1
|
Kim CM, Jaffari ZH, Abbas A, Chowdhury MF, Cho KH. Machine learning analysis to interpret the effect of the photocatalytic reaction rate constant (k) of semiconductor-based photocatalysts on dye removal. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:132995. [PMID: 38039815 DOI: 10.1016/j.jhazmat.2023.132995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/02/2023] [Accepted: 11/10/2023] [Indexed: 12/03/2023]
Abstract
Photocatalytic reactions with semiconductor-based photocatalysts have been investigated extensively for application to wastewater treatment, especially dye degradation, yet the interactions between different process parameters have rarely been reported due to their complicated reaction mechanisms. Hence, this study aims to discern the impact of each factor, and each interaction between multiple factors on reaction rate constant (k) using a decision tree model. The dyes selected as target pollutants were indigo and malachite green, and 5 different semiconductor-based photocatalysts with 17 different compositions were tested, which generated 34 input features and 1527 data points. The Boruta Shapley Additive exPlanations (SHAP) feature selection for the 34 inputs found that 11 inputs were significantly important. The decision tree model exhibited for 11 input features with an R2 value of 0.94. The SHAP feature importance analysis suggested that photocatalytic experimental conditions, with an importance of 59%, was the most important input category, followed by atomic composition (39%) and physicochemical properties (2%). Additionally, the effects on k of the synergy between the metal cocatalysts and important experimental conditions were confirmed by two feature SHAP dependence plots, regardless of importance order. This work provides insight into the single and multiple factors that affect reaction rate and mechanism.
Collapse
Affiliation(s)
- Chang-Min Kim
- Future and Fusion Lab of Architectural, Civil and Environmental Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Zeeshan Haider Jaffari
- Department of Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Ather Abbas
- Physical Science and Engineering Division, 4700 King Abdullah University of Science and Technology, Thuwal, Mecca Province, Saudi Arabia
| | - Mir Ferdous Chowdhury
- Department of Global Smart City, Sungkyunkwan University (SKKU), 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Kyung Hwa Cho
- School of Civil, Environmental, and Architectural Engineering, Korea University, Seoul 02841, Republic of Korea.
| |
Collapse
|
2
|
Petcu G, Anghel EM, Atkinson I, Culita DC, Apostol NG, Kuncser A, Papa F, Baran A, Blin JL, Parvulescu V. Composite Photocatalysts with Fe, Co, and Ni Oxides on Supports with Tetracoordinated Ti Embedded into Aluminosilicate Gel during Zeolite Y Synthesis. Gels 2024; 10:129. [PMID: 38391459 PMCID: PMC10888282 DOI: 10.3390/gels10020129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/02/2024] [Accepted: 02/03/2024] [Indexed: 02/24/2024] Open
Abstract
Ti-aluminosilicate gels were used as supports for the immobilization of Fe, Co, and Ni oxides (5%) by impregnation and synthesis of efficient photocatalysts for the degradation of β-lactam antibiotics from water. Titanium oxide (1 and 2%) was incorporated into the zeolite network by modifying the gel during the zeolitization process. The formation of the zeolite Y structure and its microporous structure were evidenced by X-ray diffraction and N2 physisorption. The structure, composition, reduction, and optical properties were studied by X-ray diffraction, H2-TPR, XPS, Raman, photoluminescence, and UV-Vis spectroscopy. The obtained results indicated a zeolite Y structure for all photocatalysts with tetracoordinated Ti4+ sites. The second transitional metals supported by the post-synthesis method were obtained in various forms, such as oxides and/or in the metallic state. A red shift of the absorption edge was observed in the UV-Vis spectra of photocatalysts upon the addition of Fe, Co, or Ni species. The photocatalytic performances were evaluated for the degradation of cefuroxime in water under visible light irradiation. The best results were obtained for iron-immobilized photocatalysts. Scavenger experiments explained the photocatalytic results and their mechanisms. A different contribution of the active species to the photocatalytic reactions was evidenced.
