Publications by authors named "Albin Pintar"

This study investigates the improvement of the photocatalytic activity of TiO-based catalysts modified with plasmonic metal nanoparticles (PM). Gold (Au), silver (Ag) and platinum (Pt) nanoparticles were uniformly deposited on TiO nanorods (TNR) by a wet impregnation method, achieving a uniform metal loading of 1.0 wt%, which was confirmed by SEM-EDXS analysis.

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This study focused on the preparation and investigation of g-CN/TiO photocatalysts using different TiO morphologies (anatase nanoparticles (TPs), poorly crystalline nanotubes (aTTs), and well-crystalline anatase nanorods (TRs)) and self-synthesized g-CN (CN). The synthesis of the g-CN/TiO composites was carried out using a mortar mixing technique and a g-CN to TiO weight ratio of 1:1. In addition, the g-CN/TiO composites were annealed in a muffle furnace at 350 °C for 2 h in air.

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Iminophosphoranes with the general formula (RP═NR') have great potential in synthetic chemistry as valuable precursors/intermediates in organic synthesis or as building blocks for various organic compounds. However, the synthetic approaches and conditions to prepare iminophosphoranes are still poorly understood, limiting the utility of this chemistry for organic materials. In this article, a simple and efficient synthesis of previously unattainable poly(arylene iminophosphoranes) is reported.

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In this article, we report a series of functionalized polyacetylene-type networks formed by chain-growth insertion coordination polymerization in high internal phase emulsions (HIPEs). All polymerized HIPEs (polyHIPEs) contain a hierarchically structured, 3D-interconnected porous framework consisting of a micro-, meso- and macropore system, resulting in exceptionally high specific surface areas (up to 1055 m·g) and total porosities of over 95%. The combination of π-conjugated and hierarchically porous structure in one material enabled the use of these polyacetylene polyHIPEs as adsorptive photocatalysts for the removal of chemical contaminants from water.

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Article Synopsis
  • - This study developed a new type of photocatalyst using nanoflower-shaped gold (Au) supported on titanium oxide (TiO) and explored its properties through different synthesis methods.
  • - The distribution of gold nanoflowers was found to be uniform with lower concentration of sodium citrate but became uneven with a higher concentration, affecting their optical properties and photocatalytic performance.
  • - The optimized catalyst demonstrated high efficiency in reducing nitric oxide (NO) to nitrogen (N) under visible light, while the poorly distributed Au nanoflowers did not show such activity, highlighting the critical role of synthesis methods in determining effectiveness.
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Highly porous metal oxide-polymer nanocomposites are attracting considerable interest due to their unique structural and functional features. A porous polymer matrix brings properties such as high porosity and permeability, while the metal oxide phase adds functionality. For the metal oxide phase to perform its function, it must be fully accessible, and this is possible only at the pore surface, but functioning surfaces require controlled engineering, which remains a challenge.

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A γ-alumina support functionalized with transition metals is one of the most widely used industrial catalysts for the total oxidation of volatile organic compounds (VOCs) as air pollutants at higher temperatures (280-450 °C). By rational design of a bimetal CuFe-γ-alumina catalyst, synthesized from a dawsonite alumina precursor, the activity in total oxidation of toluene as a model VOC at a lower temperature (200-380 °C) is achieved. A fundamental understanding of the catalyst and the reaction mechanism is elucidated by advanced microscopic and spectroscopic characterizations as well as by temperature-programmed surface techniques.

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Conjugated porous polymers through the emulsion-templating polymerization process are typically prepared as monoliths, and the emulsions are cured via metal-catalyzed cross-coupling reactions. Herein, we report the design and synthesis of well-defined, millimeter-sized conjugated porous polymer beads by combining an oil-in-oil-in-oil (O/O/O) double emulsion as a de novo template and an amino-catalyzed Knoevenagel condensation reaction as a polymerization chemistry to cure such emulsions. The 1,4-phenylenediacetonitrile is reacted with aromatic multialdehydes in the presence of piperidine, and a series of metal-free poly(arylene cyano-vinylene) beads are prepared.

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In the wood-free paper industry, whitewater is usually a mixture of additives for paper production. We are currently lacking an efficient, cost-effective purification technology for their removal. In closed whitewater cycles the additives accumulate, causing adverse production problems, such as the formation of slime and pitch.

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ZnFe2O4/rGO/g-C3N4 ternary nanocomposite photocatalysts with different ZnFe2O4/g-C3N4 weight ratio (0.5, 0.75, 1) were prepared by a stepwise solvothermal method using ethylene glycol as the solvent.

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We present here important new findings on the direct synthesis of bimetal Cu-Mn containing porous silica catalyst and the effects of structure-directing agent removal from the prepared nanomaterial on the evolution of surface catalytic sites. The extraction-calcination procedure of the structure-directing agent removal led to the formation of Cu and Mn oxo-clusters and Cu and Mn oxide nanoparticles smaller than 5 nm, while the solely calcination procedure led to the mentioned species and in addition to the appearance of CuO nanoparticles 20 nm in size. Catalysts were tested in the Fenton-like catalytic degradation of dyes with different molecular charge (cationic, anionic, and zwitterionic) as model organic pollutants in wastewater at neutral pH.

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A novel hierarchically structured composite aimed as a stable catalyst for the heterogeneous Fenton-type (HFT) oxidation process was developed by using a cost-effective and versatile technique. Prussian Blue nanoparticles (PBNP) were dispersed onto aligned macroporous TiO (rutile) monoliths prepared via directional freezing of aqueous dispersions of TiO nanoparticles. The catalytic performance was evaluated in the HFT oxidation of an azo dye frequently used as a model contaminant, Orange G (OG).

