Title: Material properties and environmental potential of developing world-derived biochar made from common crop residues
Biochar is frequently made using high-tech, high-control methods which will no doubt better optimize the final material for its intended purpose and increase its value. In contrast, we used low-tech, low-control methods to produce a developing world biochar (DWB) from two common crop wastes, cottonseed (CS) and pecan shell (PS). We created DWB biochar using a top-lit updraft microgasifier (TLUD) made from paint cans, and compared it to a biochar created in a muffle furnace held at 450 °C (MF450). We first used modern material characterization methods (yield, BET, SEM/EDS, TGA, XRD, FTIR) to understand the difference in biochar production methods on the feedstock. We then used batch equilibrium adsorption with cationic and anionic dyes (methyl orange, MO and crystal violet, CV) to examine environmental performance. The TLUD method generally has a lower biochar production yield than MF450 because we believe much of the material in the TLUD achieves temperatures > 450 °C and is sometimes difficult to retain in the device. The higher temperatures in the TLUD device lead to a biochar which is more microporous, has greater surface area, has less surface functional groups, has greater ash content, is more carbonized, and has lower residual cellulose crystallinity. There were differences in adsorption performance whereby the MF450 biochar adsorbs CV more strongly than the TLUD. For MO, PS-TLUD is less effective at adsorbing the dye when compared to PS-MF450, while CS-TLUD has a much higher adsorption strength than CS-MF450. We are not certain why the two methods show opposite effects in different feedstock but speculate that it may have to do with the much higher mineral content in the PS-TLUD compared to its MF450 counterpart. Out of many isotherms examined Freundlich and Langmuir isotherms provide a best-fit to our data only about half the time. Sometimes an S-shaped isotherm was the best fit or still fit the data reasonably well. Comparing the dye adsorption to other studies, the DWB does not adsorb as well, yet it is still effective for removal at environmental dye concentrations of relevance. Overall, we conclude that DWB, made in this uncontrolled fashion, can make a reasonably high quality biochar based on material properties and environmental performance. We suggest that additional research be done on other low-tech biochar production methods to see how to scale-up and optimize them according a developing world community's intended use. more »« less
Biochar’s ability to amend and remediate agricultural soil has been a growing interest, though the energy expenses from high-temperature pyrolysis deter the product’s use. Therefore, it is urgent to improve the pyrolysis efficiency while ensuring the quality of produced biochar. The present study utilized three types of feedstock (i.e., switchgrass, biosolid, and water oak leaves) to produce biochar via conventional slow pyrolysis and microwave pyrolysis at different temperature/energy input. The produced biochar was characterized and comprehensively compared in terms of their physiochemical properties (e.g., surface functionality, elemental composition, and thermal stability). It was discovered that microwave-mediated biochar was more resistant to thermal decomposition, indicated by a higher production yield, yet more diverse surface functional groups were preserved than slow pyrolysis-derived biochar. A nutrient (NO3-N) adsorption isotherm study displayed that microwave-mediated biochar exhibited greater adsorption (13.3 mg g−1) than that of slow pyrolysis-derived biochar (3.1 mg g−1), proving its potential for future applications. Results suggested that microwaves pyrolysis is a promising method for biochar production.
There has been a lot of attention on water pollution by dyes in recent years because of their serious toxicological implications on human health and the environment. Therefore, the current study presented a novel polyethylene glycol-functionalized graphene oxide/chitosan composite (PEG-GO/CS) to remove dyes from aqueous solutions. Several characterization techniques, such as SEM, TEM, FTIR, TGA/DTG, XRD, and XPS, were employed to correlate the structure–property relationship between the adsorption performance and PEG-GO/CS composites. Taguchi’s (L25) approach was used to optimize the batch adsorption process variables [pH, contact time, adsorbent dose, and initial concentration of methyl orange (MO)] for maximal adsorption capacity. pH = 2, contact time = 90 min, adsorbent dose = 10 mg/10 mL, and MO initial concentration = 200 mg/L were found to be optimal. The material has a maximum adsorption capacity of 271 mg/g for MO at room temperature. With the greatest R2 = 0.8930 values, the Langmuir isotherm model was shown to be the most appropriate. Compared to the pseudo-first-order model (R2 = 0.9685), the pseudo-second-order model (R2 = 0.9707) better fits the kinetic data. Electrostatic interactions were the dominant mechanism underlying MO sorption onto the PEG/GO-CS composite. The as-synthesized composite was reusable for up to three adsorption cycles. Thus, the PEG/GO-CS composite fabricated through a simple procedure may remove MO and other similar organic dyes in real contaminated water.
