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Green Catalysts: Application to Waste and Groundwater Treatment
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Green Catalysts: Application to Waste and Groundwater Treatment

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 40048

Special Issue Editors

Prof. Dr. Aurora Santos

E-Mail Website
Guest Editor
Chemical Engineering and Materials Department, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
Interests: chemical engineering; environmental engineering; wastewater treatments; soil and groundwater remediation; advance oxidation processes; chemical oxidation; chemical reduction; surfactant enhanced remediation; reactive transport modeling; applied kinetic; chemical reactors; organic pollutants
Dr. Carmen María Domínguez Torre

E-Mail Website1 Website2
Guest Editor
Chemical Engineering and Materials Department, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
Interests: chemical engineering; environmental engineering; soil and groundwater remediation; wastewater treatment; advanced oxidation processes; in situ chemical oxidation processes (ISCO); in situ chemical reduction processes (ISCR); surfactant enhanced remediation; catalytic wet peroxide oxidation; preparation and characterization of catalysts; chlorinated organic pollutants

Special Issue Information

Dear Colleagues,

Water pollution is one of the most important global problems as a result of population growth, industrial development, and associated resource consumption. This context requires solutions according to sustainability criteria, based on the application of efficient, economic, and low-environmental impact processes. Some of the major advances in the treatment of wastewater by different oxidation and reduction processes over the past decade have been in the area of catalysis, and therefore, interest in the use of green catalysts has greatly increased. Green catalysts are eco-friendly, inexpensive, reusable, and/or recyclable materials that reduce or eliminate the use or generation of hazardous substances. Therefore, sustainable water management should be focused on the development of materials that combine eco-efficiency and performance, recyclability, and costs. This Special Issue aims to report recent advances and future challenges in the use of green catalysts for the treatment of polluted waters.

Submissions are especially welcome on (but not limited to) the following topics:

  • The use of non-expensive or natural occurring catalysts, paying special attention to their durability and reusability in the process;
  • The intensification of polluted water treatments by energetically-assisted approaches (temperature, light, microwave, ultrasound, cavitation, etc.);
  • The application of catalytic processes to real polluted waters;
  • The development of catalysts for industrial-scale applications;
  • The determination of kinetic parameters and development of kinetic models for catalytic water treatments;
  • Life cycle assessment of the catalytic process.

The Special Issue will preferably include research papers, but critical overviews of the state-of-the-art in this field are also welcome. Authors with expertise in the use of catalysts for wastewater treatments are encouraged to submit their manuscripts to Catalysts.

Prof. Aurora Santos
Dr. Carmen María Domínguez Torre
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Green catalyst
  • Catalytic water treatment
  • Catalyst stability
  • Catalyst reusability
  • Catalytic wet air oxidation (CWAO)
  • Catalytic advanced oxidation processes
  • Catalytic reduction treatments

Published Papers (14 papers)

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Editorial

Jump to: Research, Review

3 pages, 177 KiB  
Editorial
Special Issue on “Green Catalysts: Application to Waste and Groundwater Treatment”
by Carmen M. Dominguez and Aurora Santos
Catalysts 2021, 11(9), 1043; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11091043 - 28 Aug 2021
Viewed by 1149
Abstract
Water and soil pollution are among the most critical global problems due to population growth, industrial development, and associated resource consumption [...] Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)

