Remediation of Hg-contaminated marine sediments by simultaneous application of enhancing agents and microwave heating (MWH)

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Falciglia, Pietro P. and Malarbi, Danilo and Maddalena, Riccardo and Greco, Valentina and Vagliasindi, Federico G.A. (2017) Remediation of Hg-contaminated marine sediments by simultaneous application of enhancing agents and microwave heating (MWH). Chemical Engineering Journal, 321. pp. 1-10. ISSN 1385-8947 (https://doi.org/10.1016/j.cej.2017.03.097)

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Abstract

The aim of this work was to investigate Hg removal ability of a novel microwave heating (MWH) treatment for marine sediment remediation enhanced by the application of several agents, biodegradable complexing agent (methylglycinediacetic acid, MGDA), surfactant (Tween® 80), and citric acid. Main results revealed that MWH allowed a very rapid heating (∼450 °C in 7 min) of the irradiated medium. However, without the addition of enhancing agents, a maximum Hg removal of ∼72% can be achieved. The application of MGDA led to a higher contaminant removal of ∼87% (residual concentration = 5.4 mg kg−1). For the treatment including the simultaneous addition of both chelating agent and surfactant, their synergetic action and stripping processes resulted in a very high Hg removal of ∼99% for an irradiation time of 7 min, corresponding to a residual concentration of 0.56 mg kg−1, which is lower than the Italian regulatory limit of 1 mg kg−1. The use of citric acid resulted in a shortening of the removal kinetics, which allowed the successful application of a shorter remediation time of 5 min. The observed strong passive ability of sediments to convert a microwave irradiation energy into a rapid and large temperature increase undoubtedly represents a key factor in the whole remediation process, making the studied treatment an excellent choice. Kinetic data are suitable for a preliminarily assessment of the effectiveness of clean-up activities, and as basis for future scaling-up studies on MWH of Hg-contaminated sediments

ORCID iDs

Falciglia, Pietro P., Malarbi, Danilo, Maddalena, Riccardo ORCID logoORCID: https://orcid.org/0000-0001-6251-3782, Greco, Valentina and Vagliasindi, Federico G.A.;
CORE (COnnecting REpositories)