Exploring the carbon capture and sequestration performance of biochar-artificial aggregate using a new method

To achieve the ambitious goal of carbon neutrality, more carbon sequestration channels need to be developed. In thisstudy, we tried to combine biochar with cold-bonded artificial lightweight coarse aggregate (ALCA) which is madefrom municipal solid household waste incineration bottom ash (MSWIBA).The strong carbon capture ability of biocharwas used to attract external CO2into the interior of ALCAs, which combined with CaO in MSWIBA to form CaCO3toachieve the effect of chemical carbon sequestration. The total carbon sequestration and carbon sequestration rate ofbiochar-ALCAs were quantified by a self-designed CO2concentration change test box, the physical and mechanicalproperties of biochar-ALCAs were investigated, as well as the changes before and after carbonization. The resultsshowed that biochar and ALCAs had good synergistic carbon sequestration ability. The total carbon sequestration ofbiochar-ALCAs could reach 30.58-33.06 kg/ton. The carbon sequestration efficiency could reach 70.2 % and84.9 % at 28 d/56 d in a low CO2concentration environment (0.05 % VOL). In addition, the water absorption ofbiochar-ALCAs decreased by 4.3 %-13.9 %, the apparent density increased by 0.9 %-2.8 %, and the strength increasedby 4.3 %-7.0 % after carbon sequestration, and the physical and mechanical properties were significantly improved.The purpose of this paper is to investigate the synergistic carbon sequestration of biochar in combination with ALCAsand to quantitatively assess its ability to solidify low concentrations of CO2in the natural environment. A new test ap-paratus and test method were designed for this purpose. This paper may contribute for an important advance on thepreparation of recyclable cement-type composites able to capture and solidify CO2from the natural environment.

Automated summary

To achieve carbon neutrality, new carbon sequestration channels are necessary. This study combines biochar with cold-bonded artificial lightweight coarse aggregate (ALCA) made from municipal solid household waste incineration bottom ash (MSWIBA) to sequester carbon. The synergistic carbon sequestration ability of biochar-ALCAs was quantified, and it was found that they could sequester up to 30.58-33.06 kg/ton of carbon. The physical and mechanical properties of biochar-ALCAs were significantly improved after carbon sequestration. This research contributes to the development of recyclable cement-type composites for carbon capture in the natural environment.