Biochar-driven reduction of As(V) and Cr(VI): Effects of pyrolysis temperature and low-molecular-weight organic acids

Qin, Junhao; Li, Qiwen; Liu, Yanqing; Niu, Anyi; Lin, Cheng‐Fang

doi:10.1016/j.ecoenv.2020.110873

Cited by 36 publications

(11 citation statements)

References 43 publications

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“…Moreover, the peak of MRBCs at 1618 cm −1 was stronger than that of RBC, indicating that the impregnation-modified biochar produced more C=O functional groups. The absorption peak of MRBCs at 1618 cm −1 showed a decreasing trend from 300 to 600 • C [38]. The peak of 2845 and 2921 cm −1 was associated with the presence of aliphatic group (-CHn) stretching [39], and the C-H stretching vibration absorption peak of modified biochar was higher than that of unmodified biochar.…”

Section: Chemical Structurementioning

confidence: 92%

Preparation and Characterization of MgO-Modified Rice Straw Biochars

et al. 2020

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Rice straw is a common agricultural waste. In order to increase the added value of rice straw and improve the performance of rice straw biochar. MgO-modified biochar (MRBC) was prepared from rice straw at different temperatures, pyrolysis time and MgCl2 concentrations. The microstructure, chemical and crystal structure were studied using X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption desorption isotherms and Elementary Analysis (EA). The results showed that the pyrolysis temperature had significant influence on the structure and physicochemical property of MRBCs. MRBC-2 h has the richest microporous structure while MRBC-2 m has the richest mesoporous structure. The specific surface area (from 9.663 to 250.66 m2/g) and pore volume (from 0.042 to 0.158 cm3/g) of MRBCs increased as temperature rose from 300 to 600 °C. However, it was observed MgCl2 concentrations and pyrolysis time had no significant influence on pore structure of MRBCs. As pyrolysis temperature increased, pH increased and more oxygen-containing functional groups and mineral salts were formed, while MgO-modified yield, volatile matter, total content of hydrogen, oxygen, nitrogen, porosity and average pore diameter decreased. In addition, MRBCs formed at high temperature showed high C content with a low O/C and H/C ratios.

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Section: Chemical Structurementioning

confidence: 92%

Preparation and Characterization of MgO-Modified Rice Straw Biochars

et al. 2020

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“…According to its redox reactivity, organic carbon might cause unwanted transformation or mobilization of PTEs. For instance, adding organic carbon to the soil would increase the mobility of As (Gong et al 2022), and its reducing potential might cause the reduction of As(V) to As(III), which is highly toxic (Alkurdi et al 2019;Qin et al 2020). The reductive formation of Tl(I), Sb(III), and Sn(II) with higher solubility was also reported owing to the broader Eh caused by the addition of biochar, increasing their mobility and potential toxicity (Rinklebe et al 2019(Rinklebe et al , 2020.…”

Section: Potential Risks Related To Soc During the Ptes Immobilizationmentioning

confidence: 99%

Redox-induced transformation of potentially toxic elements with organic carbon in soil

Tsang

2022

carbon res

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Soil organic carbon (SOC) is a crucial component that significantly affects the soil fertility, soil remediation, and carbon sequestration. Here, we review the redox-induced transformation of potentially toxic elements (PTEs) through the abiotic impact of SOC. The complex composition of SOC includes humus, pyrogenic carbon (e.g., biochar), dissolved organic matter, and anthropogenic carbon (e.g., compost), with varying concentrations and properties. The primary redox moieties on organic carbon are surface functionalities (e.g., phenol, quinone, and N/S-containing functional groups), environmentally persistent free radicals, and graphitic structures, and their contents are highly variable. Owing to these rich redox moieties, organic carbon can directly affect the reduction and oxidation of PTEs in the soil, such as Cr(VI) reduction and As(III) oxidation. In addition, the interactions between organic carbon and soil redox moieties (i.e., O2, Fe, and Mn minerals) cause the transformation of PTEs. The formation of reactive oxygen species, Fe(II), and Mn(III)/Mn(II) is the main contributor to the redox-induced transformation of PTEs, including Cr(VI) reduction and As(III)/Cr(III)/Tl(I) oxidation. We articulated both the positive and negative effects of organic carbon on the redox-induced transformation of PTEs, which could guide soil remediation efforts. Further scientific studies are necessary to better understand the potential transformations of PTEs by SOC, considering the complicated soil moieties, variable organic carbon composition, and both biotic and abiotic transformations of PTEs in the environment. Graphical Abstract

