Journal of Polymers and the Environment最新文献

Over the past few decades, the topic of recycling has become increasingly prominent in the field of sustainable materials and circular economy. One significant challenge is the physical separation of different types of plastics to obtain recyclates of one plastic type as pure as possible with comparable quality and properties to those of virgin material. Given the substantial effort involved in such separation, small amounts of contamination from other plastics may be tolerated. However, these contaminations must be monitored to ensure high-level recyclate quality. In recent years, compact, low-cost ion mobility spectrometers (IMS) with high analytical performance have been developed, and have thus become widely used in a variety of sensing applications. Due to their high sensitivity, IMS are particularly suited for detecting lowest concentration levels of various compounds, as required for the detection of impurities in recyclate quality monitoring. When coupled to a miniature gas chromatograph (GC), GC-IMS reach even higher separation power while being still compact. To bring recyclate samples to the gas phase, pyrolysis (Py) is used in this work. A first feasibility study was conducted to assess the potential of such a pyrolysis–gas chromatography-ion mobility spectrometer (Py-GC-IMS) with the objective of detecting contaminations of polyethylene terephthalate (PET) in polyethylene (PE) recyclates. The study clearly demonstrates the ability to identify PET-related fingerprints while suppressing the PE background matrix by design so that Py-GC-IMS seems a promising approach for in-process monitoring PET contaminations in PE recyclates.

In this study, a novel bio-based acrylic monomer derived from cardanol was synthesized and used in order to prepare acrylic copolymers that can be applied as thermoplastic polymers alone initially and then curable with the help of some driers to get a crosslink network similar to thermosetting polymers with their hydrophobic long alkyl chains having double bonds in their chemical structure. The synthesized polymers have the ability to be used in the paint or varnish formulations with or without paint driers. The synthesized monomers and polymers were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H NMR). Thermal properties of the polymers and obtained coatings therefrom were studied by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The varnish’s thermal and coating characteristics, such as its adhesion, gloss, hardness, salt spray resistance, and touch and hard drying times, were examined and analyzed. The results showed that the bio-based cardanol moieties improved the coatings’ resistance to chemicals and saltwater exposure as well as their thermal and mechanical characteristics through the incorporation aromatic and long linear alkyl chains. The block copolymers with cardanol units were used both on its own to produce thermoplastic polymeric films and in conjunction with driers to get thermoset crosslinking networks. The contact angle of thermoset polymeric films with driers measured as 77° but in case of thermoplastic blank polymer, it was 61°. Furthermore, the Tg of blank polymer was 13.37 °C, but with the addition of 10% cardanol units and a small amount of driers, the Tg was increased to 53.12 °C.

A nanocomposite hydrogel Co([CHITOSAN-AMPS-AA]/PEI-MBA) was synthesized using silica and graphene oxide nanoparticles by a free radical polymerization method. The hydrogel was used to adsorb tin and platinum from wastewater produced during production of a commercial dehydrogenation process. The adsorbed platinum could be selectively released from the adsorbing hydrogel platinum. Various tests including FTIR, XRD, TGA, and Rheology were conducted to identify the hydrogel’s three-dimensional structure. The adsorption performance was evaluated using ICP, SEM, and EDS tests. The ability of hydrogel for multiple adsorptions was also assessed. The thermodynamical study and adsorption isotherms were investigated, and the possible structure of the synthesized adsorbing hydrogel was presented. The results showed that while the hydrogel could adsorb platinum physically in three consecutive cycles from wastewater, tin is chemically adsorbed during the process. The physically-adsorbed platinum could then be released selective. The adsorption isotherm of platinum and tin ions followed the Langmuir adsorption isotherm model while the adsorption rate represented a pseudo-first-order kinetic model. The hydrogel had an adsorption capacity of 263.16 mg/g for platinum and 188.88 mg/g for tin with the Gibbs free energy of − 1710.86 J/mol and − 4521.08 J/mol, respectively. It was found that the hydrogel can be reused for practical and large-scale wastewater treatment as less than 10% decrease in the adsorption capacity was observed after three consecutive adsorption–desorption cycles.

