Journal of Polymers and the Environment最新文献

This study reports the hydrothermal synthesis and characterization of a chitosan-coated chromium ferrite/graphite oxide (CrFe₂O₄/GO/CS) nanocomposite with enhanced photocatalytic performance. The unique combination of the semiconductor properties of chromium ferrite, the light-harvesting capabilities of graphite oxide, and the stabilizing and adsorptive properties of chitosan resulted in a synergistic enhancement of the photocatalytic activity. The nanocomposite was characterized using FT-IR, Raman, XRD, zeta potential, DRS, BET, SEM, and EDS techniques. BET analysis revealed a specific surface area of 418.56 m²/g and a pore diameter of 2 nm for the CrFe₂O₄/GO/CS nanocomposite. The band gap of the nanocomposite was determined to be 3.5 eV, compared to 2.9 eV for CrFe₂O₄ and 2.95 eV for CrFe₂O₄/GO. The photocatalytic performance was evaluated through the degradation of Reactive Red 198 (R198) and Brilliant Blue FCF 133 (B133) dyes under UV and sunlight irradiation. The CrFe₂O₄/GO/CS nanocomposite demonstrated superior dye removal efficiency compared to CrFe₂O₄ and CrFe₂O₄/GO, achieving up to 98.2% removal for R198 at pH 8 and 98.5% for B133. The nanocomposite also showed excellent reusability, maintaining 81% removal efficiency for R198 and 77.6% for B133 after three cycles. Kinetic studies revealed that the dye removal process followed a pseudo-second-order model with R² values of 0.99 for both dyes. The nanocomposite demonstrated effective performance in real textile wastewater treatment, achieving 91.5% dye removal efficiency. The enhanced photocatalytic performance, coupled with the nanocomposite’s reusability, highlights its potential for practical applications in water purification and environmental remediation.

The high environmental impact of petroleum-based polymer has led to the study and application of biopolymers. Silk fibroin and chitosan are biopolymers with high potential for this, but current processes for obtaining films cast with silk fibroin pose significant environmental impacts including the need for use of toxic solvents and additional costs incurred through the required dialysis process. In this work it was proposed to obtain films based on chitosan and reinforced with silk fibroin, using a deep eutectic solvent formed by mixing choline chloride and citric acid. Glycerol was also added to some samples to study its effects as a plasticizer. Shape memory programming was established with tension tests to determine its fixation ratio and application of hot air at 75 °C. Two different activation temperatures were used to observe the recovery ratio, 75 and 50 °C. Silk fibroin helped improve the thermal and mechanical behavior of the films. Shape memory in these films is mainly explained by hydrogen bonding between chitosan and eutectic solvents. Films presented a recovery ratio between 86 and 54%. While shape memory was not significantly influenced by the presence of silk fibroin on its own, the shape memory activation temperature, the plasticization of chitosan by glycerol, and the mechanical reinforcement of silk fibroin enables control of the shape memory parameters of chitosan films. This behavior will allow for its potential application in areas such as biomedicine in actuators for prostheses or as smart packaging in the food industry.

The utilization of advanced adsorbents for the removal of heavy metal ion pollution from organic dyes and industrial wastewater has garnered significant research interest. In this study, a novel composite gel consisting of chitosan modified diatomite (DE/CS), sodium alginate (SA), and polyethyleneimine (PEI) (DE/CS-PEI@SA) was synthesized using the ion crosslinking method. The composite gels were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA), and Brunauer–Emmett–Teller systems (BET). Their adsorption properties and mechanisms towards copper Cu(II) and lead Pb(II) ions were investigated using infrared, X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy, (EDS) and Zeta potential analyses. The DE/CS-PEI@SA composite gels exhibited numerous uniform folds on its surface, boasting a specific surface area (18.96 m²/g) and a pore size ranging from 1.5 to 80.0 nm, demonstrating robust thermal stability pre- and post- adsorption. Notably, the composite gels demonstrated impressive adsorption capacities for Cu(II) (174.39 mg/g) and Pb(II) (295.04 mg/g), respectively. The incorporation of DE/CS and PEI into the composite gel contributed to a complex pore structure with numerous accessible sites. The adsorption behavior of the composite gel was effectively described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The primary adsorption mechanism was characterized by single-molecule chemisorption, which encompassed coordination adsorption, ion exchange, and electrostatic attraction. Furthermore, the composite gel demonstrated significant efficiency in adsorption, cost-effectiveness, and ease of separation, making it a promising candidate for wastewater treatment applications.

