Sorptive removal of nitro explosives and metals using biochar.
TL;DR: The results suggest that biochar can be an attractive and alternative option in environmental remediation of nitro explosives and metals through sorption and immobilization and that appropriate selection of biochar may be necessary according to the types of contaminant and the properties of biochars.
Abstract: The feasibility of using biochar as a sorbent to remove nitro explosives and metals from contaminated water was investigated through batch experiments. Biochar, synthesized using various biomasses, showed a porous structure and a high surface area and includes embedded carbonate minerals. Compared with granular activated carbon, biochar was competitive as a sorbent for removing Cd, Cu, Pb, and Zn from water according to the maximum sorption capacities of the metals. Some biochars also effectively sorbed nitro explosives from water. Correlation analysis between maximum sorption capacities and properties of biochar showed that the sorption capacity of biochar for cationic toxic metals is related to cation exchange capacity and that the sorption capacity of explosives is proportional to surface area and carbon content. Results from X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses and laboratory experiments suggest that surface functional groups may be responsible for the sorption of cationic metals to the biochar surface. In contrast, carbon contents may account for the sorption of explosives, possibly through π-π electron donor-acceptor interactions. Our results suggest that biochar can be an attractive and alternative option in environmental remediation of nitro explosives and metals through sorption and immobilization and that appropriate selection of biochar may be necessary according to the types of contaminant and the properties of biochar.
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TL;DR: Some biochars are good candidates for removal of halogenated phenols, triclosan, and ibuprofen from water and soil and are related to the surface area and carbon content of the biochar and the hydrophobicity of Halogenated Phenols.
Abstract: The feasibility of using biochar as a sorbent to remove nine halogenated phenols (2,4-dichlorophenol, 2,4-dibromophenol, 2,4-difluorophenol, 2-chlorophenol, 4-chlorophenol, 2-bromophenol, 4-bromophenol, 2-fluorophenol, and 4-fluorophenol) and two pharmaceuticals (triclosan and ibuprofen) from water was examined through a series of batch experiments. Types of biochar, synthesized using various biomasses including fallen leaves, rice straw, corn stalk, used coffee grounds, and biosolids, were evaluated. Compared to granular activated carbon (GAC), most of the biochar samples did not effectively remove halogenated phenols or pharmaceuticals from water. The increase in pH and deprotonation of phenols in biochar systems may be responsible for its ineffectiveness at this task. When pH was maintained at 4 or 7, the sorption capacity of biochar was markedly increased. Considering maximum sorption capacity and properties of sorbents and sorbates, it appears that the sorption capacity of biochar for halogenated phenols is related to the surface area and carbon content of the biochar and the hydrophobicity of halogenated phenols. In the cases of triclosan and ibuprofen, the sorptive capacities of GAC, graphite, and biochars were also significantly affected by pH, according to the point of zero charge (PZC) of sorbents and deprotonation of the pharmaceuticals. Pyrolysis temperature did not affect the sorption capacity of halogenated phenols or pharmaceuticals. Based on the experimental observations, some biochars are good candidates for removal of halogenated phenols, triclosan, and ibuprofen from water and soil.
80 citations
Cites background from "Sorptive removal of nitro explosive..."
...In the current study, we investigated sorption of nitro explosives to biochars synthesized from poultry litter, biosolids, fallen leaves, rice straw, corn stalk, and ground coffee waste (Oh and Seo 2014)....
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TL;DR: In this paper, the role of extracellular polymeric substances (EPS) in the electron transfer process between microbial cells and electron donor or acceptor species is investigated using cyclic voltammetry, electrochemical impedance spectrum, and chronoamperometry.
77 citations
TL;DR: In this paper, a comprehensive review on the production of both natural PyC and engineered PyC (biochars), mechanisms involved, and factors influencing their role as soil contaminant immobilizer is presented.
Abstract: Pyrogenic carbon (PyC), including soil native PyC and engineered PyC (biochars), is increasingly being recognized for its potential role as a low-cost immobilizer of contaminants in soils. Published reviews on the role of soil native PyC as a sorbent in soils have so far focused mainly on organic contaminants and paid little or no attention to inorganic contaminants. Further, a comprehensive review on the production of both natural PyC and engineered PyC (biochars), mechanisms involved, and factors influencing their role as soil contaminant immobilizer is so far not available. The objective of this review is thus to systematically summarize the sources, formation, and properties of PyC, including its quantification in soils, followed by their roles in the immobilization of both organic and inorganic contaminants in soils. Effectiveness of PyC on bioavailability, leaching, and degradation of soil contaminants was summarized. Notably, the mechanisms and factors (for the first time) influencing the i...
75 citations
Cites background from "Sorptive removal of nitro explosive..."
...Oh and Seo (2014) discovered that the sorption capacity of biochar for cationic toxic metals is related to CEC....
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TL;DR: The results suggest that Fe(0)-included biochar is a viable option to immobilize and transform redox-sensitive organic contaminants in natural environments.
66 citations
TL;DR: It is suggested that nitrate can be effectively denitrified by microbes with Fe(0) and biochar in natural and engineered systems.
