Adsorption mechanisms of five bisphenol analogues on PVC microplastics

Adsorption of Tannic Acid and Macromolecular Humic/Fulvic Acid onto Polystyrene Microplastics: A Comparison Study

Dissolved organic matter (DOM) has been widely reported to influence the environmental behavior of microplastics (MPs), but little is known about the properties and mechanisms of interaction between specific DOM components and MPs. Here, we studied the adsorption of three representative DOM components (humic acid, HA; fulvic acid, FA; and tannic acid, TA) on polystyrene (PS) MPs in batch adsorption experiments. Results revealed that HA/FA adsorption was greater under acidic conditions, while higher TA adsorption on PS was found at pH 4 and 6. The divalent cation (Ca2+) exerted a more prominent role in enhancing HA, FA, and TA adsorption on PS than did monovalent ones (K+ and Na+). The adsorption process fitted well with the Freundlich isotherm model and the pseudo-second-order kinetics model. The adsorption site heterogeneity was evaluated using the site energy distribution analysis based on the Freundlich model. The greater binding ability of HA on the PS surface caused a more negatively charged surface than FA/TA, as reflected by Zeta potential values. The findings of this study not only provide valuable information about the adsorption behavior and interaction processes of various DOM components on PS MPs, but also aid our efforts to evaluate the environmental behaviors of MPs.

A Novel Analytical Approach to Assessing Sorption of Trace Organic Compounds into Micro- and Nanoplastic Particles

Assessing the sorption of trace organic compounds (TOrCs) into micro- and nanoplastic particles has traditionally been performed using an aqueous phase analysis or solvent extractions from the particle. Using thermal extraction/desorption–gas chromatography/mass spectrometry (TD-Pyr-GC/MS) offers a possibility to analyze the TOrCs directly from the particle without a long sample preparation. In this study, a combination of two analytical methods is demonstrated. First, the aqueous phase is quantified for TOrC concentrations using Gerstel Twister® and TD-GC/MS. Subsequently, the TOrCs on the particles are analyzed. Different polymer types and sizes (polymethyl methacrylate (PMMA), 48 µm; polyethylene (PE), 48 µm; polystyrene (PS), 41 µm; and PS, 78 nm) were analyzed for three selected TOrCs (phenanthrene, triclosan, and α-cypermethrin). The results revealed that, over a period of 48 h, the highest and fastest sorption occurred for PS 78 nm particles. This was confirmed with a theoretical calculation of the particle surface area. It was also shown for the first time that direct quantification of TOrCs from PS 78 nm nanoparticles is possible. Furthermore, in a mixed solute solution, the three selected TOrCs were sorbed onto the particles simultaneously.

A comprehensive review of the polyolefin composites and their properties

Polyolefins are formed by the polymerization of olefin monomer units such as ethylene, styrene, and vinyl chloride. Polyolefins composites are a mixture of polyolefins with different types of other polymers, reinforcements, or fillers. Blending neat polyolefins with composites widens its uses in various applications that require high efficiency in the areas of environmental degradation, impact resistance, fire and chemical resistance, or strength. In this review, the effects of blending neat polyolefin with other types of polymers or wood fibers on the properties of neat polymers have been represented. Moreover, this review reveals the importance of a coupling agent or compatibilizer in the improvement of the polyolefin’s compatibility with the other added components.

Aging significantly increases the interaction between polystyrene nanoplastic and minerals

With the massive use and discarding of plastic products, plastic particles, including nanoplastics (NPs), which are continuously released under the action of environmental factors, are posing greater risk to the ecosystem and human health. NPs exposed to the environment experience aging, which can significantly change their physical and chemical properties and affect their environmental behavior. Here, we examined the adsorption behavior of polystyrene nanoplastic (PSNP) aging by ultraviolet (UV) exposure on different minerals (goethite, magnetite, kaolinite and montmorillonite). Aging not only changes the surface morphology of PSNP, but also increases the surface negative charge and produces a large number of oxygen-containing functional groups (OFGs). Incubation of aged PSNP with minerals indicated that iron oxides (goethite and magnetite) showed stronger interactions with aged PSNP than pristine PSNP, and there was an interaction between clay minerals and aged PSNP. The adsorption experiments and scanning electron microscopy (SEM) suggested that the higher adsorption capacity of a mineral surface to aged PSNP may be related to electrostatic attraction and ligand exchange. The Fourier transform infrared (FTIR) spectra after adsorption showed that the adsorption affinity between the functional groups was different, and two-dimensional correlation spectroscopy (2D-COS) analysis further indicated that the mineral preferentially adsorbed the aged PSNP in accordance with the order of OFGs. The findings provide a theoretical basis for scientific evaluation of ecological risks of NPs in the environment.

Microplastic properties and their interaction with hydrophobic organic contaminants: a review

Microplastics (MPs) have been defined as particles of size < 5 mm and are characterized by hydrophobicity and large surface areas. MPs interact with co-occurring hydrophobic organic contaminants (HOCs) via sorption-desorption processes in aquatic and terrestrial environments. Ingestion of MPs by living organisms may increase exposure to HOC levels. The key mechanisms for the sorption of HOCs onto MPs are hydrophobic interaction, electrostatic interaction, π-π interactions, hydrogen bonding, and Van der Waals forces (vdW). Polymer type, UV-light-induced surface modifications, and the formation of oxygen-containing functional groups have a greater influence on electrostatic and hydrogen bonding interactions. In contrast, the formation of oxygen-containing functional groups negatively influences hydrophobic interaction. MP characteristics such as crystallinity, weathering, and surface morphology affect sorption capacity. Matrix properties such as pH, ionic strength, and dissolved organic matter (DOM) also influence sorption capacity by exerting synergistic/antagonistic effects. We reviewed the mechanisms of HOC sorption onto MPs and the polymer and matrix properties that influence the HOC sorption. Knowledge gaps and future research directions are outlined.

Microplastics in the Gulf of Mexico: A Bird’s Eye View

Microplastic debris is a persistent, ubiquitous global pollutant in oceans, estuaries, and freshwater systems. Some of the highest reported concentrations of microplastics, globally, are in the Gulf of Mexico (GoM), which is home to the majority of plastic manufacturers in the United States. A comprehensive understanding of the risk microplastics pose to wildlife is critical to the development of scientifically sound mitigation and policy initiatives. In this review, we synthesize existing knowledge of microplastic debris in the Gulf of Mexico and its effects on birds and make recommendations for further research. The current state of knowledge suggests that microplastics are widespread in the marine environment, come from known sources, and have the potential to be a major ecotoxicological concern for wild birds, especially in areas of high concentration such as the GoM. However, data for GoM birds are currently lacking regarding typical microplastic ingestion rates uptake of chemicals associated with plastics by avian tissues; and physiological, behavioral, and fitness consequences of microplastic ingestion. Filling these knowledge gaps is essential to understand the hazard microplastics pose to wild birds, and to the creation of effective policy actions and widespread mitigation measures to curb this emerging threat to wildlife.

Sorption of Perfluorinated and Pharmaceutical Compounds in Plastics: A Molecular Simulation Study

The aim of the current study is to investigate the effect of temperature and degree of polymerisation on the thermodynamic interaction of perfluorinated compounds (PFCs) into plastics. The occurrence of contaminants of emerging concern such as pharmaceutical drugs, PFCs, microplastics (MPs), etc., in sources of drinking water have posed significant health risks to aquatic life and humans in recent years. These organic pollutants can interact with MPs and pose much higher health risks; consequently, MPs become a transport vector and thus alter their migration as well as occurrence in the environment. The purpose of this paper is to examine the adsorption mechanism of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and sulfamethazine (SMT)—relative to water—on polyethylene (PE) and polypropylene (PP) using an extended Flory–Huggins approach. The results suggest that in an aqueous environment, both PFOA and PFOS may be taken up preferentially by PP and PE, although less strongly by PE. The degree of polymerisation of PE and PP did not significantly influence the observed behaviour. In terms of sorption affinity, the observed affinity was PFOA>PFOS>SMT which was consistence for both PE and PP.