Lewis, David Bruce(
, Environmental Data Initiative)
Site description. This data package consists of data obtained from sampling surface soil (the 0-7.6 cm depth profile) in black mangrove (Avicennia germinans) dominated forest and black needlerush (Juncus roemerianus) saltmarsh along the Gulf of Mexico coastline in peninsular west-central Florida, USA. This location has a subtropical climate with mean daily temperatures ranging from 15.4 °C in January to 27.8 °C in August, and annual precipitation of 1336 mm. Precipitation falls as rain primarily between June and September. Tides are semi-diurnal, with 0.57 m median amplitudes during the year preceding sampling (U.S. NOAA National Ocean Service, Clearwater Beach, Florida, station 8726724). Sea-level rise is 4.0 ± 0.6 mm per year (1973-2020 trend, mean ± 95 % confidence interval, NOAA NOS Clearwater Beach station). The A. germinans mangrove zone is either adjacent to water or fringed on the seaward side by a narrow band of red mangrove (Rhizophora mangle). A near-monoculture of J. roemerianus is often adjacent to and immediately landward of the A. germinans zone. The transition from the mangrove to the J. roemerianus zone is variable in our study area. An abrupt edge between closed-canopy mangrove and J. roemerianus monoculture may extend for up to several hundred meters in some locations, while other stretches of ecotone present a gradual transition where smaller, widely spaced trees are interspersed into the herbaceous marsh. Juncus roemerianus then extends landward to a high marsh patchwork of succulent halophytes (including Salicornia bigellovi, Sesuvium sp., and Batis maritima), scattered dwarf mangrove, and salt pans, followed in turn by upland vegetation that includes Pinus sp. and Serenoa repens. Field design and sample collection. We established three study sites spaced at approximately 5 km intervals along the western coastline of the central Florida peninsula. The sites consisted of the Salt Springs (28.3298°, -82.7274°), Energy Marine Center (28.2903°, -82.7278°), and Green Key (28.2530°, -82.7496°) sites on the Gulf of Mexico coastline in Pasco County, Florida, USA. At each site, we established three plot pairs, each consisting of one saltmarsh plot and one mangrove plot. Plots were 50 m^2 in size. Plots pairs within a site were separated by 230-1070 m, and the mangrove and saltmarsh plots composing a pair were 70-170 m apart. All plot pairs consisted of directly adjacent patches of mangrove forest and J. roemerianus saltmarsh, with the mangrove forests exhibiting a closed canopy and a tree architecture (height 4-6 m, crown width 1.5-3 m). Mangrove plots were located at approximately the midpoint between the seaward edge (water-mangrove interface) and landward edge (mangrove-marsh interface) of the mangrove zone. Saltmarsh plots were located 20-25 m away from any mangrove trees and into the J. roemerianus zone (i.e., landward from the mangrove-marsh interface). Plot pairs were coarsely similar in geomorphic setting, as all were located on the Gulf of Mexico coastline, rather than within major sheltering formations like Tampa Bay, and all plot pairs fit the tide-dominated domain of the Woodroffe classification (Woodroffe, 2002, "Coasts: Form, Process and Evolution", Cambridge University Press), given their conspicuous semi-diurnal tides. There was nevertheless some geomorphic variation, as some plot pairs were directly open to the Gulf of Mexico while others sat behind keys and spits or along small tidal creeks. Our use of a plot-pair approach is intended to control for this geomorphic variation. Plot center elevations (cm above mean sea level, NAVD 88) were estimated by overlaying the plot locations determined with a global positioning system (Garmin GPS 60, Olathe, KS, USA) on a LiDAR-derived bare-earth digital elevation model (Dewberry, Inc., 2019). The digital elevation model had a vertical accuracy of ± 10 cm (95 % CI) and a horizontal accuracy of ± 116 cm (95 % CI). Soil samples were collected via coring at low tide in June 2011. From each plot, we collected a composite soil sample consisting of three discrete 5.1 cm diameter soil cores taken at equidistant points to 7.6 cm depth. Cores were taken by tapping a sleeve into the soil until its top was flush with the soil surface, sliding a hand under the core, and lifting it up. Cores were then capped and transferred on ice to our laboratory at the University of South Florida (Tampa, Florida, USA), where they were combined in plastic zipper bags, and homogenized by hand into plot-level composite samples on the day they were collected. A damp soil subsample was immediately taken from each composite sample to initiate 1 y incubations for determination of active C and N (see below). The remainder of each composite sample was then placed in a drying oven (60 °C) for 1 week with frequent mixing of the soil to prevent aggregation and liberate water. Organic wetland soils are sometimes dried at 70 °C, however high drying temperatures can volatilize non-water liquids and oxidize and decompose