Developing the Eastern Province of Sri Lanka through Chemistry

Chemistry is essential for sustaining all forms of life, as everything around us is made up of chemical components. This importance positions chemistry as a key discipline within the life sciences, highlighting the crucial role of chemists in overcoming obstacles to improving quality of life. In developed nations, citizens greatly benefit from the significant contributions of chemists in areas such as chemical knowledge, processes, technology, and products. In contrast, chemists in developing countries face challenges due to their limited numbers and various hindrances, resulting in a minimal impact on the population. Consequently, many individuals in these countries suffer from diseases, malnutrition, and poor living conditions. Chemists in developing nations have the potential to make a substantial difference, particularly by enhancing chemical education and improving access to food, safe drinking water, and medicines. This progress can only be achieved if chemists from developed countries possess cultural awareness and are willing to collaborate with those in need. 

Developing the Eastern Province of Sri Lanka through chemistry involves various approaches that can enhance agriculture, industry, and public health. Here are some strategies:

1. Sustainable Agriculture

• Soil Chemistry: Analyze soil composition to optimize fertilizer use, ensuring crops receive essential nutrients while minimizing environmental impact.
• Pesticides and Herbicides: Develop organic or biopesticides to reduce chemical runoff and promote healthier ecosystems.
• Biofortification: Enhance nutritional content of staple crops through chemical processes, improving food security.

2. Water Purification

• Chemical Treatment: Implement advanced water purification methods using chemicals to ensure safe drinking water.
• Wastewater Management: Develop chemical processes to treat agricultural runoff and sewage, protecting local water sources.

3. Renewable Energy

• Biogas Production: Utilize agricultural waste through anaerobic digestion to produce biogas, reducing dependence on fossil fuels.
• Solar Energy: Promote the use of materials with high photoconductivity for solar panels, harnessing the region's sunlight.

4. Industrial Development

• Material Science: Invest in research for developing new materials, such as biodegradable plastics or eco-friendly construction materials.
• Chemical Manufacturing: Establish small-scale chemical manufacturing plants that utilize local resources, creating jobs and supporting the economy.

5. Health and Sanitation

• Pharmaceutical Development: Encourage research into locally sourced medicinal plants to develop natural remedies or supplements.
• Public Health Initiatives: Use chemistry to develop low-cost diagnostic tools for prevalent diseases in the region.

6. Education and Research

• Community Workshops: Organize programs to educate farmers and entrepreneurs about sustainable practices and chemical applications in their fields.
• Collaborations with Universities: Partner with academic institutions to foster research and innovation in chemistry-related fields.

7. Environmental Protection

• Pollution Control: Implement chemical monitoring systems to track pollutants in air and water, ensuring environmental regulations are followed.
• Recycling Programs: Promote chemical processes for recycling waste materials, reducing landfill use and environmental impact.(https://amudu-gowripalan.blogspot.com/search?q=pyrolysis )

By integrating chemistry into these areas, the Eastern Province can experience sustainable growth while improving the quality of life for its residents.

 Hydrothermal carbonization (HTC) is a thermochemical process used to convert organic materials into a coal-like substance, typically referred to as hydrochar. This process occurs in the presence of water at elevated temperatures (typically between 180°C and 250°C) and under autogenous pressure (which is the pressure generated by the water at these temperatures). The process can take anywhere from a few hours to several days, depending on the desired outcome.

Key Aspects of Hydrothermal Carbonization:

1. Feedstock:

   • HTC can process a wide variety of organic materials, including agricultural residues, sewage sludge, food waste, and even wet biomass that would be difficult to process using other thermochemical methods like pyrolysis.

2. Process Conditions:

   • Temperature: Typically 180°C to 250°C.
   • Pressure: The process occurs under the pressure generated by water at the given temperature, often between 10 and 40 bar.
   • Residence Time: The reaction time can vary from several hours to a few days, depending on the feedstock and desired properties of the hydrochar.

3. Product:

   • The primary product is hydrochar, a carbon-rich solid that can be used as a soil amendment, for energy production (as a fuel), or as a precursor for activated carbon.
   • The process also produces process water, which contains dissolved organic compounds and nutrients, and gases such as CO2.