A review of interactions of microplastics and typical pollutants from toxicokinetics and toxicodynamics perspective

The widespread microplastics (MPs) pollution has become a concerning environmental issue. The interactions between MPs and typical pollutants may change the bioaccumulation, and toxicity of pollutants, leading to high uncertainty in risk assessment. Still, significant gaps remain in the knowledge available to integrate these interactions in the perspectives of toxicokinetics (TK) and toxicodynamics (TD), which is also an essential part of quantitative toxicological research. This review systematically summarizes the interaction between MPs and typical pollutants in TK and TD processes. MPs can be acted as the vector or sink of pollutants to increase or decrease their bioaccumulation, and also may not affect their bioaccumulation due to no interaction. The adverse outcome pathway (AOP) framework enables novel approaches for determining the interaction between MPs and pollutants in the TD process. MPs can directly or indirectly enhance, reduce and not affect the toxicity of pollutants. A series of factors influencing the interaction in TK and TD processes are summarized, including MPs characteristics and exposure scenarios. TK-TD approach can quantitatively understand the interaction between MPs and pollutants based on the mechanism. Given the current knowledge gap in TK and TD processes, future perspectives on combined exposure research are proposed.

Microplastics contamination of groundwater: Current evidence and future perspectives. A review

Groundwater is a primary water source which supplies more than 2 billion people. The increasing population and urbanization of rural areas stresses and depletes the groundwater systems, reducing the groundwater quality. Among the emerging contaminants, microplastics (MPs) are becoming an important issue due to their persistency in the environment. Seepage through the pores and fractures as well as the interaction with colloidal aggregates can partially affect the MPs dynamics in the subsoil, making the detection of the MPs in the groundwater systems challenging. Based on literature, a critical analysis of MPs in groundwater is presented from a hydrogeological point of view. In addition, a review of the MPs data potentially affecting the groundwater systems are included. MPs in groundwater may have several sources, including the atmosphere, the interaction with surface water bodies, urban infrastructures, or agricultural soils. The characterization of both the groundwater dynamics and the heterogeneity of MPs is suggested, proposing a new framework named "Hydrogeoplastic Model". MPs detection methods aimed at characterizing the smaller fragments are necessary to clarify the fate of these contaminants in the aquifers. This review also aims to support future research on MP contamination in groundwater, pointing out the current knowledge and the future risks which could affect groundwater resources worldwide.

Exploring the adsorption behavior of benzotriazoles and benzothiazoles on polyvinyl chloride microplastics in the water environment

As a kind of emerging pollutant, microplastics (MPs) play an important role as a carrier for pollutant migration in the water environment. Carried by the MPs, benzotriazoles, and benzothiazoles (collectively referred to as BTs)¹ are ubiquitous water contaminants. In this paper, the adsorption behavior of BTs on polyvinyl chloride (PVC) MPs was first studied systematically to explain the adsorptive mechanisms and the consequential pollution caused by the absorption-desorption process. The studies on kinetics, isotherms, and thermodynamics revealed that the adsorption of BTs on PVC MPs was a multi-rate, heterogeneous multi-layer, and exothermic process, which was affected by external diffusion, intra-particle diffusion, and dynamic equilibrium. The factors including pH, salinity, and particle size also influenced the adsorption process. In the multi-solute system, competitive adsorption would occur between different BTs. The desorption of BTs from PVC MPs was positively associated with the increase of adsorption amount. Based on the results, the adsorption mechanisms of PVC MPs were clarified, involving hydrophobic interaction, electrostatic force, and non-covalent bonds. It was demonstrated that BTs in the water environment could most probably be accumulated and migrated through MPs, and eventually carried into organisms, posing an increased risk to the ecological environment.

Interaction of tetrabromobisphenol A (TBBPA) with microplastics-sediment (MPs-S) complexes: A comparison between binary and simple systems

The presence of microplastics (MPs) and the associated organic pollutants in the aquatic environment has attracted growing concern in recent years. MPs could compete with chemicals for adsorption sites on the surface of sediment, affecting the sorption processes of pollutants on sediment. However, few studies focused on the binary system of microplastics-sediment (MPs-S), which appear much common in aquatic environment. Herein, we investigated the interactions between a continuously used flame retardant tetrabromobisphenol A (TBBPA) and four MPs-S complexes (PVC-S, PE-S, PP-S and PS-S). The equilibrium adsorption capacities were 17.1, 15.6, 15.4, and 14.0 mg/kg for PVC-S, PS-S, PE-S, and PP-S, respectively. Kinetics suggest that adsorption behavior of TBBPA was fitted by pseudo-second-order model. Co-adsorption of TBBPA in binary systems were much lower than the sum of each simple system, which may be due to the mutually occupied adsorption sites. Higher ionic strength and lower dissolved organic matter strengthened the sorption of TBBPA onto MPs-S complexes. The enhanced sorption capacities for TBBPA were observed with elevated proportion and small particle size of MPs in the MPs-S complexes. This study contributes to the knowledge on the impact of MPs in partitioning of organic pollutants in-between solid and aqueous phases in the aquatic environment.

Post COVID-19 pandemic: Disposable face masks as a potential vector of antibiotics in freshwater and seawater

With the outbreak and widespread of the COVID-19 pandemic, large numbers of disposable face masks (DFMs) were abandoned in the environment. This study first investigated the sorption and desorption behaviors of four antibiotics (tetracycline (TC), ciprofloxacin (CIP), sulfamethoxazole (SMX), and triclosan (TCS)) on DFMs in the freshwater and seawater. It was found that the antibiotics in the freshwater exhibited relatively higher sorption and desorption capacities on the DFMs than those in the seawater. Here the antibiotics sorption processes were greatly related to their zwitterion species while the effect of salinity on the sorption processes was negligible. However, the desorption processes were jointly dominated by solution pH and salinity, with greater desorption capacities at lower pH values and salinity. Interestingly, we found that the distribution coefficient (K_d) of TCS (0.3947 L/g) and SMX (0.0399 L/g) on DFMs was higher than those on some microplastics in freshwater systems. The sorption affinity of the antibiotics onto the DFMs followed the order of TCS > SMX > CIP > TC, which was positively correlated with octanol-water partition coefficient (log K_ow) of the antibiotics. Besides, the sorption processes of the antibiotics onto the DFMs were mainly predominated by film diffusion and partitioning mechanism. Overall, hydrophobic interaction regulated the antibiotics sorption processes. These findings would help to evaluate the environmental behavior of DFMs and to provide the analytical framework of their role in the transport of other pollutants.

Influence of polystyrene microplastics on the volatilization, photodegradation and photoinduced toxicity of anthracene and pyrene in freshwater and artificial seawater

In this study, the influences of polystyrene microplastics (PS MPs) on the volatilization, photodegradation and photoinduced toxicities of anthracene and pyrene were determined in freshwater and artificial seawater. The PS MPs reduced the volatilization of anthracene and pyrene, and the volatilization reduction was highly dependent on the PS MPs sizes and concentrations. The PS MPs increased the photodegradation kinetics (k_p) of anthracene by promoting ¹O₂ generation and altered the photodegradation pathways through OH attack of the photodegradation byproducts. However, the k_p of pyrene was decreased by PS MPs suppressing the transfer of electrons from excited pyrene to oxygen. The PS MPs modified the pathways of pyrene photodegradation via OH attack of the photodegradation byproducts. Due to light shielding by DOM and/or PS MPs aggregates in seawater, the modification of the photodegradation pathways of anthracene and pyrene by PS MPs was hardly happened in seawater compared with in freshwater. By changing the concentrations of anthracene or pyrene and their photodegradation byproducts, the PS MPs greatly affected the photoinduced toxicities of anthracene and pyrene to Selenastrum capricornutum and Phaeodactylum tricornutum. The influences of PS MPs on the volatilization, photodegradation and photoinduced toxicity of anthracene and pyrene are important and should be carefully considered during environmental risk assessments of anthracene and pyrene.