Recent progress in developing cardiac patches for regenerating the myocardium has opened a new hope after myocardial infarction (MI). Herein, we introduce a novel bilayer nanofiber cardiac patch composed of polycaprolactone (PCL), poly(xylitol sebacate) (PXS), and multi-walled carbon nanotubes (MWCNTs). First, we electrospun different monolayer scaffolds, including PCL, PCL/MWCNT, PCL/PXS, and PCL/PXS/MWCNTs, and characterized their physical, mechanical, and biological performance to determine the interaction effects of different material compositions on their scaffold properties. In vitro examinations confirmed the cooperative effect of PXS and MWCNT in blending with PCL to fabricate conductive and well-organized nanofibers with good biocompatibility. Subsequently, a bilayer nanofiber scaffold composed of PCL/PXS/MWCNT nanofibers electrospun over a PCL fibrous layer was fabricated to achieve an efficient structure capable of providing the desirable characteristics of a cardiac patch. The bilayer nature increased the mechanical performance of the PCL/PXS/MWCNT monolayer while preserving its appropriate wettability and acceptable conductivity. Excellent viability and proliferation of H9c2 cells on the bilayer scaffolds were observed in the live/dead assay. Moreover, cell-matrix interaction confirmed that bilayer nanofibers decrease myofibroblast differentiation of seeded NIH3T3 cells, which may be beneficial for cardiac repair post-MI. After transplantation of the bilayer nanofiber onto the infarcted heart of the MI rats for 4 weeks, the ischemic zone decreased, cardiac function significantly improved and very slightly activated macrophages were observed. These findings suggested a potentially durable nanofiber cardiac patch containing PXS for myocardial repair post-MI.

Poly (lactic acid) (PLA) membrane is fabricated through electrospinning, which effectively absorbs oil from the oil/water mixture. The prepared PLA electrospun membrane is hydrophobic with a water contact angle (WCA) of 117.2⁰. Introduction of POSS (polyhedral oligomeric silsesquioxane) particles as nanofiller into the PLA matrix, as well as a coating on the electrospun membrane, appreciably enhances the hydrophobicity and thermal stability of the nanofibrous membranes. The membranes become dense, less porous, and crystalline after heat treatment. The unannealed nanofibrous membrane with a highly porous, oleophilic surface helps to impart higher oil absorption properties than that of annealed membranes, which are 60.45 g/g and 66.03 g/g for palm oil and used engine oil respectively. The as-prepared PLA fibrous membranes can absorb oil from the oil-water interface, showing excellent recyclability and separation efficiency > 70%.

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Cassava pulp (CP) generated annually in Thailand has become the major agro-industrial solid waste problem, but its potential for volatile fatty acids (VFAs) production has not been intensively explored. Waste-derived VFAs gained attention due to their broad applications as substrates for biomethane and bioplastic or bio-based chemicals, replacing petrochemical-based ones. This study proposed the next generation of CP waste management for VFAs production as renewable and inexpensive substrates for biogas and bioplastic prospects. A microbial consortium enriched with hydrolytic and acidogenic bacteria (EHA) was used as inoculum seed for anaerobic fermentation of CP to produce VFAs. The stepwise increasing substrate to 5% CP resulted in VFAs yield of up to 0.16 g acetic acid and 0.22 g butyric acids per g of CP added, requiring only 1% of microbial inoculum. Acid-tolerant spore-forming Clostridium dominated the EHA consortium and was easy to maintain during stress conditions. If the annual CP generated is subjected to this proposed waste management system, 0.31 million tons of acetic acid and 0.43 million tons of butyric acid can be produced annually. These VFAs can be further used as mixed VFAs for biomethane and bioplastic production prospects or extracted as a pure VFA and sold to the chemicals market. Moreover, bio-transformation of CP into VFAs through fermentation using the special EHA consortium requires minimum operational cost and produces high-economy products while minimizing greenhouse gas emissions to the atmosphere. This next-generation CP waste utilization will be of good use in the future by contributing to sustainable development goals.

Breast cancer poses a significant health risk and remains the most prevalent cancer among women. The side effects associated with traditional chemotherapy, such as neurotoxicity, liver or kidney dysfunction, highlight the urgent need for novel breast cancer therapies. In this regard, local delivery of chemotherapeutics has been emerged to be one of the efficient methods to eradicate the tumor cells. Injectable hydrogels were developed as drug delivery systems for localized drug accumulation and controlled drug release at the tumor site. Hydrogels are 3D network of polymeric structures with notable biocompatibility, swelling properties and mechanical strength. In fact, an injectable hydrogel enhances drug delivery efficiency, reduces systemic drug cytotoxicity, minimizes the essential drug dosage and frequency of drug administration. The studies based on injectable hydrogels for specific cancer therapy showed that such platforms are more effective and durable methods than traditional chemotherapy. Additionally, they are vastly used in inhibiting postsurgical tumor recurrence. These hydrogel platforms can integrate multiple breast cancer therapies into a single structure to improve the treatment efficacy. In this review, a variety of injectable hydrogel drug delivery platforms were discussed for several types of applications, such as gene therapy, drug delivery, immunotherapy, photothermal therapy, photodynamic therapy, and combined therapies with synergistic effects against breast cancer. Moreover, we provided a brief summary of the recent advances in the application of such hydrogels for breast cancer treatment. This review provides insight into the recent advancements in injectable hydrogels and discusses the potential future applications and challenges associated with this drug delivery technology toward cancer therapy.

