1. Hydrazone-linked covalent organic framework catalyst via efficient Pd recovery from wastewaterMahira Bashri, Sushil Kumar, Pallab Bhandari, Sasi Stephen, Matthew J. O'Connor, Safa Gaber, Tina Škorjanc, Matjaž Finšgar, Gisha Elizabeth Luckachan, Blaž Belec, 2024, original scientific article Abstract: Global consumption and discharge of palladium (Pd) have raised environmental concerns but also present an opportunity for the sustainable recovery and reuse of this precious metal. Adsorption has proven to be an efficient method for the selective recovery of Pd from industrial wastewater. This study investigated a hydrazone-linked covalent organic framework (Tfpa-Od COF) as a potential material for the high-affinity adsorption of Pd2+ ions from wastewater, achieving a Kd value of 3.62 × 106 mL g–1. The electron-rich backbone of the COF contributes to its excellent selective removal efficiency (up to 100%) and adsorption capacity of 372.59 mg g–1. Furthermore, the Pd-adsorbed COF was evaluated as a sustainable catalyst for the Suzuki–Miyaura coupling reaction, demonstrating good catalytic conversion and recyclability. This work attempts to showcase a protocol for reusing waste palladium generated in water to fabricate heterogeneous catalysts and, thereby, promote the circular economy concept. Keywords: covalent organic frameworks, sustainability, catalysis, palladium adsorption, water purification Published in RUNG: 22.08.2024; Views: 800; Downloads: 6 Full text (4,04 MB) This document has many files! More... |
2. Hydrophobicity Tuning in Isostructural Urchin-Shaped Covalent Organic Framework Nanoparticles by Pore Surface Engineering for Oil–Water SeparationGobinda Das, Tina Skorjanc, Thirumurugan Prakasam, Bikash Garai, Salma Abubakar, Christina Zalch Saad, Felipe Gandara, Renu Pasricha, Sudhir Kumar Sharma, Sabu Varghese, Ramesh Jagannathan, Mark A. Olson, Ali Trabolsi, 2022, original scientific article Keywords: Adsorption, Covalent organic frameworks, Hydrophobicity, Lipids, Materials Published in RUNG: 26.09.2022; Views: 2447; Downloads: 0 This document has many files! More... |
3. Covalent Organic Framework Based on Azacalix[4]arene for the Efficient Capture of Dialysis Waste ProductsTina Škorjanc, Dinesh Shetty, Felipe Gándara, Pascal Simon, Nawavi Naleem, Salma Abubakar, Liaqat Ali, Abdul Khayum Mohammed, Jesus Raya, Serdal Kirmizialtin, 2022, original scientific article Keywords: azacalixarene, covalent organic frameworks, dialysis, uric acid, creatinine, adsorption Published in RUNG: 08.09.2022; Views: 2702; Downloads: 0 This document has many files! More... |
4. Synthesis and Characterization of MWCNT-COOH/Fe3O4 and CNT-COOH/Fe3O4/NiO Nanocomposites: Assessment of Adsorption and Photocatalytic PerformanceAdina Stegarescu, Humberto Cabrera, Hanna Budasheva, Maria-Loredana Soran, Ildiko Lung, Francesca Limosani, Dorota Korte, Matteo Amati, Gheorghe Borodi, Ocsana Opris, Monica Dan, Stefano Bellucci, 2022, original scientific article Keywords: carbon nanotubes, magnetite, tartrazine, photodegradation, adsorption, water decontamination Published in RUNG: 02.09.2022; Views: 2447; Downloads: 31 Full text (5,78 MB) |
5. Pollutant removal with organic macrocycle-based covalent organic polymers and frameworksTina Škorjanc, Dinesh Shetty, Ali Trabolsi, 2021, review article Abstract: Air, water, and soil pollution devastate countless ecosystems and deteriorate human health. Adsorption has commonly been used as a pollutant removal technique, but ongoing materials science research is still searching for more efficient, cheaper, and scalable sorbent materials. Herein, we discuss the synthesis and pollutant-capturing abilities of covalent polymeric structures, including covalent organic polymers and covalent organic frameworks that contain organic macrocycles in the backbone of their structures. These organic macrocycles (cyclodextrin, calixarene, cucurbituril, pillararene, and porphyrin) possess cavities and functional groups that can sequester pollutants by forming supramolecular interactions. The insolubility of these materials prominently aids in their regeneration and recyclability potentials. Following a discussion on the synthetic strategies used in the polymerization of each type of macrocycle, environmental applications of these materials are presented. Here, we focus on the removal of micropollutants, charged species, metal ions, oils and organic solvents, perfluorinated substances, iodine, and volatile organic compounds. Keywords: supramolecular interactions, host-guest chemistry, organic macrocycles, covalent polymers, covalent organic frameworks, environmental remediation, adsorption Published in RUNG: 09.04.2021; Views: 3206; Downloads: 66 Link to full text This document has many files! More... |
