Carbon Storage in Coal Fly Ash by Reaction with Oxalic Acid

Coal combustion is one of the leading sources CO2 emissions, and it predicted to remain so for foreseeable future. The environmental effects coal burning can be partially offset by utilizing fly ash, which a byproduct, mineralize store carbon. Our study tests novel method carbon storage through reaction ash with oxalic acid (H2C2O4), creating durable solid oxalate phases. results show that whewellite (CaC2O4·H2O) weddellite (CaC2O4·(2 + x)H2O, x ≤ 0.5) are formed when reacts H2C2O4 at ambient temperature pressure. We examined 2 types found occurs relatively rapidly, reaching completion within 4 days. Moreover, reacted material comprised ∼18% Ca oxalate. During reaction, portlandite, primary calcium-bearing mineral in was dissolved entirely, although mass balance calculations indicate amorphous phases also serve as an important source minerals. Reaction modeling suggests released two dissolve different rates, rapidly dissolving phase releasing rate 40 times faster than slow phase. Based on our calculations, 1 tonne could over 34 kg carbon, has potential more 35 Mt per year global scale. Thus, findings reacting reduce impact burning, adapting technique use other alkaline wastes may represent critical green technology.