Journal of Polymers and the Environment最新文献

In this study, a novel hydrogel nanofiltration (NF) membrane is developed through the coating-crosslinking method by synergistically utilizing multi-walled carbon nanotubes (MWCNTs) and titanium dioxide (TiO₂) into the hydrogel coatings of sodium alginate (SA) and polyvinyl alcohol (PVA) on a porous polyvinylidene fluoride (PVDF) matrix membrane. The experimental findings demonstrate that the P-MT@SA-PVA-PVDF hydrogel NF membrane displays outstanding separation performance, hydrophilicity, and antifouling properties. When the ratio of MWCNTs to PVP is kept at 1:4, the pure water flux of the prepared hydrogel NF membrane reaches 226.2 L/(m²ˑh). The rejection rates for Coomassie brilliant blue, Congo red, and Methylene blue are 96.3%, 95.8%, and 92.1%, respectively. Moreover, the total fouling rate of the membrane is merely 28.7%, and the flux recovery rate can attain 93.1%. The remarkable hydrophilicity and highly efficient rejection rates for dyes indicate broad application prospects of MWCNTs-modified hydrogel NF membranes in the field of printing and dyeing wastewater treatment.

In our study, in order to prepare PLA microcellular foam at high temperature, linear polylactic acid (L-lactone) (PLLA) was mixed with epoxy resin chain extender, and then blended with polylactic acid (D-lactone) (PDLA) to prepare bPLLA/PDLA mixture. The bPLLA/PDLA mixture produces stereocomplex (SC) crystals. The addition of SC crystal as a melt enhancer resulted in a significant enhancement of the melt strength of bPLLA, with an increase of 10⁴. Furthermore, the nucleation effect increased the overall crystallinity (X_C) of the bPLLA/PDLA blends from 5.29 to 23.21%, thereby enhancing the heat resistance of the bPLLA/PDLA blends. The hot deformation temperature was increased from 55.5 °C to 62.4 °C. During the foaming process, SC crystals acted as nucleating agents for bubbles, reducing the cell diameter from 30.59 μm to 3.09 μm, increasing the cell density by 10², and improving cell uniformity. In addition, an increase in PDLA content resulted in a notable enhancement in the compressive strength of bPLLA foam, from 0.44 MPa to 0.72 MPa. After heat treatment at 150 °C, the dimensional deformation was found to decrease from 42.59 to 13.13%, accompanied by an improvement in heat resistance. This study presents a simple method for the preparation of PLA microporous foam at high temperatures, resulting in the production of high-performance PLA foam, which is of great significance for the development of batch foaming towards industrial continuous foaming production.

Post-operative wound healing can be complicated due to various factors, which may lead to delay in healing and causes further infections with wound dehiscence. The bioactive compounds are considered as safe alternative for synthetic drugs in minimizing wound complications. Thus, Eucalyptus camaldulensis leaves were extracted using a hydroalcoholic solvent to obtain hydrophobic/hydrophilic fractions and tested for biomimetic attributes. Further, the extract was incorporated within Carbopol-based hydrogel to study the incision wound healing efficacy. The hydrophobic and hydrophilic fractions showed bacteriostatic properties against Acinetobacter baumannii and Staphylococcus epidermidis with the MIC values of 78 µg/mL, 625 µg/mL, and 312 µg/mL, respectively. Moreover, lipopolysaccharides-stimulated macrophage cells pretreated with hydrophobic/hydrophilic fraction indicated a concentration-dependent reduction in nitric oxide secretion with CC₅₀ of 8.72 µg/mL and 123.92 µg/mL, respectively. The Carbopol gel incorporated hydrophobic/hydrophilic fraction demonstrated insignificant changes in the physical properties of test gel, compared to Carbopol gel-base. Furthermore, the H&E-stained macroscopic image of animal skin treated with hydrophilic fraction fortified gel presented improved re-epithelization, neovascularization, infiltration of inflammatory cells, and connective tissue followed by development of scab, compared to hydrophobic fraction and control gel-base. The results suggested that both fractions of E. camaldulensis exhibit varied levels of potential therapeutic attributes, making it suitable as a wound healing agent.

This research aims to develop an effective scale inhibitor to prevent calcium carbonate and calcium sulfate scaling in industrial circulating cooling water systems. Terpolymer IA-PEG-SAMS was synthesized via free-radical polymerization using itaconic acid (IA), polyethylene glycol (PEG), and sodium methacryl sulfonate (SAMS) as monomers. The optimal synthesis parameters for the terpolymer IA-PEG-SAMS were investigated using the single-factor method. FT-IR, ¹H-NMR, and GPC characterized the terpolymer and monomers obtained. The impact of various factors on calcium scale inhibition under optimal synthesis conditions was examined. The scale inhibition performance of IA-PEG-SAMS on calcium carbonate and calcium sulfate scales was compared with current commercial scale inhibitors. The findings indicated that IA-PEG-SAMS demonstrated superior efficacy in inhibiting calcium scaling compared to most commercially available scale inhibitors. The scale inhibition efficiency was 95.16% for calcium carbonate and 92.13% for calcium sulfate at 90 mg/L and 0.2 mg/L IA-PEG-SAMS concentrations. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses demonstrated that IA-PEG-SAMS markedly altered the calcium scale’s morphology, crystal shape, and crystal structure. The terpolymer can effectively adsorb on the active component of calcium scale crystals and chelating calcium ions. The process involves a synergistic effect of lattice aberration and chelation solubilization, resulting in a loose and porous crystal structure of the calcium scale. The water flow can easily wash away this structure. Based on the above characteristics, the scale inhibitor shows considerable potential in water treatment.

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.