Project RECOVER aims to harness the potential of ships and vessels in mitigating carbon-dioxide emissions using genetically modified E. coli. This method facilitates the transformation of these emissions into isobutanol, a compound of significant value. Besides its environmental benefits, this initiative offers an onboard solution for transforming waste emissions into a potential resource. To actualize this vision, we have designed a marine bioreactor system specifically for ships and vessels, which houses and ensures the well-being of the E. coli in the challenging marine environments.
Navigating Challenges: Beyond Lab Conditions
The Dynamic Marine Environment:
Operating a bioreactor at sea is highly difficult owing to factors such as ship movement and temperature fluctuations, which can stress E. coli and impair their function. E. coli's performance tends to diminish under heightened shear stress conditions [1-3]. Within a vessel, the hull is constructed to manage shear stresses, notably into the scale of several million Pascals [4-7]. Such intensities far exceed the tolerable limits for E. coli. To ascertain real-time stress levels, roll, pitch and temperature variations, we unveil "The Nautical Nexus".
The Nautical Nexus: Revolutionizing Marine SynBio
We introduce our flagship device, "The Nautical Nexus" ,for monitoring and logging real-time fluctuations in the roll, pitch,and temperature in the marine environment.
Expert Collaborations:
We collaborated with Dr. S. Rama Reddy, Dean - Electrical Sciences, Rajalakshmi Engineering College, Chennai, India, who provided expert advice on the practical implications, potential solutions and guidance on developing a prototype for the Nautical Nexus standalone unit.
From Conception to Creation: Prototyping the Nautical Nexus
The Nautical Nexus prototype embodies our concept for sea sensing and data logging. It features an integrated MPU6050 Inertial Measurement Unit and a 0.96-inch OLED Display as the Raspberry Pi Pico development board's backbone. Data
points are logged on the SD Card. The system is equipped with Qi Wireless Charging and is powered by a 1.5Ah Lithium-Polymer battery.
We have also released a dedicated MicroPython library “igemrecchennai2023.py” for the Nautical
Nexus. Beyond its application for our device, this library serves as a versatile tool for anyone looking to interface the Raspberry Pi Pico with an SD card module, OLED display, and MPU6050 Inertial Measurement Unit.
| Component | Quantity | Unit Cost (USD) | Total Cost (USD) |
|---|---|---|---|
| Raspberry Pi Pico | 1 | $4.00 | $4.00 |
| MPU6050 IMU | 1 | $2.50 | $2.50 |
| 1500mAh LiPo Battery | 1 | $9.00 | $9.00 |
| 4056 LiPo Charger | 1 | $1.50 | $1.50 |
| Wireless Charging Receiver | 1 | $3.00 | $3.00 |
| Latching Type Push Button with LED | 1 | $0.75 | $0.75 |
| SSD1306 OLED Display | 1 | $5.00 | $5.00 |
| Perf Board | 1 | $0.50 | $0.50 |
| Casing | 1 | $3.00 | $3.00 |
| 22AWG Wires (per meter) | 2 | $0.30 | $0.60 |
| Spacers (pack of 10) | 1 | $1.00 | $1.00 |
| Total Cost | $30.35 |
Submergence Trials: Nautical Nexus Proves Its Mettle Underwater
We tested the Nautical Nexus through rigorous underwater trials to ensure that it withstands marine conditions. Our results confidently showcased its waterproof capabilities, confirming that the device remains sink proof even in challenging aquatic environments.
Empirical Assessments: Nautical Nexus in Action
After successfully proving its waterproof and sink proof capabilities, we dispatched the Nautical Nexus on a sea voyage to gather real-time data. The device actively recorded the marine environment's dynamics. The data captured provides pivotal insights into the sea-induced roll, pitch, and temperature variations, the Nautical Nexus experienced.
Crunching Numbers: Decoding the Data
Upon retrieving the Nautical Nexus from its oceanic journey, we extracted the data from its onboard SD Card. From the extracted data representing the roll, pitch, and temperature, we computed the shear stress fluctuations and methodically visualized all the information into distinct graphs.
