Papers by Laszlo Csetenyi
Cement and Concrete Research, Apr 1, 1999
Water leaching of caesium (Cs)-loaded cemented ion exchange resin and the mechanism of Cs immobil... more Water leaching of caesium (Cs)-loaded cemented ion exchange resin and the mechanism of Cs immobilization were studied in the cement-resin-zeolite (mainly clinoptilolite) system. Present work focuses on the reduction of significant Cs leaching (in terms of the total Cs adsorbed on the resin) by blending natural untreated and chemically treated zeolites to the cement. Addition of natural zeolites decreased Cs release by up to 70-75% (of the quantity originally bonded in the resin) in the course of a 3-year leaching period.
Ground engineering, 2011
Sulphate-containing clay soils are know to cause swelling with the application of lime, due to th... more Sulphate-containing clay soils are know to cause swelling with the application of lime, due to the formation of expansive compounds. Laboratory tests were carried out to examine the potential of fly ash to limit swelling. Artificial soil samples with a 4:1 sand / montmorillonite ratio and 2% added sulphate (in the form of gypsum), were combined with 6% hydrated lime and 3,6, 9 or 12% fly ash or 3,6 or 9% ground granulated blast furnace slag (GGBS). Cylindrical specimens with a 4:1 solids / moisture ratio were compacted under a fixed load and immersed in water at room temperature until their linear expansion levelled off. Most changes occurred within 10-11 days with fly ash and 5-6 days with GGBS. Both treatments gave similarly reduced expansion to that with GGBS, compared to the lime-stabilised artificial soil control. A further field study with relevant UK clay soils was conducted, comparing quicklime with and a range of UK fly ashes. Mellowing periods of 0, 1 and 3 days were considered. Specimens were prepared in accordance with BS EN 13285-53. After one day of fog room storage, the specimens were immersed in a water bath at room temperature and their linear expansion determined after 7 and 14 days. There was an increase in swelling with sulphate level, with Oxford and Kimmeridge clays giving greater expansions than those of London or Lias strata. In addition, swelling of Oxford clay continues after 7 days. Addition of fly ash to the mixes consistently reduced swelling with addition of 12-18% required. Fly ash reduced swelling of lime-stabilised clay soils, with increasing levels and coarser materials producing better results.
Applied Microbiology and Biotechnology, Nov 28, 2019
In this research, the capabilities of culture supernatants generated by the oxalate-producing fun... more In this research, the capabilities of culture supernatants generated by the oxalate-producing fungus Aspergillus niger for the bioprecipitation and biorecovery of cobalt and nickel were investigated, as was the influence of extracellular polymeric substances (EPS) on these processes. The removal of cobalt from solution was >90% for all tested Co concentrations: maximal nickel recovery was >80%. Energy-dispersive X-ray analysis (EDXA) and X-ray diffraction (XRD) confirmed the formation of cobalt and nickel oxalate. In a mixture of cobalt and nickel, cobalt oxalate appeared to predominate precipitation and was dependent on the mixture ratios of the two metals. The presence of EPS together with oxalate in solution decreased the recovery of nickel but did not influence the recovery of cobalt. Concentrations of extracellular protein showed a significant decrease after precipitation while no significant difference was found for extracellular polysaccharide concentrations before and after oxalate precipitation. These results showed that extracellular protein rather than extracellular polysaccharide played a more important role in influencing the biorecovery of metal oxalates from solution. Excitation-emission matrix (EEM) fluorescence spectroscopy showed that aromatic protein-like and hydrophobic acid-like substances from the EPS complexed with cobalt but did not for nickel. The humic acid-like substances from the EPS showed a higher affinity for cobalt than for nickel.