Collapse
Affiliation(s)
- Gabriela Petcu
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Elena Maria Anghel
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Irina Atkinson
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Daniela C Culita
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Nicoleta G Apostol
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - Andrei Kuncser
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - Florica Papa
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Adriana Baran
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| | - Jean-Luc Blin
- Faculty of Sciences and Technology, University of Lorraine, CNRS, L2CM, F-54000 Nancy, France
| | - Viorica Parvulescu
- Institute of Physical Chemistry "Ilie Murgulescu" of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania
| |
Collapse
|
3
|
Yahya NAA, Samir OM, Al-Ariki S, Ahmed AAM, Swillam MA. Synthesis of novel antibacterial nanocomposite CuO/Ag-modified zeolite for removal of MB dye. Sci Rep 2023; 13:14948. [PMID: 37696834 PMCID: PMC10495417 DOI: 10.1038/s41598-023-40790-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 08/16/2023] [Indexed: 09/13/2023] Open
Abstract
Novel CuO/Ag nanocomposites added zeolite (CAZ) were successfully fabricated, and their effectiveness as an antibacterial on S. aureus and MB removal was evaluated. EDX, XRD, and FTIR confirm the presence of the elemental compositions of CAZ. Friable CuO nanorods (10-70 nm in diameter) existed on the surface of the zeolite. Pure zeolite had a higher band gap (5.433 eV) and lower MB removal efficiency than CAZ. The adsorption method by CAZ was more effective at removing MB than photodegradation. 0.10 CAZ had the highest removal effectiveness (~ 99%) and adsorption capacity (~ 70.4 mg g-1) of MB. The inhibitory zone diameter for 0.005 CAZ against S. aureus was 20 mm, while 0.01 CAZ had a diameter of 17 mm. Azithromycin, ceftriaxone, and erythromycin antibiotics demonstrated lower or no efficacy against S. aureus than CAZ. Significant antibacterial activities and wastewater treatment were achieved by CAZ. The combination of photodegradation and adsorption enhanced pollutant removal. It will be interesting to study further the optimal molar ratio for MB removal (0.10 CAZ) in future investigations.
Collapse
Affiliation(s)
- Nabil A A Yahya
- Department of Physics, School of Sciences and Engineering, American University in Cairo, New Cairo, 11835, Cairo, Egypt
- Physics Department, Thamar University, 87246, Thamar, Yemen
| | - O M Samir
- Physics Department, Faculty of Science, Ibb University, Ibb, Yemen
- Aljanad University, Taiz, Yemen
| | - S Al-Ariki
- Physics Department, Thamar University, 87246, Thamar, Yemen
| | - Amira A M Ahmed
- Department of Physics, School of Sciences and Engineering, American University in Cairo, New Cairo, 11835, Cairo, Egypt
| | - Mohamed A Swillam
- Department of Physics, School of Sciences and Engineering, American University in Cairo, New Cairo, 11835, Cairo, Egypt.
| |
Collapse
|
4
|
Zhu S, Cheng C, Meng L, Zhang P, Sun B. Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5243. [PMID: 37569947 PMCID: PMC10420216 DOI: 10.3390/ma16155243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/13/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023]
Abstract
In this work, a series of clinoptilolite composites decorated with carbon quantum dots (CQDs/clinoptilolite) with hierarchical pore structures was demonstrated that exhibits good photocatalytic performance for the removal of xylene. The technique for the attachment of carbon quantum dots to clinoptilolite was prepared by a hydrothermal method in this study. The structural features were confirmed by SEM, TEM, EDS, XRD, BET, XPS, and solid diffuse reflection measurements, while the degradation mechanism was investigated by adding a trapping agent into the nanocomposites. The introduction of CQDs promoted the separation of photogenerated electrons and holes as well as the generation of reactive radicals, which effectively improved the light utilization and even increased the degradation rate of xylene by 73% at the optimal state. The photocatalytic test was conducted under a different dwell time, catalyst dosage, initial concentration, and illumination intensity. The results showed that the degradation rate of xylene by the CQDs/clinoptilolite catalyst reached 97.4% under the optimal reaction conditions (the catalyst was Catalyst No. 2, the residence time was 90 s, the initial concentration was 2.5 g/m3, the light intensity was three lamps for irradiation, and the catalyst dosage was 0.05 g). In addition, the degradation efficiency of the CQDs/clinoptilolite photocatalyst still reached 78% after eight consecutive catalytic regeneration cycles. This work sheds new light on the degradation of xylene.
Collapse
Affiliation(s)
- Shuguang Zhu
- Engineering Research Center of Building Energy Efficiency Control and Evaluation, Ministry of Education, Anhui Jianzhu University, Hefei 230601, China;
- Energy Saving Research Institute, Anhui Jianzhu University, Hefei 230601, China
- Key Laboratory of Water Pollution Control and Wastewater Recycling of Anhui Province, Hefei 230601, China; (C.C.); (L.M.); (P.Z.)
