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1.
Molecules ; 28(8)2023 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-37110832

RESUMO

The impacts on the morphological, electrical and hardness properties of thermoplastic polyurethane (TPU) plates using multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers have been investigated, using MWCNT loadings between 1 and 7 wt%. Plates of the TPU/MWCNT nanocomposites were fabricated by compression molding from extruded pellets. An X-ray diffraction analysis showed that the incorporation of MWCNTs into the TPU polymer matrix increases the ordered range of the soft and hard segments. SEM images revealed that the fabrication route used here helped to obtain TPU/MWCNT nanocomposites with a uniform dispersion of the nanotubes inside the TPU matrix and promoted the creation of a conductive network that favors the electronic conduction of the composite. The potential of the impedance spectroscopy technique has been used to determine that the TPU/MWCNT plates exhibited two conduction mechanisms, percolation and tunneling conduction of electrons, and their conductivity values increase as the MWCNT loading increases. Finally, although the fabrication route induced a hardness reduction with respect to the pure TPU, the addition of MWCNT increased the Shore A hardness behavior of the TPU plates.

2.
Molecules ; 26(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34072101

RESUMO

The tannery industry is one of the economic sectors that contributes to the development of different countries. Globally, Europe and Asia are the main producers of this industry, although Latin America and Africa have been growing considerably in recent years. With this growth, the negative environmental impacts towards different ecosystem resources as a result of the discharges of recalcitrated pollutants, have led to different investigations to generate alternative solutions. Worldwide, different technologies have been studied to address this problem, biological and physicochemical processes have been widely studied, presenting drawbacks with some recalcitrant compounds. This review provides a context on the different existing technologies for the treatment of tannery wastewater, analyzing the physicochemical composition of this liquid waste, the impact it generates on human health and ecosystems and the advances in the different existing technologies, focusing on advanced oxidation processes and the use of microalgae. The coupling of advanced oxidation processes with biological processes, mainly microalgae, is seen as a viable biotechnological strategy, not only for the removal of pollutants, but also to obtain value-added products with potential use in the biorefining of the biomass.


Assuntos
Resíduos Industriais/análise , Microalgas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Biocombustíveis , Análise da Demanda Biológica de Oxigênio , Biomassa , Biotecnologia , Cianobactérias , Ecossistema , Eletroquímica , Geografia , Metais Pesados , Oxirredução , Oxigênio/química , Curtume , Purificação da Água/métodos
3.
Water Sci Technol ; 82(6): 1031-1043, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055394

RESUMO

This study evaluated the capacity of a pilot-scale high-rate algal pond (HRAP) to remove pharmaceutical compounds (PCs) from domestic wastewater in the city of Santiago de Cali, Colombia. The compounds analyzed included antiepileptics, hypolipidemic drugs, tranquilizers and analgesics, and anti-inflammatory drugs. The HRAP operated under a continuous water flow of 0.2 m3d-1 and a 3-day hydraulic retention time (HRT). Removal efficiencies were high (>70%) for fenofibric acid, ibuprofen, and paracetamol; medium (30-70%) for gabapentin, lamotrigine, fenofibrate, gemfibrozil, diclofenac, ketoprofen, naproxen, and pentoxifylline; and low (<30%) for carbamazepine and its metabolite 10,11-Dihidro-10,11-dihidroxicarbamazepine (CBZ-Diol). The findings herein are similar to other studies, but were obtained with a shorter HRT. These results show that tropical environmental conditions favor photodegradation and contribute to the development of microalgae and the biodegradation process. Twenty microalgae species were identified, with the phylum Chlorophyta as the most abundant, particularly due to its natural introduction. The removal of the PCs also reflected a percentage reduction (>50%) in the ecological hazard posed by most of the compounds, although it is important to note that the hazard from gemfibrozil and ibuprofen remained high even after treatment, indicating the need for complementary treatment.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Colômbia , Lagoas , Clima Tropical , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
4.
Photochem Photobiol Sci ; 18(4): 920-928, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30758378

RESUMO

The present work reports the use of a flotation cell as a prospective reactor for ozonation and the intensification of ozonation (catalytic ozonation and photocatalytic ozonation). The effect of the pH, ozone concentration and loading catalyst was investigated. The performance of the flotation cell was compared with that of conventional reactors used in ozonation through the ozone utilized index (OUI), which was proposed in this work and relates the amount of ozone supplied to the system per milligram of degraded pollutant. The flotation cell has the lowest OUI, which indicates that the ozone supplied is highly consumed. It was found that the modified flotation cell is an efficient reactor for ozonation, catalytic ozonation and photocatalytic ozonation processes because total diclofenac degradation was achieved in a short time, mass transfer limitations were not found (Ha = 7.26), and it presented a relatively low energy consumption (1.15 kW h m-3).