Construction and Building Materials, Aug 1, 2022
Magazine of Concrete Research, Jun 1, 2015
A study examining damaging alkali-aggregate reaction (AAR) in concretes containing recycled aggre... more A study examining damaging alkali-aggregate reaction (AAR) in concretes containing recycled aggregate is described. This considered masonry units, concrete, demolition waste, road planings, slate and plasterboard. Alkali release tests indicated that masonry units tended to release more alkali than recycled concrete (with higher levels generally obtained from recently produced materials), with slate and plasterboard giving least. Accelerated mortar expansion (reactivity) test results suggested there was a low risk of AAR for the materials. Concrete tests were then made using BS 812-123 exposure conditions. The concretes were proportioned (i) following the standard mixes (Na 2 O eq 7. 0 kg/m 3) with recycled materials replacing fine or coarse aggregate in a low-reactivity aggregate combination and (ii) at high alkali level (Na 2 O eq 5. 4 kg/m 3) with the materials as fine aggregate in a normalreactivity aggregate combination. The tests for (i) gave results for the recycled materials indicating low reactivity, with classifications of non-expansive or probably non-expansive to BRE Digest 330. For (ii), expansions for the materials were mainly similar/slightly higher than those found for (i). However, recycled concrete that previously exhibited damaging AAR had greater expansions. Selected concretes were exposed at an external site for up to 8. 5 years, during which observations by microscopy were carried out. These gave general agreement with the laboratory tests. The practical implications of the study are reviewed.
Environmental Microbiology, Feb 1, 2021
Geoactive fungi play a significant role in bioweathering of rock and mineral substrates. Monazite... more Geoactive fungi play a significant role in bioweathering of rock and mineral substrates. Monazite is a phosphate mineral containing the rare earth elements (REE) cerium, lanthanum and neodymium. Little is known about geomicrobial transformations of REE-bearing minerals which are also relevant to REE biorecovery from terrestrial and extra-terrestrial reserves. The geoactive soil fungus Aspergillus niger colonized monazite in solid and liquid growth media without any apparent growth inhibition. In a glucoseminerals salts medium, monazite enhanced growth and mycelium extensively covered rock particle surfaces, probably due to the provision of phosphate and essential trace metals. Teeth-like and pagoda-like etching patterns indicated monazite dissolution, with extensive precipitation of secondary oxalate minerals. Biomechanical forces ensued causing aggressive bioweathering effects by tunnelling, penetration and splitting of the ore particles. High amounts of oxalic acid ($46 mM) and moderate amounts of citric acid ($5 mM) were produced in liquid media containing 2% (wt./vol.) monazite, and REE and phosphate were released. Correlation analysis suggested that citric acid was more effective than oxalic acid in REE mobilization, although the higher concentration of oxalic acid also implied complexant activity, as well as the prime role in REE-oxalate precipitation.
Applied Microbiology and Biotechnology, Nov 15, 2018
Lanthanum is an important rare earth element and has many applications in modern electronics and ... more Lanthanum is an important rare earth element and has many applications in modern electronics and catalyst manufacturing. However, there exist several obstacles in the recovery and cycling of this element due to a low average grade in exploitable deposits and low recovery rates by energy-intensive extraction procedures. In this work, a novel method to transform and recover La has been proposed using the geoactive properties of Aspergillus niger. La-containing crystals were formed and collected after A. niger was grown on Czapek-Dox agar medium amended with LaCl 3. Energy-dispersive X-ray analysis (EDXA) showed the crystals contained C, O, and La; scanning electron microscopy revealed that the crystals were of a tabular structure with terraced surfaces. X-ray diffraction identified the mineral phase of the sample as La 2 (C 2 O 4) 3 •10H 2 O. Thermogravimetric analysis transformed the oxalate crystals into La 2 O 3 with the kinetics of thermal decomposition corresponding well with theoretical calculations. Geochemical modelling further confirmed that the crystals were lanthanum decahydrate and identified optimal conditions for their precipitation. To quantify crystal production, biomass-free fungal culture supernatants were used to precipitate La. The results showed that the precipitated lanthanum decahydrate achieved optimal yields when the concentration of La was above 15 mM and that 100% La was removed from the system at 5 mM La. Our findings provide a new aspect in the biotransformation and biorecovery of rare earth elements from solution using biomass-free fungal culture systems.