4. Advantages:

   • HTC is particularly effective for wet biomass, as it does not require drying of the feedstock.
   • It can potentially reduce the environmental impact of waste by converting it into useful products.
   • The hydrochar produced has a higher energy density compared to the original biomass and can be used as a renewable energy source.

5. Applications:

   • Waste Management: Converting organic waste into hydrochar reduces the volume of waste and can produce a valuable product.
   • Soil Amendment: Hydrochar can improve soil properties by enhancing nutrient retention and soil structure.
   • Energy Production: Hydrochar can be used as a solid fuel or further processed into activated carbon for use in filtration systems.

HTC is seen as a promising technology for sustainable waste management and renewable energy production, particularly in applications where wet biomass is abundant.

Oxidation,Free Radicals and Antioxidants

 Oxidation:

 

Oxidation is a chemical reaction in which a substance loses electrons, becoming more positively charged. This process can occur when a substance reacts with oxygen or other electronegative elements. The most common example of oxidation is the rusting of iron when it reacts with oxygen in the presence of moisture.

 

In living organisms, oxidation is a crucial part of various physiological processes. For example, it is involved in the breakdown of nutrients to release energy in cells. However, oxidation can also lead to the production of harmful byproducts known as free radicals.

 

Free Radicals:

 

Free radicals are highly reactive molecules that contain unpaired electrons. They are produced naturally in the body during normal metabolic processes or can be generated due to external factors like pollution, radiation, or unhealthy lifestyles (e.g., smoking). These free radicals are unstable and can cause damage to cells and tissues by reacting with and stealing electrons from other molecules in the body, leading to a chain reaction of cellular damage.

 

Antioxidants:

 

Antioxidants are substances that can neutralize free radicals by donating electrons without becoming unstable themselves. They act as a defence system against the harmful effects of oxidative stress caused by free radicals. Antioxidants play a crucial role in maintaining the overall health and function of cells and tissues in the body.

 

The body has its own antioxidant defence system, including enzymes like superoxide dismutase, catalase, and glutathione peroxidase, which help counteract the harmful effects of free radicals. Additionally, many antioxidants are obtained from the diet, including vitamins C and E, beta-carotene, selenium, and various phytochemicals found in fruits, vegetables, nuts, and seeds.

 

Importance of Antioxidants:

 

Having an adequate intake of antioxidants is important because excessive free radicals can lead to oxidative stress, which has been linked to various health issues, including:

 

Ageing: Oxidative stress is considered one of the contributing factors to the ageing process.

 

Chronic Diseases: It has been associated with several chronic diseases, such as heart disease, diabetes, cancer, and neurodegenerative disorders like Alzheimer's and Parkinson's disease.

 

Inflammation: Oxidative stress can trigger inflammation, which is involved in many diseases.

 

Cellular Damage: Oxidative stress can damage cellular components like DNA, proteins, and lipids, impairing cell function and potential mutations.

 

In summary, oxidation is a chemical reaction involving the loss of electrons, and it can produce harmful free radicals. Antioxidants are essential in neutralizing these free radicals and protecting the body from the potential damage they can cause. Eating a balanced diet rich in antioxidants is a key part of maintaining good health and reducing the risk of various diseases associated with oxidative stress.

The steps to use paddy husk gasification for Rural Electrification

The energy cost now strongly depends on the prices of fossil fuels due to the world's intense fuel dependence on energy production. This is causing pain in most of the world's nations, and Sri Lanka is no different. From this perspective, the promotion of biomass as a source of renewable energy is significant to the country. Given that rice is the nation's leading food and the crop with the most considerable area under cultivation, it has been discovered that the rice husk (RH) produced during paddy processing has a significant potential for producing electricity.

Paddy husk gasification is a process that can be used to generate electricity from agricultural waste, specifically the husks of rice. The process involves heating the husks in a gasifier, which breaks down the biomass into a gas that can power an engine or a turbine to generate electricity.

