Continuous leaching modifies the surface properties and metal(loid) sorption of sludge-derived biochar

Mingyu Feng, Weihua Zhang, Xueyong Wu, Yanming Jia, Chixiao Jiang, Hang Wei, Rongliang Qiu, Daniel C.W. Tsang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

30 Citations (Scopus)


After the application of sludge derived biochar (SDBC) for soil stabilization, it is subjected to continuous leaching that may change its surface properties and metal(loid) immobilization performance. This study simulated the continuous leaching through the fresh SDBC sample in columns with unsaturated and saturated zones under flushing with 0.01 M NaNO 3 solution (pH 5.5) and acidic solution (pH adjusted to 3.2 by HNO 3:H 2SO 4 = 1:2), respectively. The resultant changes were assessed in terms of the SDBC surface characteristics and metal(loid) sorption capacities. Continuous leaching was found to gradually decrease the density of basic functional groups and increase the density of carboxyl groups as well as cation exchange capacity on the SDBC surface. It was attributed to the surface acidification and oxidation process by the leaching process, yet it occurred to a lesser extent than the atmospheric exposure. Continuous leaching increased Pb(II), Cr(VI), and As(III) sorption capacity of the SDBC, probably because the increase in carboxyl groups promoted inner-sphere complexation and Fe oxidation as revealed by spectroscopic analysis. It was noteworthy that the SDBC in the unsaturated and saturated zones under continuous leaching displayed distinctive effects on metal(loid) sorption capacity than the atmospheric exposure. Future investigations are needed for understanding the fate and interactions of the SDBC under varying redox conditions and intermittent leaching process.

Original languageEnglish
Pages (from-to)731-737
Number of pages7
JournalScience of the Total Environment
Publication statusPublished - 1 Jun 2018


  • Acidification/oxidation
  • Biochar ageing
  • Column leaching
  • Soil stabilization
  • Surface chemistry
  • Trace element immobilization

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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