6. Taming the topology of calix[4]arene-based 2D-covalent organic frameworks : interpenetrated vs noninterpenetrated frameworks and their selective removal of cationic dyesBikash Garai, Dinesh Shetty, Tina Škorjanc, Felipe Gándara, Nawavi Naleem, Sabu Varghese, Sudhir Kumar Sharma, Maria Baias, Ramesh Jagannathan, Mark Anthony Olson, 2021, original scientific article Abstract: A bowl-shaped calix[4]arene with its exciting host–guest chemistry is a versatile supramolecular building block for the synthesis of distinct coordination cages or metal–organic frameworks. However, its utility in the synthesis of crystalline covalent organic frameworks (COFs) remains challenging, presumably due to its conformational flexibility. Here, we report the synthesis of a periodic 2D extended organic network of calix[4]arenes joined by a linear benzidine linker via dynamic imine bonds. By tuning the interaction among neighboring calixarene units through varying the concentration in the reaction mixture, we show the selective formation of interpenetrated (CX4-BD-1) and non-interpenetrated (CX4-BD-2) frameworks. The cone-shaped calixarene moiety in the structural backbone allows for the interweaving of two neighboring layers in CX4-BD-1, making it a unique example of interpenetrated 2D layers. Due to the high negative surface charge from calixarene units, both COFs have shown high performance in charge-selective dye removal and an exceptional selectivity for cationic dyes irrespective of their molecular size. The charge distribution of the COFs and the resulting selectivity for the cationic dyes were further investigated using computational methods. Keywords: dyes and pigments, covalent organic frameworks, adsorption, layers, chemical structure Published in RUNG: 16.03.2021; Views: 3062; Downloads: 0 This document has many files! More... |
7. Composite films of regenerate cellulose with chitosan and polyvinyl alcohol: Evaluation of water adsorption, mechanical and optical propertiesPatricia Cazón, Manuel Vazquez, Gonzalo Velazquez, 2018, original scientific article Abstract: The aimof this study was to develop composite films from cellulose, chitosan and polyvinyl alcohol to obtain environmentally friendly materials. Toughness, burst strength, distance to burst and water adsorption properties weremeasured and analysed as a function ofcellulose (3–5%), chitosan (0–1%) andpolyvinyl alcohol (0–4%) con- tents. Polynomial modelswere obtained. Light-barrier properties, transparency, morphology, structural and ther- mal analyses were assessed. Results showed that chitosan and polyvinyl alcohol enhanced the mechanical properties of cellulose-based films. Toughness values ranged from 0.47 to 8.01 MJ/m3, burst strength values ranged from 929 to 6291 g, distance to burst ranged from 1.25 to 2.52 mm and water adsorption values ranged from52.30 to 143.56%. Cellulose and chitosan improved the UV light protection effect ofthe films. However, PVA increased the transmittance meanwhile improved the film transparency. FT-IR and DSC showed an interaction between the components ofthe films. Results showed that it is feasible to obtain cellulose-chitosan-polyvinyl alcohol composite films with improvedmechanical properties, high capacity to adsorbwater, good barrier properties against UV radiations and adequate transparency value. These properties could be useful for potential packaging applications in the food industry or as a partial alternative to synthetic films Keywords: Regenerated cellulose, Puncture test, Water adsorption Published in RUNG: 14.12.2020; Views: 2924; Downloads: 0 This document has many files! More... |
8. Cellulose-glycerol-polyvinyl alcohol composite films for food packaging: Evaluation of water adsorption, mechanical properties, light-barrier properties and transparencyPatricia Cazón, Manuel Vazquez, Gonzalo Velazquez, 2018, original scientific article Abstract: Nowadays consumers are aware of environmental problems. As an alternative to petrochemical polymers for food packaging, researchers have been focused on biopolymeric materials as raw material. The aim of this study was to evaluate mechanical properties (toughness, burst strength and distance to burst), water adsorption, light- barrier properties and transparency of composite films based on cellulose, glycerol and polyvinyl alcohol. Scanning electron microscopy, spectral analysis (FT-IR and UV–VIS-NIR) and differential scanning calorimetry were performed to explain the morphology, structural and thermal properties of the films. Results showed that polyvinyl alcohol