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How do chemists solve the problem of plastic waste conversion

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Researchers have developed a new method to turn a mixture of several types of plastic waste into a valuable raw material and then use it to produce fuel or plastic.

We tend to lump all plastics together, but as you’ve probably noticed, water bottles, milk cans, egg cartons, and credit cards are made of different materials when throwing recyclables in the recycling bin. When they arrive at the recycling center, the plastic must be separated. This process can be slow and costly and ultimately limit the types of materials that can be recycled and the amount of recycling.

A new way for converting plastic waste

Now researchers have developed a new process that can convert a mixture of several types of plastic into propane, a simple chemical building block that can be used as fuel or turned into new plastics or other products. This process works because although their exact chemistry can vary, many plastics have a similar basic building block: they’re made of long chains of mostly carbon and hydrogen.

Along with environmental protections and policies, reengineering recycling can help prevent some of the worst damage caused by plastic wastes.

More than 400 million tons of plastic are produced worldwide every year. Of this amount, less than 10% is recycled, about 30% remains in use for a while, and the rest either goes to landfills or the environment or is burned.

Plastics are one of the most effective climate change factors: their production accounted for 4.3% of global greenhouse gas emissions in 2019. Recycling keeps plastics out of landfills and oceans, and finding new ways to produce building blocks for plastics can also help reduce greenhouse gas emissions. Our goal is to eventually see plastic waste as a valuable raw material, says Julie Rohrer, a postdoctoral researcher in chemical engineering at the Massachusetts Institute of Technology and one of the latest study’s authors.

One of the main advantages of the new approach Rohrer and his colleagues developed is that it works on two common plastics: polyethene and polypropylene.

Produce propane from plastic waste

plastic waste conversion

A mixture of plastics that make up milk bottles and containers is fed into a reactor, and propane is produced. This approach has high selectivity; propane makes up about 80% of the final product gases. “It’s exciting because it’s a step towards the idea of being cyclical,” Rohrer says.

Rohrer and his colleagues use a catalyst with two components to reduce the energy required to break down plastic: cobalt and a porous sand-like material called zeolite. Researchers aren’t yet sure exactly how the compound works. Still, Rohrer says it’s likely that the selectivity results from the pores in the zeolite limiting the reaction sites of the long molecular chains in the plastic. At the same time, the cobalt prevents the zeolite from becoming inactive.

This process is still far from being ready for industrial use. Currently, the reaction is done on a small scale and needs to continue to be economical.

Researchers are also looking at what materials to use. Cobalt is more common and less expensive than other catalysts they’ve tested, such as ruthenium and platinum, but they’re still looking for better options. Rohrer says that a better understanding of how catalysts work could allow them to replace cobalt with cheaper, more abundant ones. Rohrer says the ultimate goal of a thoroughly mixed plastic recycling system is not far-fetched.

Read more: Discovering secrets of human genome by AI

However, achieving this vision requires reforms. Polyethene and polypropylene are simple chains of carbon and hydrogen, while some other plastics contain other elements, such as oxygen and chlorine, which can challenge chemical recycling methods. For example, suppose polyvinyl chloride (PVC), widely used in bottles and pipes, gets into the system. In that case, it can deactivate or poison the catalyst and produce toxic gas byproducts, so researchers still need to find other ways to manage it. Find that type of plastic.

Other scientists are also looking for different ways to recycle mixed plastics. In a study published in October in Science, researchers used a chemical process alongside genetically engineered bacteria to break down a mixture of three common plastics.

Chemical oxidation

The first step involves chemical oxidation, which breaks the long chains and produces smaller molecules with oxygen attached to them. According to Shannon Stahl, one of the study’s authors and a chemist at the University of Wisconsin, this approach is practical because oxidation acts randomly on a wide range of materials.

As a result, plastics are oxidized to produce products that can then be consumed by bacteria engineered to feed on them. Researchers could create new plastics, such as nylon forms, by changing the bacteria’s metabolism.

Allie Werner, a biologist at the National Renewable Energy Laboratory and one of the authors of the study published in Science, says the research is still ongoing. In particular, researchers are trying to better understand the metabolic pathways bacteria use to make products to speed up the process and produce more significant amounts of valuable substances. This approach could potentially be used on a larger scale, as oxidation and engineered bacteria have become ubiquitous: the petrochemical industry relies on oxidation for millions of tons of material each year, and microorganisms are used in pharmaceuticals and food processing industries.

