Unveiling Early FeAs Cluster Formation in As³⁺ Capture: A Multi-Edge XAFS Study

Arsenic (As³⁺), a highly toxic pollutant, interacts with iron (Fe) in aqueous solutions, potentially leading to its capture by the mineral tooeleite (To). Our recent research demonstrated that under low-concentration and neutral pH conditions, even small FeAs oxy-hydroxy units (considered building blocks of To) can self-assemble into clusters, contradicting existing assumptions about To formation. To gain deeper insights into the local structure of these FeAs units, we propose conducting in-situ multi-edge X-ray absorption fine structure (XAFS) spectroscopy (Fe, Zn, As) across varying Fe/As concentrations and pH levels. This investigation is expected to provide valuable details about the initial stages of Fe hydroxide nucleation, complementing our existing knowledge base. This project aims to elucidate the behaviour of Fe/As water solutions with valuable implications for practical applications in water purification.