The Husk Power Systems (HPS) and Decentralized Energy Systems India (DESI), two businesses that have successfully offered power access utilizing this resource, have popularized rice husk-based electricity generation and supply throughout South Asia. To examine the factors that make a small-scale rural power supply company profitable and determine whether a collection of villages can be electrified using a larger facility. Using a financial analysis of alternative supply alternatives that consider the residential and commercial electricity demands under various scenarios, Serving just consumers with low electricity usage results in the electricity-producing facility only being used to part of its capacity, which raises the cost of supply. Increased electricity use improves financial viability and considerably helps high-consumption clients. The feasibility and levelized cost of the collection are enhanced by integrating rice mill demand, especially during the off-peak period, with a predominant residential peak demand system. Finally, larger plants significantly reduce costs to provide a competitive supply. However, the more critical investment requirement, risks associated with the rice mill's monopoly supply of husk, organizational challenges related to managing a more extensive distribution area, and the possibility of plant failure could negatively impact investor interest.

 

Here are the steps to use paddy husk gasification for rural electrification:

 

Assess the availability of paddy husk: The first step is to determine the amount of paddy husk available in the rural area. This will help to determine the size of the gasification system that will be needed.

Choose the gasification system: There are different types of gasification systems available, including fixed beds, fluidized beds, and entrained flow gasifiers. The choice of the gasification system will depend on the amount of paddy husk available and the amount of electricity that needs to be generated. 

Install the gasification system: Once chosen, it must be installed in the rural area. The design should be located close to the source of the paddy husk to minimize transportation costs. 

Operate the gasification system: It must be operated properly to ensure electricity is generated efficiently. This involves feeding the paddy husk into the gasifier and maintaining the appropriate temperature and pressure.

 

Distribute the electricity: The generated electricity can be distributed to the surrounding rural area using a grid or a microgrid. The distribution system should be designed to meet the needs of the rural community. 

Monitor and maintain the system: It is essential to monitor the gasification system to ensure that it operates efficiently and to perform regular maintenance to prevent breakdowns and ensure a long lifespan.

 

In summary, paddy husk gasification can be a sustainable solution for rural electrification.

What is Plant-e

 

Plant-e is a technology that generates electricity from living plants through a process known as microbial fuel cells (MFCs). MFCs use the natural metabolic processes of certain bacteria to break down organic matter, such as the sugars and other compounds produced by plants during photosynthesis, and generate electricity in the process.

Microbial Fuel Cells (MFCs) have been aptly described by Du et al. (2007) as “bioreactors that convert the energy in the chemical bonds of organic compounds into electrical energy through the catalytic activity of microorganisms under anaerobic conditions”.

In Plant-e's technology, electrodes are placed in the soil near the roots of the plants, and the bacteria living in the soil around the roots consume the organic matter and produce electrons, which can then be captured and used to generate electricity. The technology has potential applications in renewable energy, agriculture, and environmental monitoring.

While the technology is still in its early stages of development, it has shown promise as a sustainable and environmentally-friendly alternative to traditional forms of energy generation.

Electrochemistry Mcq 1979 to 2020

 

Electrochemistry is the study of chemical processes that cause electrons to move. This movement of electrons is called electricity, which can be generated by movements of electrons from one element to another in a reaction known as an oxidation-reduction ("redox") reaction.

பொன் ஊமத்தை

 சித்தர்கள், முனிவர்கள், ரிஷிகள் போன்றோர் காடுகளிலும், மலைகளி லும், வனங்களிலும் குடில் அமைத்தும்,குகைகளிலும் தவம் இயற்றி வாழ்ந்து வரும் காலங்களில் கொடிய மிருகங்கள் மற்றும் விஷ ஜந்துக்களின் இடர் பாடுகளில் இருந்து காத்துக் கொள்ள, கட்டுக்குள் கொண்டு வர பல அதிசய மூலிகைகளையும், சூட்சும மந்திரங்களையும் கையாண்டு வந்துள்ளனர்.

