Lenz, Markus

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Lenz
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Markus
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Lenz, Markus

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2015 - 2019312020 - 20216
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  • Vorschaubild nicht verfügbar
    Publikation
    Crystallographic, optical, and electronic properties of the Cs2AgBi1–xInxBr6 double perovskite. Understanding the fundamental photovoltaic efficiency challenges
    (American Chemical Society, 19.02.2021) Lenz, Markus; Schade, Laura; Mahesh, Suhas; Volonakis, George; Zacharias, Marios; Wenger, Bernard; Schmidt, Felix; Kesava, Sameer Vajjala; Prabhakaran, Dharmalingam; Abdi-Jalebi, Mojtaba; Longo, Giulia; Radaelli, Paolo; Snaith, Henry; Giustino, Feliciano [in: ACS Energy Letters]
    We present a crystallographic and optoelectronic study of the double perovskite Cs2AgBi1–xInxBr6. From structural characterization we determine that the indium cation shrinks the lattice and shifts the cubic-to-tetragonal phase transition point to lower temperatures. The absorption onset is shifted to shorter wavelengths upon increasing the indium content, leading to wider band gaps, which we rationalize through first-principles band structure calculations. Despite the unfavorable band gap shift, we observe an enhancement in the steady-state photoluminescence intensity, and n-i-p photovoltaic devices present short-circuit current greater than that of neat Cs2AgBiBr6 devices. In order to evaluate the prospects of this material as a solar absorber, we combine accurate absorption measurements with thermodynamic modeling and identify the fundamental limitations of this system. Provided radiative efficiency can be increased and the choice of charge extraction layers are specifically improved, this material could prove to be a useful wide band gap solar absorber.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Biodeterioration affecting efficiency and lifetime of plastic-based photovoltaics
    (Elsevier, 16.09.2020) Schmidt, Felix; Lenz, Markus; Schaeffer, Andreas; Zimmermann, Yannick; Alves dos Reis Benatto, Gisele; Kolvenbach, Boris; Krebs, Frederik [in: Joule]
    The low environmental impact of electricity generation using solar cells crucially depends on high energy-conversion efficiencies, long lifetimes and a minimal energy and material demand during production. Emerging thin-film photovoltaics such as perovskites on plastic substrates could hold promise to fulfil all these requirements. Under real-world operating conditions photovoltaic operation is challenged by biological stressors, which have not been incorporated for evaluation in any test. Such stressors cause biodeterioration, which impairs diverse, apparently inert materials such as rock, glass and steel and therefore could significantly affect the function and stability of plastic-based solar cells. Given that different photovoltaic technologies commonly use similar materials, the biodeterioration mechanisms reviewed here may possibly affect the efficiency and lifetimes of several technologies, if they occur sufficiently fast (during the expected lifetime of photovoltaics). Once the physical integrity of uppermost module layers is challenged by biofilm growth microbially mediated dissolution and precipitation reactions of photovoltaic functional materials are very likely to occur. The biodeterioration of substrates and seals also represents emission points for the release of potentially harmful photovoltaic constituents to the environment
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Bioleaching and toxicity of metallurgical wastes
    (Elsevier, 09.09.2020) Potysz, Anna; Lenz, Markus; Hedwig, Sebastian [in: Journal of Environmental Chemical Engineering]
    Metallurgical wastes contain metals that are unrecovered during industrial processing. The disposal of these wastes is technically difficult due to the potential release of metals through weathering. Therefore, alternative management methods are currently sought. The high leaching susceptibility of these wastes combined with the need for alternative sources of rare and critical metals creates a need for residual element recovery. This study evaluated the leaching potential of lead matte and copper slag through chemical mineral acid leaching as well as indirect bioleaching with organic acids and direct bioleaching using Acidithiobacillus thiooxidans. The leaching efficiency of these acids was compared based on different normality equivalents. Additionally, the effects of pulp density (1–10%) and extraction time (24–48 h) were assessed. Slag toxicity was assessed with a germination test in concentrated and diluted leachates using Brassica juncea. The results demonstrated that copper slag is particularly suitable for chemical treatment because as much as 91 wt.