End-user Perspective: Enhancing Onboard Experience
We presented the Nautical Nexus to a seasoned vessel captain, drawing from his vast maritime knowledge. His feedback and requirements were instrumental in shaping our approach. Guided by his insights, we formulated the novel "Gyroscopic Gimbal Based Orientational Stabilization System for Marine Bioreactors".
Trailblazing Innovations: Going Beyond the Horizon
Orientational Stabilization System (OSS)
Our gyroscopic gimbal-based orientation stabilization system provides a stabilizing platform for marine bioreactors. By counteracting sea-induced movements, it maintains a consistent orientation for the bioreactor. This ensures smooth
operation and reliable on-site testing, amidst challenging maritime conditions.
In line with our objective, we have published an Indian Utility Patent which now stands in line for examination.
Patent at a Glance:
- Title: GYROSCOPIC GIMBAL-BASED ORIENTATIONAL STABILIZATION SYSTEM FOR MARINE BIOREACTORS
- Application Number: 202341040150
- Application type: Indian Utility Patent
- Applicants:
- Dr. V. Gayathri (iGEM Primary Investigator) Associate Professor, Department of Biotechnology, Rajalakshmi Engineering College (Autonomous), Thandalam, Chennai – 602105.
- Dr. R. Jayasree (iGEM Secondary Investigator), Professor, Department of Biotechnology, Rajalakshmi Engineering College (Autonomous),
- Dr. T. Thamizhselvan Professor, Department of Electrical and Electronics Engineering, Rajalakshmi Engineering College (Autonomous), Thandalam, Chennai – 602105.
- Inventor:
- Mr. Madhavan T (iGEM Team Member), Department of Electrical and Electronics Engineering, Rajalakshmi Engineering College (Autonomous), Thandalam, Chennai – 602105
- Filing Date: 12/06/2023
- Publication Date: 30/06/2023
- Status: Published, Awaiting examination.
We present our orientational stabilization system, diligently designed for marine bioreactors.
Key Features:
- Precise Orientation: Our brushless DC motors, combined with a multi-axis gyroscope and accelerometer, ensure accurate orientation measurements.
- Enhanced Stability: Digital shock absorbers are integrated to reduce disturbances.
- Reliable Communication: Our system offers wireless communication for deep-sea data transmission, with a wired communication option for added reliability.
- Redundancy for Assurance: We have included redundant motors, underscoring our focus on dependable performance.
- User-friendly Interface: The transparent display provides a clear view of essential parameters and ensures precise substance agitation.
Diving into the nuances, our system boasts three operating modes: designed for grand vessels, nimble boats and unique FLIP ships. Notably, the innovative FLIP mode ensures the bioreactor remains in harmony with the FLIP vessel's rotations.
Theoretical Underpinnings: The GG Mathematical Model
Our mathematical model for the gyroscopic gimbal provides the foundational logic and principles behind our stabilization system. It articulates how each component interacts to maintain the desired orientation, regardless of external disturbances.
We ran simulations on the gyroscopic gimbal model, assessing its performance against varying system efficiencies and their impact on shear stress. The resulting plot of system efficiency versus shear stress affirmed that our gimbal effectively mitigates shear stress.
Miniature Gyroscopic Gimbal: A Tangible Demonstration
We developed a miniature hardware model to demonstrate operational dynamics and capabilities of the gyroscopic gimbal. We used a small container that served as a representation of a fermenter. The configuration enabled us to adequately showcase the numerous functionalities of our design.
IoT Integration - The Digital Synthesis:
Focusing on critical parameters such as pH, temperature, and aeration, we devised an Internet of Things-based control system. Through the integration of an ESP32 prototype with the open cloud platform Thinger.io, we have simplified data monitoring and management.
