Polyester Plastic Research Articles

Efficient H2 Production from PET Plastic Wastes over Mesoporous Carbon-Supported Ru-ZnO Catalysts in a Mild Pure-Water System

The massive consumption of plastic is posing severe pollution-related challenges globally. As the most abundant polyester plastic, polyethylene terephthalate (PET) waste represents a largely untapped resource for generating chemicals and fuels. However, the current widespread use of alkali/organic solvents and the complex processing of PET reduce its environmental sustainability. Herein, a novel and simple one-pot strategy was first reported for the catalytic conversion of PET into H2 fuel and terephthalic acid in a pure-water system under mild conditions. A high H2 yield of 19.97 mol/kgPET and carbon conversion efficiency of 97.22% were obtained for the Ru-5ZnO/mesoporous carbon (MEC) catalyst at a low temperature of 250 °C. This process proceeds through tandem catalytic reactions with an initial PET depolymerization step, followed by in situ aqueous phase reforming (APR) of ethylene glycol of Ru. Remarkably, ZnO inhibited the deactivation of Ru/MEC in the PET depolymerization stage, causing an increase in H2 production from the in situ APR stage. Importantly, this strategy was successfully applied to four types of real-world PET waste and their mixtures, demonstrating that it has considerable potential in practical applications and provides a sustainable and clean solution to the plastic waste problem.

Converting waste PET plastics into automobile fuels and antifreeze components

With the aim to solve the serious problem of white plastic pollution, we report herein a low-cost process to quantitatively convert polyethylene terephthalate (PET) into p-xylene (PX) and ethylene glycol (EG) over modified Cu/SiO2 catalyst using methanol as both solvent and hydrogen donor. Kinetic and in-situ Fourier-transform infrared spectroscopy (FTIR) studies demonstrate that the degradation of PET into PX involves tandem PET methanolysis and dimethyl terephthalate (DMT) selective hydro-deoxygenation (HDO) steps with the in-situ produced H2 from methanol decomposition at 210 °C. The overall high activities are attributed to the high Cu+/Cu0 ratio derived from the dense and granular copper silicate precursor, as formed by the induction of proper NaCl addition during the hydrothermal synthesis. This hydrogen-free one-pot approach allows to directly produce gasoline fuels and antifreeze components from waste poly-ester plastic, providing a feasible solution to the plastic problem in islands.

Standardized method for controlled modification of poly (ethylene terephthalate) (PET) crystallinity for assaying PET degrading enzymes

Poly(ethylene terephthalate) (PET) is a polyester plastic, which is widely used, notably as a material for single-use plastic bottles. Its accumulation in the environment now poses a global pollution threat. A number of enzymes are active on PET providing new options for industrial biorecycling of PET materials. The enzyme activity is strongly affected by the degree of PET crystallinity (XC), and the XC is therefore a relevant factor to consider in enzyme catalyzed PET recycling. Here, we present a new experimental methodology, based on systematic thermal annealing for controlled preparation of PET disks having different XC, to allow systematic quantitative evaluation of the efficiency of PET degrading enzymes at different degrees of PET substrate crystallinity. We discuss the theory of PET crystallinity and compare PET crystallinity data measured by differential scanning calorimetry and attenuated Fourier transform infrared spectroscopy.•This study introduces a simple method for controlling the crystallinity of PET samples via annealing in a heat block.•The present methodology is not limited to the analytical methods included in the methods details.

Zirconium-catalysed hydrosilylation of esters and depolymerisation of polyester plastic waste

A general and practical procedure for the catalytic reduction of esters has been developed using the classical Schwartz's reagent (Cp2Zr(H)Cl) as a catalyst.

Rational Protein Engineering to Increase the Activity and Stability of IsPETase Using the PROSS Algorithm

Polyethylene terephthalate (PET) is the most widely used polyester plastic, with applications in the textile and packaging industry. Currently, re-moulding is the main path for PET recycling, but this eventually leads to an unsustainable loss of quality; thus, other means of recycling are required. Enzymatic hydrolysis offers the possibility of monomer formation under mild conditions and opens up alternative and infinite recycling paths. Here, IsPETase, derived from the bacterium Ideonella sakaiensis, is considered to be the most active enzyme for PET degradation under mild conditions, and although several studies have demonstrated improvements to both the stability and activity of this enzyme, stability at even moderate temperatures is still an issue. In the present study, we have used sequence and structure-based bioinformatic tools to identify mutations to increase the thermal stability of the enzyme so as to increase PET degradation activity during extended hydrolysis reactions. We found that amino acid substitution S136E showed significant increases to activity and stability. S136E is a previously unreported variant that led to a 3.3-fold increase in activity relative to wild type.