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Chun Cheng
- Key Laboratory of Water Pollution Control and Wastewater Recycling of Anhui Province, Hefei 230601, China; (C.C.); (L.M.); (P.Z.)
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Li Meng
- Key Laboratory of Water Pollution Control and Wastewater Recycling of Anhui Province, Hefei 230601, China; (C.C.); (L.M.); (P.Z.)
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Pengyu Zhang
- Key Laboratory of Water Pollution Control and Wastewater Recycling of Anhui Province, Hefei 230601, China; (C.C.); (L.M.); (P.Z.)
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Bai Sun
- Engineering Research Center of Building Energy Efficiency Control and Evaluation, Ministry of Education, Anhui Jianzhu University, Hefei 230601, China;
- Key Laboratory of Water Pollution Control and Wastewater Recycling of Anhui Province, Hefei 230601, China; (C.C.); (L.M.); (P.Z.)
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| |
Collapse
|
5
|
Stojanović S, Rac V, Mojsilović K, Vasilić R, Marković S, Damjanović-Vasilić L. Photocatalytic degradation of bisphenol A in aqueous solution using TiO 2/clinoptilolite hybrid photocatalyst. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:84046-84060. [PMID: 37354298 DOI: 10.1007/s11356-023-28397-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 06/19/2023] [Indexed: 06/26/2023]
Abstract
Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2 g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5 mg/L) photodegradation after 180 min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120 min of irradiation. BPA removal (60% for 180 min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst.
Collapse
Affiliation(s)
- Srna Stojanović
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 47, 11158, Belgrade 118, Serbia
| | - Vladislav Rac
- Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11080, Belgrade, Serbia
| | - Kristina Mojsilović
- Faculty of Physics, University of Belgrade, Studentski Trg 12-16, 11000, Belgrade, Serbia
| | - Rastko Vasilić
- Faculty of Physics, University of Belgrade, Studentski Trg 12-16, 11000, Belgrade, Serbia
| | - Smilja Marković
- Institute of Technical Sciences of SASA, Knez Mihailova 35/IV, 11000, Belgrade, Serbia
| | - Ljiljana Damjanović-Vasilić
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 47, 11158, Belgrade 118, Serbia.
| |
Collapse
|
6
|
Alvarez-Aguiñaga EA, Elizalde-González MP, García-Díaz E. Handleable TiO 2-coated zeolitic material for photodecomposition of caffeine boosted by urine matrix. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27490-4. [PMID: 37213014 DOI: 10.1007/s11356-023-27490-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 05/03/2023] [Indexed: 05/23/2023]
Abstract
The photocatalytic decomposition of caffeine under UV-light irradiation was observed for the first time in a matrix of synthetic urine using granules of hydrogenated and iron-exchanged natural zeolite, coated with two loadings of TiO2. A natural clinoptilolite-mordenite blend was used to prepare photocatalytic adsorbents coated with TiO2 nanoparticles. The performance of the obtained materials was tested in the photodegradation of caffeine, a water contaminant of emerging concern. The photocatalytic activity was better in the urine matrix, due to the formation of surface complexes on the TiO2 coating, cation exchange performed by the zeolite support, and use of the carrier electrons in the reduction of ions, affecting recombination of the electrons and holes during photocatalysis. The composite granules maintained photocatalytic activity for at least four cycles, with more than 50% of caffeine removal in the synthetic urine matrix.
Collapse
Affiliation(s)
- Edith A Alvarez-Aguiñaga
- Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Edif. IC7, 72570, Puebla, Mexico
| | - María P Elizalde-González
- Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Edif. IC7, 72570, Puebla, Mexico.
