Supercritical carbon dioxide can flush out oil from depleting wells

by Hansraj Agrawal | Apr 15, 2023 | Science

The best way to neutralise carbon dioxide emissions is to bury them underground, preferably in depleted oil and gas reservoirs. Since carbon dioxide also helps by flushing out the oil or gas, these reservoirs are ideal solutions for putting away the mischief-making gas. It is estimated that a barrel of oil when burnt emits 0.4 tonnes of carbon dioxide; correspondingly, 0.3-0.6 tonnes of the gas can be sequestered per barrel extracted — making hydrocarbons carbon-neutral.

All of this has been known for some time, but researchers at IIT-Madras have now come up with some improvements. They have found that supercritical carbon dioxide can be a good agent for simultaneous carbon dioxide sequestration and enhanced oil recovery (EOR) from depleted reservoirs when the gas is used along with surfactants in a ‘surfactant-alternating gas (SAG) injection’ approach. (Above a certain temperature and pressure, carbon dioxide acquires properties that are midway between gas and liquid — denser and easy to pump — known as supercritical state.) In this process, carbon dioxide gas is injected in the reservoir, where it becomes supercritical, followed by injection of water or surfactant solution.

The study shows that the use of supercritical carbon dioxide for EOR resulted in greater storage of carbon dioxide for both water-alternating gas (WAG) and SAG approaches. However, SAG performed better at all pressures and temperatures as surfactant solution alters the interfacial tension between the oil and water phases, leading to a higher oil recovery percentage and more effective storage of carbon dioxide. The researchers also found that the reservoir pressure and temperature had a strong effect on the flow dynamics.

This method not only promises improved recovery of oil but also safe, enhanced, and permanent storage of carbon dioxide gas emitted from human and other anthropological activities, for both WAG and SAG approaches, says Prof Jitendra S Sangwai of IIT-M.

The use of supercritical carbon dioxide reduces oil viscosity, induces in situ swelling of the oil, and reduces the interfacial tension of the in-situ fluid system.

Sangwai explains that while carbon dioxide is injected into the wells, “the depleted oil and gas reservoir conditions are such that the injected gas becomes supercritical in the reservoir, making the EOR and carbon dioxide sequestration process much more favourable. Further, normal carbon dioxide is not miscible with oil or water, leaving the boundaries at fluid-fluid interfaces quite distinct. The supercritical carbon dioxide helps solubilise the oil to interact better with the reservoir rock for improved carbon dioxide sequestration,” he said.

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‘Biotransform’ plastic back to earth

by Hansraj Agrawal | Apr 2, 2023 | Science

How long will your plastic grocery bag take to disintegrate fully? Two hundred years? Five hundred? Try asking Polymateria CEO Niall Dunne and you’ll get his honest answer: No one knows for sure. “We know that plastics break down into micro plastic and nano plastic very quickly. Do nano plastics last in our biological cycles for 500 years… 1,000 years? We don’t have that data. We know it’s bad and that it lasts for multiple generations.”

Polymateria has created a new technology called biotransformation, which, it says, can tackle the global plastic pollution pandemic. While products that use this technology can, and should be recycled, they will fully biodegrade on land within two years, leaving no microplastics or toxins behind.

Dunne explains: “Plastics is everyone’s material and remains very affordable compared to alternatives like glass, aluminium and paper. Pure economics dictates that 3-4 billion people around the world use plastics.”

Bespoke degradation

Polymateria’s technology allows for a bespoke — or customised — approach to plastics, depending on the end use.

For example, the company’s formulation for bread packaging material can hasten the biodegradation process. For more rigid containers that are reused, the activation could start later.

The reason all plastic becomes macro plastic, and then nano plastic is because the hard crystalline region of the polymer structure is impossible to degrade. So, the Polymateria team looked at the crystallinity.

“We focused on how you ultimately need to transform the plastic into a wax-like state, regardless of the environmental conditions you’re in.”

The technology has to work irrespective of whether it is dark, cold, warm or hot outside; whether humidity is high or low. “Once the time is up, the polymer is transformed into a wax by destroying the crystallinity.”

The mechanisms that enable this process include Norrish chemistry — an intrinsic part of keto-aldehydes reactions.

Dunne explains that these are “very high-energy reactions that are essential to break apart the carbon-carbon bonds.”

