Compacted clays are extensively used as cover barriers to control rainfall infiltration and upward migration of greenhouse gases at municipal solid waste landfills and volatile organic compounds at industrially contaminated sites. Xanthan gum (XG) amendment offers a green and low-carbon solution to improve gas breakthrough pressure and reduce gas permeability of compacted clays, sustainably improve earthen structures. This study aimed to systematically investigate the effects of XG amendment on gas breakthrough pressure, gas permeability, and hydraulic conductivity of compacted clay liners. The gas breakthrough pressure increased from 0.6 kPa to 2.2 kPa (improve similar to 4 times) and the gas permeability decreased from 2.2 x 10(-14) m(2) to 4.8 x 10(-16) m(2) (reduce similar to 200 times) when the XG dosage increased from 0 % to 2 % and apparent degree of saturation was 100 %. Hydraulic conductivity of XG-amended soil at 1 % XG dosage was 2.6 x 10(-10) m/s, which was 3 % of the value measured in unamended soil. Mechanisms of enhanced gas barrier and hydraulic performance were interpreted by the combined effects of (i) soil pore filling substantiated by the analyses of scanning electron microscopy and pore size distribution; (ii) high viscosity of XG hydrogels, validated by the measurement of rheological properties; and (iii) increased diffuse double layer thickness of the amended soils evidenced by the zeta potential analysis.

In food packaging industry, plastic was the most commonly used material for packaging, which caused serious pollution to the marine and soil environment. The researches on biodegradable films development from biodegradable polymers was arise, which was expected to ensure the quality and safety of food as much as possible. Biodegradable materials for films included polysaccharides and proteins of different biological sources, and synthetic materials. This review discussed the molecular characteristics and film-forming properties of natural polymer materials of polysaccharides from halobios, plant and microorganism, protein from animal, plant, milk. In addition, the effects of polymerization degree, crystallinity, and film-forming process of synthetic materials (polycaprolactone, polyvinyl alcohol, polylactic acid) on film performance was studied. In order to improve the practicality of biodegradable films in food packaging, many methods were explored to enhance the physical performance of the films. The enhancement strategies including: introduction of nanoparticles, chemical modification, and blending with other polymers, which can effectively enhance the mechanical properties and water vapor barrier performance of biodegradable films. Furthermore, it will provide a reference for future research interest that to development biodegradable food packaging films with high mechanical and barrier properties.

Alkali-activated materials have gained increasing popularity in the field of soil barrier materials due to their high strength and low environmental impact. However, barrier materials made from alkali-activated materials still suffer from long setting times and poor barrier performance in acidic, alkaline, and saline environments, which hinders the sustainable development of green alkali-activated materials. Herein, coconut shell biochar, sodium silicate-based adhesives, and polyether polyol/polypropylene polymers were used for multi-stage material modification. The modified materials were evaluated for barrier performance, rapid formation, and resistance to acidic, alkaline, and saline environments, using metrics such as compressive strength, permeability, mass loss, and VOC diffusion efficiency. The results indicated that adhesive modification reduced the material's setting time from 72 to 12 h. Polymer modification improved resistance to corrosion by 15-20%. The biochar-containing multi-stage modified materials achieved VOC diffusion barrier efficiency of over 99% in both normal and corrosive conditions. These improvements are attributed to the adhesive accelerating calcium silicate hydration and forming strength-enhancing compounds, the polymer providing corrosion resistance, and biochar enhancing the volatile organic compounds (VOC) barrier properties. The combined modification yielded a highly effective multi-stage green barrier material suitable for rapid barrier formation and corrosion protection. These findings contribute to evaluating multi-level modified barrier materials' effectiveness and potential benefits in this field and provide new insights for the development of modified, green, and efficient alkali-activated barrier materials, promoting the green and sustainable development of soil pollution control technologies.

To enhance the barrier performance of biomass films, carboxymethyl cellulose (CMC) was combined with montmorillonite (MMT) modified by stearyltrimethylammonium bromide (STAB) and loaded with Fe3O4 particles as a nano-filler, and a CMC/m-OMMT mulch film was fabricated using magnetic field orientation. The characterization of m-OMMT was conducted through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM), which confirmed the successful intercalation of STAB into the MMT structure, along with the effective loading of Fe3O4 particles onto the MMT matrix. A comprehensive investigation into the mechanical properties of CMC/m-OMMT films revealed that, in the dry state, the films exhibited a tensile strength of 29 MPa and an elongation at break of 64 %. A series of barrier performance tests were conducted on the films. The findings demonstrated that the incorporation of MMT and the application of a magnetic field substantially enhanced the water contact angle, increasing it from 86 degrees to 112 degrees. Additionally, water vapor permeability increased by approximately 30 %, soil erosion was reduced by about 22 %, and UV resistance was notably improved by 94 %. Moreover, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and biodegradation tests on the CMC/m-OMMT/40mT films revealed that the magnetic field effectively oriented the MMT nanosheets within the composite matrix. This study presents a novel approach for enhancing the barrier properties of biomass-based mulch films.