5.
Photochem Photobiol Sci ; 18(4): 897-904, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30457636

RESUMO

This work reports the improvement in the photon absorption and degradation of acetaminophen (ACF) and diclofenac (DFC) by photosensitizing TiO2 with two types of dyes Eosin Y (Ey) and Rhodamine B (RhB). Experimental tests were carried out in a solar simulator for three hours for different systems and both pollutants. The influences of the TiO2 concentration (100, 200 and 800 mg L-1) and the catalyst-dye ratio (2%, 5% and 10%) were investigated. The degradation of the compounds was higher in the presence of TiO2-Ey compared to the TiO2-RhB and TiO2 for both pharmaceutical compounds, which was attributed to the anionic nature of Ey. DFC total degradation was achieved using 100 mg L-1 of catalyst loading and 10% of catalyst-dye ratio and the highest ACF degradation (71%) was obtained at 800 mg L-1 of catalyst loading and 5% of catalyst-dye ratio. The photon absorption was studied for both dyes using the six-flux absorption scattering model (SFM) for estimating the LVRPA (local volumetric rate of photon absorption). This was done by modifying the apparent optical thickness equation. It was found that the presence of dye in the photocatalytic systems considerably increases the LVRPA. The rate coefficients for the degradation of pharmaceutical compounds in the presence of the organic dyes were also obtained.


Assuntos
Acetaminofen/isolamento & purificação , Corantes/química , Diclofenaco/isolamento & purificação , Fotólise , Titânio/química , Poluentes Químicos da Água/isolamento & purificação , Catálise , Amarelo de Eosina-(YS)/química , Luz , Rodaminas/química
6.
Molecules ; 20(7): 13354-73, 2015 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-26205059

RESUMO

Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC) was used to remove commercial estradiol formulations (17-ß estradiol and nomegestrol acetate) from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC). In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25) and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir-Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM).


Assuntos
Anticoncepcionais Orais/química , Estradiol/química , Megestrol/análogos & derivados , Processos Fotoquímicos , Energia Solar , Água/química , Catálise , Megestrol/química
7.
Heliyon ; 10(11): e32358, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38912490

RESUMO

In this work, a bibliometric study was carried out to perform a scientific and technological analysis of exchange-spring magnets, an alternative permanent magnet synthesized by reducing or eliminating the use of critical raw materials, such as rare earths. The bibliometric analysis utilized the Scopus database, Orbit-Intellixir, VOSviewer, Orbit-Intelligence and Loglet Lab 4 software for maturity analysis, keyword network representations, charts and graphs for scientific articles and/or patents. A special analysis was performed on nanocomposite and thin-films systems based on Nd-Fe-B, SmCo5 and Mn-Al-C alloys, either mixed or layered with a soft magnetic phase, where relevant information on their magnetic parameters was compilated in tables, highlighting the nanostructured systems that have been exhibited the best permanent magnet properties. The bibliometric analysis revealed that the primary production of scientific articles is concentrated in industrialized countries, and they are predominantly published in journals dedicated to magnetism. A patents analysis showed that Nissan motors is by far the main applicant, with most of its patents is focused on technological domains related to electrical machinery, apparatus, energy and metallurgy. On the other hand, the S-curve of maturity for scientific articles indicated that the study of exchange-spring magnets is entering a mature state. In contrast, patent production, following a bi-logistic model, is in a saturation stage for the second S-curve. Maturity analyses, employing S-curve, bi-logistic and multi-logistic models, were performed on nanocomposites and thin films based on Nd-Fe-B, SmCo5 and Mn-Al-C alloys, respectively. We found that the investigation in Nd-Fe-B-based alloys is close to enter to a scientific saturation stage, while an average growth stage is observed for the SmCo5 and Mn-Al-C-based alloys. This suggests that research on alternative magnets, capable of fulfilling technological applications where a Nd-Fe-B magnets are commonly used, is a topic of significant interest.

