Effective acid mine drainage remediation in fixed bed column using porous red mud/fly ash-containing geopolymer spheres

abstract

Acid mine drainage (AMD) poses a significant threat to water quality worldwide, being amongst the most problematic environmental concerns of the millennium. This work reports for the first time the remediation of real AMD, from a Portuguese abandoned mine, in fixed bed column using porous red mud/fly ash-based geopolymeric spheres. Porous waste-based spheres (2.6 +/- 0.2 mm) were obtained by a suspension-solidification method through the addition of optimum foaming agent dosage. The sorbent capacity in removing cations from AMD was evaluated by targeting selected hazardous elements: Zn, Cu, Co, Pb and Ni, based on their occurrence in the effluent and potential hazard. The spheres exhibited a dual mechanism of action, simultaneously neutralizing the acidic sample while removing cations through adsorption achieving removal efficiencies between 51 % and 80 %. Other elements present in high levels, such as iron were efficiently removed ( >96 %). The role of precipitation, due to the pH neutralization, and adsorption was determined. The sorbent regeneration and reusability were evaluated for up to five cycles. Moreover, the effectiveness of waste-based geopolymers treating distinct AMD waters due to seasonal variations was also evaluated, further demonstrating the effectiveness of the proposed strategy to address environmental concerns stemming from mining activities.

keywords

INORGANIC POLYMER MICROSPHERES; METAKAOLIN BASED GEOPOLYMER; HEAVY-METALS ADSORPTION; FLY-ASH; FACILE FABRICATION; EFFICIENT REMOVAL; METHYLENE-BLUE; CU(II); MECHANISM; STREAMS

subject category

Environmental Sciences & Ecology

authors

Gonçalves, NPF; Almeida, MM; Labrincha, JA; Novais, RM

Groups

G1 - Porous Materials and Nanosystems
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Multifunctional bAuXite Inorganic polyMers for acid mine drainage treatment from PortUguese Mines (MAXIMUM)

3D Printed Fouling-Resistant Photoactive Membranes for Wastewater Treatment (PURAQUA)

acknowledgements

This work was developed within the scope of the Project CICECO- Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.544 99/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.54499/UIDP/5 0011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) , financed by National funds through the FCT/MCTES (PIDDAC) . The authors would like to thank FCT project MAXIMUM (PTDC-CTM-CTM- 2205-2020, DOI 10.54499/PTDC/CTM-CTM/2205/2020) . Nuno Goncalves acknowledge the funding from the European Union's Horizon Europe research and innovation programme under the Marie Sklodowska-Curie Actions PF grant agreement No 101065059. The authors would like to thank EDM (Empresa de Desenvolvimento Mineiro, Portugal) and Dra. Catarina Diamantino for the support in the AMD sampling campaign.