Carbon dioxide capture strategies from flue gas using microalgae: a review

Global warming and pollution are the twin crises experienced globally. Biological offset of these crises are gaining importance because of its zero waste production and the ability of the organisms to thrive under extreme or polluted condition. In this context, this review highlights the recent developments in carbon dioxide (CO₂) capture from flue gas using microalgae and finding the best microalgal remediation strategy through contrast and comparison of different strategies. Different flue gas microalgal remediation strategies discussed are as follows: (i) Flue gas to CO₂ gas segregation using adsorbents for microalgal mitigation, (ii) CO₂ separation from flue gas using absorbents and later regeneration for microalgal mitigation, (iii) Flue gas to liquid conversion for direct microalgal mitigation, and (iv) direct flue gas mitigation using microalgae. This work also studies the economic feasibility of microalgal production. The study discloses that the direct convening of flue gas with high carbon dioxide content, into microalgal system is cost-effective.     

Feasibility study of using brine for carbon dioxide capture and storage from fixed sources

A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO2) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media--tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO2 to carbonic acid. The transferred CO2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca++, produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO2, with less than a 6% reduction in CO2 transferred. The CO2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.     

改性分子筛二氧化碳捕集材料的制备及其性能

以微孔分子筛为基体,用环氧树脂(EP)作交联剂,采用浸渍法将聚乙烯亚胺(PEI)或者四乙烯五胺(TEPA)浸渍在微孔分子筛上,制备了一系列的胺基吸附分子筛。通过热失重等方法对样品结构表征。研究了温度、PEI/EP质量比、TEPA/EP质量比及吸附气体中CO2初始浓度对吸附容量的影响,探讨了该吸附分子筛材料性能与结构的关系。结果表明,改性的胺基分子筛对CO2有较好的吸附效果。在333 K下,PEI改性分子筛吸附量最大,CO2初始浓度为20%时的最大吸附量为0.69 mmol/g。TEPA改性分子筛在CO2初始浓度为20%和15%时的最大吸附量分别为0.50 mmol/g和0.33 mmol/g。     

Early atmospheric detection of carbon dioxide from carbon capture and storage sites

The early atmospheric detection of carbon dioxide (CO₂) leaks from carbon capture and storage (CCS) sites is important both to inform remediation efforts and to build and maintain public support for CCS in mitigating greenhouse gas emissions. A gas analysis system was developed to assess the origin of plumes of air enriched in CO₂, as to whether CO₂ is from a CCS site or from the oxidation of carbon compounds. The system measured CO₂ and O₂ concentrations for different plume samples relative to background air and calculated the gas differential concentration ratio (GDCR = ?ΔO₂/ΔCO₂). The experimental results were in good agreement with theoretical calculations that placed GDCR values for a CO₂ leak at 0.21, compared with GDCR values of 1–1.8 for the combustion of carbon compounds. Although some combustion plume samples deviated in GDCR from theoretical, the very low GDCR values associated with plumes from CO₂ leaks provided confidence that this technology holds promise in providing a tool for the early detection of CO₂ leaks from CCS sites. Implications: This work contributes to the development of a cost-effective technology for the early detection of leaks from sites where CO₂ has been injected into the subsurface to enhance oil recovery or to permanently store the gas as a strategy for mitigating climate change. Such technology will be important in building public confidence regarding the safety and security of carbon capture and storage sites.     

CO_2捕获发展现状与障碍分析

CO2捕获后进行封存是目前被认为减少对大气碳排放和减缓气候变化的一项重要手段,而捕获技术是碳减排的关键技术之一。CO2的捕获主要通过燃烧后、燃烧前、富氧燃烧和工业分离技术来实现。虽然捕获CO2在技术上相对比较成熟,但投资、能耗、捕获成本等方面仍存在障碍,有待进一步研究。降低捕获成本和开发新技术是CO2捕获技术大规模应用和商业运作的基础。     

Effectiveness of ionic liquid-supported membranes for carbon dioxide capture: a review

Environmental Science and Pollution Research - The world’s population explosion creates a need for natural resources for energy, which will become a significant contributor to global climate...     

Purification of carbonic anhydrase from bovine erythrocytes and its application in the enzymic capture of carbon dioxide

This work presents a study of industrially applicable techniques to obtain a biologically supported carbon dioxide capture system, based on the extraction of carbonic anhydrase from bovine blood. Carbonic anhydrase is a metalloenzyme which catalyzes the reversible hydration of carbon dioxide. The objective of this study was to establish conditions to obtain carbonic anhydrase from bovine erythrocytes and apply it in the capture of carbon dioxide. To achieve this, two different purification techniques were evaluated: one by extraction with the organic solvents chloroform and ethanol, where different solvent proportions were studied; and the other by ammonium sulfate precipitation, testing percent saturations between 10% and 80%. Carbon dioxide was enzymatically captured by its precipitation as calcium carbonate with the enzyme obtained by both techniques. The enzyme extracted by ethanol and chloroform showed an activity of 2623 U mL⁻¹, recovery of 98% and purification factor of 104-fold. That precipitated by ammonium sulfate showed an activity of 2162 U mL⁻¹, recovery of 66% and purification factor of 1.4-fold using 60% ammonium sulfate saturation. The results obtained in the carbon dioxide capture experiments showed that the carbonic anhydrase extracted in this study not only enhanced the hydration of CO₂, but also promoted the formation of CaCO₃.     

A review on application of activated carbons for carbon dioxide capture: present performance,preparation, and surface modification for further improvement

Environmental Science and Pollution Research - The atmosphere security and regulation of climate change are being continuously highlighted as a pressing issue. The crisis of climate change owing to...     

