| 1. |
- Hale, Sarah E., et al.
(författare)
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A synthesis of parameters related to the binding of neutral organic compounds to charcoal
- 2016
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 144, s. 65-74
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Forskningsöversikt (refereegranskat)abstract
- The sorption strength of neutral organic compounds to charcoal, also called biochar was reviewed and related to charcoal and compound properties. From 29 studies, 507 individual Freundlich sorption.coefficients were compiled that covered the sorption strength of 107 organic contaminants. These sorption coefficients were converted into charcoal-water distribution coefficients (K-D) at aqueous concentrations of 1 ng/L, 1 mu g/L and 1 mg/L. Reported log K-D values at 1 mu g/L varied from 0.38 to 8.25 across all data. Variation was also observed within the compound classes; pesticides, herbicides and insecticides, PAHs, phthalates, halogenated organics, small organics, alcohols and PCBs. Five commonly reported variables; charcoal production temperature T, surface area SA, H/C and 0/C ratios and organic compound octanolwater partitioning coefficient, were correlated with K-D values using single and multiple-parameter linear regressions. The sorption strength of organic compounds to charcoals increased with increasing charcoal production temperature T, charcoal SA and organic pollutant octanol-water partitioning coefficient and decreased with increasing charcoal O/C ratio and charcoal H/C ratio. T was found to be correlated with SA (r(2) = 0.66) and O/C (r(2) = 0.50), particularly for charcoals produced from wood feedstocks (r2 = 0.73 and 0.80, respectively). The resulting regression: log K-D = (0.18 +/- 0.06) log K-ow + (5.74 +/- 1.40) log T + (0.85 +/- 0.15) log SA + (1.60 +/- 0.29) log OC + (-0.89 +/- 0.20) log HC + (-13.20 +/- 3.69), r(2) = 0.60, root mean squared error = 0.95, n = 151 was obtained for all variables. This information can be used as an initial screening to identify charcoals for contaminated soil and sediment remediation.
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| 2. |
- Hale, Sarah E., et al.
(författare)
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Sorption of the monoterpenes alpha-pinene and limonene to carbonaceous geosorbents including biochar
- 2015
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 119, s. 881-888
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Tidskriftsartikel (refereegranskat)abstract
- The sorption of two monoterpenes, alpha pinene and limonene to the carbonaceous geosorbents graphite, bituminous coal, lignite coke, biochar and Pahokee peat was quantified. Polyethylene (PE) passive samplers were calibrated for the first time for these compounds by determining the PE-water partitioning coefficients and used as a tool to determine sorption to the carbonaceous geosorbents. Log KPE-water values were 3.49 +/- 0.58 for alpha pinene and 4.08 +/- 0.27 for limonene. The sorption of limonene to all materials was stronger than that for a pinene (differences of 0.2-13 log units between distribution coefficients for the monoterpenes). Placing K-d values in increasing order for a pinene gave biochar approximate to Pahokee peat approximate to bituminous coal approximate to lignite coke < graphite. For limonene the order was: Pahokee peat approximate to biochar approximate to bituminous coal < graphite approximate to lignite coke. Micropore (defined as pores <1.5 nm) and nanopore surface area (defined as pores 1.5 nm to 50 nm) normalised carbonaceous geosorbent-water distribution coefficients were also calculated. There was no clear correlation of these distribution coefficients with SA. Elemental composition was used to assess the degree of condensation (or alteration) of the carbonaceous geosorbents. The degree of carbonisation increased in the order; Pahokee peat < lignite coke < bituminous coal < biochar < graphite, however this was not correlated with an increase in the experimental distribution coefficients.
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| 3. |
- Hilber, Isabel, et al.
(författare)
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Bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons from (post-pyrolytically treated) biochars
- 2017
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 174, s. 700-707
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Tidskriftsartikel (refereegranskat)abstract
- Bioaccessibility data of PAHs from biochar produced under real world conditions is scarce and the influence of feedstock and various post-pyrolysis treatments common in agriculture, such as co composting or lacto-fermentation to produce silage fodder, on their bioavailability and bioaccessibility has hardly been studied. The total (C-total), and freely dissolved (i.e., bioavailable) concentrations (C-free) of the sum of 16 US EPA PAHs of 43 biochar samples produced and treated in such ways ranged from 0.4 to almost 2000 mg/kg, and from 12 to 81 ng/L, respectively, which resulted in very high biochar-water partition coefficients (4.2 < log K-D < 8.8 L/kg) for individual PAHs. Thirty three samples were incubated in contaminant traps that combined a diffusive carrier and a sorptive sink. Incubations yielded samples only containing desorption-resistant PAHs (C-res). The desorption resistant PAH fraction was dominant, since only eight out of 33 biochar samples showed statistically significant bioaccessible fractions (f(bioaccessible) = 1 - C-res/C-total). Bioavailability correlated positively with C-total/surface area. Other relationships of bioavailability and accessibility with the investigated post-pyrolysis processes or elemental composition could not be found. PAH exposure was very limited (low C-free, high C-res) for all samples with low to moderate C-total whereas higher exposure was determined in some biochars with C-total > 10 mg/kg.