Charting the Course: Future Scope of Gyroscopic Gimbal
In our future roadmap, we plan to integrate artificial intelligence and machine learning to enhance our platform. We aim to predict sea conditions, enabling the gyroscopic gimbal to adjust and optimize its performance in real-time. This approach will refine data interpretation and foster proactive adjustments to varying marine scenarios.
- Lange, H., Taillandier, P. and Riba, J.-P. (2001), Effect of high shear stress on microbial viability. J. Chem. Technol. Biotechnol., 76: 501-505. https://doi.org/10.1002/jctb.401
- Troshko, A. A., Nikiforov, K. A., & Kashkarov, V. P. (2023). Can high hydrodynamic stresses contribute to E. coli inactivation? Experimental evidences from laminar and turbulent flows. In Proceedings of the 39th IAHR World Congress (Granada, 2022) (pp. 1244-1253). International Association for Hydraulic Research
- Vettori, D., Manes, C., Dalmazzo, D., & Ridolfi, L. (2022). On Escherichia coli resistance to fluid shear stress and its significance for water disinfection. Water, 14(17), 2637. https://doi.org/10.3390/w14172637
- American Bureau of Shipping. (2014). Rules for Building and Classing Steel Vessels. Part 2, Chapter 2, Section 1, Sub-Section 3.9 (p. 37). ABS.
- Aksu, S., Temarel, P., Robinson, D. W., Pedersen, P. T., Foy, D. B., & Hylarides, S. (1991). On the Estimation of Bending and Shear Stresses in Beamlike Ships Travelling in a Seaway. Philosophical Transactions: Physical Sciences and Engineering, 334(1634), 281–292. http://www.jstor.org/stable/53772
- Republic of the Marshall Islands Maritime Administrator. (2017, October 18). Stellar Daisy Casualty Investigation Report, Loss of Buoyancy and Foundering with Multiple Loss of Life, Official Number: 3486 IMO Number: 9038725. https://www.register-iri.com/wp-content/uploads/Republic-of-the-Marshall-Islands-Office-of-the-Maritime-Administrator-Stellar-Daisy-Casualty-Investigation-Report.pdf
- Danish Maritime Accident Investigation Board. (2013, December 19). Emma Mærsk Flooding of engine room on 1 February 2013. https://dmaib.com/media/8645/emma-maersk-flooding-of-engine-room-on-1-february-2013.pdf
Need for Recovery of Carbon Dioxide
"In light of the increasing significance of global warming, numerous nations are actively seeking ways to curb their greenhouse gas emissions, with a primary emphasis on reducing carbon dioxide (CO2) emissions. Carbon dioxide, a prominent greenhouse gas originating primarily from non-renewable sources, stands as a key driver of climate change, thus exacerbating the issue of global warming. Addressing the challenge of climate change entails the reduction of CO2 emissions, which can be achieved through the adoption of alternative energy sources or the implementation of carbon capture technologies, followed by their effective utilisation as a vital strategy to mitigate CO2 emissions."
- Global Warming
- Climate Change
- Ocean Acidification
- Melting Ice
- Sea Level Rise
- Impacts on Agriculture
- Health Risks
- Biodiversity Loss
- Economic Consequences
Facts and Figures
- Almost 30% of global greenhouse gas emissions come from industries and the energy they use, mostly carbon-based. [2]
- Researchers established a simple linear relationship between temperature rise and CO 2 release, that is, for every 1,000 tons of CO2 released into the atmosphere, the Earth's average temperature would increase by 1.5 × 10 − 9 °C. [3]
- It is predicted that the CO2 concentration in the atmosphere will pass the commonly invoked threshold level of 450 ppm by the middle of this century. This would result in an average temperature increase of over 2 ℃. [2]
- In 2018, the total amount of CO2 emitted by shipping was 1.056 billion tons, accounting for 2.89% of the global anthropogenic emissions, an increase of 9.6% compared with 2012. [7]
- According to the IMO emission reduction plan, the cumulative CO2 emissions from 2015 to 2075 need to be controlled between 28 ~ and 40 Gt. [7]
Carbon Dioxide Emissions by Sector [11]
In 2012, more than a quarter (25%) of all CO2 emissions stemmed from electricity generation, making it the largest contributor among sectors. Due to the inherent scalability of electricity generation, it presents a relatively easier short-term target for reducing CO2 emissions compared to sectors like transportation. The Maritime Industry, on the other hand, is responsible for annually emitting one billion tons of CO2 , constituting 3% of global emissions. Alarming warnings from the International Maritime Organization suggest that without intervention, this figure could soar to 15%. In light of this, our project is dedicated to addressing CO 2 emissions from ships and employing Synthetic Biology to convert them into a valuable product, Iso-Butanol addressing the WORLD MARITIME THEME 2024 “NAVIGATING THE FUTURE: SAFETY FIRST” supporting the UN Sustainability Goals.
