Postconsumer polyethylene terephthalate (PET) has potential applications in many areas of manufacturing, but contamination by hazardous polyvinyl chloride (PVC) in common waste streams can reduce its recyclable value. Separating collected PET-PVC mixtures before recycling remains very challenging because of the similar physicochemical properties of PET and PVC. Herein, we describe a novel flotation process with corona modification pretreatment to facilitate the separation of PET-PVC mixtures. Through water contact angle, surface free energy, X-ray photoelectron and FT-IR characterization, we found that polar hydroxyl groups can be more easily introduced on the PVC surface than on the PET surface induced by corona modification. This selective wetting can suppress the floatability of PVC, leading to the separation of PET as floating product. A reliable mechanism including two different hydrogen-abstraction pathways was established. Response surface methodology consisting of Plackett-Burman and Box-Behnken designs was adopted for optimization of the combined process, and control parameters were solved based on high-quality prediction models, with fitting from significant variables and interactions. For physical or chemical circulation strategies with PET purity prioritization, the validated purity of the product reached 96.05% at a 626 W corona power, 5.42 m/min passing speed, 24.78 mg/L frother concentration and 286 L/h air flow rate. For the energy recuperation strategy with PET recovery prioritization, the factual recovery reached 98.08% under a 601 W corona power, 6.04 m/min passing speed, 27.55 mg/L frother concentration and 184 L/h air flow rate. The current work provides technological insights into the cleaner disposal of waste plastics.
Renewable materials have some bearing on the environment and have since increased research works related to polymer composites. This work was conducted to investigate the effects of interwoven kenaf fibres and the use of kenaf fibres in composites. In this research, interwoven between kenaf and polyethylene terephthalate (PET) was prepared and epoxy was used as the polymer matrix to form composites. The kenaf fibre composites with various kenaf fibre contents (2, 5, 8, and 10 wt %) interwoven with (PET) fibres were prepared by using open mould method. The properties of kenaf/PET/epoxy composites (KPTE) were studied. The kenaf fibre composites characterization was determined based on their mechanical properties, water absorption, morphology and thermal properties. The tensile strength test was performed using Testometric machine. The finding shows that the strength increases as the amount of kenaf fibres in the composites increases. The composites with 10% kenaf fibres interwoven PET displayed the highest tensile strength (85.3 ± 2.9 MPa) while unfilled epoxy show the lowest tensile strength (64.1 ± 16.5 MPa). The addition of kenaf fibres minimally increases the water absorption up to about 1.4%. The increases of kenaf fibres also reduces the overall thermal stability of the composites compared to the PET and epoxy resin composites. The morphology properties of KPTE composites support the tensile properties surface of the composites. This study assists to propose the kenaf fibres as a potential filler for properties improvements in epoxy-based composites contributing to the development of another environment-friendly material.
So far, several classes of digesting solutions have been employed to extract microplastics (MPs) from biological matrices. However, the performance of digesting solutions across different temperatures has never been systematically investigated. In the first phase of the present study, we measured the efficiency of different oxidative agents (NaClO or H2O2), bases (NaOH or KOH), and acids [HCl or HNO3; concentrated and diluted (5%)] in digesting fish tissues at room temperature (RT, 25°C), 40, 50, or 60°C. In the second phase, the treatments that were efficient in digesting the biological materials (>95%) were evaluated for their compatibility with eight major plastic polymers (assessed through recovery rate, Raman spectroscopy analysis, and morphological changes). Among the tested solutions, NaClO, NaOH, and diluted acids did not result in a satisfactory digestion efficiency at any of the temperatures. The H2O2 treatment at 50°C efficiently digested the biological materials, although it decreased the recovery rate of nylon-6 (NY6) and nylon-66 (NY66) and altered the colour of polyethylene terephthalate (PET) fragments. Similarly, concentrated HCl and HNO3 treatments at RT fully digested the fish tissues, but also fully dissolved NY6 and NY66, and reduced the recovery rate of most or all of the polymers, respectively. Potassium hydroxide solution fully eliminated the biological matrices at all temperatures. However, at 50 and 60°C, it degraded PET, reduced the recovery rate of PET and polyvinyl chloride (PVC), and changed the colour of NY66. According to our results, treating biological materials with a 10% KOH solution and incubating at 40°C was both time and cost-effective, efficient in digesting biological materials, and had no impact on the integrity of the plastic polymers. Furthermore, coupling this treatment with NaI extraction created a promising protocol to isolate MPs from whole fish samples.
