Low-carbon and low-alkalinity stabilization/solidification of high-Pb contaminated soil

Lei Wang, Kequan Yu, Jiang Shan Li, Daniel C.W. Tsang, Chi Sun Poon, Jong Chan Yoo, Kitae Baek, Shiming Ding, Deyi Hou, Jianguo Dai

Research output: Journal article publicationJournal articleAcademic researchpeer-review

95 Citations (Scopus)

Abstract

Stabilization/solidification (S/S) is a low-cost and time-efficient method for soil remediation, however, delayed hydration reactions and high carbon footprint are major limitations for the treatment of high-Pb contaminated soil. This study develops a novel and low-carbon approach that combines ground granulated blast furnace slag (GGBS) and ordinary Portland cement (PC) with phosphate-/sulphate-rich byproducts to produce low-alkalinity, high-compatibility, high-strength binary cement (BC) for S/S process. Results show that contaminated soil with a large fraction of exchangeable and soluble Pb (e.g., shooting range sites) severely disturbed the formation of hydration products in conventional S/S treatment, whereas BC system could mitigate the Pb interference via precipitation and sorption evenly distributed on the BC hydrates as shown by elemental mapping. Thus, BC presented superior environmental performance in terms of toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching tests, which were substantiated by quantitative X-ray diffraction and thermogravimetric analyses. The addition of potassium dihydrogen phosphate reduced TCLP leachability of Pb by 86.9% and Pb diffusion coefficients by 69.4% due to the formation of insoluble Pb3(PO4)2. Similarly, incinerated sewage sludge ash enhanced Pb stabilization, whereas waste phosphogypsum increased early strength via precipitation of PbSO4, although the effectiveness of physical encapsulation was compromised due to reduction in hydration products. Therefore, the proposed binary binders with selected additives present a new and low-carbon S/S treatment for high-Pb shooting range soil remediation.
Original languageEnglish
Pages (from-to)418-427
Number of pages10
JournalChemical Engineering Journal
Volume351
DOIs
Publication statusPublished - 1 Nov 2018

Keywords

  • Green remediation
  • Lead-phosphate precipitation
  • Metal immobilization
  • Shooting range soil
  • Waste recycling

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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