organic matter, so 50 °C is also a common drying temperature for organic soils (Gardner 1986, "Methods of Soil Analysis: Part 1", Soil Science Society of America); we accordingly chose 60 °C as a compromise between sufficient water removal and avoidance of non-water mass loss. Bulk density was determined as soil dry mass per core volume (adding back the dry mass equivalent of the damp subsample removed prior to drying). Dried subsamples were obtained for determination of soil organic matter (SOM), mineral texture composition, and extractable and total carbon (C) and nitrogen (N) within the following week. Sample analyses. A dried subsample was apportioned from each composite sample to determine SOM as mass loss on ignition at 550 °C for 4 h. After organic matter was removed from soil via ignition, mineral particle size composition was determined using a combination of wet sieving and density separation in 49 mM (3 %) sodium hexametaphosphate ((NaPO_3)_6) following procedures in Kettler et al. (2001, Soil Science Society of America Journal 65, 849-852). The percentage of dry soil mass composed of silt and clay particles (hereafter, fines) was calculated as the mass lost from dispersed mineral soil after sieving (0.053 mm mesh sieve). Fines could have been slightly underestimated if any clay particles were burned off during the preceding ignition of soil. An additional subsample was taken from each composite sample to determine extractable N and organic C concentrations via 0.5 M potassium sulfate (K_2SO_4) extractions. We combined soil and extractant (ratio of 1 g dry soil:5 mL extractant) in plastic bottles, reciprocally shook the slurry for 1 h at 120 rpm, and then gravity filtered it through Fisher G6 (1.6 μm pore size) glass fiber filters, followed by colorimetric detection of nitrite (NO_2^-) + nitrate (NO_3^-) and ammonium (NH_4^+) in the filtrate (Hood Nowotny et al., 2010,Soil Science Society of America Journal 74, 1018-1027) using a microplate spectrophotometer (Biotek Epoch, Winooski, VT, USA). Filtrate was also analyzed for dissolved organic C (referred to hereafter as extractable organic C) and total dissolved N via combustion and oxidation followed by detection of the evolved CO_2 and N oxide gases on a Formacs HT TOC/TN analyzer (Skalar, Breda, The Netherlands). Extractable organic N was then computed as total dissolved N in filtrate minus extractable mineral N (itself the sum of extractable NH_4-N and NO_2-N + NO_3-N). We determined soil total C and N from dried, milled subsamples subjected to elemental analysis (ECS 4010, Costech, Inc., Valencia, CA, USA) at the University of South Florida Stable Isotope Laboratory. Median concentration of inorganic C in unvegetated surface soil at our sites is 0.5 % of soil mass (Anderson, 2019, Univ. of South Florida M.S. thesis via methods in Wang et al., 2011, Environmental Monitoring and Assessment 174, 241-257). Inorganic C concentrations are likely even lower in our samples from under vegetation, where organic matter would dilute the contribution of inorganic C to soil mass. Nevertheless, the presence of a small inorganic C pool in our soils may be counted in the total C values we report. Extractable organic C is necessarily of organic C origin given the method (sparging with HCl) used in detection. Active C and N represent the fractions of organic C and N that are mineralizable by soil microorganisms under aerobic conditions in long-term soil incubations. To quantify active C and N, 60 g of field-moist soil were apportioned from each composite sample, placed in a filtration apparatus, and incubated in the dark at 25 °C and field capacity moisture for 365 d (as in Lewis et al., 2014, Ecosphere 5, art59). Moisture levels were maintained by frequently weighing incubated soil and wetting them up to target mass. Daily CO_2 flux was quantified on 29 occasions at 0.5-3 week intervals during the incubation period (with shorter intervals earlier in the incubation), and these per day flux rates were integrated over the 365 d period to compute an estimate of active C. Observations of per day flux were made by sealing samples overnight in airtight chambers fitted with septa and quantifying headspace CO_2 accumulation by injecting headspace samples (obtained through the septa via needle and syringe) into an infrared gas analyzer (PP Systems EGM 4, Amesbury, MA, USA). To estimate active N, each incubated sample was leached with a C and N free, 35 psu solution containing micronutrients (Nadelhoffer, 1990, Soil Science Society of America Journal 54, 411-415) on 19 occasions at increasing 1-6 week intervals during the 365 d incubation, and then extracted in 0.5 M K_2SO_4 at the end of the incubation in order to remove any residual mineral N. Active N was then quantified as the total mass of mineral N leached and extracted. Mineral N in leached and extracted solutions was detected as NH_4-N and NO_2-N + NO_3-N via colorimetry as above. This incubation technique precludes new C and N inputs and persistently leaches mineral N, forcing microorganisms to meet