அவைகளில் ஒன்றுதான் "சித்தர்கள், முனிவர்கள், ரிஷிகள் போன்றோர் காடுகளிலும், மலைகளி லும், வனங்களிலும் குடில் அமைத்தும்,குகைகளிலும் தவம் இயற்றி வாழ்ந்து வரும் காலங்களில் கொடிய மிருகங்கள் மற்றும் விஷ ஜந்துக்களின் இடர் பாடுகளில் இருந்து காத்துக் கொள்ள, கட்டுக்குள் கொண்டு வர பல அதிசய மூலிகைகளையும், சூட்சும மந்திரங்களையும் கையாண்டு வந்துள்ளனர்.

அவைகளில் ஒன்றுதான் "பொன் ஊமத்தை" என்ற மூலிகை ஆகும். இம் மூலிகையைப் பற்றிய அகத்தியர் பெருமான் பாடல்...

காணவே பொன்னி னூமத்தை மூலி

கருவான மூலியடா கந்தர் மூலி

பாணமாம் பச்சையது தழையினாலே

பாருலகில் சொர்ணமதைக் காணலாகும்

தோணவே சாரதனைப் பிழிந்துமல்லோ

தோராமல் ரவிதனிலே காயவைத்து

மாணவே செம்புருக்கி கிராசமீய

மன்னவனே பசுமையடா தங்கந்தானே

தங்கமா மூலியது தழைதானாகும்

சாங்கமுடன் சொர்ணமென்ற பீசமாகும்

சிங்கமதைத் தான்மயக்குந் தழை தானாகும்

புகழான காயாதி இதற்கொவ்வாது

எங்கேனுந் தேடியுழைந் தலைந்திட்டாலும்

என்மகனே விதியாளி காண்பான் தானே

காண்பானே தழையினது மகிமையாலே

காவனத்தில் வசிக்கின்ற மிருகமெல்லாம்

ஆண்பான மதமடங்கி தன்முன்னாக

அப்பனே எதிர் வணங்கி பணியும் பாரு

சாண் பாம்பே யானாலு முந்தனுக்கு

சட்டமுடன் ஏவலுக்கு முன்னாய் நின்று

வீண்பாக முறையாம லடிவணங்கி

வித்தகனே முறைபாடாய் நடக்கும் பாரே

இந்த அதிசய பொன்னூமத்தை மூலிகை கந்தர் முருகனின் மூலிகை ஆகும்.இம்மூலிகையால் ரசவாதம் செய்யலாம்.இம்மூலிகையை இடித்து பிழிந்து சாரெடுத்து ரவி என்ற வெயிலில் காய விடவும். பின்பு தாமிரம் என்ற செம்பை உருக்கி இதில் சாய்க்க வேண்டும்.

இந்த செம்பை மீண்டும் உருக்கி சாய்க்க வேண்டும். ஒவ்வொரு முறை யும் புதுச்சாரு ஊற்ற வேண்டும். இது போல் பதினொரு முறை உருக்கி சாய்க்க பசுமையான தங்கமாகும்.

இம் மூலிகையின் வாசனையால் சிங்கம் மயங்கும், யானை முதல் அனைத்து மிருகங்களும் வசியமாகும். எதிர் வந்தாலும் அடிவணங்கி பணியும். பாம்பு போன்ற ஜந்துக்கள் நம் சொல்லுக்கு கட்டுப் படும்.

- சித்தர்களின் குரல்.

Qualitative Analysis - Group 1 - Inorganic Chemistry

Qualitative Inorganic Analysis  

Objective To identify ions that are present in unknown solutions and solids using "wet chemical" separation methods.  These methods are based on the behavior of different ions when they react with certain reagents.  Reagents are substances chosen because of their chemical activity with the ions being analyzed.  Learning the chemistry that governs the identifications is an important part of this experiment.

Principles All measurements are all comparisons against references.  We normally talk about quantitative measurements of meters, kilograms, and second.  But qualitative measurements are no different.  In this experiment, you compare the chemical changes you observe in a known sample with observations on your unknown sample to determine the identity of the anions and cations in the unknown.  You’ll start with a sample known to contain all 9 cations and an unknown with 4-6 cations.