Our project complies with Numerous policies and agreements that have been enacted worldwide to combat carbon emissions and combat climate change. The landmark Paris Agreement of 2015, with nearly 200 signatory nations, aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels. India, a signatory, has committed to increasing its renewable energy capacity significantly. The Kyoto Protocol, one of the first international treaties, set binding emission reduction targets for developed countries. The European Green Deal is the European Union's comprehensive framework to achieve climate neutrality by 2050 through increased renewable energy usage and emissions reduction targets. Carbon pricing mechanisms, renewable energy standards, and vehicle emission regulations have been implemented globally to incentivize cleaner practices. Reforestation and afforestation initiatives, along with agreements like the Montreal Protocol, indirectly aid in emissions reduction. The International Maritime Organization (IMO) and national climate action plans further contribute to the global effort, underscoring the commitment to combat carbon emissions and mitigate climate change
Direct Recovery of CO2 from Seawater
-
Bubbling Method:
- Previously, we experimented with a technique known as the Bubbling Method to capture CO2 directly from seawater. This method involved passing air through a column filled with seawater at an elevated temperature to collect carbon dioxide from its dissolved form and bicarbonate salts . [9]
-
Degasification
- We shifted our approach to utilise degasification. This method employs a specialised chamber, known as the Degasification Chamber, to separate dissolved carbon dioxide in water. This separation is achieved by either heating the water, which lowers the solubility of carbon dioxide or by applying a vacuum to reduce pressure, thereby encouraging the release of CO2 as a gas.
Subsequently, we opted not to pursue the extraction of CO2 from seawater. This decision stemmed from the understanding that the ocean naturally absorbs carbon dioxide from the atmosphere, effectively acting as a
carbon sink. Removing CO2 from the ocean would not adequately address the issue of Ocean Acidification. Instead, our strategic focus shifted towards the capture of CO2 from industrial emissions. Based
on available data, a significant portion of CO2 emissions arise from the energy sector, followed closely by transportation.
Given that alternative solutions are emerging for land-based vehicles, we chose to
target emissions from ships. This sector accounts for approximately 3% of the total CO2 emissions and offers a more viable avenue for mitigating carbon emissions, primarily because it has been relatively overlooked
in emissions reduction efforts.
Recovery of CO2 from Emissions
Post-combustion carbon capture represents a direct and highly efficient approach for onboard carbon capture. Therefore, it is crucial to develop absorbents for onboard carbon capture that can achieve both a high absorption rate and reduced energy consumption
during the desorption process. One of the most recognized methods for capturing CO2 is through chemical absorption using amine-based solvents, followed by desorption.
Amines are
commonly chosen due to their reactivity with CO2 under relatively mild temperatures (absorber: 40–65°C) and pressure (1–2 bar) conditions. However, amines have inherent drawbacks, including their corrosiveness, potential
equipment issues, susceptibility to degradation through oxidation reactions, and the substantial energy demand for desorption. [1]
Why Choose K2CO3 ? [2]
To address these disadvantages associated with amine-based solvents, we have adopted an eco-friendly carbon capture process that substitutes amines with potassium carbonate (K2CO3) promoted by a salt of
an amino acid Sarcosine. Potassium carbonate offers several advantages: it is less toxic and less corrosive than amines, comes at a lower solvent cost, avoids degradation concerns, and is notably attractive as a wet chemical
absorbent due to its reduced energy requirements for regeneration. Sarcosine, also known as N-methylglycine, is a naturally occurring amino acid derivative. Sarcosine is found in small amounts in various biological tissues
and is involved in several biochemical processes in the body.
