Separation of Microplastic Particles from Sewage Sludge Extracts Using Magnetic Seeded Filtration

Rhein, Frank; Nirschl, Hermann; Kaegi, Rälf

doi:10.1016/j.wroa.2022.100155

Cited by 20 publications

(11 citation statements)

References 79 publications

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“…Figure 8 highlights the advantages of an agglomeration mechanism that is based on dissimilarity in the separation criterion: In the investigated model case, MSF is able to achieve a perfect separation between hydrophilic and hydrophobic materials, since hydrophilic particles are attracted neither to magnetic nor to other hydrophobic nonmagnetic particles. This agrees well with a previously published experimental study, where hydrophobic microplastic particles were selectively separated from hydrophilic cellulose [10]. Similar to case 1, the material-specific selectivity of the MSF process is most pronounced for low agglomeration times.…”

Section: Results Case 2: Hydrophobicity-based Separationsupporting

confidence: 92%

“…Separation is, therefore, based on a similarity in the separation criterion. A previously published study on MSF [10] supports this hypothesis, as a selective separation between hydrophilic cellulose and hydrophobic microplastic particles was performed by using a hydrophobic magnetic material. It should be noted that the discussion about the hydrophobic particle-particle interactions is still ongoing, and that no overall theory has been proposed to explain all of the observed effects.…”

Section: Case Studies 41 Study Structurementioning

confidence: 57%

“…However, the expected selectivity based on component-specific separation experiments was not achieved, which was shown to be due to an undesired hetero-agglomeration between the target particles. Another preceding experimental study [10] investigated the separation based on the hydrophobic properties of the surface: By addition of hydrophobic magnetic material, hydrophobic microplastic particles were selectively separated from hydrophilic cellulose particles. The loss of selectivity observed in the charge-based system was not found in the hydrophobicity-based separation.…”

Section: Introductionmentioning

confidence: 99%

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Multidimensional Separation by Magnetic Seeded Filtration: Theoretical Study

Rhein,

Ji,

Nirschl

2024

Powders

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Magnetic seeded filtration (MSF) is a multidimensional solid–liquid separation process capable of fractionating a multimaterial suspension based on particle size and surface properties. It relies on the selective hetero-agglomeration between nonmagnetic target and magnetic seed particles followed by a magnetic separation. Experimental investigations of multimaterial suspensions are challenging and limited. Therefore, a Monte Carlo model for the simulation of hetero-agglomeration processes is developed, validated, and compared to a discrete population balance model. The numerical investigation of both charge-based and hydrophobicity-based separation in an 11-material system, using synthetic agglomeration kernels based on real-world observations, yields results consistent with prior experimental studies and expectations: Although a multidimensional separation is indeed possible, unwanted hetero-agglomeration between target particles results in a reduced selectivity. This effect is more pronounced when separation is based on a dissimilarity rather than a similarity in the separation criterion and emphasizes the advantages of hydrophobicity-based systems. For the first time, 2D grade efficiency functions T(φ,d) are presented for MSF. However, it is shown that these functions strongly depend on the initial state of the suspension, which casts doubt on their general definition for agglomeration-based processes and underlines the importance of a simulation tool like the developed MC model.

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Section: Results Case 2: Hydrophobicity-based Separationsupporting

confidence: 92%

Section: Case Studies 41 Study Structurementioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

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Multidimensional Separation by Magnetic Seeded Filtration: Theoretical Study

Rhein,

Ji,

Nirschl

2024

Powders

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“…Both magnetic and nonmagnetic fractions can be retrieved by the chemical breakup of agglomerates [ 99 ]. Moreover, using hydrophobic seed particles, the MSF approach is a promising purification step that may aid in quantifying MP extracted from complex matrices, such as sewage sludge [ 100 ]. Hydrophobic iron nanoparticles were tested by Grbic et al in seawater spiked with PE, PS, PET, PUR, PVC, and PP MPs with recovery rates higher than 90% [ 96 ].…”