8.
Environ Sci Pollut Res Int ; 31(5): 6782-6814, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38165540

RESUMO

This study presents a systematic review of the scientific and technological production related to the use of systems based on UV, H2O2, and Cl2 for the elimination of antibiotic-resistant bacteria (ARB) and genes associated with antibiotic resistance (ARGs). Using the Pro Know-C (Knowledge Development Process-Constructivist) methodology, a portfolio was created and analyzed that includes 19 articles and 18 patents published between 2011 and 2022. The results show a greater scientific-technological production in UV irradiation systems (8 articles and 5 patents) and the binary combination UV/H2O2 (9 articles and 4 patents). It was emphasized that UV irradiation alone focuses mainly on the removal of ARB, while the addition of H2O2 or Cl2, either individually or in binary combinations with UV, enhances the removal of ARB and ARG. The need for further research on the UV/H2O2/Cl2 system is emphasized, as gaps in the scientific-technological production of this system (0 articles and 2 patents), especially in its electrochemically assisted implementation, have been identified. Despite the gaps identified, there are promising prospects for the use of combined electrochemically assisted UV/H2O2/Cl2 disinfection systems. This is demonstrated by the effective removal of a wide range of contaminants, including ARB, fungi, and viruses, as well as microorganisms resistant to conventional disinfectants, while reducing the formation of toxic by-products.


Assuntos
Peróxido de Hidrogênio , Purificação da Água , Antagonistas de Receptores de Angiotensina , Purificação da Água/métodos , Cloro , Inibidores da Enzima Conversora de Angiotensina , Resistência Microbiana a Medicamentos/genética , Bactérias/genética , Desinfecção/métodos , Raios Ultravioleta
9.
Environ Sci Pollut Res Int ; 31(28): 40758-40777, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38819507

RESUMO

The presence of CECs in aquatic systems has raised significant concern since they are potentially harmful to the environment and human health. Eliminating CECs has led to the development of alternatives to treat wastewater, such as advanced oxidation processes (AOPs). The ultraviolet-mediated activation of monochloramine (UV/NH2Cl) is a novel and relatively unexplored AOPs for treating pollutants in wastewater systems. This process involves the production of amino radicals (•NH2) and chlorine radicals (Cl•) from the UV irradiation of NH2Cl. Studies have demonstrated its effectiveness in mitigating various CECs, exhibiting advantages, such as the potential to control the amount of toxic disinfection byproducts (TDBPs) formed, low costs of reagents, and low energy consumption. However, the strong influence of operating parameters in the degradation efficiency and existence of NH2Cl, the lack of studies of its use in real matrices and techno-economic assessments, low selectivity, and prolonged treatment periods must be overcome to make this technology more competitive with more mature AOPs. This review article revisits the state-of-the-art of the UV/NH2Cl technology to eliminate pharmaceutical and personal care products (PPCPs), micropollutants from the food industry, pesticides, and industrial products in aqueous media. The reactions involved in the production of radicals and the influence of operating parameters are covered to understand the formation of TDBPs and the main challenges and limitations of the UV/NH2Cl to degrade CECs. This review article generates critical knowledge about the UV/NH2Cl process, expanding the horizon for a better application of this technology in treating water contaminated with CECs.


Assuntos
Cloraminas , Raios Ultravioleta , Poluentes Químicos da Água , Cloraminas/química , Poluentes Químicos da Água/química , Desinfecção/métodos , Águas Residuárias/química , Purificação da Água/métodos , Oxirredução
10.
Heliyon ; 10(12): e32794, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38975128

RESUMO

Thermoplastic polyurethane (TPU) doped with multi-walled carbon nanotubes (MWCNTs) at 1, 3, 5, and 7 wt% has been studied. The effect of MWCNTs on thermal, viscoelastic, and electric properties in the TPU matrix was characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and by impedance spectroscopy. The results show that the thermal, electrical, and viscoelastic properties, such as the glass transition temperature, shifted towards high temperatures. The melting temperature decreased, and the conductivity and the storage modulus increased by 61.5 % and 58.3 %. The previously observed behavior on the films is due to the increase in the mass percentage of carbon nanotubes (CNTs) in the TPU matrix. Also, it can be said that the CNTs were homogeneously dispersed in the TPU matrix, preventing the movement of the polymer chains, and generating channels or connections that increase the conductivity and improve the thermal properties of the material.