One of the notable roles of sarcosine is its involvement in the one-carbon metabolism pathway, which is important for the synthesis of various molecules, including nucleic acids and creatine. It can be converted to glycine
through enzymatic reactions, and it also plays a role in the conversion of methionine to homocysteine. This metabolic pathway is crucial for the synthesis of important compounds like DNA, RNA, and various coenzymes. We use
this Sarcosine as a promoter of K2CO3 which enhances the absorption rate of CO2 as well as reduces the energy requirements in thermal regeneration of CO2 .
PROCESS UPSCALING
Simulation Model [4][8] Aspen Hysys software was employed for simulating the extraction of carbon dioxide (CO2) from the exhaust emissions of a 5RT-Flex 50 DF marine dual-fuel engine, utilising a 30% mass concentration potassium carbonate (K2CO3) solution. The exhaust gas composition of the 5RT-Flex 50 DF engine under 100% load in diesel mode is presented in the below Table. It is important to note that the CO2 capture process occurs downstream of other post-treatment equipment, specifically after the removal of NOx , SOx , and particulate matter (PM) from the exhaust gas stream. Therefore, our focus here is solely on oxygen, nitrogen, and carbon dioxide, disregarding the presence of other gases. At 100% load, the exhaust gas flow rate for the 5RT-Flex 50 DF engine operating in diesel mode amounts to 45,806 kg per hour
Engine Model - 5RT-Flex 50 DF marine dual-fuel engine Emission Details [Table 1]
| Exhaust Composition | Value |
|---|---|
| CO2 % | 5.183 |
| O2 % | 13.871 |
| NOx (ppm) | 937.8 |
| CO (ppm) | 71.3 |
| HC (ppm) | 254.1 |
| N2 % | 80.94 |
The ship's exhaust gases are directed into an absorption tower, where a diluted solution absorbs a portion of the CO2 , transforming it into a concentrated liquid. Afterward, this concentrated liquid is heated through a heat exchanger and then directed to a desorption tower. Here, it comes into contact with high-temperature steam from a reboiler, allowing the regeneration of CO2 . The resulting desorbed concentrated liquid is cooled using the heat exchanger and a separate cooling system before being returned to the absorption tower, completing the cycle of the absorbent. The efficiency of carbon dioxide absorption plays a crucial role in determining the overall investment cost. An absorption efficiency of 85% is generally considered economically favourable. To enhance the absorption rate of CO2 , particularly because of the relatively slow reaction rate of potassium carbonate with CO2 , activators such as amino acid salts or organic amines are introduced into the potassium carbonate solution
To achieve a more accurate representation of CO2 capture from marine engine exhaust gases using pure potassium carbonate, an equilibrium-based model was established. This model considers the equilibrium between different phases. Tower equipment was simulated using this equilibrium model. Additionally, the NRTL (Non-Random Two-Liquid) method was selected to simulate the absorption process of acid gases by the electrolyte system, as it is a versatile approach well-suited for predicting the physical properties of electrolyte solutions in the context of acid gases. This method relies on activity coefficients to accurately predict properties in aqueous and mixed solvent systems. For the gas phase calculations, the Redlich-Kwong equation of state was employed to determine gas-phase fugacity. Specifically, the concentrations of CO2 , O2 , and N2 were computed using Henry's law, allowing for a comprehensive analysis of the system.