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| 4. |
- Jakob, Lena, et al.
(författare)
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PAH-sequestration capacity of granular and powder activated carbon amendments in soil, and their effects on earthworms and plants
- 2012
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 88:6, s. 699-705
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Tidskriftsartikel (refereegranskat)abstract
- A field lysimeter study was carried out to investigate whether the amendment of 2% powder and granular activated carbon (PAC and GAC) to a soil with moderate PAH contamination had an impact on the PAH bioaccumulation of earthworms and plants, since AC is known to be a strong sorbent for organic pollutants. Furthermore, secondary effects of AC on plants and earthworms were studied through growth and nutrient uptake, and survival and weight gain. Additionally, the effect of AC amendments on soil characteristics like pH, water holding capacity, and the water retention curve of the soil were investigated. Results show that the amendment of 2% PAC had a negative effect on plant growth while the GAC increased the growth rate of plants. PAC was toxic to earthworms, demonstrated by a significant weight loss, while the results for GAC were less clear due to ambiguous results of a field and a parallel laboratory study. Both kinds of AC significantly reduced biota to soil accumulation factors (BSAFs) of PAHs in earthworms and plants. The GAC reduced the BSAFs of earthworms by an average of 47 +/- 44% and the PAC amendment reduced them by 72 +/- 19%. For the investigated plants the BSAFs were reduced by 46 +/- 36% and 53 +/- 22% by the GAC and PAC, respectively.
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| 5. |
- Kupryianchyk, Darya, et al.
(författare)
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Treatment of sites contaminated with perfluorinated compounds using biochar amendment
- 2016
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 142, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Per- and polyfluorinated compounds (PFCs) have been attracting increasing attention due to their considerable persistence, bioaccumulation, and toxicity. Here, we studied the sorption behavior of three PFCs, viz. perfluorooctanesulfonic acid (PFOS), perfluorooctanecarboxylic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), on one activated carbon (AC) and two biochars from different feedstocks, viz. mixed wood (MW) and paper mill waste (PMW). In addition, we explored the potential of remediating three natively PFC contaminated soils by the addition of AC or biochar. The sorption coefficient i.e. Freundlich coefficients Log KF, (μg/kg)/(μg/L)n, for the two biochars were 4.61 ± 0.11 and 4.41 ± 0.05 for PFOS, 3.02 ± 0.04 and 3.01 ± 0.01 for PFOA, and 3.21 ± 0.07 and 3.18 ± 0.03 for PFHxS, respectively. The AC sorbed the PFCs so strongly that aqueous concentrations were reduced to below detection limits, implying that the Log KF values were above 5.60. Sorption capacities decreased in the order: AC > MW > PMW, which was consistent with the material’s surface area and pore size distribution. PFC sorption to MW biochar was near-linear (Freundlich exponent nF of 0.87–0.90), but non-linear for PMW biochar (0.64–0.73). Addition of the AC to contaminated soils resulted in almost complete removal of PFCs from the water phase and a significant (i.e. 1–3 Log unit) increase in soil–water distribution coefficient Log Kd. However, small to no reduction in pore water concentration, and no effect on Log Kd was found for the biochars. We conclude that amendment with AC but not biochar can be a useful method for in situ remediation of PFC-contaminated soils.
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| 6. |
- Smebye, Andreas, et al.
(författare)
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Biochar amendment to soil changes dissolved organic matter content and composition
- 2016
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 142, s. 100-105
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Tidskriftsartikel (refereegranskat)abstract
- Amendments of biochar, a product of pyrolysis of biomass, have been shown to increase fertility of acidic soils by enhancing soil properties such as pH, cation-exchange-capacity and water-holding-capacity. These parameters are important in the context of natural organic matter contained in soils, of which dissolved organic matter (DOM) is the mobile and most bioavailable fraction. The effect of biochar on the content and composition of DOM in soils has received little research attention. This study focuses on the effects of amendments of two different biochars to an acidic acrisol and a pH-neutral brown soil. A batch experiment showed that mixing biochar with the acrisols at a 10 wt.% dose increased the pH from 4.9 to 8.7, and this resulted in a 15-fold increase in the dissolved organic carbon concentration (from 4.5 to 69 mg L-1). The pH-increase followed the same trend as the release of DOM in the experiment, causing higher DOM solubility and desorption of DOM from mineral sites. The binding to biochar of several well-characterised reference DOM materials was also investigated and results showed a higher sorption of aliphatic DOM to biochar than aromatic DOM, with DOM-water partitioning coefficients (Kd-values) ranging from 0.2 to 590 L kg(-1). A size exclusion occurring in biochar's micropores, could result in a higher sorption of smaller aliphatic DOM molecules than larger aromatic ones. These findings indicate that biochar could increase the leaching of DOM from soil, as well as change the DOM composition towards molecules with a larger size and higher aromaticity.
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