Humic substances as a washing agent for Cd-contaminated soils

Fande Meng, Guodong Yuan, Jing Wei, Dongxue Bi, Yong Sik Ok, Hailong Wang

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)

Abstract

Cost-effective and eco-friendly washing agents are in demand for Cd contaminated soils. Here, we used leonardite-derived humic substances to wash different types of Cd-contaminated soils, namely, a silty loam (Soil 1), a silty clay loam (Soil 2), and a sandy loam (Soil 3). Washing conditions were investigated for their effects on Cd removal efficiency. Cadmium removal was enhanced by a high humic substance concentration, long washing time, near neutral pH, and large solution/soil ratio. Based on the tradeoff between efficiency and cost, an optimum working condition was established as follows: humic substance concentration (3150 mg C/L), solution pH (6.0), washing time (2 h) and a washing solution/soil ratio (5). A single washing removed 0.55 mg Cd/kg from Soil 1 (1.33 mg Cd/kg), 2.32 mg Cd/kg from Soil 2 (6.57 mg Cd/kg), and 1.97 mg Cd/kg from Soil 3 (2.63 mg Cd/kg). Cd in effluents was effectively treated by adding a small dose of calcium hydroxide, reducing its concentration below the discharge limit of 0.1 mg/L in China. Being cost-effective and safe, humic substances have a great potential to replace common washing agents for the remediation of Cd-contaminated soils. Besides being environmentally benign, humic substances can improve soil physical, chemical, and biological properties.

Original languageEnglish
Pages (from-to)461-467
Number of pages7
JournalChemosphere
Volume181
DOIs
Publication statusPublished - 2017
Externally publishedYes

Bibliographical note

Funding Information:
Valuable discussion with and editorial help from Dr BKG Theng of Landcare Research, New Zealand, was greatly appreciated. This work was supported by Chinese National Key Research and Development Program (2016YFD0200303), the National Natural Science Foundation of China (21577131), the Special Funding for the Introduced Innovative R&D Team of Dongguan Municipal Government (2014607101003), and Key Research and Development Program of Shandong Province (2016CYJS05A01-1).

Publisher Copyright:
© 2017 Elsevier Ltd

Keywords

  • Cadmium
  • Calcium hydroxide
  • Leonardite
  • Soil remediation
  • Soil washing

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Chemistry
  • Pollution
  • Health, Toxicology and Mutagenesis

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