Research

Jump to: Editorial, Review

17 pages, 2262 KiB  
Article
Performance of Iron-Functionalized Activated Carbon Catalysts (Fe/AC-f) on CWPO Wastewater Treatment
by Sara Mesa Medina, Ana Rey, Carlos Durán-Valle, Ana Bahamonde and Marisol Faraldos
Catalysts 2021, 11(3), 337; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11030337 - 06 Mar 2021
Cited by 7 | Viewed by 2590
Abstract
Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk [...] Read more.
Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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21 pages, 2645 KiB  
Article
Abatement of 1,2,4-Trichlorobencene by Wet Peroxide Oxidation Catalysed by Goethite and Enhanced by Visible LED Light at Neutral pH
by David Lorenzo, Aurora Santos, Andrés Sánchez-Yepes, Leandro Óscar Conte and Carmen María Domínguez
Catalysts 2021, 11(1), 139; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010139 - 19 Jan 2021
Cited by 15 | Viewed by 2221
Abstract
There is significant environmental concern about chlorinated organic compounds (COCs) in wastewater, surface water, and groundwater due to their low biodegradability and high persistence. In this work, 1,2,4-trichlorobenzene (124-TCB) was selected as a model compound to study its abatement using wet peroxide oxidation [...] Read more.
There is significant environmental concern about chlorinated organic compounds (COCs) in wastewater, surface water, and groundwater due to their low biodegradability and high persistence. In this work, 1,2,4-trichlorobenzene (124-TCB) was selected as a model compound to study its abatement using wet peroxide oxidation at neutral pH with goethite as a heterogeneous catalyst, which was enhanced with visible monochromatic light-emitting diode (LED) light (470 nm). A systematic study of the main operating variables (oxidant and catalyst concentration and irradiance) was accomplished to investigate their influence in the abatement of 124-TCB in water. The reaction was carried out in a well-mixed reactor of glass irradiated by a visible LED light. The hydrogen peroxide concentration was tested from 0 to 18 mM, the goethite concentration within the range 0.1–1.0 g·L−1 and the irradiance from 0.10 to 0.24 W·cm−2 at neutral pH. It was found that this oxidation method is a very efficient technique to abate 124-TCB, reaching a pollutant conversion of 0.9 when using 0.1 g·L−1 of goethite, 18 mM of H2O2, and 0.24 of W·cm−2. Moreover, the system performance was evaluated using the photonic efficiency (ratio of the moles of 124-TCB abated and the moles of photons arriving at the reactor window). The maximum photonic efficiencies were obtained using the lowest lamp powers and moderate to high catalyst loads. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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18 pages, 4596 KiB  
Article
Application of Mineral Iron-Based Natural Catalysts in Electro-Fenton Process: A Comparative Study
by Zahra Heidari, Rasool Pelalak, Reza Alizadeh, Nihal Oturan, Saeed Shirazian and Mehmet A. Oturan
Catalysts 2021, 11(1), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010057 - 02 Jan 2021
Cited by 31 | Viewed by 3218
Abstract
The potential use of novel iron based mineral catalysts as an effective and available material for electrocatalytic oxidation of refractory contaminants by heterogeneous electro-Fenton (HEF) process was studied for the first time. For this purpose, four natural catalysts, namely ilmenite (FeTiO3), [...] Read more.
The potential use of novel iron based mineral catalysts as an effective and available material for electrocatalytic oxidation of refractory contaminants by heterogeneous electro-Fenton (HEF) process was studied for the first time. For this purpose, four natural catalysts, namely ilmenite (FeTiO3), pyrite (FeS2), chromite (FeCr2O4), and chalcopyrite (CuFeS2) were selected as the source of ferrous iron (Fe2+) ions. The catalyst samples were appropriately characterized by X-ray diffraction (XRD) and RAMAN analysis. The degradation kinetics and mineralization rate of 0.2 mM antibiotic cefazolin (CFZ), as a contaminant of emerging concern, were comparatively investigated by HEF using the catalysts mentioned above. The effect of important experimental parameters such as catalysts loading and current on the process efficiency was investigated. Moreover, the performance of these new mineral catalysts was compared in term of CFZ degradation kinetics, mineralization power, mineralization current efficiency and electrical energy consumption. A greater enhancement in degradation/mineralization of CFZ was obtained when using chalcopyrite as the catalyst in HEF. The stability and reusability experiments demonstrated negligible decrease in catalytic activity of chalcopyrite after five consecutive runs. Besides, the rate constant for CFZ oxidation by hydroxyl radicals was estimated according the pseudo-first-order reaction kinetics. The empirical assessment, in addition to economic evaluation, confirmed that iron based mineral catalysts and specifically chalcopyrite could be an appropriate and cost-effective alternative catalyst for HEF due to its high catalytic activity, availability, eco-friendly nature and low energy consumption compared to other synthesized catalysts. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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13 pages, 2492 KiB  
Article
Comprehensive Kinetics of the Photocatalytic Degradation of Emerging Pollutants in a LED-Assisted Photoreactor. S-Metolachlor as Case Study
by Laura Rancaño, Maria J. Rivero, Miguel Ángel Mueses and Inmaculada Ortiz
Catalysts 2021, 11(1), 48; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010048 - 31 Dec 2020
Cited by 11 | Viewed by 2273