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This work merges the fields of highly porous polymers (polymerized high internal phase emulsions, polyHIPEs) and synthetic cationic polyelectrolytes and introduces a new approach toward the synthesis of highly porous cationic polyelectrolytes. Cationic polyelectrolytes based on (3-acrylamidopropyl)-trimethylammonium chloride (AMPTMA) were synthesized directly through the oil-in-water HIPEs. The resulting polyelectrolyte-based polyHIPEs are distinguished by the highly porous morphology as well as high concentration and accessibility of the cationic N-quaternized functional groups.

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The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in vapor-phase is economically more viable route if compared to reaction in liquid-phase. To improve the GVL yield in the vapor-phase reaction, the optimization of nickel modified zeolite as bi-functional catalyst (Ni/HZSM-5) was studied. Ni/HZSM-5 materials with fixed Al/Si molar ratio of 0.

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This study assesses the impact of different support materials (Mutag BioChip™, expanded clay and activated carbon) on microbial hydrogen production in an anaerobic packed-bed reactor (APBR) treating synthetic waste water containing glucose as the main carbon source at low pH value. The APBRs were inoculated with acid pretreated anaerobic sludge and operated at pH value of 4±0.2 and hydraulic retention time (HRT) of 3h.

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Hydrogen is considered to be an ideal energy alternative to replace environmentally burdensome fossil fuels. For its long-term production the immobilized biofilm system is the most promising and to choose the right support material the most challenging. In this respect, the anaerobic up-flow bioreactors packed with four most used support materials (polyethylene, polyurethane, activated carbon and expanded clay) were tested to investigate the crucial bacteria sensitive period-the immobilization process.

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The as-synthesized TiO nanorods a-TNR (amorphous TiO layer covering the crystalline anatase TiO core) and TNR (fully crystalline anatase TiO) were decorated with reduced graphene oxide (rGO) to synthesize two series of TiO + rGO composites with different nominal loadings of GO (from 4 to 20 wt%). The structural, surface and electronic properties of the obtained TiO + rGO composites were analyzed and correlated to their performance in the photocatalytic oxidation of aqueous bisphenol A solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that charge separation in TiO + rGO composites is improved due to the perfect matching of TiO and rGO valence band maxima (VBM).

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In the present study a biological "in vivo" assay, with freshwater isopod Asellus aquaticus, was used to define and evaluate the potential impact of the wastewater treatment plant (WWTP) wastewaters on local wildlife. Samples of both untreated and mechanically and biologically treated WWTP wastewater, were tested in the presence and absence of the formulated sediment for their lethal and sublethal effects. Chronic exposures to wastewater samples caused concentration dependent reduced locomotion, body pigmentation and molting frequency in exposed organisms.

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Hydrogen could be alternative energy carrier in the future as well as source for chemical and fuel synthesis due to its high energy content, environmentally friendly technology and zero carbon emissions. In particular, conversion of organic substrates to hydrogen via dark fermentation process is of great interest. The aim of this study was fermentative hydrogen production using anaerobic mixed culture using different carbon sources (mono and disaccharides) and further optimization by varying a number of operating parameters (pH value, temperature, organic loading, mixing intensity).

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Production of bisphenol A (BPA) analogues such as bisphenol F (BPF) and bisphenol AF (BPAF) has recently increased, due to clear evidence of adverse effects of BPA on humans and wildlife. Bisphenols (BPs) have already been released into aquatic environment without previous available information about potential adverse effects of BPs and their potential risk to aquatic ecosystems. In this study, lethal and sublethal effects of BPF and BPAF to bacteria, algae, crustacea and fish embryos were investigated and the results were compared to the adverse effects obtained for BPA.

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Degradation of aqueous solution of bisphenol A (BPA) has been investigated through non-catalytic and catalytic ozonation treatments conducted in a semi-batch reactor. Non-catalytic ozonation resulted in complete degradation of aqueous BPA in less than 3 min but did not completely convert the reaction intermediates of BPA ozonation into CO2 and H2O. The main goal of this study was to find an effective heterogeneous catalyst to increase the extent of BPA mineralization at different pH conditions.

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The enhanced oxidative potential of sludge carbon/TiO2 nano composites (SNCs), applied as heterogeneous catalysts in advanced oxidation processes (AOPs), was studied. Fabrification of efficient SNCs using different methods and successful evaluation of their catalytic oxidative activity is reported for the first time. Surface modification processes of hydrothermal deposition, chemical treatment and sol-gel solution resulted in improved catalytic activity and good surface chemistry of the SNCs.

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Synopsis of recent research by authors named "Albin Pintar"

  • - Albin Pintar's recent research focuses on the development of advanced photocatalytic materials, including hierarchically porous polyacetylene networks and metal oxide-polymer nanocomposites, aimed at efficiently removing chemical contaminants such as Bisphenol A from water.
  • - His studies also explore innovative catalysts, such as TiO-supported gold nanoflowers and bimetallic Cu-Fe oxide clusters on alumina supports, for the low-temperature catalytic oxidation of volatile organic compounds, highlighting a significant reduction in required reaction temperatures.
  • - Additionally, Pintar's work incorporates microbial approaches for environmental applications, including the identification of bacteria for bioaugmentation in the wood-free paper industry to address purification challenges in whitewater recycling processes.