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C.A. Estrada-Gasca

Bio: C.A. Estrada-Gasca is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Water treatment & Water quality. The author has an hindex of 6, co-authored 8 publications receiving 92 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a multiple compound compound parabolic concentrator (MCPC) was designed to carry out photocatalytic degradation studies as a function of geometric solar concentration ratio between 1 sun and 2 suns.
Abstract: Photodegradation studies of carbaryl pesticides were performed as a function of solar concentration using newly designed CPC collectors with different geometric solar concentration ratios. Design of a Multiple Compound Parabolic Concentrator, or MCPC, was performed by taking into account both that photocatalytic degradation efficiency is a function of the square root of photon flow intensity that excites the photocatalyst and that TiO2 is able to absorb more sunlight (photons) than the provided in utilising a 1-sun geometric concentration ratio (CR). The Multiple Compound Parabolic Concentrator was initially designed to carry out photocatalytic degradation studies as a function of geometric solar concentration ratio between 1 sun and 2 suns and subsequently to explore the possibility of using CPC collectors in photocatalysis studies with a solar concentration ratio greater than 1 sun. TiO2 photocatalysts, immobilised over 1.40-meter-long Duran glass tubes, were specially fabricated for this experiment. Finally, to evaluate the photoreactor performance, the photocatalytic degradation of the carbaryl pesticide was used carried out. When the photocatalytic reactor equipped with the CPC solar concentrator of 1 sun was used to carry out degradation processes under UV + TiO2 and UV + TiO2 + H2O2 conditions, degradation levels of 41% and 79% were reached, respectively. Alternatively, when the photocatalytic reactor equipped with the CPC solar concentrator of 2 suns was used to degrade the same pollutant under the same conditions, degradation levels of 54% and 92% were achieved, respectively. To complete the characterisation of the above mentioned degradation processes, the experimental values of parameters such as global kinetic constants, TOC and COD, were determined.

24 citations

Journal ArticleDOI
TL;DR: In this paper, a mathematical model to predict the shading coefficients (SC) and solar rejection factor (SRF) of various types of chemically deposited solar control coatings is presented, and the values of SC and SRF are presented for coatings with soar absorptance in the 50-75% range and solar reflectance in a 10-25% range for typical exterior temperature of 10-50 degrees C.
Abstract: A mathematical model to predict the shading coefficients (SC) and solar rejection factor (SRF) of various types of chemically deposited solar control coatings is presented. The values of SC and SRF are presented for coatings with soar absorptance in the 50-75% range and solar reflectance in the 10-25% range for typical exterior temperature of 10-50 degrees C. Chemically deposited solar control coatings with a protective polymer coating applied on 6 mm thick sheet glass in architectural windows are seen to provide SC in the 0.3 to 0.75 range depending on the optical characteristics and exterior temperatures. A solar rejection factor of 33-56% is available from the coatings already reported.

21 citations

Journal ArticleDOI
TL;DR: In this paper, the solar control performance of chemically deposited thin film coatings is described for a 6 mm sheet glass in a tropical location showing that solar radiation rejection of [approximately] 50% is obtainable for a integrated transmittance of 17%.
Abstract: Solar control characteristics are described for chemically deposited thin film coatings consisting of an initial layer of Bi[sub 2]S[sub 3] film of [approximately] 0.05 [mu]m thickness deposited at room temperature (25 C) for 45-76 min from baths containing bismuth nitrate, triethanolamine (TEA) and thioacetamide and a Cu[sub x]S thin film of 0.1-0.25 [mu]m thickness deposited either at room temperature, for 3-6 h, or at 50 C, for 1-2 h using baths consisting of copper(II) chloride, TEA, thioureau (TU), NaOH and NH[sub 3](aq). Air annealing of these films at 150 C for 30 min yield well-desired solar control characteristics: sheet resistance in a range which signifies a low thermal emittance; integrated transmittance of 15-32% in the visible region and 11-22% in the near-infrared region; integrated transmittance of [approximately]13-25% for solar radiation and a range of shades in reflected daylight. Using a mathematical model, the solar control performance of these coatings in a 6 mm sheet glass is predicted for an architectural window in a tropical location showing that solar radiation rejection of [approximately] 50% is obtainable for a integrated transmittance of 17%.