Nanoplastic adsorption characteristics of bisphenol A: The roles of pH, metal ions, and suspended sediments

Nanoplastics (NPs) are widely found in the environment and can act as a vector for various toxic substances and promote their diffusion and bioenrichment, but the underlying mechanisms are largely unknown. Here, the adsorption characteristics of bisphenol A (BPA) onto NPs were explored. The results show that the adsorption of BPA on NPs was dominated by saturated single-layer adsorption and affected by both intra-particle diffusion and liquid film diffusion. Electrostatic interaction, π-π interaction, and hydrophobic effects played key roles in adsorption. In addition, the introduction of electrolytes inhibited the adsorption of BPA onto NPs. Interestingly, the introduction of suspended sediment promoted the formation of heterogeneous aggregates of NPs-SS, thereby reducing the adsorption capacity, indicating that aggregation may play an important role in the adsorption behavior of NPs. Overall, our results provide new insights into the adsorption behavior of BPA on NPs and the underlying mechanisms under different environmental conditions.

Adsorption of environmental contaminants on micro- and nano-scale plastic polymers and the influence of weathering processes on their adsorptive attributes

Increases in plastic-related pollution and their weathering can be a serious threat to environmental sustainability and human health, especially during the present COVID-19 (SARS-CoV-2 coronavirus) pandemic. Planetary risks of plastic waste disposed from diverse sources are exacerbated by the weathering-driven alterations in their physical-chemical attributes and presence of hazardous pollutants mediated through adsorption. Besides, plastic polymers act as vectors of toxic chemical contaminants and pathogenic microbes through sorption onto the 'plastisphere' (i.e., plastic-microbe/biofilm-environment interface). In this review, the effects of weathering-driven alterations on the plastisphere are addressed in relation to the fate/cycling of environmental contaminants along with the sorption/desorption dynamics of micro-/nano-scale plastic (MPs/NPs) polymers for emerging contaminants (e.g., endocrine-disrupting chemicals (EDCs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pharmaceuticals and personal care products (PPCPs), and certain heavy metals). The weathering processes, pathways, and mechanisms governing the adsorption of specific environmental pollutants on MPs/NPs surface are thus evaluated in relation to the physicochemical alterations based on several kinetic and isotherm studies. Consequently, the detailed evaluation on the role of the complex associations between weathering and physicochemical properties of plastics should help us gain a better knowledge with respect to the transport, behavior, fate, and toxicological chemistry of plastics along with the proper tactics for their sustainable remediation.

A critical review of presence, removal and potential impacts of endocrine disruptors bisphenol A

Bisphenol A (BPA) is a synthetic organic compound that is mainly used in the production of polymer materials polycarbonate and epoxy resin. Widespread use and irregular processing methods have led to BPA being detected globally, raising concerns about its environmental and health effects. This review outlines an overview of the presence and removal of BPA in the environment and consumer products. We also summarized the endocrine-disrupting toxicity of BPA, and the relatively less summarized neurotoxicity, cytotoxicity, reproductive toxicity, genotoxicity, and carcinogenicity. Human exposure data show that humans have been exposed to low concentrations of BPA for a long time, future research should focus on the long-term exposure and the migration of BPA from consumer products to humans and the possible health risks associated with human exposure to BPA. Exploring economical and effective methods to reduce and remove BPA from the environment is imperative. The development of safe, functional and reproducible BPA analogs and the study of its degradation products can be the focus of subsequent research.

Single and combined toxicity effects of nanoplastics and bisphenol F on submerged the macrophyte Hydrilla verticillata

Nano- and microplastics pose severe risks to the ecological environment. Nanoplastics (NPs) not only directly affect aquatic organisms, but also adsorb to other pollutants, resulting in compound pollution. Bisphenol F (BPF), an endocrine-disrupting chemical, is increasingly replacing bisphenol A (BPA) and is therefore widely distributed in the environment. In this study, the toxic effects of polystyrene nanoplastics (PS-NPs) and BPF and their combined exposure on the submerged macrophytes Hydrilla verticillata (H. verticillata) and leaf biofilms, were investigated. Results showed that 10 mg/L PS-NPs and combined exposure to 10 mg/L PS-NPs and 10 mg/L BPF significantly decreased the relative growth rate and chlorophyll content of H. verticillata, whereas BPF exposure alone had no impact on the growth and the contents of photosynthetic pigments in H. verticillata. Individual and combined exposure to PS-NPs and BPF can trigger antioxidant responses such as increased activities of superoxide dismutase, peroxidase, and malondialdehyde, as well as higher levels of glutathione S-transferase and glutathione and decreased catalase activity. The results of the scanning electron microscopy (SEM) showed that the nanoplastics particles were adsorbed on the surface of plant leaves, explaining their toxic effects, whereas BPF increases the sorption of PS-NPs on the surface of H. verticillata, potentially leading to PS-NPs enrichment in the food chain. The diversity and richness of the microbial community were altered by exposure to PS-NPs and BPF individually and in combination. The current study is the first to assess the effects of PS-NPs and BPF exposure on the growth, physiological characteristics, and leaf biofilm properties of submerged macrophytes.

Microplastics in marine and aquatic habitats: sources, impact, and sustainable remediation approaches

Plastic trash dumped into water bodies degrade over time into small fragments. These plastic fragments, which come under the category of micro-plastics (MPs), are generally 0.05-5 mm in size, and due to their small size they are frequently consumed by aquatic organisms. As a result, widespread MPs infiltration is a global concern for the aquatic environment, posing a threat to existing life forms. MPs easily bind to other toxic chemicals or metals, acting as vector for such toxic substances and introducing them into life forms. Polyethylene, polypropylene, polystyrene, and other polymers are emerging pollutants that are detrimental to all types of organisms. The main route for MPs into the aquatic ecosystems is through the flushing of urban wastewater. The current paper investigates the origin, environmental fate, and toxicity of MPs, shedding light on their sustainable remediation.

Graphical abstract

Adsorption properties and influencing factors of Cu(II) on polystyrene and polyethylene terephthalate microplastics in seawater

As an emerging contamination in the ocean, microplastics can act as effective vectors of pollutants, the ecological risks caused by the combined pollution of microplastics and other pollutants have attracted growing attention. In this work, Copper (Cu(II)) was chosen as the classic pollutant, polystyrene (PS) and polyethylene terephthalate (PET) pellets were used as the typical marine microplastics, the adsorption performance of Cu(II) on PS and PET beads was investigated by adsorption kinetics and isotherm experiments, and other influencing conditions, such as pH, salinity, coexisting heavy metals ions and aging treatment, were evaluated. The results indicated that the adsorption behavior of Cu(II) on PS and PET was spontaneous and endothermic in the simulated seawater environment, and the batch experimental data can be effectively described by pseudo-second-order model and Freundlich isothermal model. Besides, the adsorption capacity of microplastics for Cu(II) was the best at pH 7, the change of salinity had no obvious effect on the adsorption in the natural marine environment. Moreover, co-existence of lead (Pb(II)) exhibited evident impacts on Cu(II) sorption onto PS and PET, which confirmed the adsorption competition effect between them. Additionally, high temperature aging treatment of microplastics in different environments for different duration time could obviously affect the properties of microplastics. It was found that the microplastics after being exposed to high temperature environment in the air for 168 h showed relatively stronger adsorption amount for Cu(II). In summary, these findings suggested that electrostatic interaction and distributed diffusion mechanisms may be the main mechanisms of adsorption, while no new functional groups were generated after the adsorption, indicating that physisorption may dominate the adsorption performance of PS and PET pellets for Cu(II). This study provides supplementary insights into the role of microplastics as carriers of heavy metals in the marine environment.

Sorption of diclofenac by polystyrene microplastics: Kinetics, isotherms and particle size effects

Diclofenac (DCF) is a common pharmaceutical that widely distributed in natural waters, and has been received an increasing attention because of its potential toxicity. Additionally, microplastics are also ubiquitous pollutants in natural waters, but little information is available on their interactions. In this study, the sorption of DCF on polystyrene microplastics (PS MPs) with different particle sizes was investigated, and the influence of environmental factors was also explored. Results indicated that the pseudo-second-order kinetic model was suitable to describe the sorption process. The sorption capacity increased with the increase in particle size. The isotherms data for the sorption of DCF on 0.5 and 1 μm PS MPs were best fitted with the Dubinine-Radushkevich model, but the Freundlich and Langmuir models could best describe the sorption of DCF 5 and 20 μm PS MPs, respectively. It is suggested that the sorption was a chemisorption, which is also verified by Fourier transform infrared spectroscopy (FTIR) results. Furthermore, the sorption capacity decreased as pH increased, and increased as ionic strength increased. These findings give a new perspective that the microplastics with larger sizes hold promise for the treatment of DCF-contaminated water.