11.
Artigo em Inglês | MEDLINE | ID: mdl-38141124

RESUMO

There is high interest in the development of water pollution remediation technologies. Advanced oxidation processes (AOPs) are a promising alternative for the degradation of organic compounds; however, these technologies have been limited mainly by high operating costs and, in some cases, by forming byproducts, which can be more hazardous than the original pollutants. Activated carbon (AC) is a porous material that can be combined with AOP systems in various ways, given its adsorbent and catalytic characteristics. In addition, AC is a flexible, adaptable, and low-cost material. This article presents a bibliometric analysis of AOPs incorporating CA in scientific research and patents; the Scopus database was used to obtain patents and Orbit Express for patents. The most investigated AOPs incorporating AC are photocatalysis processes, Fenton processes, persulfate-based AOP, electrochemical processes, and ozonation. However, it is the persulfate-based AOP that has seen the greatest growth in scientific publications in recent years; this great interest can be related to the synergy that the process has with AC, allowing the degradation of contaminants via radical and non-radical. According to the maturity analysis of scientific publications, photocatalysis, Fenton, electrochemistry, ozonation, and persulfate technologies are in a growth stage and will reach maturity in 2034, 2042, 2040, 2034, and 2035, respectively; these technologies coupled with AC are expected to generate a greater number of patents when they reach maturity.

12.
Curr Opin Environ Sci Health ; 33: 100457, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37020893

RESUMO

The COVID-19 pandemic is considered one of the most significant global disasters in the last years. The rapid increase in infections, deaths, treatment, and the vaccination process has resulted in the excessive use of pharmaceuticals that have entered the environment as micropollutants. Considering the prior information about the presence of pharmaceuticals found in the wastewater of Cali, Colombia, which was collected from 2015 to 2022. The data monitored after the COVID-19 pandemic showed an increase in the concentration of analgesics and anti-inflammatory drugs of up to 91%. This increase was associated with the consumption of pharmaceuticals for mild symptoms, such as fever and pain. Moreover, the increase in concentration of pharmaceuticals poses a highly ecological threat, which was up to 14 times higher than that reported before of COVID-19 pandemic. These results showed that the COVID-19 had not only impacted human health but also had an effect on environmental health.

13.
Chemosphere ; 341: 139988, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37669720

RESUMO

The performance of a pilot-scale boron-doped diamond (BDD) reactor through a numerical analysis of reaction rate parameters and enhanced mass transfer has been investigated. The main objective of this research is to evaluate the efficiency of the reactor in mineralizing and degrading caffeine as an emerging contaminant. Based on the kinetic mechanisms and mass transport correlations reported in the literature, two reaction rate kinetic models for caffeine degradation are proposed and analyzed. The models consider different electrolytes (NaCl and Na2SO4) and applied current densities. The kinetic fitting process utilizes the gradient-maximal electrochemical approach, together with orthogonal placement methods, fourth-order Runge-Kutta (RK4) methods, and Nelder & Mead methods for optimization of kinetic parameters and spatial discretization of the material balance. Experimental data obtained from a factorial design with four factors and two levels (24) validate the proposed kinetic models. Caffeine degradation is achieved with NaCl and Na2SO4 electrolytes at concentrations of 60 ppm and 100 ppm, respectively. The corresponding applied loads are 1.5 AhL-1 and 3 AhL-1. Na2SO4 exhibits superior performance with a total organic carbon (TOC) removal efficiency of 99.13%, while NaCl achieves 31.47% mineralization. The behavior of caffeine degradation under the operational and scale conditions demonstrates that NaCl, as a support electrolyte, enables controlled charge transfer (current density) during the degradation process. In contrast, Na2SO4 as a support electrolyte introduces a mixed control of charge and mass transfer. The pilot-scale kinetic parameters obtained in this study provide valuable insights into the support electrolyte dynamics and current density dynamics in BDD-based Electrooxidation (EO) systems, particularly in complex matrix applications. Furthermore, the observed electrical consumption supports the potential application of EO as a viable technology for industrial-scale tertiary wastewater treatment, specifically for caffeine removal.


Assuntos
Cafeína , Cloreto de Sódio , Eletricidade , Indústrias , Cinética
14.
Toxics ; 11(4)2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-37112593

RESUMO

The textile industry is a global economic driving force; however, it is also one of the most polluting industries, with highly toxic effluents which are complex to treat due to the recalcitrant nature of some compounds present in these effluents. This research focuses on the removal of Chemical Oxygen Demand (COD), color, Total Organic Carbon (TOC), and Ammoniacal Nitrogen (N-NH3) on tannery wastewater treatment through an advanced oxidation process (AOPs) using sodium bicarbonate (NaHCO3), hydrogen peroxide (H2O2) and temperature using a central composite non-factorial design with a surface response using Statistica 7.0 software. All experiments used a 500 mL reactor with 300 mL of tannery wastewater from a company in Cúcuta, Colombia. The physicochemical characterization was done to determine the significant absorbance peaks about the color in the wavelengths between 297 and 669 nm. Statistical analysis found that the concentration of NaHCO3 affects the removal of color and N-NH3; however, it did not affect COD and TOC. The optimal process conditions for removing the different compounds under study were: NaHCO3 1 M, H2O2 2 M, and 60 °C, with efficiencies of 92.35%, 31.93%, 68.85%, and 35.5% N-NH3, COD, color, and TOC respectively. It can be concluded that AOPs using H2O2 and NaHCO3 are recommended to remove color and N-NH3.

