Combined XPS and contact angle studies of flat and rough ethylene-vinyl acetate copolymer films

Microplastics in marine invertebrates from the Red Sea Coast of Egypt: Abundance, composition, and risks

This study marked the first exploration of microplastics in marine invertebrates in the Red Sea Coast of Egypt. 110 individuals from 11 different species, including Bivalvia, Gastropoda, Echinoidea, and Holothuroidrea, were collected near a popular tourist destination. The average concentrations of microplastics varied among species, ranging from 8.2 to 136.5 items per individual or 0.2 to 18.1 items per gram of tissue wet weight, with 100 % occurrence. Bivalves had higher concentrations per gram of tissue compared to sediment dwellers and grazers, with Brachidontes pharaonis showing the highest levels. Actinopyga crassa, a sea cucumber, displayed the highest abundance per individual due to its large size and behavior. The identified plastic polymers suggested sources associated with tourism and maritime activities. The estimated human exposure to microplastics through bivalve consumption was minimal. Further research is needed to examine microplastics contamination in the Red Sea and its potential impacts on ecosystems and human well-being.

Organic or junk food? Microplastic contamination in Antarctic krill and salps

Microplastics (MP) have been reported in Southern Ocean (SO), where they are likely to encounter Antarctic zooplankton and enter pelagic food webs. Here we assess the presence of MP within Antarctic krill (Euphausia superba) and salps (Salpa thompsoni) and quantify their abundance and type by micro-Fourier transform infrared microscopy. MP were found in both species, with fibres being more abundant than fragments (krill: 56.25% and salps: 22.32% of the total MP). Polymer identification indicated MP originated from both local and distant sources. Our findings prove how in situ MP ingestion from these organisms is a real and ongoing process in the SO. MP amount was higher in krill (2.13 ± 0.26 MP ind^-1) than salps (1.38 ± 0.42 MP ind^-1), while MP size extracted from krill (130 ± 30 µm) was significantly lower than MP size from salps (330 ± 50 µm). We suggest that differences between abundance and size of MP ingested by these two species may be related to their food strategies, their ability to fragment MP as well as different human pressures within the collection areas of the study region. First comparative field-based evidence of MP in both krill and salps, two emblematic zooplankton species of the SO marine ecosystems, underlines that Antarctic marine ecosystems may be particularly sensitive to plastic pollution.

Prevalence and risk assessment of microplastics in the Nile Delta estuaries: "The Plastic Nile" revisited

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed "Plastic Nile", yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m³, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 μm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80-106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.

PVC/EVA-based polymer inclusion membranes with improved stability and Cr(VI) extraction capacity: Water plasticization effect

Polymer inclusion membranes (PIMs) are far investigated for their ability to extract heavy metals and small organic compounds from aqueous media. Polyvinyl chloride (PVC) is one of the most widely used base polymers for the PIM elaboration. However, its use requires the incorporation of a relatively expensive liquid plasticizer. In the present work, poly(ethylene-co-vinyl acetate) (EVA) serves as a polymer plasticizer for the elaboration of PIMs based on PVC as a base polymer and Aliquat 336 as a carrier. The composition of PIMs was optimized in terms of the PVC/EVA ratio and the vinyl acetate (VA) groups content (x) of EVA (i.e. EVA_x). Physical-chemical properties of the resulting membranes are analyzed and correlated with their structure. The results of SEM analysis revealed miscible PVC/EVA₇₀ blends (i.e. with 70 wt% of VA groups) and partially miscible PVC/EVA₄₀ blends. The plasticizing effect of the EVA copolymer was confirmed by the tensile test results. The results of transport measurements showed that PIMs containing EVA₄₀ and PVC are more efficient for the Cr(VI) extraction than those with only PVC. Thus, EVA₄₀ can effectively replace the conventional liquid plasticizers while improving the Cr(VI) permeability. Besides, it is stated that EVA₄₀-based PIMs are more stable as compared with conventional PIMs due to the water plasticizing effect. After the membrane optimization, the highest Cr(VI) transport flux (54.7 µmol·m^-2·s^-1) was measured. Moreover, the addition of 10 wt% of tetradecanol causes the increase of the water plasticizing effect and allows obtaining a PIM with high stability (up to 24 cycles) required for the membrane long-term operation.