As scientists like Werner and Rohrer work on ways to recycle plastic, there are opportunities to rethink how we deal with massive amounts of plastic waste. “It’s a challenge that society is well-equipped to deal with,” Rohrer says. He notes that recently many researchers have turned to work on the optimal recycling of plastic.

Via: MITTECHNOLOGYREVIEW

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Discovery of new hydrothermal wells at a depth of 2.5 km in the ocean

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Scientists have managed to discover new active hydrothermal wells at a depth of 2,550 meters below the surface of the ocean, wells that emit water with a temperature of more than 300 degrees Celsius.

Discovery of new hydrothermal wells at a depth of 2.5 km in the ocean

Five active and new hydrothermal wells have been discovered in the Pacific Ocean at a depth of 2,550 meters on the seabed. These wells are places where superheated water erupts from the sea floor.

A hydrothermal vent is a crack on the surface of the earth, which geologically heats the surrounding waters.

Hydrothermal vents are often found in areas that are volcanically active, such as areas where tectonic plates are moving apart, ocean floors, and hot spots. The most famous hydrothermal system on land is probably Yellowstone National Park in America. Under the sea, hydrothermal vents are called black chimneys and can be found in most deep ocean waters.

The surroundings of hydrothermal wells are biologically more productive and are often home to complex communities that use chemicals dissolved in well fluids. Chemosynthetic activities form the base of the food chain and are used by organisms as diverse as large tube worms, bivalves, barnacles, and shrimp.

It is believed that there are active hydrothermal vents on Jupiter’s moon Europa and also on one of Saturn’s moons Enceladus. It is also believed that there were active hydrothermal vents on Mars in the past.

hydrothermal wells

It should be mentioned that these new hydrothermal wells were discovered by Sentry, which is an autonomous underwater probe, accompanied by Alvin, a manned submarine. These two technologies together accelerated the process of this research and exploration.

“By jointly operating these two advanced deep-sea submarines, we can make significant new discoveries about how the deep ocean floor is structured in some of the most inhospitable environments on Earth,” said Ross Parnell-Turner, a member of the operations team.

The team, led by Jill McDermott of Lehigh University, discovered these wells in a highly volcanic region in the eastern Pacific. These wells spit out fluids with a temperature of more than 300 degrees Celsius.

Read more: The discovery of a “lost world” belonging to a billion years ago

Supervolcanic region

These wells are formed due to the continuous separation of tectonic or tectonic plates in the East Pacific Rise, which is located in the wide volcanic mountain chain of the mid-ocean ridge. In this section, two tectonic plates are moving away from each other by approximately 11 cm per year.

Mid-ocean ridges are underwater mountain ranges formed by plate tectonics. The mid-ocean ridges are connected and form a global mid-ocean ridge system.

Thibaut Barriere, one of the senior scientists of this exploration from the University of Brest in France, says: The mid-ocean ridge accounts for more than 75% of all volcanic activity on our planet.

He, who is an expert in thermal measurements and modeling of hydrothermal wells, added: This area is filled with thousands of hot water springs in the deep sea like this, all of which remove 10% of the total internal heat of the earth.

We want to increase our understanding of how hydrothermal vents release heat and chemicals as they pass through the seafloor and affect the global ocean.

The researchers first sent Sentry to use its sensors to create high-resolution maps during the night. Maps of this robot were analyzed to show how humans travel to this location during the day. This process allowed them to collect first-hand data.

“The high-resolution maps that Sentry produces will allow us to identify new hydrothermal fields immediately after the robot returns to the deck,” McDermott said. Sentry gives us great targets for Alvin and the opportunity for multiple discoveries in one dive.

Finding extraterrestrial life

Wells rich in chemicals are known to support life around them, even in the darkest and deepest places on the sea floor. Studying these wells can provide valuable insights into the conditions they may support beyond Earth.

Saturn’s moon Enceladus is believed to have hydrothermal vents beneath its icy surface.

Additionally, understanding hydrothermal vents helps scientists understand the geophysical, chemical, and biological processes that shape our planet.