enhances the toughness of films up to 44.30 MJ/m3. However, toughness decreases when glycerol concentration is increased (from 23.41 to 10.55 MJ/m3). Water adsorption increased with increasing polyvinyl alcohol concentration up to 222%. Polyvinyl alcohol increased the film thickness. The films showed higher burst strength (up to 12014 g) than other biodegradable films. The films obtained have optimal values of transparency like those values of synthetic polymers. Glycerol produced a UV protective effect in the films, an important effect for food packaging to prevent lipid oxidative deterioration. Results showed that it is feasible to obtain cellulose-glycerol-polyvinyl alcohol composite films with improved properties. Keywords: Cellulose, Toughness, Burst strength, Distance to burst, Water adsorption, Transparency Published in RUNG: 14.12.2020; Views: 3379; Downloads: 0 This document has many files! More... |
9. Environmentally Friendly Films Combining Bacterial Cellulose, Chitosan, and Polyvinyl Alcohol: Effect of Water Activity on Barrier, Mechanical, and Optical PropertiesPatricia Cazón, Manuel Vazquez, Gonzalo Velazquez, 2019, original scientific article Abstract: The interest in developing new materials intended for food packaging based on bacterial cellulose is growing in the recent years. Flexible and transparent films from bacterial cellulose-chitosan-polyvinyl alcohol have shown excellent UV-barrier properties. However, this composite material interacts with ambient moisture modifying its water activity due to its hydrophilic nature. In this work, an extensive study was carried out to evaluate the changes in the properties of these films as a function of water activity. Moisture adsorption isotherm were described by the GAB method. Results showed the plasticizing effect of water molecules increasing the water vapour permeability of the samples from 1.86·10-12 to 1.17·10-11 g/m·s·Pa, the percentage of elongation from 3.25 to 36.55% and the distance to burst from 0.64 to 5.12 mm. The increase of the water activity dropped the tensile strength values from 74.76 to 38.56 MPa, Young’s modulus values from 3133.46 to 30.71 MPa and burst strength to 703.87 g. The values of the UV-barrier were maintained at the wide range of water activity. Consequently, water molecules do not affect the UV-barrier properties of the films. Keywords: GAB model, moisture adsorption isotherms, plasticization, bacterial cellulose, mechanical properties, UV-barrier properties, moisture content Published in RUNG: 09.12.2020; Views: 3421; Downloads: 0 This document has many files! More... |
10. Regenerated cellulose films combined with glycerol and polyvinyl alcohol: Effect of moisture content on the physical propertiesPatricia Cazón, Gonzalo Velazquez, Manuel Vazquez, 2020, original scientific article Abstract: Regenerated cellulose-based films combined with glycerol and polyvinyl alcohol (PVOH) show interesting UV- light barrier properties, with potential application in food packaging to prevent oxidative deterioration. How- ever, these materials are sensitive to moisture, and their properties could be modified as a function of the relative humidity. Hence, the objective of the present work was to evaluate the changes in the main properties of re- generated cellulose-glycerol-PVOH films depending on the relative humidity. Using the GAB adsorption iso- therms, the moisture content was related with the water activity of the films at several relative humidity conditions. According to the obtained results, water molecules manifested a plasticizing effect modifying the mechanical, water vapour permeability and optical properties of the developed films. Tensile strength and Young’s modulus values ranged from 92.65 to 17.57 MPa and from 3639.09 to 227.89 MPa, respectively. Both of them decreased when the moisture content increased. The mechanical resistance to deformation of films enhanced at high moisture content, changing from 5.88 to 15.97% and from 0.59 to 2.97 mm in the tensile and puncture test, respectively. This effect was also observed for the burst strength. Water vapour permeability increased from 5.15⋅10?10 to 5.44⋅10?9 g/ms Pa when the moisture content increased, being more significative at higher values. No significant variations were observed in the UV-VIS transmittance at different moisture contents. The obtained results allow expanding the knowledge of the behavior of films based on regenerated cellulose. Keywords: Adsorption isotherms, Plasticization, Regenerated cellulose, Water vapour permeability, Moisture content Published in RUNG: 09.12.2020; Views: 3405; Downloads: 0 This document has many files! More... |