Section: Unveiling Microplastics In the Environment: Advances And Cha...mentioning

confidence: 99%

The Microplastics Iceberg: Filling Gaps in Our Understanding

2023

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Plastic is an indispensable material in modern society; however, high production rates combined with inadequate waste management and disposal have resulted in enormous stress on ecosystems. In addition, plastics can become smaller particles known as microplastics (MPs) due to physical, chemical, and biological drivers. MP pollution has become a significant environmental problem affecting terrestrial and aquatic ecosystems worldwide. Although the topic is not entirely new, it is of great importance to the field of polymers, drawing attention to specific gaps in the existing literature, identifying future areas of research, and improving the understanding of MP pollution and its environmental impacts. Despite progress in this field, problems remain. The lack of standardized methods for MP sampling, separation, extraction, and detection makes it difficult to collect information and establish links between studies. In addition, the distribution and pathways of MPs in ecosystems remain unknown because of their heterogeneous nature and the complex matrices in which they occur. Second, toxicological tests showed that MPs can be ingested by a wide range of organisms, such as Danio rerio and Eisenia fetida, resulting in gut obstruction, physical damage, histological changes, and oxidative stress. The uptake of MP and their toxicological effects depend on their shape, size, concentration, and polymer composition. Furthermore, MPs can enter the food chain, raising concerns regarding potential contaminations for human and environmental health. This review paper sheds light on the pressing issue of MP pollution and highlights the need for interdisciplinary collaboration between scientists, policymakers, and industry leaders.

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“…As the recognition of this lack of RMP particles is not new or unknown 10 , a lot of effort has already been made to produce RMP particles [11][12][13][14][15][16][17] . Common methods such as cryomilling for the production of MP fragments 11,14,15 or emulsion processes for the production of microbeads have been used for this purpose 16 . As a consequence, currently only RMP particles in form of microbeads, fragments or powders are commercially available 18 .…”

Section: Introductionmentioning

confidence: 99%

Development of new microplastic reference particles for usage in pre-defined numbers

Oster,

Bräumer,

Wagner

et al. 2023

Preprint

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For almost two decades now, scientists have increasingly focused on the occurrence of microplastics in the environment and their impact on environmental and human health. Currently, the variety of analytical methods used in microplastic research result in data of different quality and resolution. This largely hampers comparability between data sets and consequently prevents a reliable risk assessment. In this context, the lack of suitable reference microplastic particles that can be added as internal standard in an exactly known number further prevents quality assessment of, and harmonization in terms of comparability between different analytical methods. Although this lack has widely been recognized, currently only reference microplastic particles in form of micro-beads or -fragments (powders) are commercially available. Manual addition of such reference microplastic particles to samples in a precisely defined number as an internal standard is inefficient and the alternative use of microplastic particle suspensions does not allow for the addition of an exactly defined particle number. The optimum solution to solve this issue would be reference microplastic particles embedded in an easy-to-use soluble matrix in exact numbers. This would allow for evaluating analytical quality during microplastic analysis as well as establishing harmonization in terms of comparability between different methods. In the present study we focused on the development of such reference microplastic particles. We used CNC milling for the production of small diameter plastic columns followed by gelatine embedment and subsequent cryosectioning. This results in gelatin slices containing an exactly defined number of reference microplastic particles with well-defined size, shape and polymer type / chemical composition that can be added to a sample easily with the dissolution of the gelatine. We successfully produced square shaped reference microplastic particles in a size range of 125–1000 µm of five different polymers. The overall size-deviation of the reference microplastic particles never exceeded ± 11.2% from the mean value of a set of particles. The highest percentage weight-deviation was 25.5% from the mean value of a set of 125 x 125 x 20 µm PS reference microplastic particles. Our approach allows for the production of reference microplastic particles tailored to specific needs of all different analytical methods used in current microplastic research. Beyond analytical method validation, these reference microplastic particles furthermore open possibilities for experiments on microplastics ranging from organismic uptake to environmental distribution.

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Separation of Microplastic Particles from Sewage Sludge Extracts Using Magnetic Seeded Filtration

Cited by 20 publications

References 79 publications

Multidimensional Separation by Magnetic Seeded Filtration: Theoretical Study

Multidimensional Separation by Magnetic Seeded Filtration: Theoretical Study

The Microplastics Iceberg: Filling Gaps in Our Understanding

Development of new microplastic reference particles for usage in pre-defined numbers

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