Oxalic acid optimization for iron-based solid waste conversion into a carbon-sequestering composite building material

Abstract

The cement industry significantly contributes to global CO₂ emissions, accounting for approximately 164 million metric tonnes annually, while total emissions from all sources reach 37 billion metric tonnes. Concurrently, the iron and steel sector generates substantial waste, producing about 500 kg of waste per tonne of steel. Addressing these environmental challenges is crucial for sustainable development. This study presents a sustainable alternative to traditional cement by developing a novel binder material composed primarily of waste iron. The alternative binder not only avoids CO₂ emissions but also absorbs CO₂ during carbonation curing, effectively contributing to carbon sequestration. Key parameters, including particle size, oxalic acid dosage, and water-to-binder ratio, were individually tested and analyzed for their impact on compressive strength, leading to the finalization of a 75μm particle size and a 0.2 water-to-binder ratio, which yielded compressive strengths of up to 45 MPa. The wet mix method for oxalic acid incorporation demonstrated superior performance compared to the dry mix approach. Comprehensive analyses, including XRD, FTIR, TGA/DTG, and FESEM, confirmed the enhanced reactivity and performance of the material with finer particles and optimized oxalic acid dosage. By utilizing 80% of waste materials, this alternative binder addresses both waste management and carbon capture, aligning with global sustainability objectives and advancing the development of eco-friendly building materials.