60 citations
References
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Book•
02 Nov 1995
TL;DR: In this article, an overview of the evolution of Soil Chemistry is presented, with a case study of Pollution of Soils and Waters and a discussion of the role of organic compounds in soil chemistry.
Abstract: Environmental Soil Chemistry: An Overview: Evolution of Soil Chemistry. The Modern Environmental Movement. Contaminants in Waters and Soils. Case Study of Pollution of Soils and Waters. Soil Decontamination. Inorganic Soil Components: Pauling's Rules. Primary Soil Minerals. Secondary Soil Minerals. Specific Surface of Soil Minerals. Surface Charge of Soil Minerals. Identification of Minerals by X-Ray Diffraction Analyses. Use of Clay Minerals to Retain Organic Contaminants. Chemistry of Soil Organic Matter: Effects of Soil Formation Factors on SOM Contents. Composition of SOM. Fractionation of SOM. SOM Structure. Functional Groups and Charge Characteristics. Humic Substance-Metal Interactions. SOM-Clay Complexes. Retention of Pesticides and Other Organic Substances by Humic Substances. Soil Solution-Solid Phase Equilibria: Measurement of the Soil Solution. Speciation of the Soil Solution. Ion Activity and Activity Coefficients. Dissolution and Solubility Processes. Sorption Phenomena on Soils: Introduction and Terminology. Surface Functional Groups. Surface Complexes. Adsorption Isotherms. Equilibrium-Based Adsorption Models. Surface Precipitation. Sorption of Metal Cations. Sorption of Anions. Points of Zero Charge. Desorption. Use of Spectroscopic and Microscopic Methods in Determining Mechanisms for Sorption-Desorption Phenomena. Ion Exchange Processes: Characteristics of Ion Exchange. Cation Exchange Equilibrium Constants and Selectivity Coefficients. Thermodynamics of Ion Exchange. Relationship between Thermodynamics and Kinetics of Ion Exchange. Kinetics of Soil Chemical Processes: Rate-Limiting Steps and Time Scales of Soil Chemical Reactions. Rate Laws. Determination of Reacti
2,837 citations
TL;DR: A molecular-level assessment of the physical organization and chemical complexity of biomass-derived chars and, specifically, that of aromatic carbon in char structures suggests the existence of four distinct categories of char consisting of a unique mixture of chemical phases and physical states.
Abstract: Char black carbon (BC), the solid residue of incomplete combustion, is continuously being added to soils and sediments due to natural vegetation fires, anthropogenic pollution, and new strategies for carbon sequestration (“biochar”). Here we present a molecular-level assessment of the physical organization and chemical complexity of biomass-derived chars and, specifically, that of aromatic carbon in char structures. Brunauer−Emmett−Teller (BET)−N2 surface area (SA), X-ray diffraction (XRD), synchrotron-based near-edge X-ray absorption fine structure (NEXAFS), and Fourier transform infrared (FT-IR) spectroscopy are used to show how two plant materials (wood and grass) undergo analogous but quantitatively different physical−chemical transitions as charring temperature increases from 100 to 700 °C. These changes suggest the existence of four distinct categories of char consisting of a unique mixture of chemical phases and physical states: (i) in transition chars, the crystalline character of the precursor ma...
2,283 citations
TL;DR: The forms of alkalis of the biochars produced from the straws of canola, corn, soybean and peanut at different temperatures (300, 500 and 700°C) were studied by means of oxygen-limited pyrolysis and it was suggested that carbonates were the major alkaline components in theBiochars generated at the high temperature.
1,482 citations
TL;DR: Biochars, produced by pyrolysis of pine needles at different temperatures, were characterized by elemental analysis, BET-N2 surface areas and FTIR, and Sorption isotherms of naphthalene, nitrobenzene, and m-dinitrobenZene from water to the biochars were compared.
Abstract: The combined adsorption and partition effects of biochars with varying fractions of noncarbonized organic matter have not been clearly defined. Biochars, produced by pyrolysis of pine needles at different temperatures (100-700 degrees C, referred as P100-P700), were characterized by elemental analysis, BET-N2 surface areas and FTIR. Sorption isotherms of naphthalene, nitrobenzene, and m-dinitrobenzene from water to the biochars were compared. Sorption parameters (N and logKf) are linearly related to sorbent aromaticities, which increase with the pyrolytic temperature. Sorption mechanisms of biochars are evolved from partitioning-dominant at low pyrolytic temperatures to adsorption-dominant at higher pyrolytic temperatures. The quantitative contributions of adsorption and partition are determined by the relative carbonized and noncarbonized fractions and their surface and bulk properties. The partition of P100-P300 biochars originates from an amorphous aliphatic fraction, which is enhanced with a reduction of the substrate polarity; for P400-P600, the partition occurs with a condensed aromatic core that diminishes with a further reduction of the polarity. Simultaneously, the adsorption component exhibits a transition from a polarity-selective (P200-P400) to a porosity-selective (P500-P600) process, and displays no selectivity with P700 and AC in which the adsorptive saturation capacities are comparable to predicted values based on the monolayer surface coverage of molecule.
1,449 citations