Lenz, Markus

Profilbild
E-Mail-Adresse
Geburtsdatum
Projekt
Organisationseinheiten
Berufsbeschreibung
Nachname
Lenz
Vorname
Markus
Name
Lenz, Markus

Filter

2014 - 201934
Filter zurücksetzen

Einstellungen

Anfangsdatum: 2014 × Enddatum: 2019 ×

Suchergebnisse

Gerade angezeigt 1 - 10 von 34
  • Vorschaubild nicht verfügbar
    Publikation
    Renewable Energy from Finite Resources: Example of Emerging Photovoltaics
    (Schweizerische Chemische Gesellschaft, 01.11.2019) Schmidt, Felix; Lenz, Markus [in: Chimia]
    Renewable energies, such as sunlight, wind and geothermal heat, are resources that are replaced rapidly by natural processes. However, wind, hydro and solar installations strictly require raw materials that are, in fact, not renewable. Many raw materials are already facing a supply shortage which cannot be easily overcome. This work reviews the problem of critical raw material (CRM) use in photovoltaics (PV) as an example and explains why supply cannot be easily increased to meet demand. We discuss whether there is indeed a 'struggle for elements' in a Darwinian sense, which ultimately leads to a 'survival of the fittest' race in renewable energy technology. In the case of PV, the perception of the definition of 'fittest' needs to change from that considering energy conversion efficiency alone to that which holistically considers net energy produced per emission under the premise that sufficient environmentally and socially acceptable raw material supply exists for renewable energies and all other sectors.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Rapid metal mobilisation through litter, water and bioweathering as the legacy of historical copper smelting
    (Elsevier, 11/2019) Potysz, Anna; Hedwig, Sebastian; Lenz, Markus [in: Journal of Geochemical Exploration]
    Though activities have long ceased, historical mining sites may continue to represent a risk to the environment and human health through long-time leaching processes. This study was undertaken to assess the immediate environmental risk posed by historic metallurgical slags upon contact with litter (Fagus sylvatica leaves, Picea abies needles) and stream water. Further, the contribution of direct slag phase bioweathering was investigated using a soil solution favouring microbial growth (biostimulation) versus aqueous sterile soil extracts. The slags' exposure to Acidithiobacillus thiooxidans mimicked the extremely acidic conditions that will eventually develop under long-term weathering of the sulfidic phases present in the slags (e.g. bornite, chalcopyrite). The risk of metal mobilisation was assessed by means of both bio-chemical leaching experiments (quantification by triple quadrupole inductively coupled plasma mass spectrometry QQQ-ICP-MS) as well as phytotoxicity (Zea mays germination; direct contact and soil pot experiments). Potential metal donor slag phases were identified by scanning electron microscopy (SEM-EDS). It was shown that slags would be categorised as hazardous waste when remaining in contact with the studied weathering solutions. Lead was the most mobile element leaching from slags (up to 86%) and exceeded the legal limits for classification as a non-hazardous waste for all executed treatments. Biostimulation had little effect on Cu leaching (up to 2.6% versus 2.5% for the sterile soil extract, respectively). Litter derived solutions, in contrast, enhanced glass dissolution instead of heavy metal bearing phases. Metal leaching was rapid, raising concerns for peak loads on slag exposure to changing biogeochemical conditions. Extremely acidic conditions and bioleaching by A. thiooxidans were shown to result in metal-enriched leachates (up to 92% of Zn) as well as the lowest germination rate in Zea mays, implying a long term risk by sulphide bioweathering. Five week pot experiments with a soil/slag mixture and Zea mays revealed poor growth in all studied conditions. However, a bacterially derived citric acid was found to improve root and shoot development, possibly due to alleviating the toxic effect of some elements. Due to the observed phytotoxicity, we conclude that the phytoremediation/rehabilitation of slag impacted soils may be limited. The search for a metal tolerant plant species that would be efficient in terms of biomass production and metals uptake is a perspective of this work.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Layer-by-layer membrane modification allows scandium recovery by nanofiltration
    (Royal Society of Chemistry, 07/2019) Remmen, Kirsten; Lenz, Markus; Hedwig, Sebastian; Wintgens, Thomas [in: Environmental Science. Water, Research & Technology]
    Aluminium scandium (Sc) alloys are stronger, more corrosion resistant and more heat tolerant than classical aluminium alloys and allow for 3D printing. In particular, the aerospace industry benefits from better fuel efficiency due to lighter materials as well as the advantages of additive manufacturing. However, Sc is currently not available in sufficient quantities and has recently been identified as a raw material critical to the economy. Due to the recentness of the demand, technologies for recovery of Sc from secondary sources are in their infancy. In this study, Sc recovery from titanium dioxide pigment production waste by nanofiltration was investigated. Custom-made layer-by-layer (LbL) modified membranes were optimized with regards to their elemental retention (i.e., selectivity towards Sc) as well as their acid resistance. In model solutions, the