demand by mineralizing existing pools, and thereby directly assays the potential activity of soil organic C and N pools present at the time of soil sampling. Because this analysis commences with disrupting soil physical structure, it is biased toward higher estimates of active fractions. Calculations. Non-mobile C and N fractions were computed as total C and N concentrations minus the extractable and active fractions of each element. This data package reports surface-soil constituents (moisture, fines, SOM, and C and N pools and fractions) in both gravimetric units (mass constituent / mass soil) and areal units (mass constituent / soil surface area integrated through 7.6 cm soil depth, the depth of sampling). Areal concentrations were computed as X × D × 7.6, where X is the gravimetric concentration of a soil constituent, D is soil bulk density (g dry soil / cm^3), and 7.6 is the sampling depth in cm.
Bentley, Matthew J.; Solomon, Michelle E.; Marten, Brooke M.; Shimabuku, Kyle K.; Cook, Sherri M.(
, Environmental Science: Water Research & Technology)
Transforming the organic fraction of municipal solid waste (OFMSW) into biochar to reduce fugitive landfill emissions and control organic micropollutants (OMP) during landfill leachate treatment could provide a new circular economy organics diversion approach. However, research on landfill leachate treatment under consistent, representative conditions with biochar derived from the wide range of OFMSW components is needed. Further, the competitive nature of leachate dissolved organic matter (DOM) for biochar adsorption sites has not been examined. To this end, biochars were produced from seven diverse OFMSW types and batch tested using two representative organic contaminants. To evaluate leachate DOM impact on OMP removal and fouling mitigation with biochar enhancement methods, experiments were performed with three background matrices (deionized water, synthetic leachate, real leachate) and two enhancement methods (ash-pretreatment, double-heating). Since evaluating all possible OFMSW feedstock combinations is infeasible, fundamental relationships between individual feedstocks and biochar properties were evaluated. Overall, biochar performance varied substantially; the dose to achieve a given target removal spanned an order of magnitude between the OFMSW feedstocks. Also, the presence of leachate DOM more negatively impacted the performance of all biochars relative to the benchmark adsorbent activated carbon. Finally, the enhancement methods altered biochar pore structure by increasing micropore and slightly decreasing non-micropore surface areas, resulting in improved adsorption capacity (by 23 to 93%). By providing the basis for a low-cost, enhanced leachate treatment method, this study could incentivize a novel organics diversion approach that reduces climate change impacts, harvests energy from waste, and reduces landfill air emissions.
Cotton gin waste (CGW) is produced in large quantities (1–1.5 × 106metric ton/year) in the Texas High Plains (THP), one of the largest cotton-producing regions in the USA. We examined locally supplied CGW for soil amendment as biochar (CGW-BC) with a view toward rainfed cropping systems, which will likely become increasingly necessary due to declines in groundwater availability for irrigation. Sixteen unique biochar samples were produced under varying conditions of time, temperature, and post-processing wash in a muffle furnace. We performed material characterization on the biochar. We then incubated CGW-BC samples that seemed favorable for increasing the water holding capacity increase for 10 days with local, rainfed, clay loam soil. We found that increasing the pyrolysis time and temperature decreased the biochar yield but only up to 40 min. Beyond 40 min, the yield did not decrease further. Additionally, the majority of mass loss occurred during pyrolysis and not during crush-sieving or postproduction washes. CGW-BC produced at higher temperatures and for longer times had greater thermal stability. This interesting aspect of thermal stability, which did not always follow strict time‒temperature trends, may be because cotton gin waste is a heterogeneous material. We found that the addition of acid decreases the mineral content while lowering the thermal stability of lower temperature (450 °C) biochars. Regarding the CGW-BC surface area, we found that higher temperatures generally increase the micropore surface area. Using a GAB isotherm, water vapor surface area did not correlate with the highest WHC when water was added to the soil. In fact, biochar, which was pyrolyzed in less time at a lower temperature and with the use of acid washing, better held the water in soil-biochar mixtures. The measurements suggested that CGW-BC could be a valuable soil amendment that could increase the WHC without adversely increasing the pH. Our initial investigation revealed how scaled-up production of CGW-BC for soils might be economically and sustainably pursued for use in rainfed cropping, deficit irrigation, or ranchlands.