Surface display as a functional screening platform for detecting enzymes active on PET

Poly(ethylene terephthalate) (PET) is the world’s most abundant polyester plastic, and its ongoing accumulation in nature is causing a global environmental problem. Currently, the main recycling processes utilize thermomechanical or chemical means, resulting in the deterioration of the mechanical properties of PET. Consequently, polluting de novo synthesis remains preferred, creating the need for more efficient and bio-sustainable ways to hydrolyze the polymer. Recently, a PETase enzyme from the bacterium Ideonella sakaiensis was shown to facilitate PET biodegradation, albeit at slow rate. Engineering of more efficient PETases is required for industrial relevance, but progress is currently hampered by the dependency on intracellular expression in Escherichia coli. To create a more efficient screening platform in E. coli, we explore different surface display anchors for fast and easy assaying of PETase activity. We show that PETases can be functionally displayed on the bacterial cell surface, enabling screening of enzyme activity on PET microparticles – both while anchored to the cell and following solubilization of the enzymes.

Insights into polyester plastic biodegradation by carboxyl ester hydrolases

AbstractEnvironmental pollution caused by polyesters has become a major ecological safety concern that needs to be managed urgently. One way to resolve this problem is giving the spotlight to current emerging research of microbial biocatalysts. During the last two decades many researchers have reported the ability to break down and modify natural and synthetic polyesters using different microbial carboxyl ester hydrolases (lipases, esterases, cutinases, PETases, etc.) also called polyesterases, and contribution of these enzymes towards the reduction of plastic levels in the future. Continuous search of such lipolytic biocatalysts and their improvement via protein engineering strategies results in beneficial findings making the use of polyesterases in the biodegradation of plastics increasingly more realistic. The present review provides a comprehensive insight into the structural properties enabling microbial lipolytic‐type carboxyl ester hydrolases to effectively catalyze the cleavage of ester linkages in different polyester plastics. Moreover, the management of extensively used polyester plastics using different lipolytic enzymes as an innovative eco‐friendly solution is presented in this report. Furthermore, improvement of polyesterases via protein engineering for the development of more effective and suitable polyester‐degrading lipolytic biocatalysts is summarized in this review as well. © 2021 Society of Chemical Industry (SCI).

Construction and Cloning of Plastic-degrading Recombinant Enzymes (MHETase).

Polyethylene terephthalate (PET) is the most widely produced polyester plastic in the world. PET is very difficult to catalyze or biological depolymerization due to the limited access to ester bonds. Consequently, plastic will be stockpiled or flowed into the environment which is projected until hundreds of years. The most effective and environmental friendly plastic degradation method is biodegradation with microorganisms. Two specific enzyme for PET hydrolase, PETase and MHETase have been identified from Ideonella sakaiensis 201-F6. Recombinant genes are made to increase the effectiveness of enzymes in degrading PET. Previous studies of the PETase gene have been carried out, but to produce the final degradation PET product, the enzyme MHETase is needed. Thus, in this study the MHETase gene construction was carried out. The goal of this study is to construct MHETase gene in pUCIDT plasmid with native signal peptide from I. sakaensis 201-F6 and constitutive promoter J23106 was expressed in Escherichia coli BL21 (DE3) by heats shock. Expression analysis using SDS-PAGE and activity of enzyme is analyzed by spectrophotometry method and SEM. MHETase gene protein was successfully constructed in pUCIDT +Amp plasmid with native signal peptide from Ideonella sakaensis 201-F6, T7 terminator and constitutive promoter J23106. PCR analysis showed that the gene successfully contained in the cells by band size (1813 bp) in electrophoresis gel. Analysis using Snap Gene, pairwise alignment using MEGA X, and NCBI was demonstrated that MHETase sequence the gene was in-frame in pUCIDT plasmid. MHETase gene was successfully constructed in plasmids by in silico method. Synthetic plasmids transformed in E. coli BL21 (DE3) contain MHETase gene sequences which were in frame. Hence, the E. coli BL21 (DE3) cells have the potential to produce MHETase proteins for the plastic degradation testing process. We will patent the construct of MHETase gene using constitutive promoter and signal peptide from native which expressed in E. coli BL21 (DE3). This patent refers to a more applicable plastic degradation system with a whole cell without the need for purification and environmental conditioning of pure enzymes.

An engineered PET depolymerase to break down and recycle plastic bottles.