optimized membrane retained up to 64% ± 4% Sc, removing the major impurity, iron (Fe), efficiently (12% ± 7% retention) while achieving high flux [32 L m−2 h−1] at a low transmembrane pressure of 5 bar. Acid resistance was shown down to a pH of 0.1, which could be even further increased (up to ≤3 M HCl) by adding more bi-layers and changing the coating conditions. In real wastes, the optimized LbL membrane showed higher Sc retention (60% vs. 50%) compared to a commercial acid resistant membrane, while achieving considerably higher fluxes [27 L m−2 h−1 versus 1 L m−2 h−1, respectively at 5 bar]. It was possible to operate filtration at low transmembrane pressure with up to 70% permeate recovery and flux that was still high [∼10 L m−2 h−1]. In a nutshell, titanium dioxide pigment wastes contained sufficient amounts to satisfy the growing demand for Sc and can be exploited to their full extent by LbL nanofiltration due to the proven advantages of acid stability, Sc retention and selectivity and high achievable fluxes at low pressures.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) – A review
    (Elsevier, 01/2019) Işıldar, Arda; Lenz, Markus; Du Laing, Gijs; Cesaro, Alessandra; Marra, Alessandra; Panda, Sandeep; Akcil, Ata; Kucuker, Mehmet Ali; Kuchta, Kerstin; van Hullebusch, Eric D. [in: Journal of Hazardous Materials]
    Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to recycle metals from WEEE. These processes are deemed imperfect, energy-intensive and non-selective towards CRMs. Biotechnologies are a promising alternative to the current industrial best available technologies (BAT). In this review, we present the current frontiers in CRMs recovery from WEEE using biotechnology, the biochemical fundamentals of these bio-based technologies and discuss recent research and development (R&D) activities. These technologies encompass biologically induced leaching (bioleaching) from various matrices,biomass-induced sorption (biosorption), and bioelectrochemical systems (BES).
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Effects of barium on the pathways of anaerobic digestion
    (Elsevier, 2019) Wyman, Valentina; Lenz, Markus; Serrano, Antonio [in: Journal of Environmental Management]
    The sufficient presence of trace elements (TE) is essential for anaerobic digestion. Barium (Ba) is considered a non-essential trace element that can be collaterally added to digesters as part of low-cost trace element sources or because of its presence in some feedstocks, such as crude glycerol. In the present study, the impact of Ba supplementation (2–2000 mg/L) on each stage of the anaerobic digestion (AD) process was evaluated using pure substrates (i.e., cellulose, glucose, a mixture of volatile fatty acids, sodium acetate and hydrogen) as well as a complex substrate (i.e., dried green fodder). Hydrolytic activity was affected at dosages higher than 200 mg Ba/L, whereas cellulose degradation was completely inhibited at 2000 mg Ba/L. The negative effects of the addition of Ba to methane production were observed only in the hydrolytic activity, and no effects were detected at any barium dosage in the subsequent anaerobic steps. Because Ba does not have a reported role as a cofactor of enzymes, this response could have been due to a direct inhibitory effect, a variation in the bioavailability of other trace elements, or even the availability of CO2/SO4 through precipitation as Ba-carbonates and sulphates. The results showed that the addition of Ba modified the chemical equilibrium of the studied system by varying the soluble concentration of some TEs and therefore their bioavailability. The highest variation was detected in the soluble concentration of zinc, which increased as the amount of Ba increased. Although little research has shown that Ba has some utility in anaerobic processes, its addition must be carefully monitored to avoid an undesirable modification of the chemical equilibrium in the system.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Biodegradation of sulfamethoxazole by a bacterial consortium of Achromobacter denitrificans PR1 and Leucobacter sp. GP
    (Springer, 12/2018) Reis, Ana C.; Cvancarova Småstuen, M.; Liu, Ying; Lenz, Markus; Hettich, Timm; Kolvenbach, Boris; Corvini, Philippe; Nunes, Olga C. [in: Applied Microbiology and Biotechnology]
    In the last decade, biological degradation and mineralization of antibiotics have been increasingly reported feats of environmental bacteria. The most extensively described example is that of sulfonamides that can be degraded by several members of Actinobacteria and Proteobacteria. Previously, we reported sulfamethoxazole (SMX) degradation and partial mineralization by Achromobacter denitrificans strain PR1, isolated from activated sludge. However, further studies revealed an apparent instability of this metabolic trait in this strain. Here, we investigated this instability and describe the finding of a low-abundance and slow-growing actinobacterium, thriving only in co-culture with strain PR1. This organism, named GP, shared highest 16S rRNA gene sequence similarity (94.6–96.9%) with the type strains of validly described species of the genus Leucobacter. This microbial consortium was found to harbor a homolog to the sulfonamide monooxygenase gene (sadA) also found in other sulfonamide-degrading bacteria. This gene is overexpressed in the presence of the antibiotic, and evidence suggests that it codes for a group D flavin monooxygenase responsible for the ipso-hydroxylation of SMX. Additional side reactions were also detected comprising an NIH shift and a Baeyer–Villiger rearrangement, which indicate an inefficient biological transformation of these antibiotics in the environment. This work contributes to further our knowledge in the degradation of this ubiquitous micropollutant by environmental bacteria.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Ferritin encapsulation of artificial metalloenzymes: engineering a tertiary coordination sphere for an artificial transfer hydrogenase
