adequately recovered in comparison with the traditional methodology.
Finally, the ‘L’‐ and ‘Corner’‐arrays are applied in an archaeological site named El Pahñu, located in Central Mexico. The new methodology described here is compared with the traditional 3D procedure employing a grid of electric resistivity tomography transects. As expected, the approach discussed in this investigation produced a reasonable solution towards the central portion of the working cube. However, shallow resistive anomalies (size about the electrode interval) were not fully detected, in comparison to a traditional 3D survey, where parallel lines forming a grid could be deployed. The reason is that no electrodes were set towards the central portions of the structure under study. However, the L‐ and Corner‐arrays are more sensitive to anomalies produced by deeper objects, which cannot be observed in the traditional method, especially when objects are located in between the electric resistivity tomography transects.
As a model for the removal of complex organic contaminants from industrial water effluents, the heterogeneous photocatalytic degradation of Rhodamin 6G was studied using TiO 2-derived catalysts, incorporated in water as suspension as well as supported in raschig rings. UV and Visible light were tested for the photo-degradation process. TiO 2 catalysts were synthesized following acid synthesis methodology and compared against commercial TiO 2 catalyst samples (Degussa P25 and Anatase). The bandgap (E g) of the TiO 2 catalysts was determined, were values of 2.97 and 2.98 eV were obtained for the material obtained using acid and basic conditions, respectively, and 3.02 eV for Degussa P25 and 3.18 eV for anatase commercial TiO 2 samples. Raschig ringssupported TiO 2 catalysts display a good photocatalytic performance when compared to equivalent amounts of TiO 2 in aqueous suspension, even though a large surface area of TiO 2 material is lost upon support. This is particularly evident by taking into account that the characteristics (XRD, RD, Eg) and observed photodegradative performance of the synthesized catalysts are in good agreement with the commercial TiO 2 samples, and that the RH6G photodegradation differences observed with the light sources considered are minimal in the presence of TiO 2 catalysts. The presence of additives induce changes in the kinetics and efficiency of the TiO 2-catalyzed photodegradation of Rh6G, particularly when white light is used in the process, pointing toward a complex phenomenon, however the stability of the supported photocatalytic systems is acceptable in the presence of the studied additives. In line with this, the magnitude of the chemical oxygen demand, indicates that, besides the different complex photophysical processes taking place, the endproducts of the considered photocatalytic systems appears to be similar.
Novel Sb-doped SnO2 ceramic electrodes sintered at different temperatures, are applied to the degradation of Reactive Black 5 in both divided and undivided electrochemical reactors. In the undivided reactor the discoloration of the solution took place via the oxidation of RB5 dye, without the corresponding reduction in the chemical oxygen demand for the ceramic electrodes. However, in the divided one, it was possible to achieve the discoloration of the solution while at the same time decreasing the chemical oxygen demand through the ·OH-mediated oxidation, although the chemical oxygen demand degradation took place at a slower rate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.