Abstract
Although the potential and beneficial characteristics of photocatalysis in the degradation of a good number of emerging pollutants have been widely studied and demonstrated, process design and scale-up are restrained by the lack of comprehensive models that correctly describe the performance of photocatalytic [...] Read more.
Although the potential and beneficial characteristics of photocatalysis in the degradation of a good number of emerging pollutants have been widely studied and demonstrated, process design and scale-up are restrained by the lack of comprehensive models that correctly describe the performance of photocatalytic reactors. Together with the kinetics of degradation reactions, the distribution of the radiation field in heterogeneous photocatalytic systems is essential to the optimum design of the technology. Both the Local Volumetric Rate of Photon Absorption (LVRPA) and the Overall Volumetric Rate of Photon Absorption (OVRPA) help to understand this purpose. This work develops a Six-Flux radiation absorption–scattering model coupled to the Henyey–Greenstein scattering phase function to evaluate the LVRPA profile in a LED-assisted photocatalytic reactor. Moreover, the OVRPA has been calculated and integrated into the kinetic equation, accounting for the influence of the radiation distribution on the reaction rate. The model has been validated with experimental data for the degradation of S-Metolachlor (MTLC), and the set of operating variables that maximize the reactor performance, 0.5 g/L of TiO2 P25 and pH 3, has been determined. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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14 pages, 2461 KiB  
Article
Adsorption and Photocatalytic Mineralization of Bromophenol Blue Dye with TiO2 Modified with Clinoptilolite/Activated Carbon
by Emmanuel Kweinor Tetteh and Sudesh Rathilal
Catalysts 2021, 11(1), 7; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010007 - 23 Dec 2020
Cited by 17 | Viewed by 2475
Abstract
This study presents a hybridized photocatalyst with adsorbate as a promising nanocomposite for photoremediation of wastewater. Photocatalytic degradation of bromophenol blue (BPB) in aqueous solution under UV-irradiation of wavelength 400 nm was carried out with TiO2 doped with activated carbon (A) and [...] Read more.
This study presents a hybridized photocatalyst with adsorbate as a promising nanocomposite for photoremediation of wastewater. Photocatalytic degradation of bromophenol blue (BPB) in aqueous solution under UV-irradiation of wavelength 400 nm was carried out with TiO2 doped with activated carbon (A) and clinoptilolite (Z) via the co-precipitation technique. The physiochemical properties of the nanocomposite (A–TiO2 and Z–TiO2) and TiO2 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. Results of the nanocomposite (A–TiO2 and Z–TiO2) efficiency was compared to that with the TiO2, which demonstrated their adsorption and synergistic effect for the removal of chemical oxygen demand (COD) and color from the wastewater. At an optimal load of 4 g, the photocatalytic degradation activity (Z–TiO2 > A–TiO2 > TiO2) was found favorably by the second-order kinetic model. Consequently, the Langmuir adsorption isotherms favored the nanocomposites (Z–TiO2 > A–TiO2), whereas that of the TiO2 fitted very well on the Freundlich isotherm approach. Z–TiO2 evidently exhibited a high photocatalytic efficacy of decomposition over 80% of BPB (COD) at reaction rate constant (k) and coefficient of determination (R2) values of 5.63 × 10−4 min−1 and 0.989, respectively. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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15 pages, 4979 KiB  
Article
Photocatalytic Transformation of Triclosan. Reaction Products and Kinetics
by Sophie Schröder, Mª-Fresnedo San-Román and Inmaculada Ortiz
Catalysts 2020, 10(12), 1468; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10121468 - 16 Dec 2020
Cited by 13 | Viewed by 2082
Abstract
5-Chloro-2-[2,4-dichlorophenoxy]-phenol, or triclosan (TCS), is an antimicrobial and antifungal agent with high resistance to conventional wastewater treatments, thus, more effective remediation technologies are necessary, where photocatalytic processes deserve special attention due to the high degradation rates of TCS, and the use of a [...] Read more.
5-Chloro-2-[2,4-dichlorophenoxy]-phenol, or triclosan (TCS), is an antimicrobial and antifungal agent with high resistance to conventional wastewater treatments, thus, more effective remediation technologies are necessary, where photocatalytic processes deserve special attention due to the high degradation rates of TCS, and the use of a renewable source of energy. However, different by-products may be formed during the treatment, sometimes more harmful than the parent compounds. Efforts to detail reaction pathways continually feed into related literature; however, knowing the transformation kinetics and the dependence on the operating variables is essential for the correct design of the abovementioned remediation technologies. This work contributes to increasing the knowledge necessary for the application of photocatalytic processes for the degradation of emerging pollutants, with TCS as a case study. First, an experimental plan to analyze the influence of the operating variables was carried out, determining time courses of the parent and intermediate compounds. Next, the kinetic model and parameters that are capable of predicting TCS concentration and its derivatives as a function of the operating conditions are provided. This constitutes a very useful tool to predict the performance of wastewater remediation treatment both in the degradation of the original pollutant and in the reduction of the toxicity in the treated water. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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17 pages, 2707 KiB  