21 citations

Journal ArticleDOI
TL;DR: Theoretical efficiencies and thermal behavior of all-glass Evacuated Tube solar Collectors with an Internal Absorber Film (ETCIAF) are compared and contrasted with the traditional design of allglass ETCEAF, using the absorber film on the external surface of the inner tube as discussed by the authors.
Abstract: Theoretical efficiencies (η) and thermal behaviour of all-glass Evacuated Tube solar Collectors with an Internal Absorber Film (ETCIAF), i.e. the absorber film deposited in the inner surface of the inner tube, are compared and contrasted with the traditional design of all-glass Evacuated Tube solar Collectors with an External Absorber Film (ETCEAF), using the absorber film on the external surface of the inner tube. The values of η of the ETCIAF are unacceptably lower than that of ETCEAF for any particular value of the heat transfer coefficient (hb) for the annular space, except in the case of a highly leaky ETCEAF, with hb > 2.6 W/m2 K. However, it is shown that the use of a transparent conductive coating with moderately low emittance ∼0.1−0.25 on the outside of the absorber tube of ETCIAF can offer efficiences ∼0.75−0.63, respectively, for f = 0.1 °C m2/K, competing well (η = 0.76) with the ETCEAF design operating under best conditions (α = 0.91, ϵ = 0.05, and hb = 0.026 W/m2 K).

17 citations

Journal ArticleDOI
TL;DR: In this paper, a mathematical model enabling the prediction of the thermal performance of solar control glazings employing chemically deposited solar control coatings with or without a transparent protective polymer coating is presented.
Abstract: A mathematical model enabling the prediction of the thermal performance of solar control glazings employing chemically deposited solar control coatings with or without a transparent protective polymer coating is presented. Differential energy balance for the glazing is set up assuming one-dimensional steady state case for normal incidence of air mass 2 solar radiation and by considering conductive heat transfer within the glazing and convective and radiative heat transfer into the interior and exterior of the building. Using the specific example of the optical properties of the already reported SnSCu x S solar control coatings, the redistribution of the absorbed component of the solar radiation is evaluated for constant convective heat transfer coefficient and temperature in the interior and for exterior temperatures in the 0–50°C range. The results yield shading coefficient versus exterior temperature curves for two specific SnSCu x S coatings without and with a protective transparent varnish and offering transmittance in the visible region of 27 and 21%.

11 citations


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TL;DR: In this article, the authors discuss the next generation of smart windows based on organic materials which can change their properties by reflecting or transmitting excess solar energy (infrared radiation) in such a way that comfortable indoor temperatures can be maintained throughout the year.
Abstract: Windows are vital elements in the built environment that have a large impact on the energy consumption in indoor spaces, affecting heating and cooling and artificial lighting requirements. Moreover, they play an important role in sustaining human health and well-being. In this review, we discuss the next generation of smart windows based on organic materials which can change their properties by reflecting or transmitting excess solar energy (infrared radiation) in such a way that comfortable indoor temperatures can be maintained throughout the year. Moreover, we place emphasis on windows that maintain transparency in the visible region so that additional energy is not required to retain natural illumination. We discuss a number of ways to fabricate windows which remain as permanent infrared control elements throughout the year as well as windows which can alter transmission properties in presence of external stimuli like electric fields, temperature and incident light intensity. We also show the potential impact of these windows on energy saving in different climate conditions.

877 citations

Journal ArticleDOI
TL;DR: In this article, the authors have described in detail, chemical bath deposition method of metal chalcogenide thin films, it is capable of yielding good quality thin films and their preparative parameters, structural, optical, electrical properties etc.
Abstract: Metal chalcogenide thin films preparation by chemical methods are currently attracting considerable attention as it is relatively inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors or metals can be used since these are low temperature processes which avoid oxidation and corrosion of substrate. These are slow processes which facilitates better orientation of crystallites with improved grain structure. Depending upon deposition conditions, film growth can take place by ion-by-ion condensation of the materials on the substrates or by adsorption of colloidal particles from the solution on the substrate. Using these methods, thin films of group II–VI, V–VI, III–VI etc. have been deposited. Solar selective coatings, solar control, photoconductors, solid state and photoelectrochemical solar cells, optical imaging, hologram recording, optical mass memories etc. are some of the applications of metal chalcogenide films. In the present review article, we have described in detail, chemical bath deposition method of metal chalcogenide thin films, it is capable of yielding good quality thin films. Their preparative parameters, structural, optical, electrical properties etc. are described. Theoretical background necessary for the chemical deposition of thin films is also discussed.

