Journal of Polymers and the Environment最新文献

A comparative study of cobalt ferrite (CoFe₂O₄) catalysts synthesized via three different methods is presented, aiming to evaluate their catalytic activities in poly(ethylene terephthalate) (PET) chemical depolymerization by glycolysis. The synthesized catalysts have been characterized by X-ray photoelectron spectroscopy, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and energy dispersive spectroscopy. The conversion of PET into bis(2-hydroxyethyl)terephthalate (BHET) monomer was examined using these cobalt ferrites. The BHET in the reaction mixture was analyzed by FTIR, HPLC, DSC, and TGA and results show the catalyst synthesized by coprecipitation demonstrates the highest BHET yield (95.4%) at a temperature of 200 °C and a pressure of 0.7 bar in 1 h with only 1.0 wt% loading. Hydrothermal synthesized CoFe₂O₄ and solvent-free synthesized CoFe₂O₄ both showed lower BHET yields. The catalytic performance of the coprecipitated CoFe₂O₄ catalyst was influenced by the presence of unintentionally trapped FeCl₃ within the catalyst, which resulted in its enhanced activity. The CoFe₂O₄ catalyst from coprecipitation exhibited acceptable magnetic recoverability and reusability for four consecutive cycles, further highlighting its usefulness and sustainability.

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Targeted sorbents for the real-world adsorptive separation of heavy metals shall exhibit high sorption capacity, reusability, and cost-effectiveness. In this study, a novel composite sorbent has been synthesized for the concurrent mitigation of iron, lead, and zinc metal ions from synthetic wastewater systems. For this purpose, chitosan with alternate molecular weight (low, medium, and high) and with hydroxyl and amine functional groups was employed as a substrate. The successful anchoring of the organic compound citric acid was achieved with the glutaraldehyde crosslinker. The medium molecular weight chitosan-citric acid (medium Cit-CS) has been evaluated to achieve optimal metal uptake of 243.90, 3.93, and 144.93 mg g⁻¹ for zinc, lead, and iron from intricate Zn dominant adsorbate system. Accordingly, it was ascertained that other alternative ions in the adsorbate system significantly alter the sorption patterns. The validation of the chemisorption process was effectively established through the consistency observed in the pattern of adsorption as well as the successful modeling via the pseudo-second-order (PSO) approach. Following this, the desorption of metal ions was effective with simple basic and acidic eluents and for a three-cycle-based simultaneous regeneration. In summary, the findings demonstrate the promising performance of the sorbent for metal ions eradication from intricate solutions.

Tetracycline (TC), a widely used antibiotic, can easily enter aquatic ecosystems through soil erosion, livestock manures, and wastewater discharge, causes environmental and ecological health effects. AgCuFe₂O₄@Methylcellulose (MC)/Activated Carbon (AC) magnetic nanocomposite was synthesized accompanied by microwave-assisted co-precipitation procedure under green circumstances with high efficiency and subsequently utilized as a new heterogeneous magnetic nano-photocatalyst in the TC photodegradation from aqueous solutions. The structural characterization of AgCuFe₂O₄@MC/AC was performed by various analytical techniques. Afterwards, the key parameters of the photocatalytic TC degradation process, such as catalyst dose, TC concentration, pH, and process time, were investigated and optimized the results showed that the catalyst was synthesized on a nanometer scale (25 nm) with a quasi-spherical structure, with a high specific surface area, high magnetic strength (Ms = 19.27 emu g⁻¹), and the preservation of the crystal structure. The removal efficiency of TC under optimal conditions including pH 7, initial TC concentration of 5 mg L⁻¹, nano-photocatalyst dose of 0.5 g L⁻¹, 90 min of irradiation time was reported to be 90.91% for synthetic sample and 87.17% for real wastewater sample. The removal effectiveness of total organic carbon was 85.2% under optimal conditions. The photocatalytic degradation kinetics of TC followed pseudo-first-order and Langmuir–Hinshelwood kinetic models, with values of K_L–H = 0.633 L mg⁻¹ and K_c = 0.126 mg L⁻¹ min⁻¹. After four cycles of recovery and regeneration, the synthesized catalyst demonstrated high chemical stability and was able to remove 62% of the pollutant. Finally, this study provides a viable approach for removing antibiotics using an AgCuFe₂O₄@MC/AC-based heterogeneous nanostructured photocatalyst.