Article
Lanthanum Nickel Oxide: An Effective Heterogeneous Activator of Sodium Persulfate for Antibiotics Elimination
by Athanasia Petala, Olga S. Arvaniti, Maria Christofili, Alexandros Safakas, Zacharias Frontistis and Dionissios Mantzavinos
Catalysts 2020, 10(12), 1373; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10121373 - 25 Nov 2020
Cited by 11 | Viewed by 2480
Abstract
In recent years, the presence of pharmaceutically active compounds (PhACs) in surface waters and wastewaters has b the effectiveness of conventional water treatment methods. Towards this direction, advanced oxidation processes (AOPs) for the complete elimination of micro pollutants in waters have become an [...] Read more.
In recent years, the presence of pharmaceutically active compounds (PhACs) in surface waters and wastewaters has b the effectiveness of conventional water treatment methods. Towards this direction, advanced oxidation processes (AOPs) for the complete elimination of micro pollutants in waters have become an emerging area of research. The present study reports the heterogeneous activation of sodium persulfate (SPS) by LaNiO3 (LNO) perovskite oxide for the degradation of sulfamethoxazole (SMX), an antibiotic agent. LNO was prepared according to a combustion method, and its physicochemical characteristics were identified by means of XRD, BET, TEM, and SEM/EDS. SMX degradation results showed the great efficiency of LNO for SPS activation. Increasing LNO and SPS dosage up to 250 mg/L enhanced the SMX degradation. In contrast, increasing SMX concentration resulted in longer time periods for its degradation. Considering the pH effect, SMX removal was obstructed under basic conditions, while the efficiency was enhanced at near-neutral conditions. The present system’s activity was also tested for piroxicam (PIR) and methylparaben (MeP) degradation, showing promising results. Unfortunately, experiments conducted in real water matrices such as bottled water (BW) and wastewater (WW), showed that SMX removal was limited to less than 25% in both cases. The hindering effects were mainly attributed to bicarbonate ions and organic matter present in aqueous media. The results obtained using suitable radical scavengers revealed the contribution of both hydroxyl and sulfate radicals in degradation reactions. Finally, LNO exhibited good stability under consecutive experimental runs. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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11 pages, 2270 KiB  
Article
Catalytic Wet Peroxide Oxidation of Cylindrospermopsin over Magnetite in a Continuous Fixed-Bed Reactor
by Macarena Munoz, David Ortiz, Julia Nieto-Sandoval, Samuel Cirés, Zahara M. de Pedro, Antonio Quesada and Jose A. Casas
Catalysts 2020, 10(11), 1250; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10111250 - 29 Oct 2020
Cited by 6 | Viewed by 2043
Abstract
The development of cost-efficient and environmentally friendly technologies for the removal of cyanotoxins from water is crucial, given the increasingly frequent appearance of toxic cyanobacterial blooms. In this work, the application of catalytic wet peroxide oxidation (CWPO) promoted by natural magnetite for the [...] Read more.
The development of cost-efficient and environmentally friendly technologies for the removal of cyanotoxins from water is crucial, given the increasingly frequent appearance of toxic cyanobacterial blooms. In this work, the application of catalytic wet peroxide oxidation (CWPO) promoted by natural magnetite for the removal of the highly toxic cyanotoxin cylindrospermopsin (CYN) has been investigated. A fixed-bed reactor packed with magnetite powder and granules was used to treat a continuous flow of CYN-bearing water. Experiments were carried out under ambient conditions and circumneutral pH (pH0 = 5). The effect of the main variables of the process, viz. magnetite load (8–14 g), feed flow rate (0.1–0.25 mL min−1), H2O2 dose (0.5–8 mg L−1) and initial CYN concentration (25–100 μg L−1), were systematically analyzed. CYN conversion values and kinetic constants were calculated to evaluate the feasibility of the catalytic system. The process was highly effective in the removal of the cyanotoxin, achieving up to 80% CYN conversion under optimized conditions (flow rate = 0.2 mL min−1, [H2O2]0 = 5 mg L−1, WFe3O4 = 14 g, pH0 = 5, T = 25 °C). It also showed reasonable activity (~55% CYN conversion) in two real samples (pond and river water). The decay on CYN conversion in these cases was mainly due to the scavenging of hydroxyl radicals by the co-existing species present in the matrices. Remarkably, the catalytic system showed high stability with limited iron leaching (the iron leached at the end of the experiments represented less than 0.2 wt.% of the catalyst’s initial iron content) in all cases. Its stability was further confirmed in a long-term continuous experiment (60 h time on stream). Furthermore, the magnetite granules at the top layer of the packed bed avoided the loss of magnetite powder from the reactor, confirming the suitability of the system for continuous long-term application. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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14 pages, 809 KiB  
Article
Environmental Assessment of Humic Acid Coated Magnetic Materials Used as Catalyst in Photo-Fenton Processes
by Mattia Costamagna, Nuno P. F. Gonçalves and Alessandra Bianco Prevot
Catalysts 2020, 10(7), 771; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10070771 - 10 Jul 2020