Characterization and distribution of plastic particles along Alexandria beaches, Mediterranean Coast of Egypt, using microscopy and thermal analysis techniques

Microplastics (MPs) contamination has become a global concern with potential impacts on the marine environment. Alexandria is the second-largest city in Egypt and a significant contributor of plastic litter inputs into the Eastern Mediterranean Sea. The current study provides an in-depth analysis of the plastic particles accumulated along Alexandria beaches. Types, composition, and potential sources of MPs were investigated using microscopy and thermal analysis. A mean value of 389.1 ± 285.9 items kg^-1 dry weight was detected in the shore sediments similar to other records from the Eastern Mediterranean region. An average of 457.4 ± 281.8 items m^-3 was recorded in the surface water, which was the highest recorded MPs density in onshore waters of the Mediterranean region. Thermogravimetric analysis (TGA) showed that plastics made up 0.5% - 72% of the materials extracted from the sediment samples, and 0.58% - 20.6% from the water samples. Differential scanning calorimetry (DSC) identified ten semi-crystalline polymers. Low-density polyethylene (LDPE) and polyethylene vinyl acetate (PEVA) were the common polymers. The single-use plastic bags and detergents were the land-based sources of marine plastic litter. The sea-based sources included antifouling paints, maintenance of ships, and abandoned fishing gears. Proper management plans of domestic waste input, polluter-pay strategy, and education programs aiming at the Fishermen and how plastic pollution would impact their livelihood are urgently needed.

Towards Understanding the Chemical Structure Modification of EVA Copolymer upon MAPLE Processing of Thin Films

A series of coatings from poly(ethylene-co-vinyl acetate) (EVA) were obtained using the matrix-assisted pulsed laser evaporation (MAPLE) technique. By changing the process parameters, i.e., laser fluence and EVA co-polymer concentration in the target, coatings with various morphologies and topographies were produced. The evaluation of the film structure was based on an analysis of optical and atomic force microscopy and profilometry measurements. A detailed chemical structure investigation, conducted based on Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra, revealed that although the general structure was preserved, some alterations of ethylene (Et) and vinyl acetate (VAc) blocks took place. The most noticeable change was in the ester group that was transformed into ketone and carboxyl groups; nevertheless, some changes in the aliphatic main chain were also present. The chemical structure changes in EVA coatings took place regardless of the process parameters used. The use of chloroform as a solvent to dissolve the EVA copolymer was indicated as a possible reason of the changes as well as the tendency of EVA macromolecules to form clusters. Nevertheless, due to low level of structure alteration, it has been shown that the MAPLE technique can be successfully used to obtain coatings from polymers with more complex structures, which are soluble in a limited number of solvents.

Experimental Study of the Influence of the Adsorbate Layer Composition on the Wetting of Different Substrates with Water

Wetting is strongly influenced by adsorbate layers, which are omnipresent on surfaces. The influence of the composition and thickness of adsorbate layers on the water contact angle of sessile drops on different substrates was systematically investigated in the present work. Measurements were carried out for gold-sputtered substrates. These new results are compared to results from a previous study, in which corresponding measurements were carried out for technical steel and titanium substrates. In all experiments, different pretreatments of the samples were used to obtain variations of the adsorbate layer. The samples were either exposed to an oil bath or not, and different cleaning agents were used. The analysis of the adsorbate layer was carried out with X-ray photoelectron spectroscopy (XPS). The results for the different substrates reveal that the water contact angle depends mainly on the composition of the adsorbate layer. The substrate has only an indirect influence, as it influences the composition of the adsorbate layer. The thickness of the adsorbate layers was between 1.4 and 14 nm and was large enough to prevent a direct influence of the substrate on the water contact angle. It is shown that using the information on the adsorbate layer composition from XPS and the results for the water contact angle obtained for the gold samples alone, the water contact angles on the steel and titanium samples can be predicted.

Hyperbranch-Crosslinked S-SEBS Block Copolymer Membranes for Desalination by Pervaporation

Sulfonated aromatic polymer (SAP) featuring hydrophilic nanochannels for water transport is a promising membrane material for desalination. SAPs with a high sulfonation degree favor water transport but suffer from reduced mechanical strength and membrane swelling. In this work, a hyperbranched polyester, H302, was introduced to crosslink a sulfonated styrene-ethylene/butylene-styrene (S-SEBS) copolymer membrane. The effects of crosslinking temperature and amount of H302 on the microstructure, and the pervaporation desalination performance of the membrane, were investigated. H302/S-SEBS copolymer membranes with different crosslinking conditions were characterized by various techniques including FTIR, DSC, EA, SEM, TEM and SAXS, and tensile strength, water sorption and contact angle measurements. The results indicate that the introduction of hyperbranched polyester enlarged the hydrophilic microdomain of the S-SEBS membrane. Crosslinking with hyperbranched polyester with heat treatment effectively enhanced the mechanical strength of the S-SEBS membrane, with the tensile strength being increased by 140–200% and the swelling ratio reduced by 45–70%, while reasonable water flux was maintained. When treating 5 wt% hypersaline water at 65 °C, the optimized crosslinked membrane containing 15 wt% H302 and heated at 100 °C reached a water flux of 9.3 kg·m⁻²·h⁻¹ and a salt rejection of 99.9%. The results indicate that the hyperbranched-S-SEBS membrane is promising for use in PV desalination.

