The screening of various biochars for Cd2+ removal at relevant soil pH

•Chicken manure biochars are excellent Cd2+ adsorbents.•The optimal pyrolysis temperature to produce biochar-based Cd2+ adsorbents is 450 °C.•Precipitation is an important Cd2+ removal mechanism for chicken manure biochar.•Amorphous Cd2+ species are formed on the biochar surface.•Short Cd2+ removal...

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Published in:Waste management (Elmsford) Vol. 168; pp. 376 - 385
Main Authors: Lataf, A., Carleer, R., Yperman, J., Schreurs, S., D'Haen, J., Cuypers, A., Vandamme, D.
Format: Journal Article
Language:English
Published: Elsevier Ltd 01.08.2023
Subjects:
Adsorption
Agro-residues
Biochar
Cadmium
Long-term effect
Cadmium
Adsorption
Biochar
Long-term effect
Agro-residues
ISSN:0956-053X, 1879-2456, 1879-2456
Online Access:Get full text
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Summary:•Chicken manure biochars are excellent Cd2+ adsorbents.•The optimal pyrolysis temperature to produce biochar-based Cd2+ adsorbents is 450 °C.•Precipitation is an important Cd2+ removal mechanism for chicken manure biochar.•Amorphous Cd2+ species are formed on the biochar surface.•Short Cd2+ removal experiments might underestimate long-term biochar effects. Fourteen biochars from seven biomass sources were investigated on their long-term Cd2+ removal. The experiments consisted of a ten-day batch Cd2+ adsorption in a pH-buffered solution (pH = 6) to minimise pH effects. Insect frass, spent peat and chicken manure-derived biochars are promising Cd2+ adsorbents. Pyrolysis temperature was crucial for optimising Cd2+ removal by insect frass and spent peat-derived biochars. For these biochars, a pyrolysis temperature of 450 °C was optimal. In contrast, the Cd2+ removal by chicken manure biochars was independent of pyrolysis temperature. The Cd2+ removal by insect-frass and spent peat-derived biochars was associated with chemisorption on surface functionalities, while using chicken manure biochars was more associated with Cd2+ precipitation. The kinetics of Cd2+ removal over the course of ten days showed that insect frass biochar (450 °C) showed a gradual increase from 36 to 75 % Cd2+ removal, while chicken manure and spent peat-derived biochar (450 °C) already showed a higher Cd2+ removal (72 – 89 %) after day 1. This evidences that a long-term Cd2+ removal effect can be expected for some biochars. This should certainly be taken into consideration in future soil-based experiments.
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ISSN:0956-053X
1879-2456
1879-2456
DOI:10.1016/j.wasman.2023.06.018