(Press-News.org) These results were published in the prestigious journal ChemSusChem and thanks to the remarkable reviews, the paper was ranked among the top five percent publications in the field, thus earning a Very Important Paper (VIP) status. Furthermore, the editorial board featured this study on its cover.
Plastic pollution has become one of the most complex environmental issues, especially in the context of increasing production and demand for plastic materials. While innovations in polymer chemistry have radically changed our lives in the mid-20th century, the outstanding properties of plastics such as durability, chemical stability, strength and many other pose a serious problem when such materials are to be recycled.
According to some estimates, by the year 2050 there will be more plastic waste than fish in oceans by total weight, with the annual production of plastic materials reaching more than 1.1 billion tonnes.
Global production of plastics in 2015 was estimated to approximately 380 million tonnes, and the cumulative amount of waste generated from 1950s until 2015 was around 6.3 billion tonnes.
Only 9% of the waste was recycled and a staggering 60% of all plastics ever made ended up in the environment.
Rationalizing the use of plastic products and increasing the consumer awareness to sort and recycle waste is important in terms of pollution reduction.
However, finding technical solutions and methodologies to more efficiently process plastic waste and transform it into valuable chemicals still poses a great challenge to researchers around the world.
Polyethylene terephthalate (PET) is a synthetic polyester widely used in the production of soft-drink bottles and textile fibres. PET is a thermoplastic made of repeating units of terephthalic acid and ethylene glycol, linked together via an ester bond. Hence the popular name polyester, which is mostly used in the textile industry.
The ester linkage can be cleaved by hydrolysis to transform PET waste back into its monomer constituents.
Current chemical methods of PET recycling require the use of organic solvents at high temperatures and pressures to achieve depolymerization into monomer derivatives in practical yields.
Exploring the possibilities of using ball milling in the process of PET depolymerization, Dr. Vjekoslav Štrukil from the RBI Laboratory for Physical-Organic Chemistry successfully decomposed PET into monomer terephthalic acid at ambient temperature and pressure, with terephthalic acid being also the starting material for the production of this plastic.
Mechanochemistry has recently become one of the most promising fields of chemical science due to its extremely high efficiency, simplicity, speed, and the ability to significantly reduce the use of toxic organic solvents or completely avoid their use in chemical reactions.
''Although the International Union of Pure and Applied Chemistry (IUPAC) ranked mechanochemistry, as well as the degradation of polymers into monomers, among the top ten innovations in chemistry that will change the world, an effective mechanochemical PET degradation has not yet been described in the scientific literature'', says Dr Štrukil.
In the latest study Dr Štrukil describes a highly efficient alkaline hydrolysis of waste PET in the solid state at ambient temperature and pressure, achieved by mechanochemical ball milling with PET conversion and monomer isolated yields up to 99%.
Excellent yields were also achieved by the so-called vapor-assisted aging of manually mixed or pre-milled solid mixtures of PET and sodium hydroxide in a humid environment or in the presence of alcohol vapors. Aging in alcohol vapors represents an even milder route to PET depolymerization with 99% conversion at room temperature.
"Some of the experiments started just before the lockdown in March, followed by an earthquake. Of course, all this has slowed down and almost completely shut down the research. This meant those results were completely lost and we had to start our research all over again after the lockdown. However, that surreal situation has brought some new ideas, so when I returned to work in May, I focused my research on the aging of PET plastics at ambient temperature and pressure in vapors of different liquid phases such as acetonitrile, methanol or ethanol ", explains Dr Štrukil.
Published results show that mechanochemical milling and vapor-assisted aging, as two complementary solid-state techniques, have the potential for alkaline degradation of waste PET plastics and PET textile on larger scales as well. The described methodology could serve as a platform for the development of new and efficient environmentally-friendly processes for production of terephthalic acid from waste PET abundant in the environment, instead of non-renewable sources such as fossil fuels.
INFORMATION:
PULLMAN, Wash. - Man's best friend might actually belong to a woman.
In a cross-cultural analysis, Washington State University researchers found several factors may have played a role in building the mutually beneficial relationship between humans and dogs, including temperature, hunting and surprisingly - gender.
"We found that dogs' relationships with women might have had a greater impact on the dog-human bond than relationships with men," said Jaime Chambers, a WSU anthropology Ph.D. student and first author on the paper published in the Journal of Ethnobiology. "Humans were more likely to regard dogs as a type of person if the dogs had a special ...
Arctic sea ice is rapidly diminishing due to global warming, and scientists have found that sea ice dynamics have a big impact on circulation and precipitation patterns in Arctic Alaska, which lies at a climatological crossroads between the Arctic and North Pacific Oceans. Recent studies--most of which focus on current trends in the region and on what will happen in the future--have shown that circulation patterns in the Arctic and North Pacific Oceans influence one another.
Doctoral candidate Ellie Broadman of Northern Arizona University's School of Earth and Sustainability wanted to learn about this relationship on a longer timescale, so she developed and led a ...