Thermal analysis and enhanced visual technique for assessment of microplastics in fish from an Urban Harbor, Mediterranean Coast of Egypt

Enhanced visual counting technique coupled with combustion analysis and differential scanning calorimetry (DSC) was applied to assess microplastics (MPs) contamination in fish digestive tracts from Eastern Harbor, Egypt, to provide a simple and economic method for MPs assessment. This was the first study in Egypt to quantify MPs in fish. Plastic particles were detected in all fish samples, represented by seven thermoplastic polymers. The average number of MPs was at its highest level in Siganus rivulatus, Diplodus sargus, and Sardinella aurita (7527, 3593, and 1450MPs fish^-1, resp.) and the lowest in Sphyraena viridensis and Atherina boyeri (46 and 28MPs fish^-1, respectively). The average weight of MPs as measured by combustion ranged from 302mg kg^-1 in S. rivulatus to 2mg kg^-1 in Terapon puta.

Microplastic contamination in east Antarctic sea ice

The durability of plastics in the marine environment has led to concerns regarding the pervasiveness of this debris in remote polar habitats. Microplastic (MP) enrichment in East Antarctic sea ice was measured in one ice core sampled from coastal land-fast sea ice. The core was processed and filtered material was analyzed using micro Fourier-Transform Infrared (μFTIR) spectroscopy. 96 MP particles were identified, averaging 11.71 particles L^-1. The most common MP polymers (polyethylene, polypropylene, and polyamide) were consistent with those most frequently represented in the majority of marine MP studies. Sea-ice MP concentrations were positively related with chlorophyll a, suggesting living biomass could assist in incorporating MPs in sea ice. Our preliminary results indicate that sea ice has the potential to serve as a reservoir for MP debris in the Southern Ocean, which may have consequences for Southern Ocean food webs and biogeochemistry.

Arctic sea ice is an important temporal sink and means of transport for microplastic

Microplastics (MP) are recognized as a growing environmental hazard and have been identified as far as the remote Polar Regions, with particularly high concentrations of microplastics in sea ice. Little is known regarding the horizontal variability of MP within sea ice and how the underlying water body affects MP composition during sea ice growth. Here we show that sea ice MP has no uniform polymer composition and that, depending on the growth region and drift paths of the sea ice, unique MP patterns can be observed in different sea ice horizons. Thus even in remote regions such as the Arctic Ocean, certain MP indicate the presence of localized sources. Increasing exploitation of Arctic resources will likely lead to a higher MP load in the Arctic sea ice and will enhance the release of MP in the areas of strong seasonal sea ice melt and the outflow gateways.

Microplastic (MP) pollution in polar regions is a growing environmental concern, yet little is known regarding the role of sea-ice as a sink and transport vector of MPs. Here, the authors show that MPs in sea-ice have no uniform polymer composition and observe unique MP patterns in different sea-ice horizons.

Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques

A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC.

Selective adsorption of L1210 leukemia cells/human leukocytes on micropatterned surfaces prepared from polystyrene/polypropylene-polyethylene blends

The objective of this study is to prepare polymeric surfaces which will adsorb L1210 leukemia cells selectively more than that of healthy human leukocytes in order to develop new treatment options for people with leukemia. Chemically heterogeneous and micropatterned surfaces were formed on round glass slides by dip coating with accompanying phase-separation process where only commercial polymers were used. Surface properties were determined by using optical microscopy, 3D profilometry, SEM and measuring contact angles. Polymer, solvent/nonsolvent types, blend composition and temperature were found to be effective in controlling the dimensions of surface microislands. MTT tests were applied for cell viability performance of these surfaces. Polystyrene/polyethylene-polypropylene blend surfaces were found to show considerable positive selectivity to L1210 leukemia cells where L1210/healthy leukocytes adsorption ratio approached to 9-fold in vitro. Effects of wettability, surface free energy, microisland size geometry on the adsorption performances of L1210/leukocytes pairs are discussed.

Amphiphobic surfaces from functionalized TiO2 nanotube arrays

Perfluorinated monolayer-coated TiO₂ nanotube surfaces are repellent to a broad spectrum of liquids, and are not only of immediate interest in anti-fouling applications but also present a platform to explore wetting and imbibition phenomena in nanostructures.