Valorization of bottom ash fines by surface functionalization to reduce leaching of harmful contaminants

• Published in: Journal of environmental management 2020-10, Vol.271, p.110884-110884, Article 110884
• Main Authors: Alam, Qadeer, Dezaire, Thomas, Gauvin, Florent, Delsing, A.C.A., Brouwers, H.J.H.
• Format: Article
• Language: English
• Subjects: Functionalization; Hydrophobicity; Leaching; MSWI bottom Ash; Surface characterization
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2020.110884

This paper focuses on the functionalization of heterogeneous and highly contaminated waste material, namely bottom ashes (BA) with a particle size ≤ 125 μm that cannot be recycled with conventional treatments. The main goal of this study is to modify this waste into a valuable material that can be used in various applications, especially in the building sector. The complex mineralogical nature of this material was investigated with quantitative XRD, which confirms the presence of crystalline and amorphous phases such as silicates, carbonates, metallic oxides and amorphous glass. A hydrophobic modification was performed by using a fluorosilane grafting agent that utilizes the reactive surface sites of these minerals to form silanol bonds. Results showed that the 2.5% (m/m) of silane made the BA hydrophobic. Moreover, a thorough characterization showed that fluorosilane was well-grafted at the surface of the BA, with more than 60% of the fluorosilane chemisorbed on the surface. Additionally, the hydrophobic modification led to a significant decrease of the leaching of the contaminants (Cr, Cu, Mo and Sb) from the BA particles. Following this methodology, fine fraction of BA could be eventually used as a building material, preventing the landfill of this toxic waste. [Display omitted] •Mineralogy of bottom ash was investigated with the quantitative XRD.•Hydrophobic incineration bottom ash was synthesized by surface modification.•The bottom ashes demonstrated hydrophobicity with the contact angle of over 130°.•Quantification of the physisorbed/chemisorbed functionalizing agent was achieved.•Leaching of contaminants significantly decreases after the surface modification.