Cited by 4 | Viewed by 2023
Abstract
Persistent organic pollutants have been increasingly detected in natural waters, and this represents a real challenge to the quality of this resource. To remove these species, advanced treatment technologies are required. Among these technologies, Fenton-like and photo-Fenton-like processes have been investigated for the [...] Read more.
Persistent organic pollutants have been increasingly detected in natural waters, and this represents a real challenge to the quality of this resource. To remove these species, advanced treatment technologies are required. Among these technologies, Fenton-like and photo-Fenton-like processes have been investigated for the removal of pollutants from water. Delicate aspects of photo-Fenton processes are that light-driven processes are energy intensive and require a fair amount of chemical inputs, which strongly affects their overall environmental burdens. At present, aside from determining the efficiency of the processes to remove pollutants of a particular technology, it becomes fundamental to assess also the environmental sustainability of the overall process. In this work, the methodology of the life cycle assessment (LCA) was applied to identify the hotspots of using magnetite particles covered with humic acid (Fe3O4/HA) as a heterogeneous photo-Fenton catalyst for water remediation. The sustainability of the overall process was considered, and a comparative LCA study was performed between H2O2 and persulfate activation at different pH. The addition of humic substances to the particles allows the effectiveness of the catalyst to improve without increasing the environmental impacts; these processes are strongly correlated with energy consumption and therefore with the efficiency of the process. For this reason, working at acidic pH allows us to contain the impacts. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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12 pages, 1565 KiB  
Article
Efficient Removal of Heavy Metals from Aqueous Solutions Using a Bionanocomposite of Eggshell/Ag-Fe
by Verónica M. Alamillo-López, Víctor Sánchez-Mendieta, Oscar F. Olea-Mejía, María G. González-Pedroza and Raúl A. Morales-Luckie
Catalysts 2020, 10(7), 727; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10070727 - 30 Jun 2020
Cited by 9 | Viewed by 3279
Abstract
Eggshell and an easily synthesized bionanocomposite of eggshell with Ag-Fe nanoparticles demonstrated to be efficient adsorbent materials for the removal of lead, arsenic, and mercury from water. The natural material and the bionanocomposite were characterized by TEM and XRD. Ag-Fe nanoparticles vary from [...] Read more.
Eggshell and an easily synthesized bionanocomposite of eggshell with Ag-Fe nanoparticles demonstrated to be efficient adsorbent materials for the removal of lead, arsenic, and mercury from water. The natural material and the bionanocomposite were characterized by TEM and XRD. Ag-Fe nanoparticles vary from 1 to 100 nm in size. Equilibrium times of the adsorption systems were achieved between 4 and 8 h. The experimental adsorption data fitted the pseudo-second and Elovich models; therefore, the adsorption of heavy metals ions took place mainly by a chemical process. The adsorption capacity of eggshell in mg/g was 7.01 for As5+, 3.90 for Pb2+, and 1.51 for Hg2+, while the nanocomposite adsorption capacity was 17.7 for As5+, 27.8 for Pb2+ and 15.88 for Hg2+. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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14 pages, 2206 KiB  
Article
Electro-Absorbers: A Comparison on Their Performance with Jet-Absorbers and Absorption Columns
by Monserrat Castañeda-Juárez, Martín Muñoz-Morales, Fernanda Lourdes Souza, Cristina Sáez, Pablo Cañizares, Perla Tatiana Almazán-Sánchez, Ivonne Linares-Hernández and Manuel Andrés Rodrigo
Catalysts 2020, 10(6), 653; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10060653 - 11 Jun 2020
Cited by 14 | Viewed by 2505
Abstract
This work focuses on the removal of perchloroethylene (PCE) from gaseous streams using absorbers connected with electrolyzers. Two types of absorption devices (jet absorber and absorption column) were compared. In addition, it has been evaluated the different by-products generated when a simultaneous electrolysis [...] Read more.
This work focuses on the removal of perchloroethylene (PCE) from gaseous streams using absorbers connected with electrolyzers. Two types of absorption devices (jet absorber and absorption column) were compared. In addition, it has been evaluated the different by-products generated when a simultaneous electrolysis with diamond anodes is carried out. PCE was not mineralized, but it was transformed into phosgene that mainly derivates into carbon tetrachloride. Trichloroacetic acid was also formed, but in much lower amounts. Results showed a more efficient absorption of PCE in the packed column, which it is associated to the higher gas–liquid contact surface. Jet absorber seems to favor the production of carbon tetrachloride in gaseous phase, whereas the packed column promotes a higher concentration of trichloroacetic acid in liquid. It was also evaluated the scale up of the electrolytic stage of these electro-absorption devices by using a stack with five perforated electrode packages instead of a single cell. Clarification of the effect of the applied current density on the speciation attained after the electrolysis of the absorbent has been attempted. Experiments reveal similar results in terms of PCE removal and a reduced generation of gaseous intermediates at lower current densities. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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Review