15.
Heliyon ; 8(11): e11256, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36353151

RESUMO

Global pork production has an annual growth of approximately 2.1%, and its economic and environmental impact are related with the treatment of waste in the production chain. There is little evidence of research advances to generate alternatives for using these wastes. The lack of research related to microalgae cultivation using digestate produced by porcine residues generates negative environmental impact, inadequate and inefficient technologies, low recovery and use of waste and loss of value and competitiveness in the market. The available literature focuses mainly on the treatment of anaerobic digestion liquid effluents for the removal of components, but not on the generation of value-added products. Therefore, there is a need to collect the available information, analyze it and propose other new methodologies. This article presents the information obtained from conducting a systematic review of the literature with a bibliometric and a comparative analysis; achieving an analysis of the temporal and geographical distribution, the main topics, the most influential players, the degree of maturity of the research and different strategies collected for microalgae-based swine manure digestate treatment. In this way, it was possible to capture an overview of the current state of the development of research focused on the use of digestate for the cultivation of microalgae, visualizing important aspects as the evolution of publications, identifying China and USA as the main players in research, biomass and wastewater as potential topics also Spirulina, Astaxanthin and beta-carotene as the main products based on microalgae. Thus, achieving an structure, organized and synthesized landscape of scientific and technological knowledge available for the proposal of investigations that allow the use of anaerobic digestion liquid effluents as cultivation medium for microalgae.

16.
Heliyon ; 8(3): e09028, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35342833

RESUMO

Pollution by polymeric materials - in particular plastics - has a negative effect on the health of our planet. Approximately 4.9 billion tons of plastic are estimated to have been improperly disposed of, with the environment as their final destination. This scenario comes from a linear economic system, extraction-production-consumption and finally disposal. The alarming panorama has created the need to find technological solutions that generate new uses for discarded polymeric materials or turn them into part of the production process to produce new and novel materials, such as carbon nanotubes, graphene, or other carbonaceous materials of high added value, modifying the economy for a circular and sustainable production model. This review highlights the negative impact that the disposal of plastic materials has on the environment and the research needs that allow solving the pollution problems generated in the environment by these wastes. Also, the review highlights the current and future directions of recovery plastic waste research-based to promote innovations in the plastic production sector that could allow obtaining breakpoints in other industrial sectors with the technology-based companies.

17.
Environ Sci Pollut Res Int ; 29(28): 42120-42129, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33983609

RESUMO

This work aims to integrate several hydrogen peroxide (H2O2) activation mechanisms, photolysis (UVC irradiation), chemical electron transfer (TiO2-P25 photocatalysis), and reaction with TiO2-P25 in dark conditions, for reactive oxygen species (ROS) generation towards the removal of contaminants of emerging concern (CECs), in a single unit operated in continuous-flow mode. An H2O2 stock solution is fed by the lumen side of a tubular ceramic membrane, delivering the oxidant to the (i) catalyst immobilized in the membrane shell-side and (ii) annular reaction zone (ARZ, space between membrane shell-side and outer quartz tube) where CECs contaminated water flows with a helix trajectory, being activated by UV light provided by four lamps placed symmetrically around the reactor. First, the effect of several parameters in the removal of a CEC target molecule, amoxicillin (AMX), was evaluated using a synthetic solution ([AMX]inlet = 2.0 mg L-1): (i) light source (UVA or UVC radiation), (ii) H2O2 dose, (iii) H2O2 injection method (radial permeation vs. upstream injection), and (iv) number of TiO2-P25 layers deposited on the membrane. The UVC/H2O2/TiO2 system with radial addition of H2O2 (20 mg L-1) and 9-TiO2-P25 layers provided the highest AMX removal efficiency (72.2 ± 0.5%) with a UV fluence of 45 mJ cm-2 (residence time of 4.6 s), due to the synergic effect of four mechanisms: (i) AMX photolysis, (ii) H2O2 photocleavage, (iii) TiO2-P25 photoactivation, and (iv) chemical reactions between H2O2 and TiO2-P25. The urban wastewater matrix showed a negative effect on AMX removal (~44%) due to the presence of ROS scavengers and light-filtering species.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Amoxicilina , Cerâmica , Peróxido de Hidrogênio/química , Oxirredução , Espécies Reativas de Oxigênio , Titânio/química , Raios Ultravioleta , Águas Residuárias/química , Poluentes Químicos da Água/análise
18.
Heliyon ; 7(5): e06969, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34027174