In the classical analytical scheme the chemical properties of the different ions, both positive ions (cations) and negative ions (anions), are used to separate a mixture of them into successively smaller groups of ions, until some characteristic reaction may be used to confirm the presence or absence of each specific ion.  In addition to analyzing the unknown for its component ions, the qualitative analysis scheme highlights some of the important chemical behavior of these metal salts in aqueous solution.  The concepts of chemical equilibrium are emphasized, as illustrated by precipitation reactions, acid-base reactions, complex-ion formation, and oxidation-reduction reactions.  Each experiment presents a puzzle that is solved "detective fashion" by assembling a collection of chemical clues into an airtight case for the correct identifications.  As a bonus, the clues often take the form of colorful solutions and precipitates.

The qualitative analytical scheme is divided into three parts: 

1. Separation and identification of cations.

2. Identification of anions.  

3. Identification of an unknown in which both a cation and anion are present.

Overview of cation separation process: 

1.  Separate cations that form insoluble chlorides (Ag+, Pb2+) 

2.  Separate cations that t have highly insoluble hydroxides that precipitate when the hydroxide ion          concentration is small, approximately 10-5 M.  (Fe3+, Cr3+, Al3+) 

3.  The remaining 4 cations (Ba2+, Mg2+, Cu2+, Ni2+) cations all precipitate at when the hydroxide        ion concentration increases to 0.01 M so we add SO42- to remove the Ba2+ as BaSO4.  Next add        ammonia to form complex ions (Cu(NH3)22+ and Ni(NH3)22+.  These complex ions are more          stable than are the hydroxides so we can add hydroxide ion to precipitate Mg2+ 

4.  We have a mixture of Cu2+, which we detect by adding iodide and Ni2+, which is detected by     

      adding a reagent called dimethylglyoxime.

 

In qualitative analysis, the ions in a mixture are separated by selective precipitation. Selective precipitation involves the addition of a carefully selected reagent to an aqueous mixture of ions, resulting in the precipitation of one or more of the ions, while leaving the rest in solution. Once each ion is isolated, its identity can be confirmed by using a chemical reaction specific to that ion.

Cations are typically divided into Groups, where each group shares a common reagent that can be used for selective precipitation. The classic qualitative analysis scheme used to separate various groups of cations is shown in the flow chart below.

PYROLYSIS TECHNOLOGY

Pyrolysis is the thermal decomposition of complex organic matter in the absence of oxygen to simpler molecules that can be used as feedstocks for many processes. The main products produced by the pyrolysis process are

• activated carbon,
• biodiesel and 
• syngas.

Pyrolysis always consists of the endothermic reaction, though general combustion is done by the generation of heat reaction in the system

that produces solid, liquid, and gas, heating it at moderately high temperatures under a no oxygen or low oxygen atmosphere.

Biodiesel produced by the process of pyrolysis can be used purely as a fuel or for other petroleum products. The syngas is typically used for

combustion or to run turbines for power generation, including running the plant itself.

The biomass used in pyrolysis is typically composed of cellulose, hemicellulose, and lignin. The main parameters that govern the pyrolysis

process are 

• temperature, 
• heating rate, 
• solid residence time, 
• volatile residence time, 
• particle size and 
• density of particles.

Pyrolysis is, therefore categorised into three major types:

• flash,
• fast and 
• slow pyrolysis 

and are respectively based on

• temperature,
• heating rate and 
• residence time. 

The products of pyrolysis thus vary dramatically according to type. Cellulose is converted to

biochar and volatile compounds.

Carbon dioxide Removal from Biogas

A variety of processes are being used for removing CO2 from natural gas in petrochemical industries. Several basic mechanisms are involved to achieve selective separation of gas constituents. These may include physical or chemical absorption, adsorption on a solid surface, membrane separation, cryogenic separation and chemical conversion. 

Carbon dioxide is a noncombustible constituent of biogas lowers its heat value. Removal of carbon dioxide is not necessary when gas is to be used for cooking or lighting purposes only. A number of methods have been developed for CO2 removal (scrubbing) which depending upon the technique involved are called water-scrubbing, caustic-scrubbing, solid absorption, liquid absorption and pressure separation.

