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Bernd Nowack published an article in April 2018.
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196 shared publications
121 shared publications
Department of Material Physics, BASF SE, Advanced Materials Research, 67056, Ludwigshafen, Germany
105 shared publications
Stephen J. Klaine
101 shared publications
97 shared publications
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(2006 - 2018)
(2006 - 2018)
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Article 1 Read 0 Citations Procedures for the production and use of synthetically aged and product released nanomaterials for further environmental... Published: 01 April 2018
NanoImpact, doi: 10.1016/j.impact.2017.12.001
The use of pristine, as-produced engineered nanomaterials (ENMs) to examine environmental behavior or toxicity is convenient, but it is the aged or released ENMs that are much more likely to be present in the environment and these are the materials to which organisms will ultimately be exposed. When determining which aging processes are most relevant, a life cycle perspective can be useful to gain insight into how ENMs will be used, released from products and move through technical and environmental systems. While there are a few pristine nanomaterial standards or test materials available, procedures to create appropriate aged or released ENM standards for subsequent fate or effect studies are more rare. Whereas the aging and release processes of ENMs are studied to quite some extent, procedures for the production of these materials for further testing are still in the initial phases. Here we review the available aging and release procedures representing various stages of the product life cycle that were developed in order to collect the aged and released materials for further use. There are three main groups of aged/released materials: 1) laboratory aging of pristine ENM, 2) collection of ENMs released from nano-products, and 3) fragmentation of the product matrix combined with aging. Here, the various aging and release paradigms that may be followed are presented, each of which comes with pros and cons in terms of how close the aging parameters are to simulating real world situations and how applicable they are to different product matrices or release mechanisms. The further use of the aged/released materials in fate or effect studies is also presented when possible. We can conclude that some aging/release procedures exist which have applicability for different research questions and specific ENM/matrix/product combinations and life cycle stages, but additional research is warranted to expand the procedures for producing synthetically aged and product released ENMs to cover additional areas of interest.
Article 1 Read 4 Citations Polyester Textiles as a Source of Microplastics from Households: A Mechanistic Study to Understand Microfiber Release Du... Published: 08 June 2017
Environmental Science & Technology, doi: 10.1021/acs.est.7b01750
Microplastic fibers make up a large proportion of microplastics found in the environment, especially in urban areas. There is good reason to consider synthetic textiles a major source of microplastic fibers and it will not diminish since the use of synthetic fabrics, especially polyester, continues to increase. In this study we provide quantitative data regarding the size and mass of microplastic fibers released from synthetic (polyester) textiles during simulated home washing under controlled laboratory conditions. Consideration of fabric structure, washing conditions (use of detergents, temperature, wash duration, sequential washings) allowed us to study the propensity of fiber shedding in a mechanistic way. Thousands of individual fibers were measured (number, length) from each wash solution to provide a robust data set on which to draw conclusions. Among all the variables tested, the use of detergent appeared to affect the total mass of fibers released the most, yet the detergent composition (liquid or powder) or overdosing of detergent did not significantly influence microplastic release. Despite different release quantities due to the addition of a surfactant (approximately 0.025 and 0.1 mg fibers/g textile washed, without and with detergent, respectively), the overall microplastic fiber length profile remained similar regardless of wash condition or fabric structure, with the vast majority of fibers ranging between 100 m and 800 m in length irrespective of wash cycle number. This indicates that the fiber staple length and/or debris encapsulated inside the fabric from the yarn spinning could be directly responsible for releasing stray fibers. This study serves as a first look towards understanding the physical properties of the textile itself to better understand the mechanisms of fiber shedding in the context of microplastic fiber release into laundry wash water.
Article 1 Read 2 Citations Improvements in Nanoparticle Tracking Analysis To Measure Particle Aggregation and Mass Distribution: A Case Study on En... Published: 08 May 2017
Environmental Science & Technology, doi: 10.1021/acs.est.7b00597
Numerous nanometrology techniques have been developed in recent years to determine the size, concentration and a number of other characteristics of engineered nanomaterials (ENM) in environmental matrices. Among the many available techniques, Nanoparticle Tracking Analysis (NTA) can measure individual particles to create a size distribution and measure the particle number. Therefore, we explore the possibility to use these data to calculate the particle mass distribution. Additionally, we further developed the NTA methodology to explore its suitability for analysis of ENM in complex matrices by measuring ENM agglomeration and sedimentation in municipal solid waste incineration landfill leachates over time. 100 nm Au ENM were spiked into DI H2O, synthetic and natural leachates. We present the possibility of measuring ENM in the presence of natural particles based on differences in particle refractivity indices, delineate the necessity of creating a calibration curve to adjust the given NTA particle number concentration and determined the instruments linear range under different conditions. By measuring the particle size and the particle number distribution, we were able to calculate the ENM mass remaining in suspension. By combining these metrics together with TEM analyses, we could assess the extent of both homo- and heteroagglomeration as well as particle sedimentation. Reporting both size and mass based metrics is common in atmospheric particle measurements but now the NTA can give us the possibility to apply the same approach also to aqueous samples.