Microplastics and nanoplastics: Recent literature studies and patents on their removal from aqueous environment

The presence of microplastics (MP) and nanoplastics (NP) in the environment poses significant hazards towards microorganisms, humans, animals and plants. This paper is focused on recent literature studies and patents discussing the removal process of these plastic pollutants. Microplastics and nanoplastics can be quantified by counting, weighing, absorbance and turbidity and can be further analyzed using scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, surface-enhanced Raman spectroscopy and Raman tweezers. Mitigation methods reported are categorized depending on the removal characteristics: (i) Filtration and separation method: Filtration and separation, electrospun nanofiber membrane, constructed wetlands; (ii) Capture and surface attachment method: coagulation, flocculation and sedimentation (CFS), electrocoagulation, adsorption, magnetization, micromachines, superhydrophobic materials and microorganism aggregation; and (iii) Degradation method: photocatalytic degradation, microorganism degradation and thermal degradation; where removal efficiency between 58 and 100% were reported. As these methods are significantly distinctive, the parameters which affect the MP/NP removal performance e.g., pH, type of plastics, presence of interfering chemicals or ions, surface charges etc. are also discussed. 42 granted international patents related to microplastics and nanoplastics removal are also reviewed where the majority of these patents are focused on separation or filtration devices. These devices are efficient for microplastics up to 20 μm but may be ineffective for nanoplastics or fibrous plastics. Several patents were found to focus on methods similar to literature studies e.g., magnetization, CFS, biofilm and microorganism aggregation; with the addition of another method: thermal degradation.

Microplastics and bisphenol A hamper gonadal development of whiteleg shrimp (Litopenaeus vannamei) by interfering with metabolism and disrupting hormone regulation

Gonadal development is a prerequisite for the reproductive success of an organism, and might be affected by environmental factors such as emergent pollutants. Although marine crustaceans are threatened by ubiquitous emergent pollutants such as microplastics (MPs) and bisphenol A (BPA) under realistic scenarios, studies about the impacts of these pollutants on the gonadal development of crustacean species are rare. In this study, the effects of MPs and BPA, alone or in combination, on gonadal development were investigated in whiteleg shrimp (Litopenaeus vannamei). The results obtained demonstrated that whiteleg shrimp exposed to MPs and BPA had significantly smaller gonad-somatic index (GSI) and an obvious delay in the gonad developmental stage. In addition, exposure of whiteleg shrimp to pollutants tested resulted in a reduction in the oxygen consumption rate, elevation in the ammonia excretion rate, decline in the O: N ratio, and downregulation in the expression of metabolism-related genes, indicating significant disruptions of shrimp metabolism by the pollutants. Furthermore, in addition to a few exceptions, both the in vivo contents of gonadal development-related hormones (GIH and MIH) and the expression of genes encoding regulatory hormones (GIH, MIH, and CHH) were upregulated by the exposure of whiteleg shrimp to the pollutants investigated, suggesting a significant obstruction of endocrine regulation. Moreover, MP-BPA coexposure was shown to be more toxic to whiteleg shrimp than the corresponding single exposures and significantly greater amount of BPA accumulated in the gonads (both testis and ovaries) of shrimp with the coexistence of MPs, which may be caused by the Trojan horse effect and summation of the toxic impacts on common targets. In general, the data obtained in this study demonstrated that MPs and BPA at environmentally realistic concentrations significantly inhibited the gonadal development of whiteleg shrimp probably by interfering with metabolism and disrupting endocrine regulation.

Effect of Atom Transfer Radical Polymerization Reaction Time on PCB Binding Capacities of Styrene-CMA/QMA Core-Shell Iron Oxide Nanoparticles

Water pollution continues to be one of the greatest challenges humankind faces worldwide. Increasing population growth, fast industrialization and modernization risk the worsening of water accessibility and quality in the coming years. Nanoadsorbents have steadily gained attention as remediation technologies that can meet stringent water quality demands. In this work, core-shell magnetic nanoparticles (MNPs) comprised of an iron oxide magnetic core and a styrene based polymer shell were synthesized via surface initiated atom transfer radical polymerization (SI-ATRP), and characterized them for their binding of polychlorinated biphenyls (PCBs), as model organic contaminants. Acrylated plant derived polyphenols, curcumin multiacrylate (CMA) and quercetin multiacrylate (QMA), and divinylbenzene (DVB) were incorporated into the polymeric shell to create high affinity binding sites for PCBs. The affinity of these novel materials for PCB 126 was evaluated and fitted to the nonlinear Langmuir model to determine binding affinities (KD). The KD values obtained for all the MNP systems showed higher binding affinities for PCB 126 that carbonaceous materials, like activated carbon and graphene oxide, the most widely used adsorption materials for water remediation today. The effect of increasing ATRP reaction time on the binding affinity of MNPs demonstrated the ability to tune polymer shell thickness by modifying the reaction extent and initial crosslinker concentrations in order to maximize pollutant binding. The enhancement in binding affinity and capacity for PCB 126 was demonstrated by the use of hydrophobic, aromatic rich molecules like styrene, CMA, QMA and DVB, within the polymeric shell provides more sites for π-π interactions to occur between the MNP surface and the PCB molecules. Overall, the high affinities for PCBs, as model organic pollutants, and magnetic capabilities of the core-shell MNPs synthesized provide a strong rationale for their application as nanoadsorbents in the environmental remediation of specific harmful contaminants.

Sorption behaviors of petroleum on micro-sized polyethylene aging for different time in seawater

Microplastics (MPs; <5 mm) and oil pollution have been receiving global attention. To date, the adsorption mechanism of petroleum by MPs is largely unknown. This study investigated the adsorption of petroleum on micro-sized polyethylene (mPE) undergoing aging (days 0, 15, 30, 90 and 180). The petroleum adsorption capacity of mPE was further assessed at varying pH (2, 5, 7.32, 10 and 12), temperature (4, 15, 25, 45 and 65 °C) and in presence of coexisting pollutants (Cu, bisphenol A (BPA) and petroleum). The results indicated that the adsorption capacity of mPE increased with the prolonged aging time and smaller-sized particles, while the adsorption capacity of the 550 and 165 μm mPE undergoing aging increased by 12.7%-50.9% and 22.1%-63.9%, respectively. The adsorption kinetics and isotherm model of mPE on petroleum were well fitted by pseudo-second order, intraparticle diffusion, Freundlich and Langmuir models, showing the sorption behavior was controlled by the diffusion of pores, liquid film diffusion, and surface adsorption. The petroleum adsorption capacity of mPE was predominant affected by surface roughness, specific surface area, hydrophobicity, oxidation functional groups, adsorption sites, hydrogen bonds, while zeta potential and crystallinity may not be the crucial factors. Likewise, temperature and pH may influence the characteristics of petroleum, and further result in a decreasing adsorption capacity of mPE to petroleum. The highest adsorption capacity of mPE to petroleum was reached at pH 7.32 and 25 °C. The coexisting Cu, BPA and petroleum competed for adsorption sites on the surface of mPE. These findings could fundamentally provide new insights for environmental risk assessment of MPs, particularly for the specific location like harbor which is commonly rich in MPs and petroleum simultaneously.