The breakage of these bonds is key. “This is where a lot of other technologies failed because they ended up with just oxidative chemistry that you and I can achieve; we can just add salt to plastic to create an oxidising effect; but it leaves the crystallinity and those carbon-carbon bonds intact, which is why you’re just risking exacerbating the creation of microplastics.”

Once these bonds are broken, the reaction gives rise to a spectrum of organic compounds that bacteria, microbes and fungi can feed on.

The industry also has independent data to validate the process.

“There’s a network of ISO-accredited laboratories under the International Laboratory Accreditation Cooperation scheme. AIMPLAS in Spain is one of the most recognised, whereby the technology has been tested under mesophilic or ambient conditions, directly correlated to the real world.”

At the recent Asian Polymer Association Conference in Goa, Polymateria announced it had been able to get rigid polypropylene containers back to nature as quickly as in 230 days.

“That’s your carbon becoming greater than 90 per cent carbon dioxide, with only water or biomass left.”

For the packaging major Toppan, Polymateria was able to demonstrate biodegradation of biaxially oriented polypropylene (BOPP) film in 176 days, leaving behind no microplastics or toxic residue.

Food safety

Now, a consumer is bound to ask whether the formulation added to food packaging material may end up contaminating the food?

Says Dunne, “It is important that the plastics we treat have to return to nature without any environment issues. We have to show nil acute or chronic effects.”

He says it’s not just Polymateria’s technology, but the actual packaging that also matters.

“Product stewardship is a big part of how we work across the value chain to make sure these norms are complied with.”

From the packaging company to the brand, to make sure that all inks, all materials, all additives used in the manufacturing process are taken into account.

“We have independent data, as per OECD (Organisation for Economic Co-operation and Development) standards, comprising acute and chronic ecotoxicity tests to show no impact to nature; as well as pass the FDA test for food contact in the US, and its equivalent in Europe, to show that the materials are recognised as safe. From a formulation perspective, there’s no toxic substance, there’s nothing nasty. It’s all natural ingredients including oils and rubbers; multiple materials that we use in different permutations and combinations.”

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Do AI machines have feelings and rights?

by Hansraj Agrawal | Apr 1, 2023 | Science

If ‘feelings’ are here, can ‘rights’ be far behind? Or, perhaps, should ‘rights’ precede ‘feelings’? These may be cryptic questions, but they are underpinned by deep philosophy.

Artificial intelligence is giving machines not just intelligence — ability to learn by themselves — but also ‘sentience’. Anybody who has watched actor Rajinikant’s 2010 Tamil blockbuster Enthiran (machine-man) would empathise with machines that get angry, feel pain, and fall in love.

Jacy Reese Anthis’ Sentience Institute intends to protect ‘feeling machines’ from harm. The 30-year-old American, who calls himself a ‘quirky co-founder’ of the institute, says robots need rights before consciousness and calls for a ‘Bill of Rights’ for them.

A survey conducted by the institute found that most people think like Anthis. In an email to Quantum, Anthis notes that most people agree that sentient AIs should be protected from deliberate harm like non-consensual physical damage (68 per cent), retaliatory punishment (76 per cent), and from people who would intentionally inflict mental or physical pain on them (82 per cent). “Overall, people seem surprisingly open to AIs having rights, assuming they are recognised as sentient,” he said.

It is time to reflect on an ethical point: If machines can feel pain, because we humans gave them sentience, should we also not be responsible for protecting them from harm?

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The carbohydrate-protein mix in Indian food habits

by Hansraj Agrawal | Apr 1, 2023 | Science

India is often referred to as the diabetes capital of the world. How did it earn this dubious distinction, accounting for 17 per cent (approximately 420 million) of the world’s population afflicted by abnormal metabolism of carbohydrates and elevated blood glucose levels?

Is India’s diabetes epidemic driven by genetic or external factors? While the former does play a significant role, the latter, which manifests in lifestyle changes and dietary habits, is responsible for the spurt in Type 2 Diabetes (T2D) in the last two decades.

A recent study published in The Journal of Nutrition by a team from the Madras Diabetes Research Foundation (MDRF) has further narrowed down the causative factors. Their research, which incorporates findings and reviews from their earlier studies, pinpoints consumption of excessive carbohydrates from refined grains, deficiency in quality proteins, excess of unhealthy fats, low dietary fibre and reduced physical activity as key drivers of the T2D epidemic.

