Highlights
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Sugar cane bagasse and orange peel can be recycled into biochar for soil application.
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Application of SC–BC and OP–BC improved the physicochemical properties of the studied soil.
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Both biochars can reduce the leachability of Pb in a metal smelter-contaminated soil.
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Addition of SC–BC and OP–BC resulted in greater mobility of As in the treated soil.
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Considerable attention should be paid when using the biochar in soil contaminated with As.