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This study aims to determine the influence of carob pod powder (CP) on antimicrobial performance, thermal behavior, mechanical strength of poly-lactic acid (PLA) matrix to observe the utilization potential as an environmentally-friendly eco-composite packaging material. Subsequent to pretreatment of CP and PLA, silver nanoparticles (AgNPs) were introduced into PLA matrix. Single-stage extruder was used to enable continuous sheet extrusion and material compounding to procure three different samples of 100 wt% PLA, 80 wt% PLA-20 wt% CP, and 75 wt% PLA-20 wt% CP-5 wt% AgNPs in pellet form. Extruded pellets underwent injection molding for tensile strength tests. The samples were characterized via Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FT-IR) analyses. Dynamic Mechanical Analysis (DMA) was carried out on the specimens to achieve glass transition behavior of the samples and compare them to those of Differential Scanning Calorimetry (DSC). Thermo-gravimetric (TG) analysis was conducted to observe thermal stability. Thickness and surface roughness were analyzed using profilometer. Antibacterial performance of eco-composites against Staphylococcus (S. aureus) and Escherichia coli (E. coli) was investigated. Combined effects of pretreated CP and AgNPs incorporation in PLA matrix resulted in 20% increase in tensile strength, 2.2% increase in glass transition temperature. The death rates of E. coli and S. aureus were found to be 87.3%, and 81.3%, respectively. Promising outcomes in the fabrication of packing materials with high sterilization and resilience against heat and mechanical stress were obtained through the combined influence of sample features with accuracy and appropriate parameters in extrusion process.

In this study, we applied a hybrid protection system for encapsulating cinnamon essential oil (CEO) to achieve higher protection, stability, and masking of its intense odor and taste in a beverage system. The CEO was protected in a liposome system with an optimized formulation that maximized encapsulation efficiency while minimizing particle size, polydispersity index and zeta potential. The optimized liposomal formula (lecithin/cholesterol: 5 and wall/CEO: 7.5) was injected as the dispersed phase of the millifluidic system to produce the CEO-loaded liposome in alginate millicapsules. Size and PDI values of optimized liposome were 0.18 and 252.33 nm, respectively. Zeta potential of liposome (-33.03 mV) also confirmed its stability, and CEO was encapsulated in the liposome with high efficiency (81.40%). The feasibility of this novel liposomal-hybrid system for masking the odor and taste of CEO was evaluated in an acidic beverage. The results revealed that samples fortified with hybrid liposomal CEO yielded less cinnamaldehyde (about 20%) in the headspace than those with liposomal CEO. Accordingly, the encapsulation of CEO-loaded liposomes using the liposome-fluidic method considerably affected the release of aromatic compounds from the liposome. It successfully controlled the intense odor of essential oil. The organoleptic results confirmed the HS- GC/MS results.

A series of interpenetrating polymer networks (IPNs) were prepared in the film form using 2-hydroxypropyl methacrylate (HPMA) polyethylene glycol methacrylate (PEG-MA) and hydroxypropyl-chitosan (HPCH) for controlled release of 5-fluorouracil (5-FU). The prepared IPNs formulations have been characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), swelling, and contact angle studies. In addition, the platelet adhesion, red blood cell hemolysis, and permeability to 5-FU were also studied with prepared IPNs films. The prepared p(HPMA-co-PEG–MA/HPCH)-1-6 IPNs films were loaded with different amounts of 5-FU and the drug release was studied in a continuous release system. The drug 5-FU has four amine and oxygen groups, and these functional groups interact via hydrogen bonding interaction with PEG-MA and HPCH units of the IPNs, thus, the drug was slowly released. The amount of 5-FU release from the p(HPMA-co-PEG–MA/HPCH) networks increased when the ratio of HPMA decreased or HPCH increased. The antitumor activity of 5-FU released from the prepared IPNs and remaining biological activity was measured using a human hepatocellular carcinoma cell line (SNU398). In vitro studies showed that the tested IPNs formulations were effective for the growth of the SNU398 human hepatocellular carcinoma cells. These experimental results showed that the prepared IPN films exhibited suitable physio-chemical, biocompatibility, and desired drug release profiles, thus, they could be used in various biomedical applications such as wound dressing for skin treatment.

Bone tissue engineering has emerged as an innovative approach for repairing and regenerating bone defects. This study focuses on the development of new scaffolds with key attributes, including biocompatibility, bioactivity, biodegradability, cost effectiveness, and safety. In this investigation, we designed and synthesized a novel nanofibrous scaffold using the electrospinning method, incorporating zein/58S bioactive glass. The manufactured scaffolds underwent comprehensive characterization for morphology, sustainability, and chemical structure. Moreover, to demonstrate their efficacy in bone healing, we quantified essential factors such as biodegradation rate, contact angle, mechanical strength, bioactivity, cytotoxicity, and cell adherence. Following that, the osteogenesis effect of scaffolds was evaluated in vitro as well as in vivo through implanting them in the calvarium of the rats. Specifically, we conducted detailed investigations using alizarin red staining, real-time PCR, and histopathology, along with immunohistochemistry assessments. Based on our results, the fiber diameters were about 160.2 ± 7 nm, 163.5 ± 38.3 nm, and 164 ± 39.3 nm, respectively for zein, 2%BG, and 4%BG mats. Incorporation of 58 S increased contact angle from 96.03 ± 0.7° to 51.7 ± 2.02°, and consequently improved cell adhesion. The degradation rate of all scaffolds was about 20%, and chemical analysis (FTIR) confirmed the presence of 58 S in zein nanoscale mats. Tensile analysis presented that applying bioactive glass rescued Young’s modulus from 0.34 ± 0.07 to 0.08 ± 0.009 MPa. Meanwhile, other results revealed that 4%BG scaffolds exhibit desirable properties, being porous, safe, bioactive, and osteogenic. These findings robustly affirm the competence and potential of the manufactured nanofibrous scaffold containing 4%BG for applications in bone tissue engineering.

