Lab‐scale atmospheric CO₂ absorption for calcium carbonate precipitation in sand

Abstract

The microbial‐induced calcite precipitation (MICP) process for ground improvement uses microorganisms to hydrolyze urea, producing carbonate ions to induce in situ calcium carbonate (CaCO3) precipitation in soil to improve its strength. This paper proposes using the hydroxide‐based absorption of CO2 instead to provide the carbonate ion source. This study utilizes direct air capture (DAC) to absorb atmospheric CO2 using potassium hydroxide (KOH) in a semi‐batch bubble absorption column. Potassium carbonate (K2CO3) was then injected into sand with calcium hydroxide (Ca(OH)2 as a calcium source to precipitate CaCO3 and regenerate KOH. Batch and continuous flow precipitation methods produced a poor distribution of CaCO3, with more CaCO3 precipitated on top, resulting in unconfined compressive strength (UCS) of 6.9 to 19.6 kPa. Sand pre‐mixed with Ca(OH)2 gave well distributed CaCO3, precipitated throughout the sample with 7.56 wt% and 6.87 wt% CaCO3 content and UCS of 39.2 and 35.3 kPa before failing for batch and continuous flow precipitation respectively. This differs from MICP strength improvement of 1000 kPa with 5.3 wt% CaCO3 due to poor binding of sand with the precipitated CaCO3 crystals. However, this application provides a stable sequestration source for atmospheric CO2 in soil. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

A numerical study on the non‐isothermal flow characteristics and hydrate risk of CO2 in buried transmission pipelines under the gas‐phase transportation mode

“…Finally, the above difference equations (Eqns 6 and 7) are used to obtain the iterative solution. The detailed iteration process is as follows: Under the condition that the temperature and pressure (transmission temperature and transmission pressure) at the inlet end of the pipeline (CO 2 storage station) are known, the temperature and pressure at the outlet end of the segment i = 1 (i.e., the inlet end of i = 2 segment) can be calculated by iteration Eqns (6) and (7). Then, according to the pressure and temperature at the inlet end of the i = 2 segment, the pressure and temperature at the inlet end of the i = 3 segment can be calculated, and so on.…”

“…CO 2 capture and storage (CCS) plays an important role in controlling carbon dioxide emissions and reducing the greenhouse effect . Large‐scale CCS projects require a large amount of CO 2 to be transported .…”

“…C O 2 capture and storage (CCS) plays an important role in controlling carbon dioxide emissions and reducing the greenhouse effect. [1][2][3][4][5][6][7][8] Large-scale CCS projects require a large amount of CO 2 to be transported. [9][10][11][12][13] However, the formation of CO 2 hydrates becomes a major problem, affecting the safety of CO 2 pipeline transportation.…”

Biopolymers as Green Binders for Soil Improvement in Geotechnical Applications: A Review

“…From 2010 to 2018, the global amount of cement production increased from 3310 to 4100 million tons (23.8% increase) [14]. To reduce cement usage, researchers have attempted to replace traditional environmentally harmful materials with sustainable techniques and methods, such as bio-enzymes, CO 2 absorption, microbial-induced calcite precipitation (MICP) method with viable but low-cost medium, and biopolymers [15][16][17][18][19][20].…”

Strength and Microstructural Assessment of Reconstituted and Stabilised Soft Soils with Varying Silt Contents

“…It is crucial to develop or reclaim land with poor geotechnical conditions in order to build on it to solve the issue of land shortage. Advancements in construction material science considering sustainability [1][2][3][4][5][6] and the characterisation of soils form the basis of geoenvironmental and geotechnical design but not without challenges faced in laboratory tests [7,8], computer simulations [9,10] and inferior in situ geomaterial conditions requiring conditioning and improvement [11][12][13][14][15][16]. For example, many projects, such as the construction of coastal facilities, such as shipyard [17] and quay walls, deep excavation [18][19][20] or foundations for building basements [21,22], road embankments on flood plains [23,24] and tunnelling [25][26][27][28] require infrastructure to be built on areas with widespread soft soil deposits [29][30][31][32].…”