A group of scientists is calling on governments to consider the continued use of strict control measures as the only way to reduce the evolution and spread of new COVID-19 variants.
The experts in evolution, virology, infectious disease and genomics - at the University of East Anglia (UEA), Earlham Institute and University of Minnesota - warn that while governments are negotiating a "precarious balance" between saving the economy and preventing COVID-19 fatalities, stronger action now is the best way to mitigate against more serious outcomes from such virulent strains later.
While COVID-19 vaccine deployment is now underway, a threat to vaccine effectiveness comes from other emerging strains, both existing - such as the UK, South Africa and Brazil variants ...
New estimates reveal extent of the health burden of armed conflict--affecting at least 630 million women and children worldwide in 2017, and contributing to more than 10 million deaths among children under 5 years of age over 20 years.
Changing nature of war is a growing threat to humanitarian access and the provision of essential health services for women and children, but responses in countries like Syria, Pakistan, and Colombia may provide context-specific innovative ways forward.
Armed conflicts are becoming increasingly complex and protracted and a growing threat to humanitarian access and the delivery of essential health services, affecting at least 630 million women and ...
Dramatic changes were seen in the delivery of radiotherapy treatments for cancer during the first wave of the coronavirus pandemic in England.
Much shorter radiotherapy courses were delivered, treatments were delayed where it was safe to do so and some increases were seen in order to compensate for reduced surgical capacity.
Experts believe the changes reflect an impressive adaption of services by the NHS, and that the overall impact on cancer outcomes is likely to be modest.
The new research, led by the University of Leeds, with Public Health England and the Royal College of Radiologists, reveals that there was a decrease in radiotherapy treatment courses of 19.9% in April, 6.2% in May, and 11.6% in June 2020, compared with the same months the previous year.
These decreases equated ...
GALVESTON, Texas - The results of a study by researchers at the University of Texas Medical Branch may pave the way for a new medicine delivery system that could reduce the incidence of pre-term labor and premature birth by allowing physicians to treat the 'fetus as the patient'. The study has been published in Science Advances.
It has long been suspected that pre-term labor is triggered by inflammation caused by a sick fetus. A new study by scientists at UTMB has proved the hypothesis by studying several important assumptions about the relationship between the health of a mother and her unborn child.
According to Dr. Ramkumar Menon, ...
PROVIDENCE, R.I. [Brown University] -- Metallurgists have all kinds of ways to make a chunk of metal harder. They can bend it, twist it, run it between two rollers or pound it with a hammer. These methods work by breaking up the metal's grain structure -- the microscopic crystalline domains that form a bulk piece of metal. Smaller grains make for harder metals.
Now, a group of Brown University researchers has found a way to customize metallic grain structures from the bottom up. In a paper published in the journal Chem, the researchers show a method for smashing individual metal nanoclusters together to form solid macro-scale hunks of solid metal. Mechanical testing of the metals manufactured ...
The enzyme that makes RNA from a DNA template is altered to slow the production of ribosomal RNA (rRNA), the most abundant type of RNA within cells, when resources are scarce and the bacteria Escherichia coli needs to slow its growth. Researchers used cryo-electron microscopy (cryo-EM) to capture the structures of the RNA polymerase while in complex with DNA and showed how its activity is changed in response to poor-growth conditions. A paper describing the research led by Penn State scientists appears January 22, 2020 in the journal Nature Communications.
"RNA polymerase is an enzyme that produces a variety of RNAs using information encoded in DNA," said Katsuhiko Murakami, professor of biochemistry and molecular biology at Penn State and the leader of the research ...
In a new publication from Cardiovascular Innovations and Applications; DOI https://doi.org/10.15212/CVIA.2019.1267, Hai Zou and Shengqing Li from the Institute of Pulmonary and Critical Care Medicine, Huashan Hospital, Fudan University, Shanghai, China consider ECMO/CRRT combined support in the treatment of critically ill SARS-CoV-2 pneumonia patients.
The authors of this article explored the experience with, and complications of, extracorporeal membrane oxygenation (ECMO) combined with continuous renal replacement therapy (CRRT) for treatment of critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia.
The survival rate of patients with cardiopulmonary failure treated with ECMO/CRRT in whom conventional ...
In a new publication from Cardiovascular Innovations and Applications; DOI https://doi.org/10.15212/CVIA.2019.1263, Yao Dong, Jun-E Liu and Ling Song from the Capital Medical University, Beijing, China consider risk factors for intraoperative pressure injury in aortic surgery.
Intraoperative pressure injuries are some of the most significant health problems in clinical practice. Patients undergoing aortic surgery are at high risk of developing an intraoperative pressure injury, with an incidence much higher than that associated with other types of cardiac surgery.
In this article the authors identify risk factors associated with an increased risk of intraoperative pressure injury in patients undergoing aortic ...