Present estimates suggest that of the 359 million tons of plastics produced annually worldwide1, 150-200 million tons accumulate in landfill or in the natural environment2. Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging3. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties4. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units-which reduce chain mobility-PET is a polyester that is extremely difficult to hydrolyse5. Several PET hydrolase enzymes have been reported, but show limited productivity6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200grams per kilogram of PET suspension, with an enzyme concentration of 3milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme8,9 from the bacterium Ideonella sakaiensis strain 201-F6 (even assisted by a secondary enzyme10) and related improved variants11-14 that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.

Use of poly(ethylene naphthalate) as a self-vetoing structural material

The discovery of scintillation in the blue regime from poly(ethylene naphthalate) (PEN), a commonly used high-performance industrial polyester plastic, has sparked the interest of the physics community as a new type of plastic scintillator material. This observation in addition to its good mechanical and radiopurity properties makes PEN an attractive candidate as an active structure scintillator for low-background physics experiments. This paper reports on investigations of its potential in terms of production tests of custom made tiles and various scintillation light output measurements. These investigations substantiate the high potential of usage of PEN in low-background experiments.

Study of water wetting in oil-water flow in a small-scale annular flume

Proper characterization of the phase wetting regime (water wet or oil wet) in two-phase oil-water flow can lead to optimized measures for pipe integrity management and save cost. In previous work it was demonstrated that not only the physicochemical properties of the produced oil and water have an important impact on flow patterns, but also the wettability of the pipe surface can favor or hamper the contact with water. Since the wettability of steel pipes can be altered by the chemical composition of the oil and water phases, and due to the wide diversity of the chemical composition of produced crude oils and water, as well as different chemicals injected in production systems (e.g., corrosion inhibitors, scale inhibitors, de-emulsifiers), it is important to perform phase wetting experiments in dynamic conditions using representative fluids and pipe material. This study presents an experimental assessment of the phase wetting regime of oil-water flow using a small-scale annular flume of 5 l capacity, which is advantageous as a potential testing tool for crude oil-water flows compared to regular multiphase flow loops. A model oil and brine were used as experimental fluids and three different materials (carbon steel, stainless steel and a polyester plastic) were used to analyze the effect of flume surface wettability on the phase wetting regime. The results indicate that the annular flume is a promising low-cost tool to test dynamic phase wetting and dispersed flow of petroleum-water systems qualitatively as well as quantitatively. Moreover, basic hydrodynamic assessment of the annular flume flow was performed to evaluate available criteria to predict the stability of fully dispersed flow.

Enhanced Poly(ethylene terephthalate) Hydrolase Activity by Protein Engineering

Abstract Poly(ethylene terephthalate) hydrolase (PETase) from Ideonella sakaiensis exhibits a strong ability to degrade poly(ethylene terephthalate) (PET) at room temperature, and is thus regarded as a potential tool to solve the issue of polyester plastic pollution. Therefore, we explored the interaction between PETase and the substrate (a dimer of the PET monomer ethylene terephthalate, 2PET), using a model of PETase and its substrate. In this study, we focused on six key residues around the substrate-binding groove in order to create novel high-efficiency PETase mutants through protein engineering. These PETase mutants were designed and tested. The enzymatic activities of the R61A, L88F, and I179F mutants, which were obtained with a rapid cell-free screening system, exhibited 1.4 fold, 2.1 fold, and 2.5 fold increases, respectively, in comparison with wild-type PETase. The I179F mutant showed the highest activity, with the degradation rate of a PET film reaching 22.5 mg per μmol·L−1 PETase per day. Thus, this study has created enhanced artificial PETase enzymes through the rational protein engineering of key hydrophobic sites, and has further illustrated the potential of biodegradable plastics.

Perbaikan Tata Letak Lantai Produksi untuk Meminimasi Waktu Produksi dengan Menggunakan Metode Simulasi Pada PT. Argha Karya Prima Industry, Tbk

PT. Argha Prima Karya Industry is a company engaged in the field of flexible packaging. Problems found on the production floor of PT. Argha Karya Prima Industry is a delay in production time due to the engine distance that is too far and the availability of material handling is lacking. The product studied in this study is polyester plastic film with a production capacity of 1 unit within 11 hours equivalent to 2 days, while the production target set is 1 unit within 8 hours equivalent to 1 day. Layout the initial model of PT. Argha Karya Prima Industry was analyzed by simulation using ProModel software. Then after the initial layout was declared valid, improvements were made to the problems of the production floor layout using the Systematic Layout Planning method. From this method, two alternative layouts are obtained. The difference from the two proposed layouts is in the initial model, the slitter unwinder machine adjacent to the waste trimming area, while in the proposed layout 1, the slitter unwinder machine is located adjacent to the temporary storage rack. Then in the proposed layout 2, the slitter rewinder machine is adjacent to the finishing good area, while in the initial layout, the rewinder machine is adjacent to the temporary storage rack.