Environmental Microbiology, Apr 1, 2020
Struvite (magnesium ammonium phosphate-MgNH 4 PO 4 Á6H 2 O), which can extensively crystallize in... more Struvite (magnesium ammonium phosphate-MgNH 4 PO 4 Á6H 2 O), which can extensively crystallize in wastewater treatments, is a potential source of N and P as fertilizer, as well as a means of P conservation. However, little is known of microbial interactions with struvite which would result in element release. In this work, the geoactive fungus Aspergillus niger was investigated for struvite transformation on solid and in liquid media. Aspergillus niger was capable of solubilizing natural (fragments and powder) and synthetic struvite when incorporated into solid medium, with accompanying acidification of the media, and extensive precipitation of magnesium oxalate dihydrate (glushinskite, Mg(C 2 O 4).2H 2 O) occurring under growing colonies. In liquid media, A. niger was able to solubilize natural and synthetic struvite releasing mobile phosphate (PO 4 3−) and magnesium (Mg 2+), the latter reacting with excreted oxalate resulting in precipitation of magnesium oxalate dihydrate which also accumulated within the mycelial pellets. Struvite was also found to influence the morphology of A. niger mycelial pellets. These findings contribute further understanding of struvite solubilization, element release and secondary oxalate formation, relevant to the biogeochemical cycling of phosphate minerals, and further directions utilizing these mechanisms in environmental biotechnologies such as element biorecovery and biofertilizer applications.
Fuel, Feb 1, 2012
The paper describes a study carried out to examine the effects of fly ash in limiting damaging su... more The paper describes a study carried out to examine the effects of fly ash in limiting damaging sulfateheave (swelling) in lime-stabilized soils. This considered three clays with various sulfate levels; seven fly ashes covering a range of physical and chemical properties, and stored under different conditions (dry, stockpiled and ponded); and a typical quicklime. The initial part of the study examined the effects of fly ash (applied at levels of 6 to 24% by mass of dry soil) on compaction (in terms of density/moisture relationships) of the lime-stabilized soils (using 3.0% lime) to establish mix compositions and provide an insight to their resulting structure. This indicated that maximum dry density (MDD) and optimum moisture content (OMC) were influenced by the characteristics of fly ash (reducing and increasing respectively with increasing fly ash coarseness and loss-on-ignition (LoI; including that under wet storage)) and, depending on these, by the level of application. Tests for sulfate-heave were made following the BS EN 13286-49 volumetric swelling method. Fly ash gave systematic reductions in sulfate-heave with increasing application level up to 24% for the lime-stabilized soils tested. It was found that coarse, high LoI fly ashes, stored under wet conditions, were most effective in limiting the process, suggesting that the coarser structure obtained during compaction with these materials, i.e. lower MDD, is an important factor influencing this. The presence of high sulfate levels in fly ash reduced the effectiveness of the material in this role. The practical implications are considered and a nomogram relating fly ash fineness and application level, MDD and sulfate-swelling is developed, which demonstrates a possible methodology for material selection with regard to minimizing damage.
Applied Microbiology and Biotechnology, Jul 9, 2019
The ureolytic activity of Neurospora crassa results in an alkaline carbonate-rich culture medium ... more The ureolytic activity of Neurospora crassa results in an alkaline carbonate-rich culture medium which can precipitate soluble metals as insoluble carbonates. Such carbonates are smaller, often of nanoscale dimensions, than metal carbonates synthesized abiotically which infers that fungal excreted products can markedly affect particle size. In this work, it was found that amino acid excretion was a significant factor in affecting the particle size of copper carbonate. Eleven different amino acids were found to be secreted by Neurospora crassa, and L-glutamic acid, L-aspartic acid and L-cysteine were chosen to examine the impact of amino acids on the morphology and chemical composition of copper carbonate minerals. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained copper carbonate samples. Copper carbonate nanoparticles with a diameter of 100-200 nm were produced with L-glutamic acid, and the presence of L-glutamic acid was found to stabilize these particles in the early phase of crystal growth and prevent them from aggregation. FTIR and TG analysis revealed that the amino acid moieties were intimately associated with the copper mineral particles. Component analysis of the final products of TG analysis of the copper minerals synthesized under various conditions showed the ultimate formation of Cu, Cu 2 O and Cu 2 S, suggesting a novel synthesis method for producing these useful Cu-containing materials.