Synthesis of reusable and renewable microporous organic networks for the removal of halogenated contaminants

Microporous organic networks (MONs) have shown great potential in the removal of environmental contaminants. However, all studies have focused on the design and construction of novel and efficient adsorbents, and the recycling and reuse of adsorbates were disregarded. In this study, we report a feasible approach to synthesize renewable and reusable MONs by using target halogenated contaminants such as tetrabromobisphenol A (TBBPA), 2,3-dichlorophenol (2,3-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) as starting monomers. TBBPA, 2,3-DCP, and 2,4,6-TCP acted as hazardous contaminants and starting monomers for MONs, leading to the recycling of both adsorbents and adsorbates. The obtained TBBPA-MON, 2,3-DCP-MON, and 2,4,6-TCP-MON not only offered good reusability and large adsorption capacity for their elimination but also provided good adsorption for other phenolic contaminants relying on multiple interactions. Density functional theory calculation indicated the dominant role of π-π and hydrophobic interactions and the secondary role of hydrogen bonding interactions during the adsorption process. The used TBBPA-MON could be reused and the eluted TBBPA could be recycled and renewed for the construction of fresh MONs. This study provided a feasible approach to design and synthesize renewable MONs for environmental contaminants.

Adsorption behaviors and mechanisms of antibiotic norfloxacin on degradable and nondegradable microplastics

The misuse of both antibiotics and plastics significantly increases the environmental pollution problems associated with these contaminants. Moreover, microplastics can adsorb other pollutants in the environment. However, the mechanisms of antibiotic adsorption by degradable and nondegradable microplastics are not completely understood. In this study, we investigated the environmental behavior of norfloxacin (NOR) using polybutylene succinate (PBS), which is a degradable microplastic, and compared it with conventional microplastics, polystyrene (PS) and polyethylene (PE). The order of adsorption capacity was PS > PBS ≫ PE. The adsorption behavior fitted well with the pseudo-second-order kinetic and Langmuir isotherm models, indicating monolayer adsorption. The process is thermodynamically endothermic and non-spontaneous and is controlled by chemical and physical mechanisms, including π-π conjugation, hydrogen bonds, ion exchange, and electrostatic interactions. The adsorption capacity of microplastics was higher when the solution pH was around the pKa value of NOR than at other pH values. Ionic strength and dissolved organic matter inhibited the adsorption process. For PS and PBS, the amount of NOR adsorbed onto MPs initially decreased and then increased with the increase of coexisting heavy metal ions. Zn²⁺ and Pb²⁺ could promote the adsorption of NOR by PE. This study reveals the interaction mechanisms between microplastics and antibiotics and provides a more comprehensive theoretical basis for an ecological environmental risk assessment of different microplastics.

New insights on aging mechanism of microplastics using PARAFAC analysis: Impact on 4-nitrophenol removal via Statistical Physics Interpretation

The aging effects of Polyethylene terephthalate (PET) microplastics were studied under Fenton process and Seawater. This research work mainly focuses on the aging mechanism of PET microplastics under two different conditions and their effect of aging on the adsorption of organic contaminants. The results of optical microscopic images, Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy, carbonyl, carboxyl index, X-ray powder diffraction (XRD) and dissolved organic carbon (DOC) help to understand the aging mechanism of PET microplastics. Parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2D-COS) were performed using 3D Excitation-Emission Matrix (3D-EEM) to understand the possible dissolved organic matter released during the Fenton process and seawater. The release of protein/phenol like components was observed in seawater whereas humic acid-like component was noted in the Fenton process. Later, the aged PET microplastics were tested for their adsorption capacity towards 4-nitrophenol at three different temperatures (15, 30 and 45 °C). The adsorption capacity of aged microplastics was found to be higher than the normal PET microplastics for all three different temperatures. Hydrogen bonding, n-pi interaction performed a significant role than pi-pi and hydrophobic interaction in the adsorption mechanism. A double layer with double energy model was found to be the best fit in the adsorption processes. The calculated adsorption energies (ΔE₁, ΔE₂) from the statistical physics modeling also confirms the physisorption mechanism. The above experimental results help to understand the behavior of microplastics at different aging period and how it acts as a carrier for pollutant in the marine environment.

Effects of environmental aging on the adsorption behavior of antibiotics from aqueous solutions in microplastic-graphene coexisting systems

The extensive use of nanofillers, such as graphene oxide (GO) and reduced graphene oxide (rGO), as plastic additives has led to the coexistence of microplastics (MPs) and nanomaterials in aquatic environments. However, there is a lack of studies on the adsorption behavior of MPs when coexisting with GO. Moreover, MPs and GO are prone to undergoing aging processes in real environments under conditions such as sunlight exposure, which changes their physicochemical properties and affects their adsorption behavior. In this study, the aging processes of MPs and GO in a real environment were simulated by ultraviolet (UV) irradiation and thermal treatments, respectively. The adsorption behavior of ciprofloxacin (CIP) on three types of MPs (polypropylene (PP), polyamide (PA), and polystyrene (PS)) before and after aging was explored. The MPs are ordered in terms of CIP adsorption capacity as aged-PA > aged-PS > aged-PP > PA > PP > PS, and the adsorption capacity of aged MPs was approximately twofold higher than that of pristine MPs. This paper also studied the adsorption performance of antibiotics in a coexisting system of aged MPs and GO/rGO, and the tetracycline (TC) adsorption capacity was increased by ~336% in aged PP-GO and ~100% in an aged PP-rGO coexisting system. GO/rGO with high degree of oxidation and concentration in an aged- PP-GO/rGO coexisting system are more conducive to the TC adsorption, due to the contribution of oxygen-containing functional groups. Surface and partition adsorption co-occurred during the TC adsorption process. The TC adsorption behavior in the MPs-GO/rGO coexisting system was strongly dependent on the solution pH, which was more favorable under acidic (pH = 3) or alkaline (pH = 11) conditions. This study improves the understanding of the environmental behavior of MPs, graphene, and antibiotics and guides research on strategies for preventing the migration of antibiotics in MPs-GO/rGO coexisting systems.

Distribution, characteristics, and human exposure to microplastics in mangroves within the Guangdong-Hong Kong-Macao Greater Bay Area

In this study, three mangroves in the Guangdong-Hong Kong-Macao Greater Bay Area- Qi'ao Island in Zhuhai, Nansha in Guangzhou, and Futian in Shenzhen-were selected for investigating the distribution of microplastics and their characteristics The average microplastic abundance in each descended in the order: Futian (1600 n/kg) > Nansha (1100 n/kg) > Qi'ao Island (440 n/kg), with values from the forest fringe being significantly higher than those in the forest interior. The microplastics were mainly fibers, 1-5 mm in size, and white/black in color; they consisted of polypropylene and polyethylene, with foam and polystyrene accounting for a high proportion in Nansha. The exposure of humans to microplastics in the Futian forest fringe reached 35.95 ng/d·kg; it was one order of magnitude higher than the exposures in Qi'ao Island and Nansha. Furthermore, ingestion accounted for approximately 74% of the total exposure to the human body, dermal contact constitutes 25%, and sediment inhalation accounted for less than 1%.

Release of tens of thousands of microfibers from discarded face masks under simulated environmental conditions

While mechanical abrasion by water and sediment is a primary and critical step in weathering process, the upsurge of discarded face masks will undoubtedly become a potential source of micro-/nanofibers owing to the spread of novel coronavirus (COVID-19) pneumonia. However, effects of mechanical abrasion on discarded face masks have neither been seriously addressed nor understood. Therefore, we conducted a simulated experiment to explore abundance, size distribution and morphology of microfibers released from common, surgical and face filtering piece (FFP) masks after mechanical abrasion. Technologies such as Fourier transform infrared spectrometry, fluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy were used. Results showed that the abundance of released microfibers followed order of surgical > common > FFP in both water and sediment environments, and the maximum abundance reached 272 ± 12.49 items per square centimeter of mask (items·cm^-2) after sediment abrasion. Taking surgical mask for further investigation, the length of released fiber was observed to vary from 47.78 μm to 3.93 mm, and 72.41-89.58% of the total number of released microfibers fell in the range of 0.1-1 mm. However, microfibers with a very small length (1-100 μm) can occupy 0.09-13.59% of the total number of released fibers in sediment environment. The roughness of fiber surface after sediment abrasion was successively increased. Furthermore, the morphology analysis showed significant changes with countless cracks and many prominent protrusions on fiber surface after sediment abrasion. The cracks and protrusions may further accelerate mask decomposition, thereby potentially resulting in the adsorption of other contaminants and the release of self-containing chemicals. This study provides a valuable database of microfibers released from discarded face masks at the primary but critical stage, and further contributes knowledge on environmental impact of discarded personal protective equipment due to COVID-19.