| | - Esmeralda García-Díaz
- Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Edif. IC7, 72570, Puebla, Mexico
| |
Collapse
|
7
|
Sodha V, Koshti H, Gaur R, Ahmad I, Bandyopadhyay R, Shahabuddin S. Synthesis of zeolite-doped polyaniline composite for photocatalytic degradation of methylene blue from aqueous solution. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:46159-46174. [PMID: 36710314 DOI: 10.1007/s11356-023-25556-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 01/21/2023] [Indexed: 06/18/2023]
Abstract
The generation of wastewater has increased rapidly with the expansion of industries, hence, posing a risk to human health and the environment. The development of novel materials and technologies for textile wastewater treatment is constantly evolving. In this work, the photocatalytic degradation of methylene blue employing ZSM-5 zeolite-doped polyaniline composites is presented. To fabricate ZSM-5-based polyaniline (PANI) composites, the simple approach of in situ oxidative polymerization has been adopted. Different weight ratios of ZSM-5 have been used for the synthesis, and samples have been labelled as PAZe-1, PAZe-5, and PAZe-10. Different characterization techniques were used to characterize the prepared composites, including field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and thermo-gravimetry analysis (TGA). The photocatalytic performance of polyaniline, ZSM-5, and their composites was assessed by monitoring the degradation of methylene blue in the presence of visible light. Degradation results of the polyaniline-doped composites were found to be better than that of the polyaniline alone. When the photocatalytic efficiencies of different composites were compared, the PAZe-1 showed the best performance, with 99.9% degradation efficiency after 210 min of irradiation, while PANI, PAZe-5, PAZe-10, and ZSM-5 show 38%, 82%, 71%, and 99% removal efficiency. Apart from methylene blue, the composite PAZe-1 was further explored for the degradation of other organic pollutants such as methyl orange, chlorpyrifos, 2,4-dichlorophenoxy acetic acid, and p-nitroaniline. To determine the reactive species involved in the photocatalysis mechanism, scavenger studies were performed.
Collapse
Affiliation(s)
- Veena Sodha
- Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar, 382426, Gujarat, India
| | - Hardik Koshti
- Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar, 382426, Gujarat, India
| | - Rama Gaur
- Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar, 382426, Gujarat, India
| | - Irfan Ahmad
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, 61421, Saudi Arabia
| | - Rajib Bandyopadhyay
- Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar, 382426, Gujarat, India
| | - Syed Shahabuddin
- Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar, 382426, Gujarat, India.
| |
Collapse
|
8
|
Sodha V, Shahabuddin S, Gaur R, Ahmad I, Bandyopadhyay R, Sridewi N. Comprehensive Review on Zeolite-Based Nanocomposites for Treatment of Effluents from Wastewater. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12183199. [PMID: 36144986 PMCID: PMC9504493 DOI: 10.3390/nano12183199] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/12/2022] [Accepted: 09/12/2022] [Indexed: 05/12/2023]
Abstract
All humans and animals need access to clean water in their daily lives. Unfortunately, we are facing water scarcity in several places around the world, and, intentionally or unintentionally, we are contaminating the water in a number of ways. The rise in population, globalization, and industrialization has simultaneously given rise to the generation of wastewater. The pollutants in wastewater, such as organic contaminants, heavy metals, agrochemicals, radioactive pollutants, etc., can cause various ailments as well as environmental damage. In addition to the existing pollutants, a number of new pollutants are now being produced by developing industries. To address this issue, we require some emerging tools and materials to remove effluents from wastewater. Zeolites are the porous aluminosilicates that have been used for the effective pollutant removal for a long time owing to their extraordinary adsorption and ion-exchange properties, which make them available for the removal of a variety of contaminants. However, zeolite alone shows much less photocatalytic efficiency, therefore, different photoactive materials are being doped with zeolites to enhance their photocatalytic efficiency. The fabrication of zeolite-based composites is emerging due to their powerful results as adsorbents, ion-exchangers, and additional benefits as good photocatalysts. This review highlights the types, synthesis and removal mechanisms of zeolite-based materials for wastewater treatment with the basic knowledge about zeolites and wastewater along with the research gaps, which gives a quality background of worldwide research on this topic for future developments.
Collapse
Affiliation(s)
- Veena Sodha
- Department of Chemistry, School of Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar 382426, Gujarat, India
| | - Syed Shahabuddin
- Department of Chemistry, School of Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar 382426, Gujarat, India
- Correspondence: or (S.S.); (R.B.); (N.S.); Tel.: +91-858-593-2338 (S.S.); +60-124-675-320 (N.S.)
| | - Rama Gaur
- Department of Chemistry, School of Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar 382426, Gujarat, India
| | - Irfan Ahmad
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha 61421, Saudi Arabia
| | - Rajib Bandyopadhyay
- Department of Chemistry, School of Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar 382426, Gujarat, India
- Correspondence: or (S.S.); (R.B.); (N.S.); Tel.: +91-858-593-2338 (S.S.); +60-124-675-320 (N.S.)
| | - Nanthini Sridewi
- Department of Maritime Science and Technology, Faculty of Defence Science and Technology, National Defence University of Malaysia, Kuala Lumpur 57000, Malaysia
- Correspondence: or (S.S.); (R.B.); (N.S.); Tel.: +91-858-593-2338 (S.S.); +60-124-675-320 (N.S.)