733 citations

Journal ArticleDOI
TL;DR: In this paper, the use of TiO2 photocatalysis for water and waste treatment, treating contaminants of emerging concern (CECs), pesticides, endocrine disrupters (EDs) and bacteria using both UV and visible light irradiations is discussed.
Abstract: Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a promising AOT to alleviate the problem of water pollution. Despite recent research into other photocatalysts (e.g. ZnO, ZnS, Semiconductor-Graphene composites, perovskites, MoS2, WO3 and Fe2O3), titanium dioxide (TiO2) remains the most popular photocatalyst due to its low cost, nontoxicity and high oxidising ability. Moreover, titania photocatalysts can easily be immobilized on various surfaces and be scaled up for large scale water treatment. The current review aims to highlight recent advancements in photocatalytic AOTs with main emphasis on TiO2 photocatalysis. This review also discusses the use of TiO2 photocatalysis for water and waste treatment, treating contaminants of emerging concern (CECs), pesticides, endocrine disrupters (EDs) and bacteria using both UV and visible light irradiations. It was concluded that with efficient photoreactor configuration and further studies on the photocatalyst regeneration, TiO2 photocatalysis is a viable option for the reclamation of agricultural/irrigational waste water. Novel doped photocatalysts such as ZnS-CuS-CdS, carbon spheres/CdS, g-C3N4-Au-CdS, ZnS-WS2-CdS, C3N4-CdS and Pd-Cr2O3-CdS have also been discussed. Finally, the advances in the actively studied metal organic framework based photocatalysts that are emerging as effective alternate for metal oxide based photocatalysts is also discussed in detail.

488 citations

Journal ArticleDOI
TL;DR: In this article, the basic concepts underlying the chemical bath deposition technique and recipes developed in our laboratory during the past ten years for the deposition of good-quality thin films of CdS, CdSe, ZnS, PbSe, SnS, Bi2S3, BiSe3, SbS3 Sb2S2, CuS, CuSe, etc.
Abstract: In this paper we present the basic concepts underlying the chemical bath deposition technique and the recipes developed in our laboratory during the past ten years for the deposition of good-quality thin films of CdS, CdSe, ZnS, ZnSe, PbS, SnS, Bi2S3, Bi2Se3, Sb2S3, CuS, CuSe, etc. Typical growth curves, and optical and electrical properties of these films are presented. The effect of annealing the films in air on their structure and composition and on the electrical properties is notable: CdS and ZnS films become conductive through a partial conversion to oxide phase; CdSe becomes photosensitive, SnS converts to SnO2, etc. The use of precipitates formed during deposition for screen printing and sintering, in polymer composites and as a source for vapor-phase deposition is presented. Some examples of the application of the films in solar energy related work are presented.

345 citations

Journal ArticleDOI
TL;DR: A review of the science behind the performance of visible/solar light active photocatalysts is presented in this article, which includes the fundamentals of photocatalysis, including thermodynamics, reaction kinetics and recombination.
Abstract: Intensive research work is being undertaken globally to effectively use the process of photocatalysis for the degradation of organic pollutants from industrial effluents. For the same, TiO2 has been extensively explored, which however, has a limitation of being able to utilise the UV spectrum only, due to its high band gap property. Since a substantial percentage of the solar spectrum is visible light, it is imperative that for an effective and versatile utilisation of the incident solar energy, visible light active photocatalysts, having a relatively smaller band gap are developed. Smaller band gap, however, often results in rapid recombination and conversion of photonic energy into non-usable heat. This article is a review of the science behind the performance of visible/solar light active photocatalysts. The first part includes the fundamentals of photocatalysis, including thermodynamics, reaction kinetics and recombination. The second part reviews the visible/solar light active photocatalytic materials as well as the significant research efforts made so far in the exploration of possible mechanisms of photoexcitation and remedies for minimization of recombination. Finally, an operational overview is provided which is helpful in assessing the influence of key parameters on the photocatalytic activity. This review presents a single point reference for a comparative study and ready assimilation of the basics and new directions in photocatalysis, thus making it more conducive to further research and active commercialisation.

290 citations