The long-term disposal of high-level radioactive waste (HLW) in deep geological repositories requires the reliable performance of engineered barrier systems (EBS). Compacted bentonite, widely used for its high swelling capacity, low permeability, and self-sealing properties, plays a critical role in these barriers. However, understanding the complex coupled thermo-hydro-mechanical (THM) behavior governing water infiltration dynamics remains a significant challenge, especially when gap spaces (or technological voids) are present. This study investigates water infiltration dynamics in bentonite-based EBS using a novel laboratory-scale experimental setup. Time-lapse photography was employed to monitor the evolution of hydration and swelling under thermal gradients and varying gap sizes, simulating repository conditions. The experimental program was designed to compare the effects of two gap sizes on infiltration rates, swelling behavior, and desiccation cracking. Results demonstrated that larger void spaces accommodated greater swelling, leading to lower dry density and higher permeability, while smaller gaps restricted desiccation cracking due to mechanical constraints. The correlation between pixel intensity and water content allowed the derivation of a linear calibration model, enabling real-time, non-destructive estimation of moisture distribution in bentonite. Findings in this study highlight the interplay between gap size, water infiltration, and thermal effects, emphasizing the need for optimized EBS designs to balance mechanical integrity and hydraulic performance. It is anticipated that the insights provided by this study contribute to the refinement of predictive models and advancing the safe and effective containment of HLW over geological timescales.

The European earwig F. auricularia L. is an omnivore that has only recently been identified as a direct, fruit-feeding pest of citrus. Here, we start to build the basic tools needed for integrated pest management for this species. We introduce a time-efficient sampling method based on small wooden boards placed on the ground, and we use them in a 2-yr survey of 93 commercial citrus blocks in California's San Joaquin Valley. Insecticides were not applied targeting F. auricularia in any of these citrus blocks. We find that F. auricularia populations are very low or undetectable in most blocks, with higher densities occurring only sporadically. To know when control measures should be implemented, we used video-monitoring of citrus tree trunks to characterize the timing of F. auricularia movement from their soil nests into the tree canopy. Movement of earwigs along the tree trunks was observed throughout our sampling period (22 March to 18 June), suggesting that control measures (sticky bands placed on trunks, or insecticides applied to trunks and surrounding soil surface) should be applied early, well before petal fall when fruit are susceptible to F. auricularia herbivory. Sticky barriers effectively reduced the vertical movement of 2 crawling arthropods, F. auricularia and the Fuller rose beetle Napactus godmanni, along citrus trunks. We failed to find any relationship between estimated F. auricularia densities and damage to maturing or harvested fruit. This highlights a set of important and still unresolved questions about the biology of this species, underscoring the need for additional research.

Currently, traditional vertical barrier materials are associated with large carbon footprints and high costs (in some regions) due to the widespread use of Portland cement and sodium-based bentonite materials. In recent years, a new technology of Carbonized Reactive Magnesia Cement (CRMC) has gradually been developed to sequester CO2 using Eco-cement. The application prospects of CRMC in vertical barrier materials are explored in this study. The changes in flowability of Reactive Magnesia Cement (RMC) slurry and the unconfined compressive strengthen (UCS) and permeability characteristics of CRMC treated soils are investigated. The results show that the fluidity of RMC slurry decreases further with the increase of MgO substitute cement content. For RMC slurry meeting the fluidity requirements, UCS increased rapidly in the early period (3 h) after carbonization, reaching 348.33 kPa, and the hydraulic conductivity k decreased (k < 1 x10(- 7) cm/s) in the later period (14d), and the final hydraulic conductivity reached 6.13 x 10(- 8) cm/s (28d). The pores of the material are filled with a large number of hydration products and carbonates, which alters the pore size distribution structure of the material. This is the reason for the mechanical properties and permeability performance of CRMC treated soils. The overall results of this study well demonstrate that CRMC treated soils, as a new, environmentally friendly, and cost-effective material, have great potential in the construction of vertical barriers.