RESUMO

A methodology for the analysis of the behavior of complex reactors based on the construction of profiles of a dimensionless number (Damköhler) for each main chemical species ( D a i ) was proposed. A 4-chlorophenol mineralization reaction in a heterogeneous solar reactor with suspended TiO2 and addition of H2O2 with tubular geometry and radiation collectors, fluid flow and a recirculation system was selected as a complex model system in order to validate the approach. The dynamic behavior of the reactor in dimensionless variables was modeled as a function of D a i . Where D a i ( z , t ) is a local property and grouped the optical and surface's properties of the catalyst, catalyst load, radiation intensity, the photon absorption rate, rate of non-photochemical reactions, the H2O2 effect, the reaction rate of different stages like adsorption, attack of radicals, surface reactions, plus design and operation variables like reactor volume and volumetric flow. A coupling of orthogonal collocation and Runge-Kutta methods were used to solve the PDEs and carry out the simulations to the different experimental conditions, resulting in profiles of D a i , C i , and conversion in function of time and space. The D a i profiles proposed in the new methodology are capable of describing the disturbances in solar reactors, to indicate consumption and generation rates, instantaneous changes of reaction rate, to describe competitive reactions and quenching effects and to determine equilibrium concentrations, all of the above at each time and space. Therefore, this approach is a analysis tool of reactors which complements the concentration profile. This methodology can be extended to other reactive systems, adapting the intrinsic reaction rates.

19.
Heliyon ; 7(9): e07949, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34541354

RESUMO

This research deepens the analysis of the mineral water footprint, especially that of gold, in regions that are understudied and where mining has been an intensified extractive activity since the colonial era, as is the case in the northern part of department of Cauca in Colombia. Thus, the purpose was to estimate the water footprint indicators in gold mining in Suárez (Cauca, Colombia), to quantify the impacts generated by the non-returned water in the production process and the levels of pollutants in the wastewater, aimed to strength public policies, control strategies and mitigation that generates reductions in the impacts from mining activities on the environment. The blue water footprint was estimated in 79.91 m3 per kg of gold extracted and the gray water footprint was found to be in the range of 272,125.39 to 404,825.11 m3 per kg of gold extracted. The water footprint values obtained were compared with other mines with similar operations. These results generate a baseline for decision making, providing elements for environmental strategic planning, regulations and showing the great environmental pressure that gold activity exerts on water resources and the territories.

20.
Environ Sci Pollut Res Int ; 28(19): 24079-24091, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33439445

RESUMO

This work proposes a novel approach for the coupling of ozonation and Fenton processes using a new prototype of a high rotation bubble reactor (HRBR), which improves utilization of the ozone and hydrogen peroxide through bubble generation and axial and radial dispersion of the flow. The HRBR integrates the rotor and the diffuser in the same device facilitating the generation and dispersion of the ozone bubbles inside the reaction tank. Thus, the mass transfer to the liquid phase is enhanced. Most of the experiments were carried out under neutral pH and 1580 rpm of agitation during the 20 min of reaction. Total ibuprofen degradation was achieved within 20 min of operation for most of the couplings and individual processes evaluated. It was successfully demonstrated that the HRBR can be used as a reactive system for heterogeneous Fenton and ozonation coupling because it presents a high synergy. For the ozonation process, the reactor also displayed a good performance because the residual ozone in the gas is lower than 0.4 mg/L, which indicates that there is a suitable ozone utilization. Ibuprofen degradation by other processes like oxidation direct by H2O2 and heterogeneous Fenton was 28.0% and 73.1%, respectively. It was determined that the reaction rate, synergy, OUI (ozone utilized index), and consumption of electrical energy (EE/O) of the coupled processes could be improved by using the HRBR depending on the experimental conditions.


Assuntos
Poluentes Ambientais , Ozônio , Poluentes Químicos da Água , Peróxido de Hidrogênio , Compostos de Ferro , Minerais , Oxirredução , Rotação
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