Adsorption-desorption dynamics of synthetic and naturally weathered microfibers with toxic heavy metals and their ecological risk in an estuarine ecosystem

Influence of cephalexin on cadmium adsorption onto microplastic particles in water: Human health risk evaluation

This paper explores the impact of environmental factors on the adsorption of cadmium (Cd) and cephalexin (CEX) onto polyethylene (PE) microplastics. The study focused on Cd adsorption behavior on microplastics (MPs) of various sizes, revealing that particles sized 30-63 μm exhibited the highest adsorption capacity compared to other sizes. Cd sorption was significantly influenced by initial pH and salinity levels. Experimental data closely matched both the Langmuir (R2 > 0.91) and Freundlich (R2 > 0.92) isotherms. Cd adsorption onto PE particles was greater than CEX adsorption, with the maximum Cd uptake capacity measured at 1.8 mg/g. FTIR analysis indicated that Cd and CEX adsorption onto MPs was likely governed by physical interactions, as no new functional groups were detected post-uptake. The desorption rates of Cd and CEX from PE microplastics were evaluated in various liquids, including aqueous solution, tap water, seawater, and synthetic gastric juice. The health risks associated with Cd, in combination with MPs and CEX, for both children and adults were assessed in groundwater and aqueous solutions. This study offers scientific insights and guidelines for examining the environmental behavior, migration, and transformation of microplastics and their related ecological risks in scenarios of combined pollution.

Photodegradation Processes and Weathering Products of Microfibers in Aquatic Environments

Microplastics, particularly microfibers (MFs), pose a significant threat to the environment. Despite their widespread presence, the photochemical reactivity, weathering products, and environmental fate of MFs remain poorly understood. To address this knowledge gap, photodegradation experiments were conducted on three prevalent MFs: polyester (POL), nylon (NYL), and acrylic (ACR), to elucidate their degradation pathways, changes in surface morphology and polymer structure, and chemical and colloidal characterization of weathering products during photochemical degradation of MFs. The results showed that concentrations of dissolved organic carbon, chromophoric dissolved organic matter (DOM), and fluorescent components consistently increased during weathering, exhibiting a continuous release of DOM. Scanning electron microscopy and Raman spectroscopy revealed changes in the surface morphology and polymer spectra of the MFs. During the weathering experiments, DOM aromaticity (SUVA254) decreased, while spectral slope increased, indicating concurrent DOM release and degradation of aromatic components. The released DOM or nanoplastics were negatively charged with sizes between 128 and 374 nm. The production rate constants of DOM or the photochemical reactivity of MFs followed the order ACR > NYL ≥ POL, consistent with their differences in chemical structures. These findings provide an improved understanding of the photochemical reactivity, degradation pathways, weathering products, and environmental fate of microfibers in the environment.

Carrier effects of face mask-derived microplastics on metal ions: Enhanced adsorption by photoaging combined with biofilms, exemplified with Pb(Ⅱ)

Face masks have emerged as a significant source of microplastics (MPs) under the influence of biotic and abiotic interactions. However, the combined effects of abiotic photoaging and biofilm-loading on mask-derived MPs as carriers of metal ions are not clear. We investigated the Pb(Ⅱ) adsorption onto polypropylene (PP) and polyurethane (PU) mask-derived MPs treated by photoaging, biofilm-loading, and both combinations, evaluating the composite risks. PU mask-derived MPs (1.157.47 mg/g) exhibited greater Pb(Ⅱ) adsorption capacity than PP mask-derived MPs (0.842.08 mg/g) because of the presence of intrinsic carbonyl functional groups. Photoaging (30.5%, 88.4%), biofilm-loading (110.7%, 87.1%), and both combinations (146.7%, 547.0%) of PP and PU masks enhanced Pb(Ⅱ) adsorption compared to virgin mask-derived MPs due to the increase of oxygen-containing functional groups. High-throughput sequencing indicated that the structural morphology and chemical composition of masks significantly affected the microbial community. Adsorption mechanisms involved electrostatic force and surface complexation. A combination of photoaging and biofilms increased the ecological risk index of mask-derived MPs in freshwater, showing the risk level to be high (PP mask) and very high (PU mask). This research highlights the crucial role of photoaging combined with biofilms in controlling metal ion adsorption onto mask-derived MPs, thereby increasing the composite risks.

