Description

Excess carbon dioxide (CO2) in the atmosphere affects the ecosystem as a greenhouse gas. Carbon dioxide may be reduced through lowering fuel emissions and carbon usage. In addition to reductions in emissions and to mitigate this condition, it is important to consider mechanisms that can remove CO2 from the atmosphere. There are two main forms of soil carbon sequestration. First is geological storage, which is defined as subterranean injection of CO2 such as below the salt domes, or within a depleted oil reservoir. The second form of carbon capture is passive soil sequestration, which will be the subject of this study. Soil carbon capture involves natural processes that remove atmospheric CO2 through photosynthesis and pedogenic carbonates minerals. Some researches were investigated in the world about this method. The work of Washbourne et al. (2012) at showed that the urban soils can remove 100 t CO₂ per hectare monthly.

Formation of pedogenic carbonates, (predominantly composed of the mineral calcite (CaCO₃)), depends on the availability of calcium and carbonate in solution. Carbon dioxide precipitation from soil that contains metallurgical slag into calcite may be maximized through material additions and foliage. Within the metallurgical slag, there are carbonate, silicate, and magnesium oxide that are often utilized to react with the carbon dioxide. The maximum CO2 intake occurred at the highest temperature and smallest grain size for several different types of slag and intake quantities. Concentrations of mineral calcite on slag soil were measured in different soils and show the increase of the CaCO₃ in the soil (Pelnap & Kacem, 2018).

A good evaluation of the use of soil need to know what controls the maximum amount of carbon can be captured in as soil. Investigation is needed to evaluate soils characteristics. A good control of all factors can help to develop the CO₂ capture by urban soil.

The goal of this PhD work is to give the method to use to have an ideal soil or material to use on the CO₂ capture.

During this work, the carbon capture process will performed to determine the characteristics that would enhance the quantity of capture as well as the kinetic of the reaction. Material samples (slag, concrete waste, etc) will be tested.  At first, the pedological characteristics and the calcite content were determined. Accelerated carbonation of technosol based on slags and construction waste will be done using an experimental device developed at LTDS.

From results of the first step a relationship between characteristics and carbon capture capacities will be identified. This work can define an “optimum soil/material” which can give a better CO₂ capture.

The last step is testing the use of the optimum soil/material as an urban soil or on the layout of urban spaces will be tested.

Skills required

Gas/solid adsorption isotherms, Characterization of civil engineering materials, skills in experimental manipulation (speaking French or English or both)

Bibliography

R. Baciocchi, G. Costa, A. Polettini, R. Pomi, (2009). Influence of particle size on the carbonation of stainless steel slag for CO 2 storage. Energy Procedia, 1(1), 4859- 4866. Bao (2010). IECR. Abs. Selective leaching of steelmaking slag for indirect CO2 mineral sequestration. M.E. Jorat, M.A. Goddard. B.W. Kolosz, S.P. Sohi and D.A.C. Manning. (2015). Sustainable Urban Carbon Capture: Engineering Soils for Climate Change (SUCCESS). Geotechnical Engineering for Infrastructure and Development 2559-2564 D.A.C. Manning and Ph. Renforth. (2013). Passive sequestration of Atmospheric CO2 through coupled plant mineral reactions in Urban Soils. Environmental Science and Technology 47. 135-141 R.M. Pelnap, M. Kacem. “Effect of material addition and specific seed on calcite formation in metallurgic slag”. 2nd Scientific Workshop on Rehabilitation of polluted Sites and Soils. Saint-Etienne, October, 29 & 30, 2018. C-L. Washbourne. E. Lopez-Capel, Ph. Renforth. Ph.L. Ascough, and D.A.C. Manning. (2015). Rapid Removal of Atmospheric CO2 by Urban Soils. Environmental Science and Technology. C.L. Washbourne. Ph.Renforth. D.A.C. Manning. (2012). Investigating carbonate formation in urban soils as a method for capture and storage of atmospheric carbon Science of total environment. 431. 166-175

Keywords

carbonation, construction waste, slag, optimisation