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One of the significant challenges of the twenty-first century will be feeding the growing world population while reducing the environmental impact and costs of agricultural production. In the case of extensive cropping, using mineral fertilizers or agrochemicals can contaminate the environment, decreasing the rivers and soil health and contributing to the emission of greenhouse gases. In this scenario, plant growth-promoting bacteria (PGPB) or inoculants have emerged as an alternative for overcoming the need for agrochemicals. The PGPB has gained wide prominence as an alternative to enable more sustainable, low-cost, and high-yield agriculture. It can promote plant growth by producing ammonia, from atmospheric nitrogen, and phytohormones through symbiotic relationships. However, the inoculant industries face many challenges related to the biotic and abiotic stress in soil, which decreases the bacteria’s survival, and its efficiency after inoculation. To enhance the effectiveness of microbial inoculants herein, we describe the encapsulation of A. brasilense FP2 (wild-type) into gum Arabic-based hydrogels (HG). A high population of encapsulated A. brasilense (10⁷ CFU/g of dry hydrogel) could survive in the polymeric matrix for seven months. The effect on plant growth-promoting was evaluated on maize (Zea mays), which was the plant model. Compared with inoculation via furrow, the encapsulated PGPB enhanced root diameter and volume above 20%. In addition, it resulted in increments above 60% for root and shoot fresh weight compared to the uninoculated HG. Our results indicated that the gum Arabic hydrogels protect A. brasilense and are suitable for biofertilizer formulations.

Poly(butylene succinate) (PBS), a biodegradable material, has excellent mechanical properties and processing properties. Brassylic acid (BA) is a kind of diacid with long chains derived from biomass. In this study, poly(butylene succinate-co-butylene brassylate) is synthesized to investigate the effects of BA on the structure and properties of PBS. The relationship between the melting temperature of copolyesters and the content of butylene brassylate units is V-shaped, which is typical of isodimorphic random copolyesters. Due to the introduction of BA, the density of unstable ester bonds in copolyesters gradually decreases and the initial thermal decomposition temperature of copolyesters gradually increases with the increase of BA. The dynamic mechanical analysis showed that the glass transition temperature of PBS was reduced by the introduction of BA. When the BA content is 25%, the copolyesters and PBS have the same crystal structure. When the BA content is 50–100%, the copolyesters and poly(butylene brassylate) have the same crystal structure, which indicates that the butylene brassylate units are easier to crystallize than the butylene succinate units. The ductility of copolyesters increases with the addition of BA. When the BA content is 50%, the elongation at break reaches the maximum (> 2000%). The copolyesters are suited for films due to high elongation at break.

Addressing the complex issue of lost circulation in drilling operations is crucial as it increases nonproductive time and costs. Conventional gel plugging materials often exhibit low temperature resistance, poor pumpability, and low pressure-bearing capacity. To overcome the limitations, a self-made polymer (HSA) was initially synthesized and mixed with two crosslinker agents (MBA/PEI) at room temperature to induce a new type of high-temperature-resistant and pressure-resistant polymer gel agent (HSA-G). Investigating the gel strength and plugging capacity, the vertical inverted tube observation, 71-type high-temperature and high-pressure (HTHP) instruments, and high-pressure filter with varying fracture cracks (3–5 mm) were employed. HSA-G demonstrated excellent gelation strength for 4–5 h at 140 °C, while retaining more than 57% of its gel strength after aging at 140 °C for 144 h, which is 3 times higher than the commercially available hydrolyzed polyacrylamide (HPAM + PEI). The excellent performance was attributed to the synergy between PEI-MBA, which induces tight-crosslinked interconnected structure within HSA-G, mitigating fluid losses to only 72 mL compared to 194 mL for HPAM-G, under 8.5 MPa in the HTHP sand bed at 140 °C. In the fracture leakage simulations using a 5 mm crack performed at 6 MPa at room temperature, the filtration loss of HSA-G is 300 mL, almost half that of HPAM-G, showcasing its superior plugging and high-pressure bearing performance. In conclusion, HSA-G has not only demonstrated operational effectiveness in reducing downtime costs and fluid losses but can also temporally replace cement plugging to prevent reservoir contamination in alignment with environmentally friendly practices.