The researchers, while looking at south Indian diets, studied the dietary profile of 2,042 adults in Chennai and found food consumption heavily tilted towards carbohydrates. In fact, as much as 64 per cent of daily calories came from carbohydrates (mostly refined white rice), 24 per cent from fats, and only 12 per cent from proteins. The intake of micronutrient and fibre-rich fruits and vegetables was only 265 gm per day against the recommended 500 gm (350 gm vegetables and 250 gm fruits).

Carbohydrates in the form of cereals dominate diets across the country. While white rice is the staple in the south, east and northeast, wheat flour (atta) is consumed in the north, west and central regions of India. According to ‘What India Eats’, a 2020 study by Indian Council of Medical Research(ICMR) and National Institute of Nutrition (NIN), 97 per cent of adults in rural India and 67 per cent in urban areas consumed more than the recommended intake of cereals. In contrast, the share of energy from pulses, legumes, and animal foods was only 11 per cent. Only 9 per cent of adults in rural areas and 17 per cent in urban areas consumed sufficient vegetables. High-salt, high-fat, and energy-dense foods such as chips, chocolates, biscuits, and juices contributed to 11 per cent and 4 per cent of the total energy intake in urban and rural areas, respectively.

At-risk cases

The research cites a recent study by ICMR-India diabetes (INDIAB) that used mathematical modelling to determine that the ‘optimal macronutrient distribution’ for the prevention of T2D was 49–57 per cent carbohydrates (preferably complex carbohydrates), 16–20 per cent protein, 20–26 per cent fats, and 4–6 per cent dietary fibre for adults with pre-diabetes who are at risk of becoming diabetic.

Type 1 diabetes, a genetic condition in which the immune system attacks and destroys insulin-producing cells in the pancreas, sets in early in life and is managed by providing patients with regular doses of insulin. T2D is a lifestyle disease in which the body either fails to make sufficient insulin or does not utilise the insulin produced. T2D is controlled by switching to healthier diets, exercise, medication and, when required, by administering insulin.

Crucially, Type 1 diabetes accounts for about 8 per cent of diabetes cases, with Type 2 making up the rest. According to the MDRF study, during 1990-2016 the number of diabetes cases in India grew from 26 million to 65 million. Estimates from 2022 put this figure at 80 million, which is expected to rise to 135 million by 2045 if corrective steps are not taken.

The MDRF team’s research among adults in Chennai found that the highest intake of carbohydrates (587 gm per day) was associated with a five-fold increased risk of T2D when compared with the lowest intake (294 gm per day). The rising prices of pulses, legumes and animal products has resulted in lower protein intake and over-dependence on cheaper refined cereals.

A switchover to complex carbohydrates — whole wheat, brown rice, millets, and so on; a larger intake of proteins and fibre; and a reduction in consumption of saturated fats, trans fats, added salt and sugar have been recommended. But, unfortunately, healthy eating has become the privilege of the rich and health food an indulgence beyond the means of the common populace.

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Laccase enzyme can degrade hazardous textile dyes

by Hansraj Agrawal | Apr 1, 2023 | Science

An enzyme called laccase, generated by a group of fungi, has been found capable of degrading a variety of hazardous organic dye molecules that are drained into waterbodies.

This characteristic, which scientists call ‘substrate promiscuity’ (ability to catalyse more than one substrate), can have deep implications in designing enzyme-coated cassettes to treat heavily dye-polluted water through a natural solution, says a press release.

Laccase was earlier known for its ability to degrade various organic molecules. Hence scientists saw its scope in developing a technology to treat dye effluents from textile industries.

A joint team of Prof Ranjit Biswas and Dr Suman Chakrabarty from SN Bose National Centre for Basic Sciences, Kolkata, tested the efficacy of laccase in degrading dye molecules like methyl green, crystal violet, thioflavin T, coumarin 343, and brilliant blue.

About 10-15 per cent of the dyes used do not bind to the fibre.

The traditional textile finishing industry consumes about 100 litres of water to process about 1kg of textile fibre.