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“…The formation, migration, transformation, adsorption, and biodegradation of LMWOAs play an important role in the global carbon cycle. In addition, LMWOAs are involved in mineral transformation, dissolution, and the fixation and migration of metal elements such as iron, aluminum, cadmium, arsenic, and so on (Qin et al 2020;Wang et al 2014), the biodegradation of organic contaminants such as polycyclic aromatic hydrocarbons and petroleum hydrocarbons (Sun et al 2016;Martin et al 2014), phosphorus, potassium and other nutrient elements release (Zhang et al 2020a). The LMWOAs influence the large geological cycle of chemical elements, the immobilization of nutrients and pollutants in the soil, stimulating or inhibiting the growth and development of plants.…”

Section: Introductionmentioning

confidence: 99%

“…The humic acid adsorbed on the biochar surface significantly improved the CCC value of the biochar colloid from 183 to 806 mM due to increasing the repulsive force and steric force on the biochar surface. Some studies have shown that LMWOAs could affect the physical and chemical properties of biochar (e.g., porosity, functional properties, and inorganic minerals) (Liu et al 2017), the release of nutrients such as phosphorus and potassium in biochar (Zhang et al 2020a), and the adsorption capacity of biochar for heavy metals or organic contaminations (Sun et al 2016;Qin et al 2020;Wang et al 2014). However, most of these studies focus on the effect of LMWOAs on bulk biochar particles.…”

Section: Introductionmentioning

confidence: 99%

Effects of low molecular weight organic acids on aggregation behavior of biochar colloids at acid and neutral conditions

Wang

Xiong

et al. 2022

Biochar

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Low molecular weight organic acids (LMWOAs), as active components in the rhizosphere carbon cycling, may influence the environmental behaviors of biochar colloids. This study selected the pine-wood and wheat-straw biochars (PB and WB) as two typical biochars. The effects of typical LMWOAs (oxalic acid, citric acid, and malic acid) on aggregation kinetics of PB and WB colloids were investigated under pH 4 and 6 conditions. Critical coagulation concentrations (CCCs) of both PB and WB colloids were decreased with the LMWOAs regardless of the types of biochar and the solution pH, and the most significant effect occurred in pH 4 due to more LMWOAs sorption on the biochar colloids. The different types of LMWOAs caused various CCCs changes. For example, the CCC values of PB colloids decreased from 75 mM to 56, 52, and 47 mM in the pH 4 NaCl solutions when 1 mM oxalic acid, citric acid, and malic acid were present in the suspensions, respectively. The chemical structure (functional groups) and molecular weight of LMWOAs, solution pH, and the electrophoretic mobility (EPM) of biochar co-influence the interactions between biochar colloids and LMWOAs, thus affecting the stability of biochar colloids in the presence of LMWOAs. The presence of LMWOAs accelerated the aggregation of colloidal biochar by increasing the interaction of surface bridging bonds (hydrogen bonding) and decreasing the repulsive force between colloidal biochar particles. This study showed that LMWOAs could accelerate the aggregation of biochar colloids in acidic or neutral environments and reduce the mobility of biochar colloids in soil rhizosphere.

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Biochar-driven reduction of As(V) and Cr(VI): Effects of pyrolysis temperature and low-molecular-weight organic acids

Cited by 36 publications

References 43 publications

Preparation and Characterization of MgO-Modified Rice Straw Biochars

Preparation and Characterization of MgO-Modified Rice Straw Biochars

Redox-induced transformation of potentially toxic elements with organic carbon in soil

Effects of low molecular weight organic acids on aggregation behavior of biochar colloids at acid and neutral conditions

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