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A Brief Review of Photocatalytic Reactors Used for Persistent Pesticides Degradation. CHEMENGINEERING 2022. [DOI: 10.3390/chemengineering6060089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pesticide pollution is a major issue, given their intensive use in the 20th century, which led to their accumulation in the environment. At the international level, strict regulations are imposed on the use of pesticides, simultaneously with the increasing interest of researchers from all over the world to find methods of neutralizing them. Photocatalytic degradation is an intensively studied method to be applied for the degradation of pesticides, especially through the use of solar energy. The mechanisms of photocatalysis are studied and implemented in pilot and semi-pilot installations on experimental platforms, in order to be able to make this method more efficient and to identify the equipment that can achieve the photodegradation of pesticides with the highest possible yields. This paper proposes a brief review of the impact of pesticides on the environment and some techniques for their degradation, with the main emphasis on different photoreactor configurations, using slurry or immobilized photocatalysts. This review highlights the efforts of researchers to harmonize the main elements of photocatalysis: choice of the photocatalyst, and the way of photocatalyst integration within photoreaction configuration, in order to make the transfer of momentum, mass, and energy as efficient as possible for optimal excitation of the photocatalyst.
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Elumalai N, Prabhu S, Selvaraj M, Silambarasan A, Navaneethan M, Harish S, Ramu P, Ramesh R. Enhanced photocatalytic activity of ZnO hexagonal tube/r-GO composite on degradation of organic aqueous pollutant and study of charge transport properties. CHEMOSPHERE 2022; 291:132782. [PMID: 34748798 DOI: 10.1016/j.chemosphere.2021.132782] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 10/11/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
ZnO hexagonal tube and ZnO/r-GO nanocomposites were synthesized by hydrothermal method and the nanostructures were characterized by XRD, UV-DRS, PL, FTIR, FESEM, and TEM techniques. The main violet emission peak of the synthesized nanostructures is due to the transition between interstitial zinc and hole (valence band) of ZnO. The potential of ZnO/r-GO nanocomposite was evaluated using methyl orange (MO) and rhodamine-B (RhB), and the results were compared with the activity of synthesized ZnO nanostructures. More than 95% of MO and RhB were by ZnO/r-GO nanocomposite and it was found to be higher than that of ZnO hexagonal tube. The degradation MO and RhB were found to follow first-order kinetics and it has a rate constant of 7.68 × 10-2and 7.83 × 10-2 min-1, respectively. These results are mainly due to the enhanced charge transport property. Trapping experiments show that superoxide radical anion and hydroxide radicals are chief species responsible for the degradation of MO and RhB. The chemical stability of the nanocomposite was evaluated by cycle test experiments and it reveals that the catalyst can be reused up to few cycles without considerable loss of photocatalytic activity. This work affords a simple stratagem to integrate ZnO hexagonal tubes and r-GO nanosheets to construct effective catalysts for the degradation of organic compounds.
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Affiliation(s)
- N Elumalai
- Department of Physics, Government Arts College (Autonomous), Salem, 7, Tamil Nadu, India; Department of Physics, Periyar University, Salem, 11, Tamil Nadu, India
| | - S Prabhu
- Department of Physics, Periyar University, Salem, 11, Tamil Nadu, India
| | - M Selvaraj
- Department of Chemistry, Faculty of Science, King Khalid University, Abha, 61413, Saudi Arabia.
| | - A Silambarasan
- Department of Chemistry, Vivekanandha College of Arts and Sciences for Women (Autonomous), Elayampalayam, Namakkal, 637 205, Tamil Nadu, India.
| | - M Navaneethan
- Nanotechnology Research Centre, SRM Institute of Science and Technology, Kanchepuram, Tamil Nadu, India; Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kanchepuram, Tamil Nadu, India.
| | - S Harish
- Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kanchepuram, Tamil Nadu, India
| | - P Ramu
- Department of Physics, Government Arts College (Autonomous), Salem, 7, Tamil Nadu, India.
| | - R Ramesh
- Department of Physics, Periyar University, Salem, 11, Tamil Nadu, India.
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Frišták V, Bošanská D, Pipíška M, Ďuriška L, Bell SM, Soja G. Physicochemical Characterization of Cherry Pits-Derived Biochar. MATERIALS 2022; 15:ma15020408. [PMID: 35057128 PMCID: PMC8779365 DOI: 10.3390/ma15020408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/29/2021] [Accepted: 01/04/2022] [Indexed: 11/16/2022]
Abstract
Although the suitability of some biochars for contaminants' sorption separation has been established, not all potential feedstocks have been explored and characterized. Here, we physicochemically characterized cherry pit biochar (CPB) pyrolyzed from cherry pit biomass (CP) at 500 °C, and we assessed their As and Hg sorption efficiencies in aqueous solutions in comparison to activated carbon (AC). The basic physicochemical and material characterization of the studied adsorbents was carried out using pH, electrical conductivity (EC), cation exchange capacity (CEC), concentration of surface functional groups (Boehm titration), and surface area (SA) analysis; elemental C, H, N analysis; and Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). AsO43- anions and Hg2+ cations were selected as model contaminants used to test the sorption properties of the sorption materials. Characterization analyses confirmed a ninefold increase in SA in the case of CPB. The total C concentration increased by 26%, while decreases in the total H and N concentrations were observed. The values of carbonate and ash contents decreased by about half due to pyrolysis processes. The concentrations of surface functional groups of the analyzed biochar obtained by Boehm titration confirmed a decrease in carboxyl and lactone groups, while an increase in phenolic functional groups was observed. Changes in the morphology and surface functionality of the pyrolyzed material were confirmed by SEM-EDX and FTIR analyses. In sorption experiments, we found that the CPB showed better results in the sorption separation of Hg2+ than in the sorption separation of AsO43-. The sorption efficiency for the model cation increased in the order CP < CPB < AC and, for the model anion, it increased in the order CPB < CP < AC.
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Affiliation(s)
- Vladimír Frišták
- Department of Chemistry, Trnava University in Trnava, 91843 Trnava, Slovakia; (D.B.); (M.P.)
- Correspondence: ; Tel.: +421-33-592-1459
| | - Diana Bošanská
- Department of Chemistry, Trnava University in Trnava, 91843 Trnava, Slovakia; (D.B.); (M.P.)
| | - Martin Pipíška
- Department of Chemistry, Trnava University in Trnava, 91843 Trnava, Slovakia; (D.B.); (M.P.)
| | - Libor Ďuriška
- Institute of Materials Science, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 91724 Trnava, Slovakia;
| | - Stephen M. Bell
- Institute of Environmental Science and Technology (ICTA-UAB), Universitat Autónoma de Barcelona, 08193 Barcelona, Spain;
| | - Gerhard Soja
- Energy Department, Austrian Institute of Technology GmbH, 3430 Tulln, Austria;
- Institute for Chemical and Energy Engineering, University of Natural Resources and Life Sciences Vienna, 1190 Vienna, Austria
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