This paper reports a case of double orifice mitral valve which was treated conservatively. A new scheme of classification of this entity linked to the accepted lines of surgical treatment is introduced.
This paper reports on the preparation of magnetic lumen loaded handsheets from bleached and unbleached mixed tropical hardwood kraft pulps. The lumen coating technique is a physical approach whereby fillers were deposited inside the fibre lumen. In order to produce magnetically responsive fibres, magnetic fillers were loaded into the fibre lumen. The magnetic filler chosen was magnetite which is usually used to make mylar as found in a diskette. Low and high molecular weights of polyacrylamide (PAM) were used as retention aids. The effect of different molecular weight of PAM on filler content in the bleached and unbleached handsheets were studied. The results showed that the amount of fillers deposited in the pulp fibres increased with increasing molecular weight of PAM using both pulps. However the bleached pulps gave better lumen loading than the unbleached when using high molecular weight of PAM.
In this study, poly(ethylene terephthalate) (PET) wastes bottle was recycled by glycolysis process using ethylene glycol. The unsaturated polyester resin (UPR) was then prepared by reacting the glycolysed product with maleic anhydride. The blend of UPR based on recycled PET wastes with liquid natural rubber (LNR) was carried out by varying the amount of LNR from 0 to 7.5 wt%. Mechanical tests such as tensile and impact were conducted to investigate the effects of LNR on the mechanical properties. Scanning Electron Microscopy (SEM) was used to analyze the morphology of the breaking area resulted from the tensile tests on the UPR and blend samples. From the results, the blend of 2.5 wt% LNR in UPR based recycled PET wastes achieved the highest strength in the mechanical properties and showed a well dispersed of elastomer particles in the sample morphology compared to other blends concentrations. This blend sample was then compared to the optimum blend of LNR with commercial resin through the glass transition temperature value Tg, mechanical strength and morphology properties. The comparison study showed that the Tg for UPR based recycled PET was higher than the value represented from commercial resin due to the degree of crystalinity in the molecular structure of the materials. LNR was found to be an effective impact modifier which gave a greater improvement in UPR from recycled PET wastes structure but not to the commercial one which needs 5% LNR to achieve the optimum properties. Thus, the compatibility between the UP resin based recycled PET and LNR was much better than with the commercial resin.
The development of a non-thermal plasma jet with a capillary configuration working at atmospheric pressure is reported
in this paper. The plasma jet is powered by a power source with frequency of several kilohertz. The working gas is
argon. The plasma obtained has been characterized by optical emission spectroscopic measurements and electrical
measurements of the discharge using voltage and current probes. The electron temperature has been estimated by using
the modified Boltzmann plot method utilizing the Ar 4p-4s transition. The electron temperatures at various positions
along the plasma jet length have been obtained and it is found that the electron temperature decreases at position further
from orifice. The electron density has been estimated from current and voltage measurements using the power balance
method. The effects of gas flow rate, applied voltage and frequency on the characteristics of the plasma jet have also been
investigated. The applications of the atmospheric pressure plasma jet (APPJ) developed to modify the surface properties
of Polyethyleneterephthalate (PET) and polycarbonate (PC) have been tested. Our results showed that the atmospheric
pressure non-thermal plasma jet can be effectively used to enhance the surface wettability and surface energy of the
PET and PC. The plasma jet has also been tested for inactivation of prokaryotic cells (Escherichia coli, Staphylococcus
aureus). In the case of E. coli, better than 4 log10 reduction can be achieved. The effect of plasma jet on the pH of cell
culture medium has suggested that the plasma species, particularly the electrons, are solely responsible for the effect
of inactivation of living cells.
Composite materials used in the prosthetic and orthotic fields have helped improve the fabrication of sockets. Laminated sockets proved to be stronger than conventional thermoplastic sockets. The internal surface of a laminated socket plays an important role in patient comfort and is influenced by the material used to fabricate the socket. This study analyzes the internal surface profile of five different materials, that is, Dacron felt, fiberglass, Perlon stockinette, polyester stockinette, and elastic stockinette. All sockets were fabricated using an acrylic resin mix with hardener powder at a ratio of 100:3. The internal surface of the sockets was tested using the Mitutoyo SurfTest SJ-210 series for 20 trials. The overall Ra values were 2.318, 2.380, 2.682, 2.722, and 3.750 µm for fiberglass, polyester, Perlon, elastic stockinette, and Dacron felt. Dacron felt yielded the lowest Ra value, thus, producing the smoothest internal surface but requiring high skill and the correct technique during the fabrication of a laminated socket. Fiberglass is considered the best material for the internal surface despite not producing the lowest value individually but overall is the lowest and most consistent, indicating that it is easy to use to laminate prosthetic sockets.