\[2H_2O + 2HCO_3^- \rightleftharpoons CO_3^{2-} + H_3O^+\]
\[2H_2O + CO_2 \rightleftharpoons HCO_3^- + H_3O^+\]
\[2H_2O \rightleftharpoons OH^- + H_3O^+\]
The operational pressure for both towers was standardised at 1 bar, and the pertinent parameters can be found in Table 2. To optimise heat recovery, a heat exchanger was employed. The HeatX model was utilised to replicate the processes occurring within the heat exchanger, with a simplified approach for ease of computation. Additionally, it's crucial to maintain a minimum temperature difference of 5 Kelvin at the outlet of both the cold and hot ends of the lean/rich absorbent heat exchanger to ensure effective heat transfer. To adhere to this requirement, the temperature difference at the outlet of both ends of the lean/rich absorbent heat exchanger has been set at 5(K). [Table 2]
| Equipment | Column diameter | Packing | Packing Height |
|---|---|---|---|
| Absorption Tower | 2.6 m | Plastic Pall Rings Dg380 | 8 |
| Desorption Tower | 1.4 m | Stainless Steel Pall Rings Dg380 | 10 |
The simulation results of the stable circulating potassium carbonate CO2-lean and CO2-rich parameters are [Table 3]
| Stream | Type | Value |
|---|---|---|
| CO2-lean | Mass Flow (kgh-1 ) | 106000 |
| HCO3-(kgh-1 ) | 5863.81 | |
| CO32-(kgh-1 ) | 8664.43 | |
| CO2-rich | Mass Flow(kgh-1 ) | 107232 |
| HCO3-(kgh-1 ) | 14193.75 | |
| CO2-rich | Mass Flow(kgh-1 ) | 4569.97 |
REAGENTS USED [Table 4]
| Reagents Used | Purity | Molecular weight |
|---|---|---|
| Potassium hydroxide | 95% | 56.11 |
| Potassium carbonate | 99% | 138.21 |
| Sarcosine | 99% | 89.09 |
The Rate of Absorption in the Absorber is calculated and a graph of Rate of absorption Vs Partial Pressure of CO2 was plotted
The desorption of CO2 in the Stripper is Calculated and a graph is plotted for the amount of CO2 desorbed per min.
Process Description (for Pilot Scale Lab Exp)
This process comprises a two-pronged setup:
a. A vessel designed for the capture of flue gas.
b. A vessel designated for the controlled release of CO2
Within the first vessel, a continuous supply of potassium
carbonate (K2CO3) solution is introduced, and the flue gas from 4-Stroke Single Cylinder CI Engine is subsequently channelled into this vessel using a pipe that is immersed in the solution. Incoming flue gas
from the engine has a high temperature and requires a cooling pipe to aid the reduction in temperature. This vessel also contains an agitator to ensure continuous mixing and to enhance the dissolution of CO2 into the
K
2CO3 solution. K2CO3 is particularly used due to its capability of selectively reacting with CO2 present in the flue gas, which is described by the stoichiometric relation:
\[K_2CO_3 \text{(aq)} + CO_2 \text{(g)} + H_2O \text{(l)} \rightarrow 2 \, KHCO_3 \text{(aq)}\]
This is an exothermic reaction. The resulting potassium bicarbonate (KHCO3) is then redirected to another vessel using a peristaltic pump, where it undergoes heating, thereby ensuring that the reverse of the above reaction occurs. Heating of KHCO3 results in the formation of K2CO3 and H2O, liberating CO2 gas in the process:
\[2 \, \text{KHCO}_3 \, (\text{aq}) \rightarrow \text{K}_2\text{CO}_3 \, (\text{aq}) + \text{CO}_2 \, (\text{g}) + \text{H}_2\text{O}\]
The liberated carbon dioxide gas is then directed to a storage vessel, which can later be routed to the bioreactor for subsequent utilisation.
