Pinewood outperformed bamboo as feedstock to prepare biochar-supported zero-valent iron for Cr6+ reduction

Min Zhou; Changai Zhang; Yangfan Yuan; Xiaoyun Mao; Yuncong Li; Nong Wang; Shengsen Wang; Xiaozhi Wang

doi:10.1016/j.envres.2020.109695

Pinewood outperformed bamboo as feedstock to prepare biochar-supported zero-valent iron for Cr⁶⁺ reduction

Environ Res. 2020 Aug:187:109695. doi: 10.1016/j.envres.2020.109695. Epub 2020 May 20.

Authors

Min Zhou¹, Changai Zhang², Yangfan Yuan¹, Xiaoyun Mao³, Yuncong Li⁴, Nong Wang⁵, Shengsen Wang⁶, Xiaozhi Wang⁷

Affiliations

¹ College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China.
² School of Environmental and Natural Resources, Zhejiang University of Science & Technology, Hangzhou, 310023, PR China.
³ Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China.
⁴ Soil and Water Sciences Department, Tropical Research and Education Center, IFAS, University of Florida, Homestead, FL, 33031, USA.
⁵ Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture/Tianjin Key Laboratory of Agro-environment and Safe-product, Tianjin, 300191, China.
⁶ College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China; Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture/Tianjin Key Laboratory of Agro-environment and Safe-product, Tianjin, 300191, China. Electronic address: wangss@yzu.edu.cn.
⁷ College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China. Electronic address: xzwang@yzu.edu.cn.

PMID: 32480029
DOI: 10.1016/j.envres.2020.109695

Abstract

In this work, pinewood and bamboo were pyrolyzed at 600 °C to prepare PBC and BBC-supported zerovalent iron (ZVI), respectively. Raman spectra suggested PBC was more intensively carbonized than BBC as indicated by higher I_D/I_G ratio. XRD and TEM confirmed nanoscaled ZVI was well dispersed in PBC but soldered in chain-structure in BBC. Maximal chromate (Cr(VI)) sorption capacity followed the order of PBC/ZVI (5.93 g kg^-1)>BBC/ZVI (3.61 g kg^-1)>BBC (3.55 g kg^-1)>PBC (2.59 g kg^-1). Desorption and XPS of four Cr-spent sorbents suggested reduction accounted for 79-88% of overall Cr(VI) detoxification. Greater Cr(VI) reduction of BBC than PBC indicated greater tendency of BBC to donate electrons. However, Cr(VI) reduction by PBC/ZVI was 1.7 times greater than BBC/ZVI, corresponding to greater electron transfer of PBC/ZVI (2.5 μA e^-) than BBC/ZVI (0.5 μA e^-). Thus, PBC is more conducible to transfer electrons as evidenced by Tafel and Amperometric analyses. Demineralization of pristine BC enhanced the difference between PBC/ZVI and BBC/ZVI regarding Cr(VI) reduction, suggesting the dominant role of biopolymers in biomass in terms of electron transfer capacity. Three model biopolymers were compared which indicated lignin-BC had lower electron transfer rates than cellulose-BC and hemicellulose-BC. BC prepared by lignin extracted from pinewood exhibited higher corrosion rate and lower electrical resistance than that from bamboo. Thus, unfavorable lignin in bamboo compromised electron transfer of BBC and Cr(VI) reduction by BBC/ZVI.

Keywords: Biochar; Biomass; Electron transfer; Heavy metals; Soil and water remediation; Zerovalent iron.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Charcoal
Chromium / analysis
Iron
Pinus*
Water Pollutants, Chemical*

Substances

Water Pollutants, Chemical
biochar
Chromium
Charcoal
Iron