% Cu and 85 wt.% Zn or 70 wt.% Cu and 81 wt.% Zn were extracted using HNO3 or bacterial leaching, respectively. The residual slag was characterized by significant metal depletion and the presence of gypsum, rendering it more suitable for further use or disposal. Lead matte released 65 wt.% Cu and 8 wt.% Zn using mineral acid leaching while 70 wt.% Cu and 12 wt.% Zn were released using bacterial leaching. Further process optimization is needed for lead matte to generate residue depletion in toxic metals. Toxicity assessment showed toxic characteristics in metal-loaded leachates originating from waste treatment that inhibited germination rates and root development.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Low-Temperature Reactive Aerosol Processing for Large-Scale Synthesis of Selenium Nanoparticles
    (American Chemical Society, 22.08.2020) Viacava, Karen; Ammann, Erik; Lenz, Markus [in: Industrial & Engineering Chemistry Research]
    Selenium nanoparticles (SeNPs) have been suggested for various applications such as food, animal feed, and biomedicine. However, thus far, wet chemical synthesis cannot produce sufficient quantities of SeNPs at the required quality. In this study, reactive aerosol processing is employed to produce SeNPs as powder concentrates of 2.2 to 4.0% (dry weight basis) on the scale of hundreds of kilograms. Citric acid is the most efficient organic precursor (92.5% SeNPs), but polydisperse particles are obtained, and some unknown dissolved Se species are present in the final product. Glycine is less efficient (82.2% SeNPs); however, monodisperse nanoparticles (153 nm; D90 = 215 nm) are obtained, with selenite being the only residue in the final product. The obtained particles consisted of X-ray amorphous (i.e., not diffracting) Se, since no elemental Se allotrope or other solid Se phases were indicated in X-ray diffraction. Reactive aerosol processing involves a limited number of preparation steps (i.e., dissolution and atomization), uses only food-/feed-approved ingredients (selenite, citric acid, glycine) and allows continuous operation and zero waste generation. This makes reactive aerosol processing ideal for the large-scale production of SeNPs.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Deterioration of sandstones: Insights from experimental weathering in acidic, neutral and biotic solutions with Acidithiobacillus thiooxidans
    (Elsevier, 24.02.2020) Potysz, Anna; Schmidt, Felix; Lenz, Markus; Bartz, Wojciech; Zboińska, Katarzyna [in: Construction and Building Materials]
    The susceptibility of sandstones to deteriorative factors when used for construction requires detailed experimental evaluation. This study investigated the (bio)weathering behaviour of Lower-Silesian Cretaceous sandstones (quartz arenites) to quantify the deteriorative effect of bacterium Acidithiobacillus thiooxidans. For controls, ultrapure water (in undersaturated conditions) and sterile acidic medium (in abiotic acidic conditions pH 2.5) were used. Sandstone exposure to A. thiooxidans mimicked the extremely acidic conditions (pH up to 0.9) that may develop under long-term weathering, which promote microbial activity and acidic metabolite production. Element release was assessed using triple quadrupole inductively coupled plasma mass spectrometry (QQQ-ICP-MS) and identifying potential element donor minerals through scanning electron microscopy, coupled with energy dispersive spectrometer (SEM-EDS). The results demonstrated that sandstones were relatively susceptible to weathering, especially when exposed to aggressive acidic conditions, where the presence of bacteria apparently acts as an accelerating factor in deterioration. Based on Si release, sandstone degradation under biotic conditions was 0.27% within 86 days, whereas the dissolution achieved in ultrapure water did not exceed 0.02%. A highly pronounced weathering feature observed on sandstones was the dissolution of goethite and/or kaolinite cement, whereas quartz was less susceptible to weathering under the conditions studied. Bioweathering investigations may help solve deterioration issues in sandstone building materials.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Characterization of heavy metal toxicity in some plants and microorganisms—A preliminary approach for environmental bioremediation
    (Elsevier, 13.01.2020) Diaconu, Mariana; Corvini, Philippe; Lenz, Markus [in: New Biotechnology]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • 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