Interactions of microplastics, antibiotics and antibiotic resistant genes within WWTPs

Microplastics (MPs) have been detected in atmosphere, soil, and water and have been characterized as contaminants of emerging concern. When exposed to these environments, MPs interact with the chemical compounds as well as the (micro)organisms inhabiting these ecosystems. This paper overviews the interactions and significant factors influencing the sorption process of antibiotics on MPs since distinct interactions are developed between MPs and antibiotics. The interplay between the MPs and the antibiotic resistant genes (ARGs) microbial hosts is presented and the important factors that may shape the plastisphere resistome are discussed. The interactions of MPs, antibiotics and antibiotic resistant bacteria (ARB) and ARGs in wastewater treatment plants (WWTPs) were discussed with the aim to provide a perspective for better understanding of the role of WWTPs in bringing together MPs, antibiotics and ARB/ARGs and further as release points of MPs carrying antibiotics, and ARB/ARGs.

Seasonal distribution of microplastics in the surface water and sediments of the Vellar estuary, Parangipettai, southeast coast of India

Microplastics (MPs) are toxic pollutants, which are found ubiquitously in the marine environment. The present study aimed to assess the level of MP contamination in Vellar estuary, southeast coast of India. MP abundance in surface water and sediments ranged from 1.15 ± 0.01 to 5.14 ± 0.04 items/m³ and 24.8 ± 0.75 to 43.4 ± 0.98 particles/kg d.w., respectively. Fiber, fragment, film, pellet and glitter were present in the study area. In total, ten colors of MPs were found in the study, of which black was the most abundant. Seven polymers in sediments and four polymers in water were characterized from the study area, among which LDPE was the most dominant. Sediment texture results showed that clay particles were able to retain a greater number of MPs. This study shows that the Vellar estuary is contaminated with MPs; however, further investigation is required to classify the estuary as polluted.

Microplastics lag the leaching of phenanthrene in soil and reduce its bioavailability to wheat

Microplastics wildly occur in soil and they can become the carriers of persistent contaminants. However, the influence of microplastics on polycyclic aromatic hydrocarbons vertical translocation in the soil system after rainfall is limitedly understood. Here, experiments were conducted to study the influence of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) microplastics on the leaching behavior and bioavailability of phenanthrene (Phe). The adsorption capacity of phenanthrene on the microplastics followed the order of PS > PE > PVC. The Phe concentrations in the top soil layer after 15 days of leaching with water were 30.25, 28.32 and 27.25 mg kg^-1 for the treatments of Phe-PS, Phe-PE and Phe-PVC respectively, which is consistent with the adsorption capacities of microplastics. The concentrations of Phe were correlated with the microplastic adsorption capacities at soil depths of 5-45 cm. Under long-term leaching, Phe could reach the deeper soil layer. Phe concentrations significantly decreased in the leachate over time. Phe concentrations in wheat had a positive correlation with that in leachate/leached top soil layer. Our findings are beneficial to accurately evaluate the ecological risk of the combined contamination of PAHs and microplastics, and improve the understanding of the environmental behaviors of different microplastics.

Size-dependent adsorption of waterborne Benzophenone-3 on microplastics and its desorption under simulated gastrointestinal conditions

Microplastics (MPs) are global pollutants with heightened environmental and health concerns in recent years because of their worldwide distribution across aquatic environments, ability to load chemical contaminants and the potential for ingestion by animals, including human. In this study, three commonly used and environmentally detected plastics, i.e. polystyrene, polyethylene, polypropylene with sizes of 550, 250 and 75 μm, plus two submicron-sized polystyrene microplastics (5 and 0.5 μm) were assessed as solid adsorbents for a prevalent UV filter, benzophenone-3 (BP-3). The affinity and process of adsorption exhibited differentials among different sizes and types of MPs. Apparent desorption of BP-3 from MPs under simulated gastrointestinal conditions was not significantly enhanced, which might be due to the presence of the enzyme proteins, indicating potential risk of the contaminants carried by MPs. The desorption of BP-3 from MPs was affected by the size, type of MPs and the components of the gastrointestinal fluid.

Polystyrene microplastics increase estrogenic effects of 17α-ethynylestradiol on male marine medaka (Oryzias melastigma)

Microplastics (MPs) and endocrine disrupting chemicals are ubiquitous pollutants in marine environments, but their combined ecological risk is unclear. This study exposed male marine medaka (Oryzias melastigma) to 10 ng/L 17α-ethynylestradiol (EE₂) alone or EE₂ plus 2, 20, and 200 μg/L polystyrene MPs for 28 days to investigate the impacts of MPs on the reproductive disruption of EE₂. The results showed that 10 ng/L EE₂ alone did not affect biometric parameters, while co-exposure to EE₂ and 20, 200 μg/L MPs suppressed the growth and decreased gonadosomatic and hepatosomatic indices. Compared to EE₂ alone, EE₂ plus MPs exposure significantly increased plasma 17β-estradiol (E₂) levels in a dose-dependent manner, and co-exposure to EE₂ and 20, 200 μg/L MPs significantly increased the ratios of E₂/testosterone (T). Moreover, EE₂ plus MPs exposure elevated the transcription levels of estrogen biomarker genes vitellogenin and choriogenin, and estrogen receptor (ERα and ERβ). Morphological analysis also showed that co-exposure to EE₂ and MPs induced more severe damage to the testes and livers, indicating that MPs increased the toxicity of EE₂. The actual EE₂ concentrations in the solution increased with the exposure concentrations of MPs, suggesting that MPs changed the fate and behavior of EE₂ in the seawater. These findings demonstrate that MPs could increase the estrogenic effects of EE₂ on marine fish, suggesting that the combined health risk of MPs and endocrine disrupting chemicals on marine organisms should be paid great attention.

Adsorption mechanism of two pesticides on polyethylene and polypropylene microplastics: DFT calculations and particle size effects

Polyethylene (PE) and polypropylene (PP) microplastics (MPs), as carriers, can bind with pesticides, which propose harmful impacts to aqueous ecosystems. Meanwhile, carbofuran and carbendazim (CBD), two widely used carbamate pesticides, are toxic to humans because of the inhibition of acetylcholinesterase activity. The interaction between two MPs and two pesticides could start in farmland and be maintained during transportation to the ocean. Herein, the adsorption behavior and mechanism of carbofuran and carbendazim (CBD) by PE and PP MPs were investigated via characterization and density functional theory (DFT) simulation. The adsorption kinetic and thermodynamic data were best described by pseudo-second-order kinetics and the Freundlich models. The adsorption behaviors of individual carbofuran/CBD on both MPs were very similar. The CBD adsorption rate and capacity of PE and PP MPs were higher than those of carbofuran. This phenomenon explained the lower negative effects of DOM (oxalic acid, glycine (Gly)) on CBD adsorption relative to those of carbofuran. The presence of oxalic acid and Gly decreased the PE adsorption by 20.40-48.02% and the PP adsorption by 19.27-42.11%, respectively. It indicated the significance of DOM in carbofuran cycling. The adsorption capacities were negatively correlated with MPs size, indicating the importance of specific surficial area. Fourier transformation infrared spectroscopy before and after adsorption suggested that the adsorption process did not produce any new covalent bond. Instead, intermolecular van der Waals forces were one of the primary adsorption mechanisms of carbofuran and CBD by MPs, as evidenced by DFT calculations. Based on the zeta potential, the electrostatic interaction explained the higher adsorption CBD by MPs than carbofuran.