Microplastics and Co-pollutants in soil and marine environments: Sorption and desorption dynamics in unveiling invisible danger and key to ecotoxicological risk assessment

Microplastics (MPs) and their co-pollutants pose significant threats to soil and marine environments, necessitating understanding of their colonization processes to combat the plastic pandemic and protect ecosystems. MPs can act as invisible carriers, concentrating and transporting pollutants, leading to a more widespread and potentially toxic impact than the presence of either MPs or the pollutants alone. Analyzing the sorption and desorption dynamics of MPs is crucial for understanding pollutants amplification and predicting the fate and transport of pollutants in soil and marine environments. This review provides an in-depth analysis of the sorption and desorption dynamics of MPs, highlighting the importance of considering these dynamics in ecotoxicological risk assessment of MPs pollution. The review identifies limitations of current frameworks that neglect these interactions and proposes incorporating sorption and desorption data into robust frameworks to improve the ability to predict ecological risks posed by MPs and co-pollutants in soil and marine environments. However, failure to address the interplay between sorption and desorption can result in underestimation of the true impact of MPs and co-pollutants, affecting livelihoods and agro-employments, and exacerbate poverty and community disputes (SDGs 1, 2, 3, 8, 9, and 16). It can also affect food production and security (SDG 2), life below water and life on land (DSGs 14 and 15), cultural practices, and natural heritage (SDG 11.4). Hence, it is necessary to develop new approaches to ecotoxicological risk assessment that consider sorption and desorption processes in the interactions between the components in the framework to address the identified limitations.

Microfiber Pollution: A Systematic Literature Review to Overcome the Complexities in Knit Design to Create Solutions for Knit Fabrics

The absence of standardized procedures to assess microfiber pollution released during laundering, alongside textile complexities, has caused incomparability and inconsistency between published methodologies, data formats, and presentation of findings. Yet, this information needs to be clear and succinct to engage producers and consumers in reducing microfiber pollution through solutions, such as eco-design. This review analyses source directed interventions through design and manufacturing parameters that can prevent or reduce microfiber shedding from knit fabrics during washing. Contradicting results are critically evaluated and future research agendas, alongside potential areas for voluntary and involuntary sustainable incentives are summarized. To do this, a systematic review was carried out, using the PRISMA approach to verify which fabrics had been investigated in terms of microfiber shedding. Using selected keywords, a total number of 32 articles were included in this review after applying carefully developed inclusion and exclusion criteria. The influence of fabric parameters such as fiber polymer, length of fibers and yarn twist alongside fabric construction parameters such as gauge of knit and knit structure are critically evaluated within the systematically selected studies. This review highlights the agreed upon fabric parameters and constructions that can be implemented to reduce microfiber pollution released from knit textiles. The complexities and inconsistencies within the findings are streamlined to highlight the necessary future research agendas. This information is critical to facilitate the adoption of cross-industry collaboration to achieve pollution reduction strategies and policies. We call for more systematic studies to assess the relationship between individual textile parameters and their influence on microfiber shedding. Additionally, studies should work toward standardization to increase comparability between studies and created more comprehensive guidelines for policy development and voluntary actions for the textile and apparel industry to participate in addressing more sustainable practises through eco-design.

Removal of microfiber and surfactants from household laundry washing effluents by powdered activated carbon: kinetics and isotherm studies

Domestic laundry wastewater discharge contributes significantly to the presence of microfiber and surfactant pollutants in aquatic ecosystems, which have detrimental and toxic effects on humans and the environment. Investigating the efficacy of powdered activated carbon (PAC) in removing micro-/nanofibers with or without surfactant from household laundry effluent is the purpose of the current research. To simulate real-world scenarios, PAC adsorption kinetics and isotherms in laundry effluents under controlled conditions were studied. These studies showed that the kinetics obeyed a pseudo-second-order process and the isotherms varied between Langmuir and Freundlich models depending on the water types. In the results of experiments using distilled water and tap water, it was observed that the adsorption capacity was higher in tap water. When the adsorption of 0.1 μm filtered synthetic garments, detergent, and tap water was compared with the adsorption of the raw sample, it was observed that the adsorption capacity of the 0.1 μm filtered version was higher. Even though this study is preliminary, the results indicate that PAC has the capacity to serve as a viable approach for mitigating micro-/nanoplastic and surfactant contamination from laundry wastewater, thereby offering valuable guidance for advancing eco-friendly laundry techniques.