Reaction Mechanism
CO2 is absorbed into the Potassium Carbonate solution based on the following overall reaction:
\[K_2CO_3 + CO_2 + H_2O \rightleftharpoons 2KHCO_3\]
In the carbonate system, CO2 is chemically consumed by the following overall reaction
\[CO_2 + CO_3^{2-} + H_2O \rightarrow 2HCO_3^-\]
where the rate-limiting step is:
\[CO_2 + CO_3^{2-} + H_2O \rightarrow 2HCO_3^-\]
The hydration of CO2 can also proceed via direct reaction with water, although under industrial CO.2 capture conditions where the pH is greater than 9, the contribution of this reaction can be deemed negligible. The rate of reaction is given by
\[ r_{\text{CO}_2} = \frac{d[\text{CO}_2]}{dt} = -k_{\text{OH}}[\text{CO}_2][\text{OH}^-] \]
The value of k OH was determined as a function of temperature using the Arrhenius expression
\[ k_{\text{OH}} [\text{M}^{-1}\text{s}^{-1}] = 2.53 \times 10^{11} e^{-\frac{4311}{T} [\text{K}]} \]
Aqueous amino acids such as sarcosine exist in three states:
- Acidic
- Zwitterionic
- Basic or Deprotonated
The acidic state and zwitterionic state of the amino acids are much less reactive toward CO2 than the deprotonated state. Deprotonation of the zwitterionic amino acids is achieved by adding an equimolar amount of a strong base potassium hydroxide (KOH) which dissociates completely in water
\[\text{KOH} \, (\text{s}) \rightleftharpoons \text{K}^+ + \text{OH}^-\]
The deprotonation of the zwitterions can then be written as
\[ \text{NH}_2\text{R}_1\text{R}_2\text{COO}^- + \text{OH}^- \rightleftharpoons \text{NHR}_1\text{R}_2\text{COO}^- + \text{H}_2\text{O} \]
The reaction between CO2 and the deprotonated amino acids then proceeds via a zwitterionic carbamate intermediate (forward rate constant k2 and reverse rate constant k-1 )
\[ \text{CO}_2 + \text{NH}_2\text{R}_1\text{R}_2\text{COO}^- \rightleftharpoons -\text{OOCNH}_2\text{R}_1\text{R}_2\text{COO}^- \]
This reaction is followed by the removal of a proton from the zwitterionic carbamate by any base B, to form a neutral carbamate
\[ -\text{OOCNH}_2\text{R}_1\text{R}_2\text{COO}^- + \text{B} \rightarrow -\text{OOCNR}_1\text{R}_2\text{COO}^- + \text{BH}^+ \]
In our system, water (H2O), carbonate ions (CO32- ), bicarbonate ions (HCO3-), and the deprotonated Amino Acid (AA) itself can all act as bases. The overall reaction rate for the reaction of CO2 with potassium salts of sarcosine be expressed as
If the formation of the zwitterionic carbamate (Eq.6) is the rate-limiting step, then 1 ≫ k−1 /∑kb[B] and thus, Eq. (8) reduces to a simple second-order kinetic relationship as follows:
\[ r_{\text{CO}_2} = -k_2[\text{CO}_2][\text{AA}] \]
When the pH of the solution is above 10, the contribution of the CO2 + OH− reaction to the overall consumption of carbon dioxide must also be taken into account (Eqs. (2), (3)). Therefore Eq. (9) becomes:
\[ -r_{\text{CO}_2} = k_2[\text{CO}_2][\text{AA}] + k_{\text{OH}}[\text{OH}^-][\text{CO}_2] \]
However, if the proton removal from the zwitterionic carbamate is the rate-limiting step (Eq. (7)), then the reverse is true (i.e. 1 ≪ k−1 /∑kb[B]) and thus Eq. (8) becomes:
\[ r_{\text{CO}_2} = -k_2[\text{CO}_2][\text{AA}]\left(\frac{\sum k_b[B]}{k_{-1}}\right) \]
In this latter case, the reaction order dependency on the amino acid concentration varies from unity
\((k_{\text{AA}}[\text{AA}] \ll k_{\text{H}_2\text{O}}[\text{H}_2\text{O}] + k_{\text{CO}_3}[\text{CO}_3^{2-}] + k_{\text{HCO}_3}[\text{HCO}_3^-])\) to \(2(k_{\text{AA}}[\text{AA}] \ll k_{\text{H}_2\text{O}}[\text{H}_2\text{O}] + k_{\text{CO}_3}[\text{CO}_3^{2-}] + k_{\text{HCO}_3}[\text{HCO}_3^-])\)
In the presence of potassium carbonate where the pH of the solution is above 10, Eq. (11a) becomes:
\[ -r_{\text{CO}_2} = \left(k_2[\text{CO}_2][\text{AA}]\frac{\sum k_b[B]}{k_{-1}}\right) + k_{\text{OH}}[\text{OH}^-][\text{CO}_2] \]
The Arrhenius expressions for the reaction between CO2 and amino acid kSar [M−1 s −1 ] = 6.24 × 1010 exp(−1699/T [K]). The reaction order concerning sarcosine is observed to be in the range of 1.3–1.6.