Interaction of Microplastics with Antibiotics in Aquatic Environment: Distribution, Adsorption, and Toxicity

As two major types of pollutants of emerging concerns, microplastics (MPs) and antibiotics (ATs) coexist in aquatic environments, and their interactions are a source of increasing concern. Therefore, this work examines the interaction mechanisms of MPs and ATs, and the effect of MPs on ATs bioavailability and antibiotic resistance genes (ARGs) abundance in aquatic environments. First, the mechanisms for ATs adsorption on MPs are summarized, mainly including hydrophobic, hydrogen-bonding, and electrostatic interactions. But other possible mechanisms, such as halogen bonding, CH/π interaction, cation-π interaction, and negative charge-assisted hydrogen bonds, are newly proposed to explain the observed ATs adsorption. Additionally, environmental factors (such as pH, ionic strength, dissolved organic matters, minerals, and aging conditions) affecting ATs adsorption by MPs are specifically discussed. Moreover, MPs could change the bioaccumulation and toxicity of ATs to aquatic organisms, and the related mechanisms on the joint effect are reviewed and analyzed. Furthermore, MPs can enrich ARGs from the surrounding environment, and the effect of MPs on ARGs abundance is evaluated. Finally, research challenges and perspectives for MPs-ATs interactions and related environmental implications are presented. This review will facilitate a better understanding of the environmental fate and risk of both MPs and ATs.

The influence of humic and fulvic acids on polytetrafluoroethylene-adsorbed arsenic: a mechanistic study

The large-scale use of polytetrafluoroethylene has resulted in ever-increasing amounts of polytetrafluoroethylene (PTFE) microplastic particles entering the environment. Given that the environment is polluted with arsenic (As(III)), and that the environment contains significant levels of humic acid (HA) and fulvic acid (FA), how PTFE and As(III) in water interacting in the presence of HA and FA needs to be urgently investigated. The results showed that As(III) was adsorbed by PTFE in the presence of HA and FA more markedly than the absence of them Adsorption equilibrium was reached at approximately 960 min and the adsorption isotherms were found to be best fitted by the Toth model. An increase in temperature was found to destroy hydrogen bonds, resulting in inhibited, non-spontaneous adsorption; a higher pH inhibited adsorption in the range 3-7. Computational and mechanistic studies revealed that PTFE formed π complexes with HA units, which increased the number of oxygen-containing functional groups on its surface. The surface of the PTFE-HA π complex was mostly negatively charged; however, the hydrogen atoms of the hydroxyl and carboxylic acid groups exhibited large positive potentials that enabled the adsorption of As(III). When the oxygen atom on As was close to the oxygen-containing functional group on PTFE-HA, the more electronegative oxygen atom forms a special intermolecular interaction in the form of O-H···O through the medium of hydrogen, which makes As adsorb on the surface of PTFE. Pore filling, hydrogen bonding, and covalent bonding are the main ways in which PTFE adsorbs As(III) in the presence of HA and FA. PTFE also adsorbed more As(III) in the presence of HA than in the presence of FA.

Fabrication of stable multivariate metal-organic frameworks with excellent adsorption performance toward bisphenols from environmental samples

As a type of environmental endocrine disrupting chemicals, bisphenols (BPs) have a certain embryonic toxicity and teratogenicity, which can significantly increase the risks of breast cancer, prostate cancer, leukemia and other cancers. In this work, stable multivariate metal-organic frameworks (UiO-66-NH₂/TCPP_x) were synthesized via in situ one-pot method and used as miniaturized dispersive solid-phase extraction (dμSPE) sorbents for extraction of trace BPs from environmental samples. The phase purity, crystal morphology and physical properties of UiO-66-NH₂/TCPP_x samples were varied by adjusting the mass ratio of TCPP. The extraction performance of UiO-66-NH₂/TCPP_x samples were investigated and UiO-66-NH₂/TCPP_1.0 exhibited the highest adsorption efficiency. Besides, UiO-66-NH₂/TCPP_1.0 possessed excellent recycling stability for the adsorption and desorption of BPs more than 20 cycles. The experimental parameters including amount of adsorbent, adsorption time, sample solution pH, temperature, desorption time and desorption solvents which affecting the efficiency of dμSPE were studied, respectively. Good linearity (R² > 0.9992) in range of 0.1-200 ng mL^-1 was obtained. The detection limits (S/N = 3) and quantification limits (S/N = 10) were achieved at 0.03-0.08 ng mL^-1 and 0.1-0.5 ng mL^-1, respectively. The relative standard deviations (RSDs) of intra-day and inter-day ranged from 2.5 to 5.5% and 1.1-6.8%. Enrichment factors were calculated in the range of 303-338. The obtained recoveries of bisphenol F (BPF), bisphenol A (BPA), bisphenol B (BPB) and bisphenol AF (BPAF) were 81.26-91.03% (RSDs = 0.96-6.47%), 82.2-97.27% (RSDs = 0.45-6.15%), 87.56-97.26% (RSDs = 1.1-6.22%) and 82.2-100.8% (RSDs = 0.46-4.07%). The UiO-66-NH₂/TCPP_1.0 can be employed as potential dμSPE sorbents for the enrichment of trace BPs in the environmental samples.

Adsorption behaviour and interaction of organic micropollutants with nano and microplastics - A review

Nano/microplastics (NPs/MPs) and organic micropollutants are contaminants exerting serious threats to aquatic ecosystems, which are further aggravated through their interactions. Organic micropollutants can adsorb on the surface of NPs/MPs, enter to the digestive systems of aquatic organisms with NPs/MPs, and desorb from the surface inside the organism. Consequently, the migration behaviour of organic micropollutants is significantly affected increasing their risk to accumulate in the food chain. Therefore, understanding the adsorption interactions between NPs/MPs and organic micropollutants is critical for evaluating the fate and impact of NPs/MPs in the environment. This review article provides an overview about the role of NPs/MPs as (temporary) sinks for organic micropollutants but also as primary sources of organic micropollutants through the leaching of plastic additives. Specifically, the following aspects are discussed: adsorption/desorption mechanisms (e.g., hydrophobic partitioning interaction, surface adsorption by van der Waals forces or hydrogen bonding, and pore filling), influencing environmental factors (e.g., pH, salinity, and dissolved organic matter), leaching of plastic additives from NPs/MPs, and potential ecotoxicological effects arising from the interactions of NPs/MPs and organic micropollutants.

Sorption of endocrine disrupting compounds onto polyamide microplastics under different environmental conditions: Behaviour and mechanism

Microplastics of polyamide are commonly found in aquatic environments and might act as vectors of different contaminants such as endocrine disrupting compounds (EDC). Therefore, sorption of 17α-ethynylestradiol (EE2), 17β-estradiol (E2), and estriol (E3) on polyamide microplastics was studied under different simulated environments. The results suggest that the sorption process was affected by the presence of dissolved organic matter (DOM) and salinity, where both positive and negative effects were observed. Kinetics revealed that the process occurs through multiple steps wherever the sorption rate depicting the transportation of EDC molecules from the liquid phase to the solid boundary of the sorbent, is higher than the intraparticle and pore diffusion process. In addition, the sorption rate of E2 decreased with the increase of water matrix complexity from ultrapure water (UPW) > artificial seawater (ASW) > fulvic acid water (FAW) > artificial seawater with fulvic acid (AS/FAW), while the sorption rate of EE2 decreased from UPW > ASW > FAW and increased in the matrix combining salinity and organic matter (AS/FAW). On the contrary, the E3 sorption rate increased with matrix complexity, from UPW < ASW < FAW and decreased with the influence of salinity and organic matter combination (AS/FAW). The sorption capacity of the EDC reached maximum values of 82% for E2, 90% for EE2 and 56% for E3. Isotherms demonstrated the occurrence of multilayer sorption. A positive relationship has been found between the hydrophobicity of polyamide microplastics and the Log K_ow of EDC, showing an important role of hydrophobic interactions in the sorption process under all the studied conditions. Moreover, hydrogen bonding and binding of contaminants and DOM to microplastics through bridges were also suggested. The results show that salinity and DOM can greatly influence the sorption and transportation of EDC in the aquatic environment and pose a risk to aquatic ecosystems.