Recycling is one of the most efficient methods for environmental friendly waste management. Among municipal wastes, plastics are the most common material that can be easily recycled and polyethylene terephthalate (PET) is one of its major types. PET material is used in consumer goods packaging such as drinking bottles, toiletry containers, food packaging and many more. Usually, a recycling process is tailored to a specific material for optimal purification and decontamination to obtain high grade recyclable material. The quantity and quality of the sorting process are limited by the capacity of human workers that suffer from fatigue and boredom. Several automated sorting systems have been proposed in the literature that include using chemical, proximity and vision sensors. The main advantages of vision based sensors are its environmentally friendly approach, non-intrusive detection and capability of high throughput. However, the existing methods rely heavily on deterministic approaches that make them less accurate as the variations in PET plastic waste appearance are too high. We proposed a probabilistic approach of modeling the PET material by analyzing the reflection region and its surrounding. Three parameters are modeled by Gaussian and exponential distributions: color, size and distance of the reflection region. The final classification is made through a supervised training method of likelihood ratio test. The main novelty of the proposed method is the probabilistic approach in integrating various PET material signatures that are contaminated by stains under constant lighting changes. The system is evaluated by using four performance metrics: precision, recall, accuracy and error. Our system performed the best in all evaluation metrics compared to the benchmark methods. The system can be further improved by fusing all neighborhood information in decision making and by implementing the system in a graphics processing unit for faster processing speed.
We describe herein a modified technique for reconstruction of chronic rupture of the quadriceps tendon in a patient with bilateral total knee replacement and distal realignment of the patella. The surgery involved the application of a Dacron graft and the ‘double eights’ technique. The patient achieved satisfactory results after surgery and we believe that this technique of reconstruction offers advantages over other methods.
Bisphenol A (BPA) is a controversial plastics ingredient used mainly in the production of polycarbonate plastics (PC) and epoxy resins that widely used nowadays in food and drink packaging. Even though BPA is not involved in polyethylene terephthalate (PET) manufacturing, recent study had reported the present of BPA in PET water bottle. This study was conducted to investigate effects storage conditions on release of BPA from PC and PET bottled water as well as to assess health risks associated with consumption. Methods: Solid phase extraction (SPE) was used to extract the samples, followed by analysis using ultra high performance liquid chromatography with fluorescence detector (UHPLC-FLD). The possibility of developing chronic non-carcinogenic health risk among consumers of bottled water was evaluated using hazard quotient (HQ). Results: Results showed that BPA migrated from PC and PET water bottles at concentrations ranging from 9.13 to 257.67 ng/L and 11.53 ng/L to 269.87 ng/L respectively. Concentrations of BPA were higher in PET bottled water compared to PC bottled water across all storage conditions. Higher storage temperature and longer storage duration increased BPA concentrations in PC and PET bottled water. Concentrations of BPA in bottled water which were kept in a car and were exposed to sunlight were higher than control samples which were stored indoor at room temperature. Conclusion: No significant chronic non-carcinogenic health risks were calculated for daily ingestion of BPA-contaminated bottled water; calculated HQ was less than one.
Aortic malignant neoplasms are rare; these may be primary or secondary (metastatic). Increasing use of cross-sectional imaging has allowed better detection and diagnosis of these conditions. We encountered a young woman presenting with acute abdomen who was found on cross-sectional imaging to have a malignant tumor involving the aortic bifurcation. An en bloc excision of the tumor was performed, with distal aorta reconstruction using an aortoiliac Dacron graft; this was complicated with infection and graft occlusion, necessitating total removal and extra-anatomic bypass. A pathologic diagnosis of metastatic adenocarcinoma involving the aortic bifurcation, with an unknown primary, was made.
A method is described for the fabrication of a closed hollow bulb obturator prosthesis using a hard thermoforming splint material and heat-cured acrylic resin. The technique allowed the thickness of the thermoformed bulb to be optimized for weight reduction, while the autopolymerized seal area was covered in heat-cured acrylic resin, thus eliminating potential leakage and discoloration. This technique permits the obturator prosthesis to be processed to completion from the wax trial denture without additional laboratory investing, flasking, and processing.