Photo-aged non-biodegradable and biodegradable mulching film microplastics alter the interfacial behaviors between agricultural soil and inorganic arsenic

The impacts of microplastics (MPs) prevalent in soil on the transport of pollutants were urged to be addressed, which has important implications for ecological risk assessment. Therefore, we investigated the influence of virgin/photo-aged biodegradable polylactic acid (PLA) and non-biodegradable black polyethylene (BPE) mulching films MPs on arsenic (As) transport behaviors in agricultural soil. Results showed that both virgin PLA (VPLA) and aged PLA (APLA) enhanced the adsorption of As(Ⅲ) (9.5%, 13.3%) and As(Ⅴ) (22.0%, 6.8%) due to the formation of abundant H-bonds. Conversely, virgin BPE (VBPE) reduced the adsorption of As(Ⅲ) (11.0%) and As(Ⅴ) (7.4%) in soil owing to the "dilution effect", while aged BPE (ABPE) improved arsenic adsorption amount to the level of pure soil due to newly generated O-containing functional groups being feasible to form H-bonds with arsenic. Site energy distribution analysis indicated that the dominant adsorption mechanism of arsenic, chemisorption, was not impacted by MPs. The occurrence of biodegradable VPLA/APLA MPs rather than non-biodegradable VBPE/ABPE MPs resulted in an increased risk of soil accumulating As(Ⅲ) (moderate) and As(Ⅴ) (considerable). This work uncovers the role of biodegradable/non-biodegradable mulching film MPs in arsenic migration and potential risks in the soil ecosystem, depending on the types and aging of MPs.

Robust microfluidic construction of polyvinyl pyrrolidone microfibers incorporated with W/O emulsions stabilized by amphiphilic konjac glucomannan

In this work, we prepared polyvinyl pyrrolidone (PVP) microfibers incorporated water-in-oil (W/O) emulsions. The W/O emulsions were fabricated by hexadecyl konjac glucomannan (HKGM, emulsifier), corn oil (oil phase) and purple corn anthocyanins (PCAs, water phase). The structures and functions of emulsions and microfibers were characterized by confocal laser scanning (CLSM) and scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Raman and nuclear magnetic resonance (NMR) spectroscopy. The results showed that W/O emulsions exhibited good storage stability for 30 d. Microfibers presented ordered and uniform arrays. Compared with pure PVP microfiber films, the addition of W/O emulsions with PCAs improved the water resistance (WVP from 1.28 to 0.76 g mm/m² day kPa), mechanical strength (Elongation at break from 18.35 % to 49.83 %), antioxidation (free radical scavenging rate from 2.58 % to 16.37 %), and antibacterial activity (inhibition zone against E. coli: 27.33 mm and inhibition zone against S. aureus: 28.33 mm) of microfiber films. Results showed that microfiber film exhibited controlled release of PCAs in W/O emulsions, and about 32 % of the PCAs were released from the microfiber film after 340 min. The as-prepared microfiber films exhibited potential applications for food packaging.

Production of Activated Carbons from Food/Storage Waste

This paper deals with the adsorption of organic and inorganic pollutants on the surface of carbonaceous adsorbents prepared via the chemical activation of expired or broken food products-the solid residue of the "cola-type" drink as well as spoilt grains of white rice and buckwheat groats. The activation process was conducted in the microwave furnace with the use of two activating agents of different chemical nature-potassium carbonate and orthophosphoric acid. The activated carbons were characterized based on the results of elemental analysis, low-temperature nitrogen adsorption/desorption, Boehm titration, thermal analysis, and scanning electron microscopy. Additionally, the suitability of the materials prepared as the adsorbents of methylene blue and iodine from the aqueous solutions was estimated. The materials obtained via chemical activation with H₃PO₄ turned out to be much more effective in terms of both model pollutant adsorptions. The maximum sorption capacity toward iodine (1180 mg/g) was found for the white-rice-based activated carbon, whereas the most effective in the methylene blue removal (221.3 mg/g) was the sample obtained from the solid residue of the expired "cola-type" drink. For all carbonaceous materials, a better fit for the experimental adsorption data was obtained with the Langmuir isotherm model than the Freundlich one.

Microplastic Textile Fibers Accumulate in Sand and Are Potential Sources of Micro(nano)plastic Pollution

Agricultural soils have been identified as sinks for microplastic fibers; however, little information is available on their long-term fate in these soils. In this study, polyester and nylon fibers were precisely cut to relevant environmental lengths, using novel methodology, and their behavior in sand columns was studied at environmental concentration. The longer fibers (>50 μm) accumulated in the upper layers of the sand, smaller fibers were slightly more mobile, and nylon showed marginally higher mobility than polyester. Previous studies have overlooked changes in microplastic morphology due to transport in soil. Our study is the first to show that fibers exhibited breakage, peeling, and thinning under flow conditions in soil, releasing smaller, more mobile fragments. Furthermore, the peelings exhibited different adsorption properties compared to the core fiber. This suggests that microplastic fibers can become a source of smaller micro(nano)plastics and potential vectors for certain molecules, risking continuous contamination of nearby soils, surfaces, and groundwater.