Thomas Telford eBooks, 2002
... of Building Materials Technion Israel Institute of Technology, Israel Professor JMJM Bijen, P... more ... of Building Materials Technion Israel Institute of Technology, Israel Professor JMJM Bijen, Professor Delft University of Technology, Netherlands Professor A Brandt, Head of Department Insistute of Fundamental Tech Research, Poland Professor KJ Byun, Dean/Professor in ...
Acta Crystallographica Section C-crystal Structure Communications, Jun 15, 1993
/3=111.60(4) ° , V =355.4(3) A 3, Z=4, Ox= 1.903 Mg m-3, a(Mo Ka) = 0.71069/~, /z = 0.27 mm-1, F(... more /3=111.60(4) ° , V =355.4(3) A 3, Z=4, Ox= 1.903 Mg m-3, a(Mo Ka) = 0.71069/~, /z = 0.27 mm-1, F(000)= 208, room temperature, R = 0.030 for 882 observed reflections with I > 3o-(/). The structure consists of six-coordinate Na + in cavities in a hydrogen-bonded framework of BOa tetrahedra. Only three of the four H atoms of the anions are involved in O-H...O bonding.
Access microbiology, Mar 1, 2019
Bacterial infection and corrosion are two of the most common causes of the failure for the use of... more Bacterial infection and corrosion are two of the most common causes of the failure for the use of biomedical metallic implants. In this paper, we developed a facile two-step approach for synthesizing a TiO 2-PTFE nanocomposite coating on stainless steel substrate with both antibacterial and anticorrosion properties by using a solgel dip coating technique. A sub-layer of bioinspired polydopamine (PDA) was first coated on the stainless steel substrate to improve the adhesion and reactivity, then TiO 2-PTFE was uniformly co-deposited onto the PDA sublayer. Both PTFE and TiO 2 contents had a significant influence on the surface energy of the TiO 2-PTFE coating. The coating with the total surface energy of 26 mJ/m 2 exhibited minimal bacterial adhesion against both Gramnegative Escherichia coli WT F1693 and Gram-positive Staphylococcus aureus F1557, which was explained using the extended DLVO theory. Benefiting from the synergistic effect between TiO 2 and PTFE, the TiO 2-PTFE coating showed improved corrosion resistance in artificial body fluids compared with the sole TiO 2 coating or PTFE coating. The TiO2-PTFE coating also demonstrated extraordinary biocompatibility with fibroblast cells in culture, making it a prospective strategy to overcome current challenges in the use of metallic implants.
Journal of Materials in Civil Engineering, Feb 1, 2019
Designing concrete to attain its durability requirements is a tough challenge. Chloride ingress i... more Designing concrete to attain its durability requirements is a tough challenge. Chloride ingress is one of the most severe problems affecting the durability of concrete and has been investigated extensively. There has also been a growing interest to reduce the use of conventional natural aggregates to promote sustainability in construction industry. In this study, quartz sandstones are replaced for natural coarse aggregates in concrete and tested for chloride and corrosion resistance. The study revealed that the concrete containing quartz sandstones as coarse aggregates performed well in corrosive environment. In the chloride ion penetration test, concrete with 20% quartz sandstones showed a similar pattern to that of the control concrete made solely from natural coarse aggregates.