The study team aims to further investigate this hydrothermal activity and volcanoes along the eastern Pacific mid-ocean ridge in a subsequent mission that will also include the use of Sentry and Alvin.

It is worth mentioning that the Alvin probe has been involved in the discovery of several hydrothermal vents since 1977 and began its work by investigating an ocean ridge in the north of the Galapagos Islands.

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Climate change slows down the rotation of the earth!

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Climate change slows down the rotation of the earth!
Researchers at the University of California, San Diego have written in a new paper that climate change significantly alters the Earth’s rotation and disrupts time.

Climate change slows down the rotation of the earth!

Climate change seems to be disrupting time.

According to the Washington Post, the melting of polar ice caps due to global warming affects the rotation of the Earth and can also affect accurate timekeeping.

The planet is not going to stop, nor is it going to speed up so much that everyone is launched into space, but timing is an exact science in a high-tech society. For this reason, humans were forced to invent the concept of “leap second” more than half a century ago by observing slight changes in the Earth’s rotation.

Climate change has now complicated these calculations. In just a few years it may be necessary to introduce a “negative leap second” into the calendar to bring the planet’s rotation into line with the Universally Coordinated Clock.

University of California, San Diego (UCSD) geophysicist Duncan Agnew said: Global warming actually measurably affects the rotation of the entire Earth. Things are happening that have not happened before.

The main problem with timing

Chronology has traditionally had an astronomical basis. The earth is a kind of clock. In simpler times, the planet made one complete revolution on its axis, and everyone called that a day.

However, technologists are looking for difficult levels of accuracy. Atomic clocks already tell us what time it is. The goal of people who want to do things exactly right is to make sure that atomic time is perfectly aligned with astronomical time. For example, GPS-equipped satellites must know exactly where the earth is below them and exactly what time it is in order to accurately get you from home to your destination.

But the earth does not rotate at a constant speed. Our planet is in a complex gravitational dance with the moon, sun, ocean tides, its atmosphere, and the motion of the solid inner core.

Agnew noted that the Earth’s core is not accessible for close inspection and is a bit like a black box. By drilling into certain areas of the sea floor, geophysicists can understand details about the planet’s interior. Last year, it was reported that scientists had detected changes in the Earth’s rotation that seemed to match the 70-year fluctuations in the core’s rotation.

When scientists try to describe what the Earth is doing at any given moment, they have to account for a lot of tilting and shaking.

Read More: Climate changes will continue for 50 thousand years

Earth is no longer slowing down. In fact, the Earth has sped up quite a bit, and not a single leap second has been added since the end of 2016.

تغییرات اقلیمی، سرعت چرخش زمین را کند می‌کنند!

Melting of the Antarctic and Greenland ice sheets transports the melt water towards the equator. This process increases the equatorial bulge of the planet. Meanwhile, land compressed by ice rises at the poles, making the Earth more spherical. National Institute of Standards and Technology (NIST) physicist Judah Levine, who was not involved in this research, said: These two changes in the shape of the planet have opposite effects on its rotation.

Agnew’s new paper says that although the core makes the planet spin faster, changes in the planet’s shape caused by warming climates slow it down. Without this effect, the overall acceleration of the planet’s rotation might require timers to enter a negative leap second at the end of 2026, Agnew wrote. Due to climate change, this may not be necessary until 2029.

This research was published in “Nature” magazine.

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A device that produces endless energy from soil

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A device that produces endless energy from soil

A new fuel cell harnesses energy from soil-dwelling microbes to power sensors, harvesting nearly unlimited energy from the soil. In this article we will talk about a device that produces endless energy from soil.

A device that produces endless energy from soil

A team from Northwestern University has demonstrated a new way to generate electricity. They introduced a device the size of a book that sits on top of the soil and collects the force generated by microbes breaking down the soil (as long as there is carbon in the soil).

According to New Atlas, microbial fuel cells, as their name suggests, have been around for over 100 years. They work a bit like a battery, with an anode, cathode, and electrolyte, but instead of taking electricity from a chemical source, they work with bacteria that naturally donate electrons to nearby conductors.

This newly invented fuel cell relies on the ubiquitous natural microbes in the soil to generate energy.

Powered by soil, this device is a viable alternative to batteries in underground sensors used for precision agriculture.