A brief description of these methods is as follows:

For biogas scrubbing physical/chemical absorption method is generally applied as they are effective even at low flow rates that the biogas plants are normally operating at. Also, the method is less complicated, requires fewer infrastructures and is cost-effective. 

Method # 1. Water Scrubbing:

One of the easiest and cheapest methods involves the use of pressurized water as an absorbent. The raw biogas is compressed and fed into a packed bed column from the bottom; pressurized water is sprayed from the top. The absorption process is, thus a counter-current one. This dissolves CO2 as well as H2S in water, which are collected at the bottom of the tower. 

In this method, gas is made to pass through water which absorbs part of CO2. The inherent limitation of this method is that it requires a large quantity of water. Based on studies carried out by H.M. Lapp, 7 ft3 (0.2 m3) of biogas at 68°F (20°C) and 1 atmospheric pressure (1.03 kg/cm2) requires 2.7 gallons (12.3 litres) of water for CO2 removal. CO2 is highly soluble in water. Spent water following absorption of CO2 becomes acidic and hence unsuitable for several applications as it corrodes metallic surface it comes in contact with.

Method # 2.CHEMICAL ABSORPTION

Caustic Scrubbing:

Chemical absorption involves the formation of reversible chemical bonds between the solute and the solvent. Regeneration of the solvent, therefore, involves breaking of these bonds and correspondingly, a relatively high energy input. Chemical solvents generally employ either aqueous solutions of amines, i.e. mono-, di- or tri-ethanolamine or an aqueous solution of alkaline salts, i.e. sodium, potassium and calcium hydroxides. Biswas et al. reported that by bubbling biogas through 10% an aqueous solution of mono-ethanolamine (mea), the co2 content of the biogas was reduced from 40 to 0.5-1.0% by volume. A solution can be completely regenerated by boiling for 5 min and thus can be used again

This method works on the principle that when caustic solutions are made to react with CO2 bearing gas streams, an irreversible carbonate-forming reaction followed by reversible bicarbonate forming reac­tion take place as per the following equations. This process involves the use of hydroxides of sodium, potassium and calcium.

In most industrial applications, no attempt is made to regenerate spent bicarbonate solution due to high steam requirement for this process. Carbon dioxide absorption into alkaline solution is adversely affected by slow conver­sion of dissolved CO2 molecules into more reactive ionic species. Mixing of liquid during absorption helps to achieve diffusion of gas molecules in the liquid and prolongs their contact time which adds to the former’s absorptivity.

Normality of caustic solution also affects the rate of absorptivity. With sodium hydroxide solution (NaOH), for instance, it was found that the rate of reaction is more rapid if normality lies between 2.5 to 3. Potassium hydroxide (KOH) is more commonly used in industrial scrubbing but it suffers from the limitation that it is not readily available in rural areas where biogas plants are normally located.

Calcium hydroxide [Ca(OH)2] on the other hand is generally preferred for biogas scrubbing as this chemical is more readily available and cost of operating a lime-water scrubber is also relatively less. The main limitation of lime-water scrubbing are difficulties faced in controlling solution strength, and removal of large amounts of precipitate from mixing tank and scrubber.

In most cases, sediment and suspended particulate matter need be removed in order to avoid clogging in pumps, high-pressure spray nozzles, packing and bubbling ap­paratus. Sodium hydroxide has the major advantage of being available in easily handled pellet forms that enable rapid and simple recharging of the scrubber. However, with NaOH solutions problems of suspended particulate matter are not totally eliminated.