Utilization of waste bittern from saltern as a source for magnesium and an absorbent for carbon dioxide capture

During solar salt production, large quantities of bittern, a liquid by-product containing high inorganic substance concentrations, are produced. The purpose of this research was to examine the utilization of waste bittern generated from salterns as a source for Mg production and as an absorbent for carbon dioxide (CO₂) capture. The study was conducted in a sequential two-step process. At NaOH/Mg molar ratios of 2.70–2.75 and pH 9.5–10.0, > 99% Mg precipitation from the bittern was achieved. After washing with water, 100–120 g/L of precipitate containing 94% Mg(OH)₂ was recovered from the bittern. At the optimum NH₄OH concentration of 5%, 120 g of sodium bicarbonate precipitate per liter of bittern were recovered, which was equivalent to 63 g CO₂ captured per liter of bittern. These results can be used to support the use of bittern as a resource and reduce economic losses during solar salt production.     

Continuous observations of carbon dioxide at Mace Head,Ireland from 1995 to 1999 and its net European ecosystem exchange

A 5-yr record of continuous high-frequency carbon dioxide CO₂ observations over the 1995–1999 period for the Mace Head Atmospheric Research Station has been examined to reveal a complex interplay between local- and regional-scale sources and sinks. During the winter months, an additional CO₂ source, over and above fossil fuel combustion, is required to support the observed concentrations of CO₂ in European regionally polluted air masses. During the summer months, an additional CO₂ sink is required. Over the entire study period, the additional net European ecosystem exchange source–sink required is –0.36±0.4 Gtonne C yr⁻¹.     

On the variability of atmospheric carbon dioxide concentration at Barrow,Alaska during summer

Atmospheric carbon dioxide data obtained at Barrow, Alaska for the May–September period of 1978 were studied to understand the causes of the day-to-day and within-day variations. Sixteen instances of 24-h change in average CO₂ concentration of from 15 to 50% of the annual range (approx. 14 ppm) were identified. Within-day variations of up to 50% of the annual range were noted. The variations were found to be related to local and synoptic scale meteorology interacting with local and regional sources and sinks of CO₂. The results are consistent with an overall source of CO₂ in the tundra of the Alaskan North Slope and a significant sink for CO₂ in the ice-free areas of the seas bordering Alaska. The analysis provides an interpretation of the Barrow CO₂ record which can be used in the selection of representative data for studying large scale trends.     

A study of winter variability in carbon dioxide and Arctic haze aerosols at Barrow,Alaska

Relationships among atmospheric CO₂ concentration, excess sulfate and vanadium, and meteorological analyses for one winter at Barrow, Alaska were investigated. The results provided a basis for understanding the causes of short term CO₂ variability. The study indicated that peaks in CO₂ concentration were related to direct atmospheric transport of industrial pollutants from Eurasia. Evidence that background Arctic concentrations contained a pollution component was also found. Lowest CO₂ concentrations occurred with intrusions of Pacific air above the surface-based polluted Arctic air mass.     

Process optimization for enhanced carbon capture and cyclic stability using adsorbents derived from coal fly ash

Environmental Science and Pollution Research - Zeolites and metal–organic frameworks (MOFs) are popular adsorbents when it comes to capturing CO2 from the gaseous feed stream. In this study,...     

Modeling of carbon dioxide fixation by microalgae using hybrid artificial intelligence (AI) and fuzzy logic (FL) methods and optimization by genetic algorithm (GA)

Environmental Science and Pollution Research - In this study, we are reporting a novel prediction model for forecasting the carbon dioxide (CO2) fixation of microalgae which is based on the hybrid...     

Characterization of activated carbon fiber filters for pressure drop, submicrometer particulate collection, and mercury capture

The use of activated carbon fiber (ACF) filters for the capture of particulate matter and elemental Hg is demonstrated. The pressure drop and particle collection efficiency characteristics of the ACF filters were established at two different face velocities and for two different aerosols: spherical NaCl and combustion-generated silica particles. The clean ACF filter specific resistance was 153 kg m-2 sec-1. The experimental specific resistance for cake filtration was 1.6 x 10(6) sec-1 and 2.4 x 10(5) sec-1 for 0.5- and 1.5-micron mass median diameter particles, respectively. The resistance factor R was approximately 2, similar to that for the high-efficiency particulate air filters. There was a discrepancy in the measured particle collection efficiencies and those predicted by theory. The use of the ACF filter for elemental Hg capture was illustrated, and the breakthrough characteristic was established. The capacity of the ACF filter for Hg capture was similar to other powdered activated carbons.     

Kinetics of the extraction of pyrene using carbon dioxide in dense phase

Bath extraction experiments of pyrene from two spiked soils with different textural composition (sandy, sandy-clay) were performed with near-critical and supercritical CO(2) at different pressures (7.5, 15, 20, 25 MPa) and temperatures (40, 50, 60 degrees C) in order to obtain mass transfer rate data. An empirical equation whose parameters depend on type of soil but are independent of pressure and temperature is proposed. The comparison between individual mass transfer coefficients shows that the extraction is controlled by the resistance within the particle. Effective diffusivities between 0.4 and 6.0 x 10(-10) m(2)/s are deduced.     

Seasonal variation in amylase, invertase, cellulase activity and carbon dioxide evolution in a tropical protected grassland of Orissa, India, sprayed with carbaryl insecticide

A distinct seasonal variation in the enzyme activities and carbon dioxide evolution in soil, with a maximum in summer, was observed in soil treated with carbaryl and in control soil. There was no significant difference in the rate of enzyme activity between 0 and 10 cm and 10 and 20 cm depth of soil. Carbaryl insecticide applied at a normal agricultural dose did not have any inhibitory effect on soil enzyme activity, or on the rate of CO(2) evolution. However, the cellulase activity was greater in the surface soil of the control plot than in the treated plot.