Inefficiently treated wastewater, which contains a high concentration of pollutants, is hazardous when it is mixed with the clean water of rivers and lakes. Nitrate in particular is a major global problem that leads to eutrophication and poses a threat to both aquatic ecosystems and human health. To address this issue, this work assessed the efficiency of polymeric cryogel (PC) and biopolymer (EPS)-blended composites (EPS@PC) in removing nitrates. Tests were also conducted to quantify the decrease in phosphate, chloride ions, and chemical oxygen demand (COD) in real water samples taken from the Ankara stream, which receives effluents from both urban (UWTP) and industrial (IWTP) wastewater treatment plants. Five different columns with varying adsorptive properties were prepared, some of which were combined with iron. The EPS-@PC-C5 column demonstrated the highest adsorption ratio for nitrate removal compared to the other tested columns. The EPS@PC-C5 achieved a high removal efficiency of 126.38 mg nitrate/g and showed COD reduction ranging from 60.2 to 94.1%. The removal ratio of chloride concentration varied between 56.0 and 75.7%, while the removal of phosphates ranged from 87 to 99%. Columns composed of EPS (EPS@PC) with both negatively and positively charged ligands are dependable and suitable options for water remediation.

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Recently, the polymer-nanoparticle combination has garnered significant interest in enhanced oil recovery (EOR) due to its promising experimental results. However, the previous research was mostly directed at silica, while alumina and zirconia nanoparticles have gotten the least consideration. Unlike previous works, this study aims to investigate the influence of three NPs: Silica (SiO₂), Alumina (Al₂O₃), and Zirconia (ZrO₂) on hydrolyzed polyacrylamide (HPAM). To this end, three nanocomposites were formulated: HPAM-SiO₂, HPAM-Al₂O₃, and HPAM-ZrO₂. Rheological evaluations were performed to examine the viscosity degradation of the three nanocomposites and HPAM under reservoir conditions. Furthermore, interfacial tension (IFT) at the oil–water interface and wettability studies were investigated. Moreover, sand-pack flooding was performed to examine the incremental oil recovery. The results revealed that the polymer viscosity was boosted by 110%, 45%, and 12% for HPAM-SiO₂, HPAM-Al₂O₃, and HPAM-ZrO₂ respectively under the investigation range of temperature. Moreover, the polymer viscosity was improved by 73%, 48%, and 12% for HPAM-SiO₂, HPAM-Al₂O₃, and HPAM-ZrO₂ respectively under the investigation range of salinity. Nanocomposites are also found to be a remarkable agent for reducing interfacial tension and changing the contact angle. The flooding experiments confirmed that the EOR by HPAM, HPAM-SiO₂, HPAM-Al₂O₃, and HPAM-ZrO₂, was 8.6%, 17.4%, 15.3%, and 13.6% of OOIP respectively. Moreover, the results of flooding experiments were well validated and matched by numerical simulation. Such findings of this work afford new insights into EOR and reinforce the promising outlook of such technique at the field scale.

Enzymatic hydrolysis of polyethylene terephthalate (PET) for surface modification of polyester fibers has attracted considerable research attention in recent years. However, the high crystallinity of polyester fibers, combined with limited enzyme activity and stability, challenges the surface modification study of enzymes. Deep eutectic solvents (DES) can create a favorable environment for proteins and are a new generation of biodegradable solvents. Few studies have been conducted on the use of DES to enhance enzymatic degradation. Therefore, we attempted to hydrolyze PET with DES-activated enzymes to increase the hydrolysis yield and thus improve PET modification. Using betaine and choline chloride as hydrogen bond acceptors and polyols as hydrogen bond donors, we investigated the effects of DES type, molar ratio, and concentration on enzymatic hydrolysis. Humicola insolens cutinase (HiC) was used as the biocatalyst for PET fabric hydrolysis, the role of DES as an additive in improving the yield of enzymatically hydrolyzed PET fabric was investigated. The results showed that under the conditions of an enzyme concentration of 6.5% v/v (volume of enzyme on the total volume), a temperature of 60 °C, and a reaction time of 72 h, the low concentration (20% v/v) of DES (betaine: sorbitol; 1:2 molar ratio) increased the hydrolysis yield by more than 1.5 times. Enzymatic hydrolysis in DES aqueous solution (betaine: sorbitol; 1:2 molar ratio) and DES single-component aqueous solution (betaine, sorbitol without synthesis of DES) indicated that the increase in hydrolysis yield was mainly due to the formation of hydrogen bonds between betaine and sorbitol, rather than the superposition of individual components. Further analysis revealed that HiC exhibited high relative enzyme activity and stability at low DES concentrations. Additionally, CD spectroscopy and fluorescence spectroscopy analyses demonstrated the effective preservation of HiC structure by DES. Our work provides insights into the development of efficient and sustainable methods to enhance HiC hydrolysis of PET fabric, unlocking new opportunities and potential for the comprehensive utilization of DES in the bio-modification of PET fabric.

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