| |
Collapse
|
9
|
Acidity and Stability of Brønsted Acid Sites in Green Clinoptilolite Catalysts and Catalytic Performance in the Etherification of Glycerol. Catalysts 2022. [DOI: 10.3390/catal12030253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Natural zeolite clinoptilolite CLIN with a framework ratio of Si/Al ≥ 4 containing mainly potassium and calcium ions in its internal channel system was used as a starting material. The acidic HCLIN catalysts were prepared under soft conditions avoiding the use of environmental less-benign mineral acids. The starting material was ion exchanged using a 0.2 M aqueous ammonium nitrate solution at a temperature 80 °C for 2 h. The obtained NH4CLIN was converted into the acid HCLIN catalyst by calcination at 300–600 °C. The obtained samples were characterized by XRD, FTIR, SEM/TEM, AAS, and EDX element mapping. The state of aluminium and silicon was studied by 27Al- and 29SiMAS NMR spectroscopy. The textural properties of the catalysts were investigated by nitrogen adsorption and desorption measurements. The Brønsted acidity of the HCLIN catalysts was studied by temperature-programmed decomposition of the exchanged ammonium ions releasing ammonia as well as 1H MAS NMR, {1H–27Al} Trapdor, and {1H–27Al} Redor experiments. The strongly agglomerated samples were crystalline and thermally stable up to >500 °C. Although a part of the clinoptilolite framework is maintained up to 600 °C, a loss of crystallinity is already observed starting from 450 °C. The specific surface areas of the starting CLIN and ammonium exchanged NH4CLIN are low with ca. 26 m2/g. The pores are nearly blocked by the exchangeable cations located in the zeolite pores. The thermal decomposition of the ammonium ions by calcination at 400 °C causes an opening of the pore entrances and a markable increase in the specific micropore area and micropore volume to ca. 163 m2/g and 0.07 cm3/g, respectively. It decreases with further rising calcination temperature indicating some structural loss. The catalysts show a broad distribution of Brønsted acid sites (BS) ranging from weak to strong sites as indicated the thermal decomposition of exchanged ammonium ions (TPDA). The ammonium ion decomposition leaving BS, i.e., H+ located at Al–O–Si framework bridges, starts at ≥250 °C. A part of the Brønsted sites is lost after calcination specifically at 500 °C. It is related to the formation of penta-coordinated aluminium at the expense of tetrahedral framework aluminium. The Brønsted sites are partially recreated after repeated ammonium ion exchange. The catalytic performance of the acidic HCLIN catalysts was tested in the etherification of glycerol as a green renewable resource with different C1-C4 alcohols. The catalysts are highly active in the etherification of glycerol, especially with alcohols containing the branched, tertiary alkyl groups. Highest activity is observed with the soft activated catalyst HCLIN300 (300 °C, temperature holding time: 1 min). A total of 78% conversion of glycerol to mono and di ether were achieved with tert-butanol at 140 °C after 4 h of reaction. The mono- and di-ether selectivity were 75% and 25%, respectively. The catalyst can be reused.
Collapse
|
10
|
Studies of Clinoptilolite-Rich Zeolitic Tuffs from Different Regions and Their Activity in Photodegradation of Methylene Blue. Catalysts 2022. [DOI: 10.3390/catal12020224] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocatalytic activity in the degradation of cationic organic dyes. CLI from different regions was tested in the photocatalytic degradation of methylene blue (MB) as a model cationic dye. The photocatalytic tests were performed at room temperature and atmospheric pressure under visible light irradiation. For all the CLI samples, the highest activity was observed at pH = 6. Total MB degradation varied between 70 and 91% (C0 = 10 mg dm–3, 0.2 g dm–3 of photocatalyst, during 300 min). It is suggested that the presence of Fe species in the studied tuffs is responsible for the photocatalytic activity. The activity increases linearly with the Fe content in the tuffs. The MB photodegradation follows the Langmuir–Hinshelwood kinetic model. The recyclability tests showed good stability and efficiency of the photocatalyst. The degradation rate decreased from 91 to 69% during three reaction cycles, indicating a promising potential of natural zeolites in the treatment of textile industry wastewater.
Collapse
|
11
|
Natural-zeolite purification by a sacrificial scavenger porous layer. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2021.139307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|