Biofilms are a severe problem for public health because of the contributing recurrence of infections. Therefore, combating biofilms is a critical issue. In our study, we loaded zinc oxide (ZnO), zinc oxide borax (ZnOBorax), zinc copper oxide (ZnCuO₂) nanoparticles and borax into bacterial cellulose (BC) to impart anti-biofilm and wound healing activity. The prepared BC loaded with nanoparticles (BC–NPs) was analysed via scanning electron microscopy. The nanoparticles’ geometric structure and placement in BC fibres were observed. We evaluated the biofilm inhibition and biofilm degradation activities of the BC–NPs against some pathogens via a crystal violet (CV) assay and XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2 H-tetrazolium-5-carboxanilide) reduction assay. The effects of BC–NPs on cell proliferation and wound-healing ability were analysed in L929 cell line. BC–NPs exhibited better biofilm degradation activity than biofilm inhibition activity. According to the results of the CV assay, BC–ZnONPs, BC–Borax and BC–ZnOBoraxNPs inhibited 65.53%, 71.74% and 66.60% of biofilm formation of Staphylococcus aureus, respectively. BC–ZnCuO₂NPs showed the most degradation activity on Pseudomonas aeruginosa and Listeria innocua biofilms. The XTT reduction assay results indicated a considerable reduction in the metabolic activity of the biofilms. Moreover, compared to the control group, BC loaded with borax and ZnO nanoparticle promoted cell migration without cytotoxicity.

Biodegradable polymers, particularly Polyhydroxyalkanoates (PHAs) and their derivatives, have garnered increasing attention across diverse industries owing to their distinct advantages such as bio-based sourcing, biocompatibility, and impressive biodegradability performance. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the most attractive members of PHAs with a great potential to replace conventional non-biodegradable polymers. However, one critical drawback restricting PHBV usage is its thermal instability, which could bring about a narrow processing window, especially for conventional melt processing methods such as injection molding. Moreover, the high crystallinity and slow nucleation rate make PHBV brittle, leading to poor mechanical performance. This study incorporated epoxidized natural rubbers (ENR-25 and ENR-50) into PHBV through a melt blending process to enhance PHBV toughness and flexibility. Incorporation of 5wt% polybutadiene grafted maleic anhydride (PB-g-MA) as a compatibilizer notably enhances mechanical properties. Furthermore, the study introduces the concept of thermoplastic vulcanizate (TPV) through melt blending using dynamic vulcanization (DV) to enhance mechanical properties, particularly the toughness of the 70/30 PHBV/ENR blends, identified as the optimal blending ratio based on prior research. The resulting blend vulcanizate (PHBV/ENRv) exhibits toughness values of 63.0 ± 14.8 J m^− 1 and 24.4 ± 2.8 J m^− 1 for blends with ENRv-25 and ENRv-50, respectively. These findings hold promise for advancing the design and development of biodegradable polymer blend systems, with a focus on enhancing processability and mechanical performance.

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Lignin is classified as the second most abundantly available biopolymer after cellulose and as a main aromatic resource material. Lignin structure differs based on sources of origin and species of biomass with around 15–40% of lignin content based on dry weight. It is extracted from various types of lignocellulosic biomass through different pulping extraction methods. After extraction, lignin can be further functionalized through different chemical reactions to meet the requirements and specifications before being used in end products. Therefore, in this review paper, the details on extraction and the type of lignin, as well as chemical functionalization, are discussed. The chemical functionalization can be used to modify the lignin such through phenolic depolymerization or by other aromatic compounds, creating novel chemical active sites to impact a reactivity of lignin and through functionalization of hydroxyl functional group for enhancing its reactivity. Furthermore, the recent sustainable application of lignin was discussed in different fields such as nanocomposite, flame retardant, antioxidant, cosmetic, natural binder and emulsifier. This review hence provides a summary of the current stateoftheart in lignin technology and future outlook of potential application areas.

Compared to traditional invasive techniques for wound closure, photocrosslinkable surgical adhesives with antibacterial properties offer significant advantages. These include ease of application, a controllable and efficient curing reaction, reduced risk of pain and infection, and effective leakage prevention. This study introduces a novel soybean oil-based nonisocyanate polyurethane prepolymer for use in such adhesives. The prepolymer, a hydroxyurethane functionalized with methacrylate and quaternary ammonium groups (QAs), was characterized through spectroscopic methods. The resulting UV-curable bioadhesives, synthesized via thiol-ene-methacrylate click-photopolymerization, incorporated limonene as a reactive diluent, a tetra-functional thiol crosslinker, and a photoinitiator. Elemental analysis confirmed the uniform distribution of QAs and sulfur atoms, indicating a homogeneous network structure, corroborated by high gel content values in both organic (84–92%) and aqueous media (91–99%), and a consistent tan δ peak as per DMTA. The optimized adhesives exhibited strong adhesion (up to 377 kPa) to gelatin sheets—a tissue-analogous substrate—and displayed suitable surface free energy (45–52 mN/m) as determined by contact angle measurements, suggesting favorable thermodynamic adhesion to skin. Additionally, the adhesives showed satisfactory cytocompatibility with L-929 fibroblast cells and antimicrobial efficacy against two gram-positive and gram-negative bacterial strains, indicating promising biological activity.