    (Royal Society of Chemistry, 07/2018) Hestericová, Martina; Heinisch, Tillmann; Lenz, Markus; Ward, Thomas R. [in: Dalton Transactions]
    Ferritin, a naturally occuring iron-storage protein, plays an important role in nanoengineering and biomedical applications. Upon iron removal, apoferritin was shown to allow the encapsulation of an artificial transfer hydrogenase (ATHase) based on the streptavidin-biotin technology. The third coordination sphere, provided by ferritin, significantly influences the catalytic activity of an ATHase for the reduction of cyclic imines.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    An artificial metalloenzyme for carbene transfer based on a biotinylated dirhodium anchored within streptavidin
    (Royal Society of Chemistry, 04/2018) Zhao, Jingming; Bachmann, Daniel G.; Lenz, Markus; Gillingham, Dennis G.; Ward, Thomas R. [in: Catalysis Science & Technology]
    We report on artificial metalloenzymes that incorporate a biotinylated dirhodium core embedded within engineered streptavidin (Sav hereafter) variants. The resulting biohybrid catalyzes the carbene insertion in C–H bonds and olefins. Chemical- and genetic optimization allows to modulate the catalytic activity of the artificial metalloenzymes that are shown to be active in the periplasm of E. coli (up to 20 turnovers).
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Can iron plaque affect Sb(III) and Sb(V) uptake by plants under hydroponic conditions
    (Elsevier, 04/2018) Ji, Ying; Vollenweider, Pierre; Lenz, Markus; Schulin, Rainer; Tandy, Susan [in: Environmental and Experimental Botany]
    Antimony (Sb) contamination of soils is of concern due to human activities such as recycling of Sb containing Pb acid batteries, shooting and mining. However Sb uptake by plants is poorly documented, especially when plants are growing on waterlogged soils and iron plaques form on their roots. The effect of iron plaques on Sb uptake has been investigated in rice, but not so far in other plants. Here, rye, ryegrass, wheat and meadow fescue were induced to form iron plaques and then exposed to antimonite (Sb(III)) or antimonate (Sb(V)) under hydroponic conditions. In the Sb(III) treatment, although iron plaques adsorbed Sb(III), this did not affect root and shoot Sb concentrations of plants. In the Sb(V) treatment, iron plaques adsorbed Sb(V) to a lesser extent than for Sb(III), although it was still significant in all plants but wheat. Iron treatments also significantly increased root Sb concentrations of fescue while they significantly decreased shoot Sb concentrations in rye, ryegrass and fescue. This may be due to other factors as well as antimony adsorption to iron plaques.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Re-using bauxite residues: benefits beyond (critical raw) material recovery
    (Wiley, 2018) Ujaczki, Eva; Feigl, Victoria; Molnar, Monika; Cusack, Patricia; Curtin, Teresa; Courtney, Ronan; Ronan, Lisa; Davris, Panagiotis; Hugi, Christoph; Evangelou, Michael; Balomenos, Efthymios; Lenz, Markus [in: Journal of Chemical Technology & Biotechnology]
    Since the world economy has been confronted with an increasing risk of supply shortages of critical raw materials (CRMs), there has been a major interest in identifying alternative secondary sources of CRMs. Bauxite residues from alumina production are available at a multi-million tonnes scale worldwide. So far, attempts have been made to find alternative re-use applications for bauxite residues, for instance in cement / pig iron production. However, bauxite residues also constitute an untapped secondary source of CRMs. Depending on their geological origin and processing protocol, bauxite residues can contain considerable amounts of valuable elements. The obvious primary consideration for CRM recovery from such residues is the economic value of the materials contained. However, there are further benefits from re-use of bauxite residues in general, and from CRM recovery in particular. These go beyond monetary values (e.g. reduced investment / operational costs resulting from savings in disposal). For instance, benefits for the environment and health can be achieved by abatement of tailing storage as well as by reduction of emissions from conventional primary mining. Whereas certain tools (e.g. life-cycle analysis) can be used to quantify the latter, other benefits (in particular sustained social and technological development) are harder to quantify. This review evaluates strategies of bauxite residue re-use / recycling and identifies associated benefits beyond elemental recovery. Furthermore, methodologies to translate risks and benefits into quantifiable data are discussed. Ultimately, such quantitative data are a prerequisite for facilitating decision-making regarding bauxite residue re-use / recycling and a stepping stone towards developing a zero-waste alumina production process.
    01A - Beitrag in wissenschaftlicher Zeitschrift