 The absorption of CO2 in alkaline solution is assisted by agitation. The turbulence in the liquid aids to the diffusion of the molecule in the body of liquid and extends the contact time between the liquid and gas. Another factor governing the rate of absorption is the concentration of the solution. The rate of absorption is most rapid with NaOH at normalities of 2.5-3.0. 
CARBON DIOXIDE REMOVAL USING AMMONIA IN BIOGAS 
Ammonia is used as an absorbent in chemical scrubbing to remove CO2 from biogas. A continuous system consisting of the 1L digester was used for biogas production which was bubbled through an absorbent in 500mL gas washing bottle at a constant temperature in a water bath. The obtained biomethane potential was found to be 0.387 m3 CH4/ kg VS which simply means that more methane gas can be obtained when using ammonia for absorption. An increase in the gas flow rate leads to an increase in the mass transfer coefficient resulting in an increase in the rate of absorption. The initial CO2 concentration affects the removal efficiency because more work needs to be done for biogas with a high initial concentration of CO2. NH3 has better absorption capacity because higher biogas purity was achieved at lower NH3 concentration. The removal efficiency for NH3 increased from 69%-79% on average with CH4 concentration reaching over 85% vol. This is equivalent to a calorific value ranging from 25- 33.5 MJ/Nm3 which is promising in terms of the gas ability to run in an automobile engine. 

Method # 3. Method Developed by the IARI, New Delhi:

T.D. Biswas, et al., developed another method for CO2 scrubbing. It was found that biogas can be removed by bubbling it through 10 per cent aqueous solution of mono-ethanolamine (MEA). By single bubbling through a plain column of 6 cm height, carbon dioxide content in biogas was reduced to 0.5-1 per cent by volume from the initial value of 40 per cent.

Scrubbing column was made of an inexpensive plastic bubbler of 5 cm diameter and 15 cm height with only one orifice. The maximum removal of carbon dioxide was observed when bubbles moved out individually without colliding one another to form a continuous stream. Optimum gas flow rate to the regulator was estimated as 100 ml per minute which gave 60 ml of purified gas per minute in the reservoir.

The decrease in this rate of flow was not found to cause any further scrubbing. The initial pressure of the gas introduced into the bubbler was 10 cm of the water column and drop in pressure head was about 5 cm of the water column. Both caustic potash and monoethanolamine solution were effective in reducing the carbon dioxide content to 0.5 to 1 per cent.

Whereas spent caustic potash solution cannot be regenerated, MEA solution can be completely regenerated by boiling for five minutes and thus can be used again and again. Furthermore, MEA solution is far less caustic than other solutions used and therefore pose much fewer hazards for the skin. This method is thus very practical and economic for biogas scrubbing.

Method # 4. Pressure Separation:

This method works on the principle of compressing biogas beyond the limit of the critical partial pressure of impurities (CO2) with a temperature greater than the critical temperature of methane but below those of impurities. For instance, carbon dioxide liquefies when the gas temperature falls below 89.6 F (32 C) after compressing beyond 1106 psi (77.76 kg/cm).

Thanks, http://www.geographynotes.com/

Pressure Swing Adsorption (PSA) Systems for CO2 and Hydrogen Sulphide Scrubbing

Pressure swing adsorption (PSA) systems, can be thought of as being molecular-sieves for carbon. PSA has been described are the second most commonly used biogas upgrading technology in Europe, after water scrubbing which is most likely the most popular. A typical system is composed of four vessels in series that are filled with adsorbent media which is capable of removing not only the CO2 but also water vapour, N2, and O2 from the biogas flow.

Typically in order to eliminate CO2 from biogas, the PSA upgrading takes place over 4 phases: pressure build-up, adsorption, depressurization and regeneration. The pressure build-up occurs by equilibrating pressure with a vessel that is at depressurization stage. Final pressure build-up occurs by injecting raw biogas. During adsorption, CO2, N2, and O2 are adsorbed by the media and the purified gas discharges as pure methane to a quality which will be far less corrosive and has a higher calorific value.

Recently developed gas-liquid membranes have been introduced, which operate at atmospheric pressures thereby reducing the energy consumption of compression. The use of specific solvent solutions allows the separation and recovery of the H2S and CO2.

Another approach to improving the economics of gas upgrading has been to recover the CO2 by cooling and recovering dry ice. This can then be sold as an industrial gas whilst the biogas is either used in its more concentrated form (80-90% CH4) or further refined to vehicle quality standard (>96% CH4).

Pressure Swing Adsorption

Pressure swing adsorption (PSA) is a method for the separation of carbon dioxide from methane by adsorption/desorption of carbon dioxide on zeolites or activated carbon at alternating pressure levels. This technology is often applied in the gas treatment industry as it also effectively removes volatile organic compounds, nitrogen and oxygen from industrial gas streams.

