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

Pietro P. Falciglia, Danilo Malarbi, Riccardo Maddalena, Valentina Greco, Federico G.A. Vagliasindi

Research output: Contribution to journalArticle

15 Citations (Scopus)
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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
Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalChemical Engineering Journal
Volume321
Early online date22 Mar 2017
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • citric acid
  • marine sediment
  • non-ionic surfactant
  • MGDA
  • mercury (Hg)
  • microwave heating (MWH)

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