Radio frequency heating of corn flour: Heating rate and uniformity

Abstract Non-uniform heating is a major challenge for using radio frequency (RF) heat treatment in pasteurization of low moisture food products. The objective of this study was to evaluate the effect of different electrode gaps, moisture content (MC), bulk density and surrounding materials on RF heating uniformity and rate in corn flour. Additionally, the dielectric and thermal properties of corn flour were determined as affected by MC, temperature (°C), and frequency (MHz). Changes in MC, water activity (a w ) and color in the sample after RF heating were measured to evaluate treatment effect on food quality. A precision LCR meter and a liquid test fixture were used to study DP of the sample at RF frequency ranging from 1 to 30 MHz. The RF heating uniformity and temperature profiles of corn flour as exposed to RF heating were obtained with an infrared camera and a data logger connected to a fiber optic sensor. The DP values increased with increasing MC and temperature, but decreased with frequency. The heating rate increased from 3.5 to 6.8 °C min − 1 with increasing MC (from 10.4 to 16.7%), but decreased from 12.7 to 5.2 °C min − 1 with increasing electron gap (from 11 to 15 cm). The corner and edge heating were observed at all layers of the samples for all the distances, and the hottest and the most uniform layer were determined as the middle layer at an electrode gap of 15 cm. Glass petri dish provided better uniformity than those of polyester plastic petri dish. Covering by foam led to more uniform RF heating uniformity in corn flour, and better moisture and a w distribution. This study provided useful information to develop an effective RF process as an alternative of conventional thermal treatments for pasteurization of low-moisture products. Industrial relevance This paper describes a novel methodology based on Radio Frequency heating to pasteurize food powder while maintaining the quality. The study addresses the ever-increasing global demand from consumers for safe food products.

Talented 12 class of 2015: Where are they now?

TALENTED 12 Talented 12 class of 2015: Where are they now?Changing the world takes a while. We asked our inaugural class what they’ve been up to this past year. ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2016, 94 (33), p 50August 22, 2016Cite this:C&EN 94, 33, 50Here, Erb (left) celebrates the feat with grad student Thomas Schwander. “Put your helmets on, we are going to cycle CO2!” (Credit: Erb Lab )Figure1of2Balskus, a microbial metabolism expert, poses with Hitomi Nakamura (left) and Smaranda Bodea (right). (Credit: Courtesy of Emily Balskus)Figure1of2 Brad OlsenMIT Olsen reports that his group published its first paper on loop defects in polymer networks in Physical Review Letters (DOI: 10.1103/physrevlett.116.188302). Tobias ErbMax Planck Institute for Terrestrial Microbiology Erb’s team successfully engineered enzymes to pull CO2 from the atmosphere and efficiently convert it into useful carbon-based compounds. Luke LavisHoward Hughes Medical Institute’s Janelia Research Campus “After a year of heavy traveling and writing papers, I finally got back into the lab and made some dyes with my own hands.” Matt MacDonaldAir Products & Chemicals MacDonald tells us he’s been whipping up new silicon-based compounds to build microelectronic devices with three-dimensional memory technology. Troy ListerSpero Therapeutics Lister disclosed his company’s lead drug candidate, SPR741, for the first time at a meeting in Boston. SPR741 is a molecule that disrupts the outer membrane of resistant bacteria so that antibiotics can sneak in and attack. Denis MalyshevTop secret start-up “I got a job at a biotech company that I’m super stoked about.” The firm is still in stealth mode, though, so Malyshev wouldn’t name names. Kami HullUniversity of Illinois, Urbana-Champaign Hull reports that her lab has “successfully done both directed and undirected anti-Markovnikov-selective amination” this year. (Translation for nonorganickers: They’ve achieved both tight and loose control over a reaction that adds amines to the most crowded carbon in a carbon-carbon double bond.) Hosea NelsonUCLA “My lab ran its first experiment. It worked!” Nelson says. The organic chemist adds that he also taught his first classes ever. “The second class was 100 times better than the first.” Karen HavenstriteTangible Science Havenstrite says her firm was issued two patents and received U.S. Food & Drug Administration clearance for its contact lens technology, which helps treat dry eye. Emily BalskusHarvard “I graduated my first class of Ph.D. students this year!” Jacob HookerHarvard Medical School Hooker celebrated his first graduate student getting her Ph.D. And the radiochemist will soon celebrate the birth of his second child, in mid-September. Matt KananStanford Kanan pointed us to a paper his team published in Nature on a reaction that uses simple molten salts to convert greenhouse gas CO2 into building blocks for making a type of polyester plastic (DOI: 10.1038/nature17185).

