Humic substances as a washing agent for Cd-contaminated soils

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

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30 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 Jan 1
Externally publishedYes

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Keywords

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

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemistry(all)

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