Flexible plastic packaging waste causes serious environmental issues due to challenges in recycling. This study investigated the conversion of flexible plastic packaging waste with 11.8 and 27.5 wt.% polyethylene terephthalate (PET) (denoted as PET-12 and PET-28, respectively) into oil and multi-walled carbon nanotubes (MWCNTs). The mixtures were initially pyrolyzed and the produced volatiles were processed over 9.0 wt.% Fe2O3 supported on ZSM-5 (400 °C) to remove oxygenated hydrocarbons (catalytic cracking of terephthalic and benzoic acids) that deteriorate oil quality. The contents of oxygenated hydrocarbons were decreased in oil from 4.6 and 9.4 wt.% per mass of PET-12 and PET-28, respectively, to undetectable levels. After catalytic cracking, the oil samples had similar contents of gasoline, diesel and heavy oil/wax fractions. The non-condensable gas was converted into MWCNTs over 0.9 wt.% Ni supported on CaCO3 (700 °C). The type of plastic packaging influenced the yields (2.4 and 1.5 wt.% per mass of PET-12 and PET-28, respectively) and the properties of MWCNTs due to the differences in gas composition. Regarding the electrocatalytic application, both MWCNTs from PET-12 and PET-28 outperformed commercial MWCNTs and Pt-based electrodes during oxygen evolution reaction, suggesting that MWCNTs from flexible plastic packaging can potentially replace conventional electrode materials.
Pistachio nut (Pistacia vera L.) is one of the popular tree nuts in the world. Proper selection of packaging materials is necessary to prevent absorption of moisture and aflatoxin formation which will influence the overall product quality and safety. This research is undertaken to study the effect of different type of flexible packaging films on the moisture and aflatoxin contents of whole pistachio nuts during storage at ambient temperature (22-28 °C) and relative humidity of 85-100%. Five types of plastic films tested were low density polyethylene (LDPE) which serves as the control, food-grade polyvinyl chloride (PVC), nylon (LDPE/PA), polyamide/polypropylene (PA/PP) and polyethylene terephthalate (PET). The moisture content and aflatoxin content of pistachio nuts were measured using oven drying method and HPLC, respectively. Sample were analysed at 0, 2, 4, 6, 8 and 10 months during the storage period. Results showed that there was an increase in moisture content with the increase in storage time of pistachio nuts. The increase in moisture content was associated with the aflatoxin level of pistachio nuts during storage time. All the packaging materials except LDPE delayed the moisture absorption and aflatoxin formation of the product. The most suitable packaging materials for maintaining the quality and safety of pistachio nuts is PET films followed by nylon, PA/PP and PVC. The shelf-life of pistachio can be extended from 2 months (Control) to 5 months when PET is used as the packaging material.
In-situ bioremediation of mangrove soil contaminated with polyethylene terephthalate (PET) and polystyrene (PS) microplastics was investigated using indigenous microbial consortium with adequate capacity to degrade the plastics. Eight (8) bacteria were isolated from plastic/microplastic-inundated mangrove soil and screened for the ability to degrade PET and PS microplastics. Optical density at 600 nm and colony forming unit counts were measured to evaluate the growth response of the microbes in the presence of PS and PET microplastics at different times of exposure. Structural and surface changes that occurred post biodegradation on the microplastics were determined through EDS and SEM analysis. The obtained results demonstrated the elongation and disappearance of peaks, suggesting that the microbial consortium could modify both types of microplastics. The overall results of the microplastic degradation showed varied degrees of weight loss after 90 experimental days, with the treated plot recorded 18% weight loss. The augmented soil was increased in the concentrations of Si S, and Fe and decreased in the concentrations of C, O, Na, Mg, Al, Cl, and K after bioremediation.
Frictional and nanomechanical properties of nanostructured polymer surfaces are important to their technological and biomedical applications. In this work, poly(ethylene terephthalate) (PET) surfaces with a periodic distribution of well-defined nanopillars were fabricated through an anodization/embossing process. The apparent surface energy of the nanopillared surfaces was evaluated using the Fowkes acid-base approach, and the surface morphology was characterized using scanning electron microscope (SEM) and atomic force microscope (AFM). The normal and lateral forces between a silica microparticle and these surfaces were quantified using colloidal probe atomic force microscopy (CP-AFM). The friction-load relationship followed Amonton's first law, and the friction coefficient appeared to scale linearly with the nanopillar height. Furthermore, all the nanopillared surfaces showed pronounced frictional instabilities compared to the smooth sliding friction loop on the flat control. Performing the stick-slip amplitude coefficient (SSAC) analysis, we found a correlation between the frictional instabilities and the nanopillars density, pull-off force and work of adhesion. We have summarised the dependence of the nanotribological properties on such nanopillared surfaces on five relevant parameters, i.e. pull-off force fp, Amontons' friction coefficient μ, RMS roughness Rq, stick-slip amplitude friction coefficient SSAC, and work of adhesion between the substrate and water Wadh in a radar chart. Whilst demonstrating the complexity of the frictional behaviour of nanopillared polymer surfaces, our results show that analyses of multiparametric nanotribological properties of nanostructured surfaces should go beyond classic Amontons' laws, with the SSAC more representative of the frictional properties compared to the friction coefficient.
