1. Continuous leaching modifies the surface properties and metal(loid) sorption of sludge-derived biochar
- Author
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Chixiao Jiang, Daniel C.W. Tsang, Wu Xueyong, Weihua Zhang, Rongliang Qiu, Hang Wei, Mingyu Feng, and Yanming Jia
- Subjects
Atmospheric exposure ,Environmental Engineering ,010504 meteorology & atmospheric sciences ,Chemistry ,technology, industry, and agriculture ,Sorption ,010501 environmental sciences ,complex mixtures ,01 natural sciences ,Pollution ,Redox ,Metal ,visual_art ,Environmental chemistry ,Biochar ,visual_art.visual_art_medium ,Cation-exchange capacity ,Environmental Chemistry ,Oxidation process ,Leaching (metallurgy) ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
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 0.01M NaNO3 solution (pH5.5) and acidic solution (pH adjusted to 3.2 by HNO3:H2SO4=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.
- Published
- 2017