Waste Management & Research, Jul 28, 2020
Oil-based mud (OBM) waste from the oil and gas exploration industry can be valorised to tailor-ma... more Oil-based mud (OBM) waste from the oil and gas exploration industry can be valorised to tailor-made reclaimed clay-reinforced lowdensity polyethylene (LDPE) nanocomposites. This study aims to fill the information gap in the literature and to provide opportunities to explore the effective recovery and recycling techniques of the resources present in the OBM waste stream. Elemental analysis using inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray fluorescence analysis, chemical structural analysis by Fourier transform infrared (FTIR) spectroscopy, and morphological analysis of LDPE/organo-modified montmorillonite (LDPE/ MMT) and LDPE/OBM slurry nanocomposites by scanning electron microscopy (SEM) have been conducted. Further analysis including calorimetry, thermogravimetry, spectroscopy, microscopy, energy dispersive X-ray analysis and X-ray diffraction (XRD) was carried out to evaluate the thermo-chemical characteristics of OBM waste and OBM clay-reinforced LDPE nanocomposites, confirming the presence of different clay minerals including inorganic salts in OBM slurry powder. The microscopic analysis revealed that the distance between polymer matrix and OBM slurry filler is less than that of MMT, which suggests better interfacial adhesion of OBM slurry compared with the adhesion between MMT and LDPE matrix. This was also confirmed by XRD analysis, which showed the superior delamination structure OBM slurry compared with the structure of MMT. There is a trend noticeable for both of these fillers that the nanocomposites with higher percentage filler contents (7.5 and 10.0 wt% in this case) were indicated to act as a thermal conductive material. The heat capacity values of nanocomposites decreased about 33% in LDPE with 7.5 wt% MMT and about 17% in LDPE with 10.0 wt% OBM slurry. It was also noted, for both nanocomposites, that the residue remaining after 1000°C increases with the incremental wt% of fillers in the nanocomposites. There is a big difference in residue amount (in %) left after thermogravimetric analysis in the two nanocomposites, indicating that OBM slurry may have significant influence in decomposing LDPE matrix; this might be an interesting area to explore in the future. The results provide insight and opportunity to manufacture waste-derived renewable nanocomposites with enhanced structural and thermal properties.
Magazine of Concrete Research, May 1, 2020
Low-lime fly ashes produced from modern coal-fired power technologies (developed to enhance effic... more Low-lime fly ashes produced from modern coal-fired power technologies (developed to enhance efficiency/lower emissions), including nitrogen oxide (NO x) reduction, co-combustion, supercritical steam and oxy-fuel combustion, and their effects on chloride ingress and carbonation of concrete are investigated in this paper. Earlier work indicates that some of these technologies influence fly ash properties, but they mainly follow typical behaviour found for the material (consistence and compressive strength) in concrete. Both accelerated and normal-type exposure tests were carried out on a range of practical water/cement ratio concretes (also enabling interpolation for comparisons at equal 28 d strength). The test fly ash concretes were evaluated against (i) those containing three reference fly ashes covering a range of fineness and (ii) corresponding studies on fly ash concretes from the 1990s. The results show that there was an influence of fly ash fineness, reflected in reactivity/porosity (measured on mortar), and aspects of chemistry on chloride ingress, but there appeared to be minor material effects on carbonation. Comparison with the 1990s data indicated similar behaviour for the materials between studies for both properties. A relationship was also identified for the product of reactive alumina and sub-10 μm contents of the modern fly ashes and chloride resistance of concrete. Cite this article McCarthy MJ, Yakub HI and Csetenyi LJ (2020) Fly ash from modern coal-fired power technologies: chloride ingress and carbonation of concrete.
Journal of Cleaner Production, 2022
Microbial biotechnology, Jun 11, 2021
There are a need for novel, economical and efficient metal processing technologies to improve cri... more There are a need for novel, economical and efficient metal processing technologies to improve critical metal sustainability, particularly for cobalt and nickel which have extensive applications in low-carbon energy technologies. Fungal metal biorecovery processes show potential in this regard and the products of recovery are also industrially significant. Here we present a basis for selective biorecovery of Co and Ni oxalates and phosphates using reactive spent Aspergillus niger culture filtrate containing mycogenic oxalate and phosphate solubilized from struvite. Selective precipitation of oxalates was achieved by adjusting phosphate-laden filtrates to pH 2.5 prior to precipitation. Co recovery at pH 2.5 was high with a maximum of~96% achieved, while~60% Ni recovery was achieved, yielding microscale polyhedral biominerals. Co and Ni phosphates were precipitated at pH 7.5, following prior oxalate removal, resulting in neartotal Co recovery (>99%), while Ni phosphate yields were also high with a recovery maximum of 83.0%.
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Papers by Laszlo Csetenyi