Monovalent−Divalent Element Quotient Drives Lead(Ii) Removal in Aqueous Solutions by Nitric Acid-Modified Biochar

33 Pages Posted: 18 Feb 2022

See all articles by Christopher Nzediegwu

Christopher Nzediegwu

University of Alberta

M. Anne Naeth

University of Alberta

Scott X. Chang

University of Alberta

Abstract

We evaluated the effects of elements that dissolved from nitric acid-modified biochars into aqueous solutions on lead(II) removal and the associated mechanisms for biochars derived from four biomasses at three production temperatures. Monovalent-divalent element quotient was calculated as the sum of monovalent element concentrations divided by that of divalent element concentrations to study their relative effects on lead(II) removal. Lead(II) removal reached 54% and increased with increasing monovalent-divalent element quotient due to increasing chemical activity. Compared to the pristine biochars, activation with nitric acid increased lead(II) adsorption rate, although the effect on the maximum adsorption capacity was mainly biomass-depended, increased for sawdust biochars but decreased for canola straw, manure pellet and wheat straw biochars. Regardless of biomass type and production temperature, lead(II) was mainly bounded as Pb-O and PbCO3 on the modified biochars through surface complexation and cation-π interaction, and the adsorption was best explained by Freundlich and pseudo-second-order models. However, precipitation and cation exchange were negligible in the adsorption process because minerals and elements were significantly dissolved from the biochars during the activation. Our results suggest that nitric acid activation is effective to increase lead(II) adsorption for biochars produced from mineral−depleted biomasses, such as sawdust.

Keywords: chemical activation, Dissolution, Feedstock type, Freundlich model, Precipitation

Suggested Citation

Nzediegwu, Christopher and Naeth, M. Anne and Chang, Scott X., Monovalent−Divalent Element Quotient Drives Lead(Ii) Removal in Aqueous Solutions by Nitric Acid-Modified Biochar. Available at SSRN: https://ssrn.com/abstract=4037952 or http://dx.doi.org/10.2139/ssrn.4037952

Christopher Nzediegwu

University of Alberta ( email )

Edmonton, T6G 2R3
Canada

M. Anne Naeth

University of Alberta ( email )

Edmonton, T6G 2R3
Canada

Scott X. Chang (Contact Author)

University of Alberta ( email )

Edmonton, T6G 2R3
Canada

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