Aggregation kinetics of microplastics in aquatic environment: Complex roles of electrolytes, pH, and natural organic matter

Li, Shuocong; Liu, Hong; Gao, Rui; Abdurahman, Abliz; Dai, Juan; Zeng, Feng

doi:10.1016/j.envpol.2018.02.042

Cited by 202 publications

(83 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To assess the potential effects of microplastics and associated contaminants on ecosystems it is important to properly evaluate the particle–pollutant interactions, especially since this determines their bioavailability which is yet not well understood. Hydro- and geochemical parameters as well as contact with biota may change particle characteristics, e.g., their surface charge and texture, and may procure aggregation [ 22 , 38 ]. Thus, it is essential to analyze whether sorption interactions occur which are going beyond mere partitioning as investigated here.…”

Section: Discussionmentioning

confidence: 99%

A combined experimental and modeling study to evaluate pH-dependent sorption of polar and non-polar compounds to polyethylene and polystyrene microplastics

et al. 2018

View full text Add to dashboard Cite

BackgroundThe contamination of aquatic ecosystems with both anthropogenic pollutants and particles in particular (microscopic) plastic debris items is of emerging concern. Since plastic particles can accumulate contaminants and potentially facilitate their transport, it is important to properly investigate sorption mechanisms. This is especially required for a large variety of chemicals that can be charged under environmental conditions and for which interactions with particles may hence go beyond mere partitioning.ResultsIn this study, sorption experiments with two types of microplastic particles (polyethylene and polystyrene) and 19 different contaminants (pesticides, pharmaceuticals, and personal care products) were performed at three different pH values. We could show that sorption to plastic particles is stronger for hydrophobic compounds and that neutral species usually contribute more to the overall sorption. Bulk partitioning coefficients were in the same order of magnitude for polyethylene and polystyrene. Furthermore, our results confirm that partition coefficients for polar compounds can only be accurately determined if the solid-to-liquid ratio in batch experiments is more than 6–7 orders of magnitude higher than any plastic concentration detected in the environment. Consequently, only a minor fraction of pollutants in water bodies is associated with microplastics.ConclusionsAlthough neutral species primarily dominate the overall sorption, hydrophobic entities of ionic species cannot be neglected for some compounds. Notwithstanding, our results show that since microplastic concentrations as currently observed in the environment are very low, they are only a relevant sorbent for strongly hydrophobic but not for polar compounds.Electronic supplementary materialThe online version of this article (10.1186/s12302-018-0155-z) contains supplementary material, which is available to authorized users.

show abstract

Section: Discussionmentioning

confidence: 99%

A combined experimental and modeling study to evaluate pH-dependent sorption of polar and non-polar compounds to polyethylene and polystyrene microplastics

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The plateau height (C/C 0 ) of Pb decreased with the increased IS ( Figure 5A,B). The elution time of r-Pb was delayed in CaCl 2 compared to that in NaCl, which can be attributed to competition of Ca with Pb to N-CD surfaces, the aggregation of N-CDs in CaCl 2 , and thus N-CD straining in the quartz column, or to the attachment of N-CDs to quartz surfaces via van der Waals interactions [9]. The recovery of N-CDs and r-Pb decreased with increases in NaCl and CaCl 2 concentrations (Table 2).…”

Section: Effects Of Phmentioning

confidence: 98%

“…Several studies investigated the transport of carbon-based nanoparticles in sand columns under saturated conditions [9]. These studies demonstrated that solution chemistry (e.g., pH, ionic strength (IS) and composition, and ion valency) and soil properties (e.g., grain size, charge behavior, etc.)…”

Section: Introductionmentioning

confidence: 99%

Transport of N-CD and Pre-Sorbed Pb in Saturated Porous Media

et al. 2020

View full text Add to dashboard Cite

Carbon dots (CDs) are a new type of nanomaterials of the carbon family with unique characteristics, such as their small size (e.g., <10 nm), high water solubility, low toxicity, and high metal affinity. Modification of CDs by Nitrogen functional groups (N-CDs) enhances their metal adsorption capacity. This study investigated the influences of pH (4, 6, and 9), ionic strength (1, 50, and 100 mM), and cation valency (Na+ and Ca2+) on the competitive adsorption of Pb to quartz and N-CD surfaces, the transport and retention of N-CDs in saturated porous media, and the capacity of N-CDs to mobilize pre-adsorbed Pb in quartz columns. Pb adsorption was higher on N-CDs than on quartz surfaces and decreased with increases in ionic strength (IS) and divalent cations (Ca2+) concentration. N-CD mobility in quartz columns was highest at pH of 9- and 1-mM monovalent cations (Na+) and decreased with decreases in pH and increases in ionic strength and ion valency. N-CDs mobilized pre-adsorbed Pb from quartz due to the higher adsorption affinity of Pb to N-CD than to quartz surfaces. These findings provide valuable insights into the transport, retention, and risk assessment of lead in the presence of carbon-based engineered nanoparticles.

show abstract

“…Natural organic matter (NOM) is also used in some studies to stabilize MP and mimic environmental conditions, but the effect of NOM on dispersion stability has not been fully resolved yet. Reported results indicate a stabilizing as well as no effect using NOM standard samples from the International Humic Substances Society (IHSS) in MP dispersions [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Zeta potential measurements are widely used to study the effects of ion strength, pH and humic substances on the stability of MP and nanoplastic (NP) dispersions [12,13,15,16]. This parameter is essential to characterize dispersions, but measurements are elaborate and time-consuming and limited to smaller particle sizes depending on the density of the particle.…”

Section: Introductionmentioning

confidence: 99%

Particle Size and Pre-Treatment Effects on Polystyrene Microplastic Settlement in Water: Implications for Environmental Behavior and Ecotoxicological Tests

Eitzen

Ruhl

Jekel

2020

Water

View full text Add to dashboard Cite

Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. In this study, manual/automated shaking and ultrasonic treatment as different mechanical dispersion techniques were applied for the dispersion of cryomilled polystyrene (PS). Particle numbers and size distribution of dispersions were analyzed by a light extinction particle counter and the dispersion efficiency (ED) as the ratio between calculated volume and theoretical volume of suspended particles was used to compare techniques. PS dispersions (20 mg/L) treated for 90 min in an ultrasonic bath (120 W, 35 kHz) were evenly dispersed with a particle concentration of 140,000 particles/mL and a high reproducibility (rel. SD = 2.1%, n = 6). Automated horizontal shaking for 754 h (250 rpm) reached similar particle numbers (122,000/mL) but with a lower reproducibility (rel. SD = 9.1%, n = 6). Manual shaking by hand dispersed the lowest number of particles (55,000/mL) and was therefore found to be unsuitable to counteract homo-agglomeration. ED was calculated as 127%, 104% and 69% for ultrasonic treatment, horizontal shaking and manual shaking, respectively, showing an overestimation of volume assuming spherical shaped particles.

show abstract

Aggregation kinetics of microplastics in aquatic environment: Complex roles of electrolytes, pH, and natural organic matter

Cited by 202 publications

References 66 publications

A combined experimental and modeling study to evaluate pH-dependent sorption of polar and non-polar compounds to polyethylene and polystyrene microplastics

A combined experimental and modeling study to evaluate pH-dependent sorption of polar and non-polar compounds to polyethylene and polystyrene microplastics

Transport of N-CD and Pre-Sorbed Pb in Saturated Porous Media

Particle Size and Pre-Treatment Effects on Polystyrene Microplastic Settlement in Water: Implications for Environmental Behavior and Ecotoxicological Tests

Contact Info

Product

Resources

About