Serotonin

Serotonin is created by a biochemical conversion process that combines tryptophan, a component of proteins, with tryptophan hydroxylase, a chemical reactor. Together, they form 5-hydroxytryptamine (5-HT), or serotonin.

Serotonin is most commonly believed to be a neurotransmitter, although some consider it to be a hormone. It is produced in the intestines and the brain. It is also present in the blood platelets and the central nervous system (CNS).

As it occurs widely throughout the body, it is believed to influence a variety of body and psychological functions.

Serotonin cannot cross the blood-brain barrier, so any serotonin that is used inside the brain must be produced inside the brain.

Have you ever wondered what hormone is responsible for your mood and feelings? Serotonin is the key hormone that stabilizes our mood, feelings of well-being, and happiness. This hormone impacts your entire body. It enables brain cells and other nervous system cells to communicate with each other. Serotonin also helps with sleeping, eating, and digestion. However, if the brain has too much serotonin, it may lead to depression. If the brain has too much serotonin, it can lead to excessive nerve cell activity. It also helps reduce depression, regulate anxiety, and maintain bone health.

Serotonin is an important chemical and neurotransmitter in the human body.

It is believed to help regulate mood and social behavior, appetite and digestion, sleep, memory, and sexual desire and function.

There may be a link between serotonin and depression. If so, it is unclear whether low serotonin levels contribute to depression, or if depression causes a fall in serotonin levels.

Drugs that alter serotonin levels are used to treat depression, nausea, and migraine, and they may have a role in obesity and Parkinson's disease.

Other ways to increase body serotonin levels may include mood induction, light, exercise, and diet

How Does Your Body Use Serotonin? 

Your body uses serotonin in various ways:

Mood

• Serotonin is in the brain. It is thought to regulate mood, happiness, and anxiety.
• Low levels of serotonin are linked to depression, while increased levels of the hormone
• may decrease arousal.
  
  

Bowel Movements 

• Serotonin is found in your stomach and intestines. It helps control your bowel
• movements and function.
  
  

Nausea 

• Serotonin is produced when you become nauseated. Production of serotonin increases to
• help remove bad food or other substances from the body. It also increases in the
• blood, which stimulates the part of the brain that controls nausea.
  
  

Sleep

• Serotonin is responsible for stimulating the parts of the brain that control sleep and
• waking. Whether you sleep or wake depends on the area is stimulated and which
• serotonin receptor is used.
  
  

Blood Clotting 

• Serotonin is released to help heal wounds. Serotonin triggers tiny arteries to narrow,
• which helps forms blood clots.
  
  

Bone Health 

• Having very high levels of serotonin in the bones can lead to osteoporosis, which
• makes the bones weaker.
  
  

How Does Serotonin Impact Your Mental Health? 

Serotonin helps regulate your mood naturally. When your serotonin levels are at a normal level, you should feel more focused, emotionally stable, happier, and calmer.

What Problems are Associated with Low Levels of Serotonin? 

Low levels of serotonin are often associated with many behavioral and emotional disorders. Studies have shown that low levels of serotonin can lead to depression, anxiety, suicidal behavior, and obsessive-compulsive disorder. If you are experiencing any of these thoughts or feelings, consult a health care professional immediately. The sooner treatment starts, the faster you’ll see improvements.

What Problems are Associated with High Levels of Serotonin? 

Serotonin syndrome can occur when you take medications that increase serotonin action leading to side effects. Too much serotonin can cause mild symptoms such as shivering, heavy sweating, confusion, restlessness, headaches, high blood pressure, twitching muscles, and diarrhea. More severe symptoms include high fever, unconsciousness, seizures, or irregular heartbeat. Serotonin syndrome can happen to anyone, but some people may be at higher risk. You are at a higher risk if you increased the dose of medication that is known to raise serotonin levels or take more than one drug known to increase serotonin. You may also be at risk if you take herbal supplements or an illicit drug known to increase serotonin levels.
https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/serotonin
https://www.medicalnewstoday.com/kc/serotonin-facts-232248