PurposeThe present work aims to prepare biocomposites blend based on linear low density polyethylene/ starch without using harmful chemicals to improve the adhesion between two phases. Also, the efficiency of essential oils as green plasticizers and natural antimicrobial agents were evaluated.Design/methodology/approachBarrier properties and biodegradation behavior of linear low density polyethylene/starch (LLDPE/starch) blends plasticized with different essential oils including moringa oleifera and castor oils wereassessed as a comparison with traditional plasticizer such as glycerol. Biodegradation behavior forLLDPE/starch blends was monitored by soil burial test. The composted samples were recovered then washed followed by drying, and weighting samples after 30, 60, and 90 days to assess the change in weight loss. Also, mechanical properties including retention values of tensile strength and elongation at break were measured before and after composting. Furthermore, scanning electron microscope (SEM) was used to evaluate the change in the morphology of the polymeric blends. In addition to, the antimicrobial activity of plasticized LLDPE/starch blends films was evaluated using a standard plate counting technique.FindingsThe results illustrate that the water vapor transition rate increases from 2.5 g m-2 24 h-1 for LLDPE/5starch to 4.21 g m-2 24 h-1 and 4.43 g m-2 24 h-1 for castor and moringa oleifera respectively. Also, the retained tensile strength values of all blends decrease gradually with increasing composting period. Unplasticized LLDPE/5starch showed highest tensile strength retention of 91.6% compared to the other blends that were 89.61, 88.49 and 86.91 for the plasticized LLDPE/5starch with glycerol, castor and M. oleifera oils respectively. As well as, the presence of essential oils in LLDPE/ starch blends increase the inhibition growth of escherichia coli, candida albicans and staphylococcus aureus.Originality/valueThe objective of this work is to develop cost-effective and environmentally-friendly methods for preparing biodegradable polymers suitable for packaging applications.

Although poly (lactic acid) (PLA) is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films, the barrier properties of PLA films are still insufficient for high-barrier packaging applications. In this study, oxygen scavenger hydroxyl-terminated polybutadiene (HTPB) and cobalt salt catalyst were incorporated into the PLA/poly (butylene adipate-co-terephthalate) (PLA/PBAT), followed by melting extrusion and three-layer co-extrusion blown film process to prepare the composite films. The oxygen permeability coefficient of the composite film combined with 6 wt% oxygen scavenger and 0.4 wt% catalyst was decreased significantly from 377.00 cc mil m-2 day-1 0.1 MPa-1 to 0.98 cc mil m-2 day-1 0.1 MPa-1, showing a remarkable enhancement of 384.69 times compared with the PLA/PBAT composite film. Meanwhile, the degradation behavior of the composite film was also accelerated, exhibiting a mass loss of nearly 60% of the original mass after seven days of degradation in an alkaline environment, whereas PLA/PBAT composite film only showed a mass loss of 32%. This work has successfully prepared PLA/PBAT composite films with simultaneously improved oxygen barrier property and degradation behavior, which has great potential for high-demanding green chemistry packaging industries, including food, agricultural, and military packaging. (c) 2024 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

A capillary barrier cover (CBC) is a geotechnical structure which a coarse-grained soil layer covered by a fine-grained soil layer. A CBC can retain downward water infiltration, increase water storage capacity and lateral diversion, and prevent capillary rise. Geotextiles are usually set up as isolation layers between fine-grained and coarse-grained layers to prevent fine particles entering the coarse-grained layer, resulting in a decrease in downward water infiltration and water storage capacity. However, crustal stress, farming, animal, plant activities, and other factors may cause damage to the isolation layer. At present, there is no reliable and accurate method to determine the location and degree of damage to the isolation layer. The existing methods search for the damage location by excavating the whole fine layer, which incurs high maintenance costs. If the damaged position of the CBC isolation layer can be accurately obtained, it can reduce maintenance costs. Therefore, this study investigated the influence of a coarse-grained layer mixed with different particle sizes and proportions of fine particles on water storage capacity through laboratory soil column experiments. The results are as follows: (1) Fine particle mixing into the coarse-grained layer will reduce water storage capacity, and there is a worse admixture ratio that minimizes water storage capacity. (2) The CBC enhances the fine-grained layer volumetric water content (VWC), but the enhancement degree decreases as the distance from the fine-coarse interface increases. (3) A method has been proposed to determine the location and degree of damage to the isolation layer. When the VWC at the fine-coarse interface reaches a stable level during breakthrough, the CBC effect exists, the higher the VWC at the fine-coarse interface, the stronger the CBC; when the VWC at the fine-coarse interface is unstable during breakthrough, the CBC effect disappears, and the median diameter of the fine particles mixed into the coarse-grained layer is finer than or equal to the fine-grained particles' median diameter.