Article 0 Reads 8 Citations Envisioning Nano Release Dynamics in a Changing World: Using Dynamic Probabilistic Modeling to Assess Future Environment... Published: 16 February 2017
Environmental Science & Technology, doi: 10.1021/acs.est.6b05702
The need for an environmental risk assessment for engineered nanomaterials (ENM) necessitates the knowledge about their environmental emissions. Material flow models (MFA) have been used to provide predicted environmental emissions but most current nano-MFA models consider neither the rapid development of ENM production nor the fact that a large proportion of ENM are entering an in-use stock and are released from products over time (i.e., have a lag phase). Here we use dynamic probabilistic material flow modeling to predict scenarios of the future flows of four ENM (nano-TiO2, nano-ZnO, nano-Ag and CNT) to environmental compartments and to quantify their amounts in (temporary) sinks such as the in-use stock and ("final") environmental sinks such as soil and sediment. In these scenarios, we estimate likely future amounts if the use and distribution of ENM in products continues along current trends (i.e., a business-as-usual approach) and predict the effect of hypothetical trends in the market development of nanomaterials, such as the emergence of a new widely used product or the ban on certain substances, on the flows of nanomaterials to the environment in years to come. We show that depending on the scenario and the product type affected, significant changes of the flows occur over time, driven by the growth of stocks and delayed release dynamics.
Article 3 Reads 6 Citations Textile functionalization and its effects on the release of silver nanoparticles into artificial sweat Published: 20 May 2016
Environmental Science & Technology, doi: 10.1021/acs.est.5b06137
This study addresses the release of total silver (Ag) and silver nanoparticles (Ag-NPs) from textiles into artificial sweat, particularly considering the functionalization technology used in textile finishing. Migration experiments were conducted for four commercially available textiles and for six laboratory-prepared textiles. Two among these lab-prepared textiles represent materials in which Ag-NPs were embedded within the textile fibers (composites), whereas the other lab-prepared textiles contain Ag particles on the respective fiber surfaces (coatings). The results indicate a smaller release of total Ag from composites in comparison to surface-coated textiles. The particulate fraction determined within the artificial sweat was negligible for most textiles, meaning that the majority of the released Ag is present as dissolved Ag. It is also relevant to note that nanotextiles do not release more particulate Ag than conventional Ag textiles. The results rather indicate that the functionalization type is the most important parameter affecting the migration. Furthermore, after measuring different Ag-NP types in their pristine form with inductively coupled plasma mass spectrometry in the single particle mode, there is evidence that particle modifications, like surface coating, may also influence the dissolution behavior of the Ag-NPs in the sweat solutions. These factors are important when discussing the likelihood of consumer exposure.
Article 0 Reads 2 Citations Unraveling the Complexity in the Ageing of Nano-Enhanced Textiles: a Comprehensive Sequential Study on the Effect of Sun... Published: 17 May 2016
Environmental Science & Technology, doi: 10.1021/acs.est.6b01478
The scientific understanding of nanoparticle (NP) release and transformations they undergo during the product life cycle is hampered by the narrow scope of many research endeavors in terms of both breadth of variables and completeness of analytical characterization. We conducted a comprehensive suite of studies to reveal overarching mechanisms and parameters for nanosilver transformations either still adhered to the fabric or when released after washing. Laboratory prepared nanoenhanced fabrics were investigated: three Ag variants and one Au used as an unreactive reference to separate mechanical from chemical releases. Sequential combinations of sunlight irradiation and/or washing in seven different detergent formulations was followed by NP characterization divided into two groups: (1) dissolved and particulate matter in the wash solutions and (2) the fraction that remained on the fabric. Analytical techniques included spICP-MS, XANES, TEM, SEM, and total metals analysis of fabric digests and wash water filtrates. Sunlight irradiation stabilizes metallic Ag upon washing. Detergents containing oxidizing agents assisted with Ag particle release but not Au NPs, inferring additional chemical mechanisms. While particle size played some role, the NP capping agent/fabric binder combination was a key factor in release. When particles were released, little alteration in size was observed. The use of well-controlled fabrics, unreactive reference materials, and a life-cycle based experimental regime are paramount to understanding changes in Ag speciation and release upon use of nanoenhanced textiles.