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The schematic diagram illustrating different stages of the study, including; zein/BG scaffold synthesis, characterizations and osteogenesis evaluation in vitro and in vivo

Polyurethane, a hydrophobic polymer with limited water solubility, is widely employed in applications including foam insulation, adhesives, coatings, and both flexible and rigid plastics. Waterborne polyurethane (WBPU) has emerged as a focal point due to its water-dispersible nature Its beneficial qualities, such as low emissions of volatile organic compounds (VOCs), simplicity of use, and environmental friendliness, are the reason for its appeal. WBPU is recognized for being non-toxic, non-flammable, and low VOC properties so it can help prevent the pollution of air water rather than increase. Moreover, it exhibits remarkable adhesion properties to a wide range of surfaces, such as glass and polymeric fibres. These exceptional qualities of WBPU have piqued the interest of researchers worldwide. This review focuses on the fundamental principles of WBPU chemistry and explores its physical attributes. It proceeds to provide an extensive examination of various studies, shedding light on the reaction procedures and mechanisms involved. Additionally, the article delves into the modifications introduced in the production process, the selection of source materials, and associated limitations.

The presence of Persistent Organic Pollutants (POP) in consumer products such as electrical and electronic equipment represents a major obstacle for the recycling of the materials they contain at their end-of-life. Current technologies applied to recover plastics from waste electric and electronic equipment (WEEE) struggle to meet the requirements from recyclers regarding restrictions on some of these POPs, mainly brominated flame retardant (BFR) content. In this study, laser-induced breakdown spectroscopy (LIBS) technique combined with partial least squares regression (PLSR) was investigated for the real-time classification of WEEE plastics based on their total bromine (Br) content, in order to foster their reintroduction into the market as secondary raw materials. With this aim, a classification method was trained and tested in a sorting prototype using mixed plastic samples from TV set and computer monitor housings containing an average of 1.34% of Br. Regardless of polymer colour and type, up to 56% of the tested material could be segregated into a single fraction with a final Br concentration of 1,280 mg/kg. The achieved values met the requirements established in the CENELEC EN 50625 series of standards for the depollution of BFRs (< 2,000 mg/kg of Br) and the concentration of polybrominated diphenyl ethers (PBDEs) was estimated to be 213 mg/kg. These findings demonstrate the potential of the LIBS technique together with multivariate data analysis to ensure WEEE plastic sorting and depollution compliance with current regulations, reducing disposal rates and ultimately contributing to its circularity.

The development of sustainable polyurethane (PU) materials is crucial for minimizing the environmental impact of conventional solvent-based PUs. This study presents a novel approach to synthesizing and characterizing an imine-containing self-healing waterborne polyurethane (WPU) coating derived from bio-based polyester polyol. The process involves the synthesis of an imine-containing diol (IM-diol) from terephthalaldehyde and ethanolamine, followed by the creation of a series of bio-based dynamic bond-containing WPU using bio-based polyester polyol, IM-diol, isophorone diisocyanate (IPDI), and other additives. The imine dynamic bonds within the WPU exhibit excellent self-healing, reprocessability, and degradability. The mechanical and thermal properties of the synthesized bio-based WPU materials were characterized. Dynamic light scattering (DLS) results showed excellent stability in the prepared imine-containing WPU particles. Scratched WPUs exhibited practical self-healing ability at 80 °C after 30 min. The reprocessed imine-containing WPU grains fully recovered their mechanical properties (healing efficiency of 95%) for the first time. Thermogravimetric analysis (TGA) revealed that the thermal decomposition temperature of the synthesized imine-containing WPU exceeds 230 °C, indicating high thermal stability and potential for high-temperature applications. This study provides a promising method to produce a bio-based WPU elastomer with robust self-healing subjected to a dynamic exchange reaction under mild conditions. The findings suggest promising applications for bio-based WPUs in various fields, including coatings and adhesives, highlighting their potential for sustainable solutions in industries that require robust performance. The outstanding properties of the synthesized materials inspire confidence in their potential for various applications and the exploration of new uses that meet both performance and sustainability criteria.

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