A field effect transistor (FET)-based immunosensor for detection of HbA1c and Hb

A field effect transistor (FET)-based immunosensor was developed for diabetes monitoring by detecting the concentrations of glycated hemoglobin (HbA1c) and hemoglobin (Hb). This immunosensor consists of a FET-based sensor chip and a disposable extended-gate electrode chip. The sensor chip was fabricated by standard CMOS process and was integrated with signal readout circuit. The disposable electrode chip, fabricated on polyester plastic board by Micro-Electro-Mechanical-Systems (MEMS) technique, was integrated with electrodes array and micro reaction pool. Biomolecules were immobilized on the electrode based on self-assembled monolayer and gold nanoparticles. Experimental results showed that the immunosensor achieved a linear response to HbA1c with the concentration from 4 to 24μg/ml, and a linear response to Hb with the concentration from 60 to 180μg/ml.

Multiplex Lateral-Flow Test Strips Fabricated by Two-Dimensional Shaping

We have fabricated paper- and nitrocellulose-based lateral-flow devices that are shaped in two dimensions by a computer-controlled knife. The resulting star, candelabra, and other structures are spotted with multiple bioassay reagents to produce multiplex lateral-flow assays. We have also fabricated laminar composites in which porous nitrocellulose media are sandwiched between vinyl and polyester plastic films. This minimizes evaporation, protects assay surfaces from contamination and dehydration, and eliminates the need for the conventional hard plastic cassette holders that are typically used to package commercial lateral-flow diagnostic strips. The reported fabrication method is novel, low-cost, and well-suited to (i) fabrication and adoption in resource-poor areas, (ii) prototype development, (iii) high-volume manufacturing, and (iii) improving rates of operator error.

Effect of deposit conditions on magnetic parameters of electroless CoFeB films

Electroless CoFeB films with soft magnetic characteristics were fabricated on poly-ester plastic substrate using sodium tetrahydroborate (NaBH4) as reducer. The change of film composition corresponding to magnetic characteristics was dependent on deposition conditions. As the concentration of NaBH4 and bath pH increase, the surface roughness of films reduces approximately from 160 to 137 nm. The soft magnetic film exhibited large saturation magnetization of 145 emμ/cc and low coercivity of about 7.6 Oe. Low boron content in film was found resulting in higher coercivity. At 2 GHz, the real permeability and imaginary permeability of films are respectively 275 and 141 as the concentration of reducer is 0.066 mol/L. Hysteresis loops of films show a remanence close to the saturation magnetization and along the hard axis display anisotropic field of 75 Oe.

The linear regression method for improving magnetic parameter of the electroless CoFeB films

The kinetics equation of deposition rate was implemented to help explain some of the mechanisms responsible for structures observed during the deposition of CoFeB films on poly-ester plastic. The plating rate of electroless CoFeB films is a function of concentration of sodium tetrahydroborate, pH of the plating bath, plating temperature and the metallic ratio. The estimated regression coefficient, confidence interval, residual error and confidence interval were confirmed by computer program. The optimal composition of the plating bath was obtained and the dynamic electromagnetic parameters of films were measured in the 2–10 GHz range. At 2 GHz, the permeability, magnetic loss of the electroless CoFeB films were 304,76.6 respectively as the concentration of reducer is 1 g·L−1.

Magnetic Properties and Kinetics Parameters of Electroless Magnetic Loss CoFeB Films

Electroless CoFeB films with good soft magnetic properties were fabricated on polyester plastic substrate from sodium tartarate as a complexing agent. The plating rate of electroless CoFeB films is a function of concentration of sodium tetrahydroborate, pH of the plating bath, plating temperature and the metallic ratio. The estimated regression coefficient b0 — b3 confidence interval, residual error r and confidence interval rint were confirmed by a computer program. The optimal composition of the plating bath was obtained and the dynamic electromagnetic parameters of films were measured in the 2–10 GHz range. At 2 GHz, the μ', μ” of the electroless CoFeB films were 304 and 76.6, respectively, as the concentration of reducer is 1 g/L. Magnetic hysteresis loop of the deposited CoFeB films show a remanence close to the saturation magnetization and coercivity of about 55.7–127.4 A/m. The loops along the hard axis display low anisotropic field Hk of 2 388–3 582 A/m.