- Lange, H., Taillandier, P. and Riba, J.-P. (2001), Effect of high shear stress on microbial viability. J. Chem. Technol. Biotechnol., 76: 501-505. Altway, S., Kuswandi, K., Zulfetra, I., & Maharani, F. (2016). CO2 Solubility in Electrolyte Solution of Potassium Carbonate with the Addition of Promotor Amines (MDEA-DEA/ PZ-DEA) at Various Temperatures. Journal of Engineering and Technological Sciences, 48(6), 665–678. https://doi.org/10.5614/J.ENG.TECHNOL.SCI.2016.48.6.3
- Bioenergy with Carbon Capture and Storage - Energy System - IEA. (n.d.). Retrieved October 1,2023. https://www.iea.org/energy-system/carbon-capture-utilisation-and-storage/bioenergy-with-carb on-capture-and-storage
- Chapter 1 — Global Warming of 1.5 oC. (n.d.). Retrieved October 1, 2023, from https://www.ipcc.ch/sr15/chapter/chapter-1/
- CO2 absorption into concentrated carbonate solutions with promoters at elevated temperatures - CORE. (n.d.). Retrieved October 1, 2023, from https://core.ac.uk/display/20442209?utm_source=pdf&utm_medium=banner&utm_campaign =pdf-decoration-v1
- Decarbonation the Removal of CO2 from Water. (n.d.). Retrieved October 1, 2023, from https://www.deloachindustries.com/blog/decarbonation-the-removal-of-CO2-from-water
- Duan, Y., Luebke, D. R., Pennline, H. W., Li, B., Janik, M. J., & Halley, J. W. (2012). Ab initio thermodynamic study of the CO 2 capture properties of potassium carbonate sesquihydrate, K 2CO 3·1.5H2O. Journal of Physical Chemistry C, 116(27), 14461–14470. https://doi.org/10.1021/JP303844T/ASSET/IMAGES/MEDIUM/JP-2012-03844T_0002.GIF
- International Maritime Organization. (n.d.). Retrieved October 1, 2023, from https://www.imo.org/en
- Karali, D., Peloriadi, K., Margaritis, N., & Grammelis, P. (2022). CO2 Absorption Using Potassium Carbonate as Solvent. Engineering Proceedings 2023, Vol. 31, Page 39, 31(1), 39. https://doi.org/10.3390/ASEC2022-13824
- Koweek, D. A., Mucciarone, D. A., & Dunbar, R. B. (2016). Bubble Stripping as a Tool to Reduce High Dissolved CO2 in Coastal Marine Ecosystems. Environmental Science and Technology,50(7),3790–3797. https://doi.org/10.1021/ACS.EST.5B04733/SUPPL_FILE/ES5B04733_SI_001.PDF
- National Institute of Standards and Technology | U.S. Department of Commerce. (n.d.). Retrieved October 1, 2023, from https://www.commerce.gov/bureaus-and-offices/nist
- https://ourworldindata.org/emissions-by-sector