Howell, Nathan, Pimentel, Andy, and Bhattacharia, Sanjoy. Material properties and environmental potential of developing world-derived biochar made from common crop residues. Retrieved from https://par.nsf.gov/biblio/10482901. Environmental Challenges 4.C Web. doi:10.1016/j.envc.2021.100137.
Howell, Nathan, Pimentel, Andy, & Bhattacharia, Sanjoy. Material properties and environmental potential of developing world-derived biochar made from common crop residues. Environmental Challenges, 4 (C). Retrieved from https://par.nsf.gov/biblio/10482901. https://doi.org/10.1016/j.envc.2021.100137
Howell, Nathan, Pimentel, Andy, and Bhattacharia, Sanjoy.
"Material properties and environmental potential of developing world-derived biochar made from common crop residues". Environmental Challenges 4 (C). Country unknown/Code not available: Elsevier. https://doi.org/10.1016/j.envc.2021.100137.https://par.nsf.gov/biblio/10482901.
@article{osti_10482901,
place = {Country unknown/Code not available},
title = {Material properties and environmental potential of developing world-derived biochar made from common crop residues},
url = {https://par.nsf.gov/biblio/10482901},
DOI = {10.1016/j.envc.2021.100137},
abstractNote = {Biochar is frequently made using high-tech, high-control methods which will no doubt better optimize the final material for its intended purpose and increase its value. In contrast, we used low-tech, low-control methods to produce a developing world biochar (DWB) from two common crop wastes, cottonseed (CS) and pecan shell (PS). We created DWB biochar using a top-lit updraft microgasifier (TLUD) made from paint cans, and compared it to a biochar created in a muffle furnace held at 450 °C (MF450). We first used modern material characterization methods (yield, BET, SEM/EDS, TGA, XRD, FTIR) to understand the difference in biochar production methods on the feedstock. We then used batch equilibrium adsorption with cationic and anionic dyes (methyl orange, MO and crystal violet, CV) to examine environmental performance. The TLUD method generally has a lower biochar production yield than MF450 because we believe much of the material in the TLUD achieves temperatures > 450 °C and is sometimes difficult to retain in the device. The higher temperatures in the TLUD device lead to a biochar which is more microporous, has greater surface area, has less surface functional groups, has greater ash content, is more carbonized, and has lower residual cellulose crystallinity. There were differences in adsorption performance whereby the MF450 biochar adsorbs CV more strongly than the TLUD. For MO, PS-TLUD is less effective at adsorbing the dye when compared to PS-MF450, while CS-TLUD has a much higher adsorption strength than CS-MF450. We are not certain why the two methods show opposite effects in different feedstock but speculate that it may have to do with the much higher mineral content in the PS-TLUD compared to its MF450 counterpart. Out of many isotherms examined Freundlich and Langmuir isotherms provide a best-fit to our data only about half the time. Sometimes an S-shaped isotherm was the best fit or still fit the data reasonably well. Comparing the dye adsorption to other studies, the DWB does not adsorb as well, yet it is still effective for removal at environmental dye concentrations of relevance. Overall, we conclude that DWB, made in this uncontrolled fashion, can make a reasonably high quality biochar based on material properties and environmental performance. We suggest that additional research be done on other low-tech biochar production methods to see how to scale-up and optimize them according a developing world community's intended use.},
journal = {Environmental Challenges},
volume = {4},
number = {C},
publisher = {Elsevier},
author = {Howell, Nathan and Pimentel, Andy and Bhattacharia, Sanjoy},
}
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