Histopathological damage and stress- and immune-related genes' expression in the intestine of common carp, Cyprinus carpio exposed to copper and polyvinyl chloride microparticle

The present study aimed at assessing the singular and combined effects of water copper and polyvinyl chloride microplastic (MPVC) on intestinal copper accumulation, histopathological damage, and stress-/immune-related genes' expression in common carp, Cyprinus carpio. Four groups of fish were maintained in triplicate: control (kept in clean water), Cu (exposed to 0.25 mg/L of copper), MPVC (exposed to 0.5 mg/L of MPVC), and Cu-MPVC (exposed to 0.25 mg/L of copper + 0.5 mg/L of MPVC). After 14-day exposure, the fish of Cu and Cu-MPVC treatments exhibited significantly higher intestinal copper contents, compared to the fish of control and MPVC treatments. In this regard, the Cu-MPVC fish had significantly higher copper content than the Cu fish. Exposure to copper and/or MPVC significantly upregulated the intestinal heat shock protein 70 (hsp70), cytochrome P450 family 1 subfamily A member 1 (cyp1a1), lysozyme (lys), defensin (def), mucin 2 (muc2), and mucin 5 (muc5) expression. The highest expression of hsp70, cyp1a1, lys, and def was related to Cu-MPVC treatment; whereas, the highest expression of muc2 and muc5 was observed in Cu and MPVC treatments. Exposure to copper and/or MPVC induced intestinal damage, which Cu-MPVC fish exhibited the highest severity. The present study revealed that exposure to copper and/or MPVC causes intestinal histopathological damage and upregulation in stress- and immune-related genes' expression. The most serious effects were observed in Cu-MPVC treatment that might be due to additive effects of copper and MPVC and/or higher copper accumulation in this treatment.

Co-occurrence of co-contaminants: Cyanotoxins and microplastics, in soil system and their health impacts on plant - A comprehensive review

Cyanotoxins (CTX) and micro/nanoplastics (M/NP) are ubiquitously distributed in every environmental compartment. But the distribution, abundance and associated ecological risks of CTX are still poorly understood in soil system. On the other hand, M/NP could serve as vectors for persistent organic/inorganic pollutants in the natural environment through the sorption of pollutants onto them. Thus, co-occurrence of CTX and M/NP in soils suggests the sorption of CTX onto M/NP. So, major aim of this review is to understand the relevance of CTX and M/NP in soils as co-contaminants, possible interactions between them and ecological risks of CTX in terms of phytotoxicity. In this study, we comprehensively discuss different sources and fate of CTX and the sorption of CTX onto M/NP in soil system, considering the partition coefficient of different phases of soil and mass balance. Phytotoxicity of CTX, CTX mixture and co-contaminants has also been discussed with insights on the mechanism of action. This study indicates the need for the evaluation of sorption between co-contaminants, especially CTX and M/NP, and their phytotoxicity assessment using environmentally relevant concentrations.

Effects of chemical and natural ageing on the release of potentially toxic metal additives in commercial PVC microplastics

Various chemical substances, such as potentially toxic trace metals, are used as plastic additives to improve the performance of polymers and extend the service life of plastic products. However, these added trace metals are likely released from plastic into the environment when the plastic becomes a pollutant, although the process is poorly understood. In this study, chemical ageing of commercial polyvinyl chloride (PVC) microplastics using hydrogen peroxide (H₂O₂) and natural ageing of PVC that had been added to an alkaline paddy soil were undertaken to evaluate the potential release of trace metals from PVC. Enhanced release of trace metals from PVC with the increasing H₂O₂ concentrations was observed, in which the released Pb was 1-2 orders of magnitude higher than other metals (p < 0.01). The released Cr, Ni, Pb, Cu, Zn, Cd and Mn accounted for 87.37%, 79.27%, 22.02%, 20.93%, 17.06%, 15.11%, and 11.02% of their total concentrations (0.28 ± 0.03, 0.08 ± 0.01, 13.67 ± 0.18, 1.07 ± 0.02, 2.20 ± 0.18, 0.05 ± 0.00 and 1.26 ± 0.08 mmol kg^-1) in PVC after ageing with 30% H₂O₂, respectively. Compared with the control treatment without PVC addition, the concentrations of CaCl₂-extractable Cu, Mn, Ni, Pb, and Zn in the soil treated with 5% PVC are significantly increased after incubation for 60 days (p < 0.01). In conclusion, chemical and natural ageing have the potential to lead to the release of Cu, Mn, Ni, Pb, and Zn from the commercial PVC into aquatic and terrestrial environments.

Adsorption of micropollutants onto realistic microplastics: Role of microplastic nature, size, age, and NOM fouling

This work aims at evaluating the role of nature, size, age, and natural organic matter (NOM) fouling of realistic microplastics (MPs) on the adsorption of two persistent micropollutants (diclofenac (DCF) and metronidazole (MNZ)). For such goal, four representative polymer types (polystyrene (PS), polyethylene terephthalate (PET), polypropylene (PP) and high-density polyethylene (HDPE)) were tested. MPs were obtained by cryogenic milling of different commercial materials (disposable bottles, containers, and trays), and fully characterized (optical microscopic and SEM images, FTIR, elemental analysis, water contact angle and pH_slurry). The micropollutants hydrophobicity determined to a high extent their removal yield from water. Regardless of the MP's nature, the adsorption capacity for DCF was considerably higher than the achieved for MNZ, which can be related to its stronger hydrophobic properties and aromatic character. In fact, aromatic MPs (PS and PET) showed the highest adsorption capacity values with DCF (~100 μg g^-1). The MP size also played a key role on its adsorption capacity, which was found to increase with decreasing the particle size (20-1000 μm). MPs aging (simulated by Fenton oxidation) led also to substantial changes on their sorption behavior. Oxidized MPs exhibited acidic surface properties which led to a strong decrease on the adsorption of the hydrophobic micropollutant (DCF) but to an increase with the hydrophilic one (MNZ). NOM fouling (WWTP effluent, river water, humic acid solution) led to a dramatic decrease on the MPs sorption capacity due to sorption sites blocking. Finally, the increase of pH or salinity of the aqueous medium increased the micropollutants desorption.

Is froth flotation a potential scheme for microplastics removal? Analysis on flotation kinetics and surface characteristics

Increasing microplastics (MPs) cause significant threats to the ecosystem and society. The tremendous advances concerning the sources, occurrence, chemical behavior, toxicology, and ecological effects contribute to the emerging MPs removal. Based on the intrinsic hydrophobicity of MPs, froth flotation can remove MPs from water environments via bubble attachment on hydrophobic surfaces. This study comprehensively investigated plastic, aqueous, and operating variables in the flotation removal of polyethylene terephthalate (PET) and polystyrene (PS) MPs, assisted by numerous bench-scale experiments and a first-order model with rectangular distribution of floatability. Froth flotation performed better to remove MPs with higher density, larger size, and lower concentration. K⁺ (0-50 mM), Na⁺ (0-150 mM), and Ca²⁺ (0-10 mM) did not affect the flotation recovery of MPs. MPs particles could be thoroughly removed by froth flotation when humic acid (HA) and Al³⁺ concentrations were less than 30 mg/L and 0.05 mM, respectively. 100% of MPs could be removed at a rapid flotation rate under aeration volume of 5.4 mL/min and frother dosage of 28 mg/L. Non-covalent interactions and near-surface water film might favor the adhesion of hydrophilic species and obstruct the flotation removal of MPs. The froth flotation-based MPs removal had potential application in multiple flow systems due to its simplicity and continuity.

Adsorption of progesterone onto microplastics and its desorption in simulated gastric and intestinal fluids

The sorption of hydrophobic organic compounds (HOC) onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, especially in biological fluids. The present study investigated the sorption and desorption of progesterone on polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics. The sorption experiments showed that the equilibrium was reached in a few hours for all plastics. A sorption efficiency of 357.1 μg g^-1 was found for PE and PS, and 322.6 μg g^-1 for PP. Sorption experiments indicated that adsorption would certainly happen via surface sorption and a potentially pore-filling mechanism. The desorption was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), whose formulations were more complex than similar models reported so far. It has been found that the desorption was higher in SIF as compared to SGF, due to micelle formation in SIF promoting the pollutant solubilization. The sorption of pepsin onto microplastics has also been revealed, suggesting a competition between pollutants and pepsin for sorption sites and a potent reduction in pollutant solubilization. This study indicates that the ingestion of microplastics could be considered as an additional route of exposure to pollutants and therefore emphasizes pollutant bioavailability for aquatic organisms.