A Pichia pastoris transformant carrying the cutinase cDNA of Glomerella cingulata was over-expressed in a 5L bioreactor (2.0L working volume) under fed-batch conditions. Bioreactor experiments rely on varying selected parameters in repeated rounds of optimisation: here these included duration of induction, pH and temperature. Highest cell densities (320gL(-1) wet cell weight) with a cutinase production of 3800mgL(-1) and an activity of 434UmL(-1) were achieved 24h after induction with methanol in basal salt medium (at pH 5 and 28°C). Characterisation of the cutinase showed that it was stable between pH 6 and pH 11, had an optimum pH of 8.0 and retained activity for 30min at 50°C (optimum temperature 25°C).The preferred substrates of G. cingulata cutinase were the medium- to long-chain ρ-nitrophenyl esters of ρ-nitrophenylcaprylate (C8), ρ-nitrophenyllaurate (C12) and ρ-nitrophenylmyristate (C14), with the highest catalytic efficiency, kcat/Km of 7.7±0.7mM(-1)s(-1) for ρ-nitrophenylcaprylate. Microscopic analyses showed that the G. cingulata cutinase was also capable of depolymerising the high molecular weight synthetic polyester, polyethylene terephthalate.
Measurement of major cation such as Na+, K+, and Ca2+ in water are normally carried out using
AAS, ICP-OES or flame photometry. In this study, an attempt was made to measure these cations
using Energy Dispersive X-ray Fluorescent Spectrometry (EDXRF). Hot spring s water was taken from varies hot spring in Selangor and divided into two portions that is filtered and unfiltered. 5 mL of water samples were pipette into a special liquid cups (sample holders) which has a thin mylar film underneath. The MiniPal4 XRF instrument was used in this study. The resolution for the instrument use is 145 keV with energy resolution at 5.9 keV. The spectrum of cations were analysed by using MiniPal/MiniMate software to determine the cations concentration. For K+ and Ca2+, Al-thin filter was used and default filter was used for Na+. The concentration of Na+ obtained for filtered and unfiltered samples were ranged from 38.00 to 66.05 and 43.26 to 76.95 ppm. Meanwhile, concentrations of K+ for filtered and unfiltered samples were ranged from 2.42 to 8.07 and 6.18 to 29.28 ppm. Concentrations of Ca2+ for filtered and unfiltered samples were ranged from 2.59 to 10.94 and 3.18 to 12.99 ppm.
Enzyme immobilization has been known to be one of the methods to improve the stability and reusability of enzyme. In this study, a strategy to optimize laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat (PET-g-MAH ENM) was developed. The development involves the screening and optimization processes of the crucial factors that influence the immobilization yield such as enzyme concentration, pH values, covalent bonding (CV) time, CV temperature, crosslinking (CL) time, CL temperature and glutaraldehyde concentration using two-level factorial design and Box-Behnken design (BBD), respectively. It was found that laccase concentration, pH values and glutaraldehyde concentration play important role in enhancing the immobilization yield of laccase on PET-g-MAH ENM in the screening process. Subsequently, the optimization result showed at 0.28 mg/ml laccase concentration, pH 3 and 0.45% (v/v) glutaraldehyde concentrations gave the highest immobilization yield at 87.64% which was 81.2% increment from the immobilization yield before optimization. Under the optimum condition, the immobilized laccase was able to oxidize 2, 2-azino-bis 3-ethylbenzothiazoline-6- sulfonic acid (ABTS) in a broad range of pH (pH 3-6) and temperature (20- 70 °C). Meanwhile, the kinetic parameters for Km and Vmax were 1.331 mM and 0.041 mM/min, respectively. It was concluded that the optimization of immobilized laccase on PET-g-MAH ENM enhance the performance of this biocatalyst.