A microbial fuel cell (MFC) or biological fuel cell is a biochemical system that produces electric current by mimicking the activity of bacteria that occurs in nature. A microbial fuel cell is a type of biochemical fuel cell system that generates electric current by diverting electrons produced from the microbial oxidation of reduced compounds (also known as fuel or electron donors) on the anode to oxidizing compounds (known as oxidizing agents or also known as electron acceptor) on the cathode through an external electrical circuit.

Fuel cells can be divided into two general categories “mediated and non-mediated”. The first fuel cells, introduced in the early 20th century, used a mediator, a chemical substance that transfers electrons from the bacteria in the cell to the anode. Non-intermediate fuel cells emerged in the 1970s. In this type of fuel cell, bacteria usually have electrochemically active proteins such as cytochromes on their outer membrane that can transfer electrons directly to the anode.

Read More: What if all the fish in the ocean disappeared?

Northwestern University researchers note the durability of their powerful fuel cell and have shown its ability to withstand various environmental conditions, including dry soil and flood-prone areas.

The issue so far has been to supply them with water and oxygen while they are buried in the soil. Although these devices have existed as a concept for more than a century, their uncertain performance and low power output have hampered efforts to put them into practice, especially in low-power conditions, says Northwestern University graduate student Bill Yen, who led the project. The humidity had stopped.

So the team set out to create several new designs aimed at providing cells with continuous access to oxygen and water and succeeded with a cartridge-shaped design that sits vertically on a horizontal disk.

A disk-shaped carbon-felt anode sits horizontally at the bottom of the device and goes deep into the soil, where it can capture electrons as microbes break down the soil.

Meanwhile, the conductive metal cathode is placed vertically above the anode. So the lower part goes deep enough to access the deep soil moisture, while the upper part is flush with the ground and a fresh air gap runs the entire length of the electrode, and a protective cap on top prevents soil from falling and It becomes waste and cuts off the cathode’s access to oxygen. Part of the cathode is also covered with a water-insulating material so that when water is present, a hydrophobic part of the cathode is still in contact with oxygen for the fuel cell to work.

The researchers used a waterproof material on the surface of the cathode, which allows it to work even during flooding and ensures gradual drying after immersion in water.

“These microbes are everywhere,” says George Wells, lead author of the study. They live in the soil everywhere now and we can use very simple engineered systems to get electricity from them. We’re not going to power entire cities with this energy, but we can capture very small amounts of energy to fuel essential, low-consumption applications.

Also, chemicals left over from batteries can potentially seep into the soil. This new technology is an environmentally friendly alternative that reduces environmental concerns associated with hazardous battery components and is also non-combustible.
The design performed consistently well in tests at varying levels of soil moisture, from completely waterlogged to relatively dry, and produced, on average, about 68 times more energy than its sensors needed to operate. It was also strong enough to survive extreme changes in soil moisture.

As with other sources of long-term electricity generation, such as diamond beta-voltaic batteries made from nuclear waste, the amount of electricity produced here is not enough to start a car or power a smartphone, but rather to power small sensors that can be used for long periods. work for a long time without needing to replace the battery regularly.

In addition, the researchers attached the soil sensor to a small antenna to enable wireless communication. This allowed the fuel cell to transmit data to a nearby station by reflecting existing radio frequency signals.

It is noteworthy that this soil fuel cell has a 120% better performance than similar technology.
Bill Yen says: “If we imagine a future with trillions of devices, we can’t make them all out of lithium, heavy metals, and toxins that are dangerous to the environment.” We need to find alternatives that can provide small amounts of energy to power a decentralized network of devices. In our search for a solution, we turned to soil microbial fuel cells, which use special microbes to break down soil and use that small amount of energy. As long as there is organic carbon in the soil for microbes to break down, our fuel cells can potentially survive.

Therefore, sensors like these can be very useful for farmers looking to monitor various soil elements including moisture, nutrients, pollutants, etc., and to use a technology-based precision agriculture approach. So if you put several of these devices around your farm, they can generate data for you for years, maybe even decades.

It should be mentioned that according to the research team, all the components of this device can be purchased from hardware stores. Therefore, there is no problem in the supply chain or materials for the widespread commercialization of this product.

This research was published in the ACM Journal on Interactive, Mobile, Wearable, and Ubiquitous Technologies.​

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