Jump to: Editorial, Research

43 pages, 2131 KiB  
Review
Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review
by Alicia Checa-Fernandez, Aurora Santos, Arturo Romero and Carmen M. Dominguez
Catalysts 2021, 11(6), 722; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11060722 - 10 Jun 2021
Cited by 26 | Viewed by 5623
Abstract
Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation [...] Read more.
Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of the application of CAs to enhance the Fenton process for the remediation of soils polluted with the most common organic contaminants, especially for a deep understanding of the activation mechanisms and influential factors. The existing shortcomings and research needs have been highlighted. Finally, future research perspectives on the use of CAs in MF and recommendations have been provided. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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22 pages, 1532 KiB  
Review
Heterogeneous Electro-Fenton as “Green” Technology for Pharmaceutical Removal: A Review
by Jessica Meijide, Patrick S. M. Dunlop, Marta Pazos and María Angeles Sanromán
Catalysts 2021, 11(1), 85; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010085 - 09 Jan 2021
Cited by 42 | Viewed by 4703
Abstract
The presence of pharmaceutical products in the water cycle may cause harmful effects such as morphological, metabolic and sex alterations in aquatic organisms and the selection/development of organisms resistant to antimicrobial agents. The compounds’ stability and persistent character hinder their elimination by conventional [...] Read more.
The presence of pharmaceutical products in the water cycle may cause harmful effects such as morphological, metabolic and sex alterations in aquatic organisms and the selection/development of organisms resistant to antimicrobial agents. The compounds’ stability and persistent character hinder their elimination by conventional physico-chemical and biological treatments and thus, the development of new water purification technologies has drawn great attention from academic and industrial researchers. Recently, the electro-Fenton process has been demonstrated to be a viable alternative for the removal of these hazardous, recalcitrant compounds. This process occurs under the action of a suitable catalyst, with the majority of current scientific research focused on heterogeneous systems. A significant area of research centres working on the development of an appropriate catalyst able to overcome the operating limitations associated with the homogeneous process is concerned with the short service life and difficulty in the separation/recovery of the catalyst from polluted water. This review highlights a present trend in the use of different materials as electro-Fenton catalysts for pharmaceutical compound removal from aquatic environments. The main challenges facing these technologies revolve around the enhancement of performance, stability for long-term use, life-cycle analysis considerations and cost-effectiveness. Although treatment efficiency has improved significantly, ongoing research efforts need to deliver economic viability at a larger scale due to the high operating costs, primarily related to energy consumption. Full article
(This article belongs to the Special Issue Green Catalysts: Application to Waste and Groundwater Treatment)
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