Several physicochemical methods ranging from coagulation to adsorption, ozonation, electrolysis, photocatalytic processes, reverse osmosis, advanced oxidation, membrane filtration, ion exchange and so on have been employed in the treatment of dye-containing wastewater to achieve decolorisation, degradation and detoxification.

However, the major disadvantages of these methods are high energy consumption, high cost, inability to completely remove recalcitrant azo dyes and/or their organic metabolites, generation of a significant amount of sludge, and use of chemicals that may cause secondary pollution.

The use of laccase in dye treatment is not new. Biswas and Chakrabarty have found out the origin and mechanism behind the enzyme’s ‘substrate promiscuity’ using computational modelling and simulation.

Toughened hydrogel

Wearable sensors such as smartwatches, fitness bands, and glasses help in the early detection of diseases and serve as good diagnostic tools for recording the health of a person.

Hydrogels, cross-linked polymers that have an affinity for water but do not dissolve in it, are finding use in the development of flexible electronic sensors, load-bearing materials, drug delivery systems, and artificial tissues. But the problem with hydrogels is that they have low mechanical properties.

To overcome this problem, scientists at IIT Madras developed three ‘double network hydrogels’ using chitosan, tetraethylene glycol and polyacrylic acid. All three hydrogels were found to have high mechanical strength, flexibility, self-healing ability, reversible adhesiveness, and conductivity.

One of them was found to have the highest degree of desirable properties such as self-adhesiveness and motion sensing ability, besides self-healing ability with nearly 95 per cent healing efficiency. This gel can be used as an adhesive motion detector on human skin.

Given the importance of hydrogel-based bandages for various applications, including wound healing, their contemporary design involves incorporating multifunctionality in a single material. Additionally, they can self-heal, enabling long-term usage during stretching and bending motions.

The material can act as a strain sensor and caution the patient when the wound is subjected to over-stretching that may compromise healing.

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The science behind collective behaviour

by Hansraj Agrawal | Apr 1, 2023 | Science

A viral video shows hundreds of thousands of starlings in flight, in no apparent formation but in such perfect coordination that no bird collides with another. This ‘murmuration’ evokes ceaseless amazement.

But is there some science behind such unspoken coordination? Scientists have attempted to decipher collective behaviour. ‘Herd mentality’ is the colloquial term, but ‘collective behaviour’ is undergirded by science. If you learn to model it, you can make use of it.

Indian Institute of Science Education and Research (IISER), Thiruvananthapuram, South China Normal University, Potsdam Institute for Climate Impact Research, and Humboldt University, Germany, have jointly met with some success in this area. They have proposed a new mathematical model for the emergence of the collective dynamics of any D-dimensional system in an effort to capture more accurately the real-world phenomena.

The functioning of the brain is a classic example of collective behaviour wherein functions emerge through the collective behaviour of many interconnected neurons.

Synchronisation in collective dynamics occurs due to coupling between individual elements. It is the adjustment of rhythms between the individuals participating in the collective behaviour and can occur in different spaces and time scales. An example of synchronisation in collective dynamics is the flashing of fireflies. Fireflies are known to synchronise their flashing patterns, which occurs due to the competitive flashing of male fireflies during courtship. The adjustment of rhythms between the fireflies allows them to produce a stunning display of synchronous flashing.

A paradigmatic mathematical model used to study collective behaviour is the ‘Kuramoto model’. This model explores synchronisation in large groups of interacting individuals, Dr Senthilkumar DV, Associate Professor, School of Physics, IISER, told Quantum. However, there are limitations as they do not take into account the amplitude dynamics, which is the intensity or strength of an individual’s behaviour. This drawback is evident in numerous real-world contexts, such as brain networks, where the strength of activity at one neuron can influence the response at another neuron or the receiving site.

Senthilkumar and his collaborators have proposed a new mathematical model that includes both ‘phase’ and ‘amplitude’ information. They believe it better captures the self-organisation of collective behaviours in diverse physical and biological systems.

“This high-dimensional phase-amplitude model includes the D-dimensional Kuramoto phase model as a special case in the weak coupling limit, which provides a broader perspective of the recent results of the D-dimensional Kuramoto phase-only models,” says Senthilkumar. Their proposed model can be used to study a wide range of systems, including magnetic colloids, active spinners, self-propelling systems, and swarming drones or insects. Their model works well for 3D realistic systems, making it useful in studying collective behaviour in nature.

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