Upload
others
View
8
Download
0
Embed Size (px)
Citation preview
10/29/2018
1
Properties of Biochar & Torrefied Biomass
Jillian Goldfarb, Ph.D.Department of Biological & Environmental Engineering
College of Agriculture and Life Sciences
Cornell University
Session 2Biochar and Torrefied Biomass Short CoursePenn State Bioenergy Short Course Series
So you made biochar… now what?
To determine applicability and marketability, need to benchmark biochar with standard characterization techniques
10/29/2018
2
Not All Biochar is Created Equal
Image: https://pyrotechenergy.com/products/biochar‐options‐transparent/
Degree of carbonization, which is a function of feedstock and processing conditions, dictates chemical, biological, and physical properties, and therefore stability and applicability!
Physical PropertiesPorosity DensitySurface Area Mechanical StrengthMoisture Content Particle Size Distribution
Chemical PropertiespH Heating ValueElectrical Conductivity Proximate Analysis (Fixed Carbon, Ash)Liming Ultimate Analysis (H:C:O:N)Organic Composition Thermal StabilityNutrient Composition Cation Exchange Capacity
Biological PropertiesGermination Inhibition Microbial CommunitiesBiological Oxygen Demand Respired CO2
“Disclaimer” on Characterization
• There are a limited number of “standard” measurement practices in Biochar Industry (though this is changing…)
• Use care when evaluating “literature” –char measurements depend on the char preparation quality, exact analytical conditions, and the skill of the researcher
• Biomass is inherently heterogeneous. Pyrolysis helps remove some of this variation, but not all
10/29/2018
3
Efforts Towards Standardization“…biochar characteristics shall be assessed according to a defined set of test categories intended to provide increasing levels of physicochemical property reporting…”
Test Category A ‐ Basic Utility Properties (Required)
Test Category B – Toxicant Assessment (Required)
Test Category C – Advanced Analysis and Soil Enhancement Properties (Optional)
IBI Standards – Category A (Required)
https://www.biochar‐international.org/wp‐content/uploads/2018/04/IBI_Biochar_Standards_V2.1_Final.pdf
Parameter Unit Test Method
Proximate Analysis:Moisture ContentTotal Ash
% of total dry mass ASTM D1762‐84
Ultimate Analysis: Organic Carbon (Corg)H:CorgTotal Nitrogen
% of total dry mass Dry combustion Elemental Analyzer (for Ctotal, H, N)Inorganic CO2‐C via ASTM D4373
pH pH 1:20 biochar: DI Water dilution, 90 min equilibration on shaker
Liming (if pH > 7) % CaCO3 Potentiometric titration
Electrical Conductivity dS/m 1:20 biochar: DI Water dilution, 90 min equilibration on shaker
Particle size distribution
% mass in each fraction
Progressive dry sieving with 50, 25, 16, 8, 4, 2, 1 and 0.5 mm sieves
10/29/2018
4
Proximate Analysis: ASTM D1762‐84
• Sample is sized “representative to the lot”
• Moisture: sample heated to 105°C, held to constant mass (change less than 0.0005 g) –mass loss = H2O
• Volatile Matter: heat dry sample in covered crucible in muffle furnace to 950°C, insure no “sparking” of sample, cool sample and weigh – mass loss = VM
• Ash: uncover sample, heat in muffle furnace to 750°C, cool sample and weigh; repeat until constant weight – mass loss = fixed carbon; mass remaining = ash
Proximate Analysis: TGA MethodWhy the ASTM method is not “my favorite”:
Biomass Proximate Analysis
90 min 180 min 360 min 720 min
Sample Muffle 1 Muffle 2 Muffle 1 Muffle 2 Muffle 1 Muffle 2 Muffle 1 Muffle 2
Phragmites Stem
Volatile Matter 0.080 0.088 0.087 0.085 0.068 0.075 0.084 0.008
Fixed Carbon 0.043 0.058 0.034 0.057 0.027 0.055 0.003 0.073
Ash 0.878 0.854 0.879 0.858 0.905 0.870 0.912 0.920
Wood Chip
Volatile Matter 0.063 0.084 0.069 0.051 0.060 0.056 0.008 0.066
Fixed Carbon 0.045 0.036 0.042 0.041 0.052 0.040 0.073 0.048
Ash 0.891 0.881 0.889 0.909 0.888 0.904 0.920 0.886
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0 200 400 600 800
Sample Mass (mg)
Sample Temperature (°C)
Moisture
Volatile Matter
Fixed CarbonAsh
10/29/2018
5
Corg: Measurement
ASTM D4373‐14: Standard Test Methods for Rapid Determination of Carbonate Content of Soils
https://compass.astm.org/EDIT/html_annot.cgi?D4373+14
Treat 1 g of dried biochar with HCl in a closed container.CO2 is evolved (acid + carbonte reaction).Resulting pressure directly proportional to mass CaCO3 (inorganic carbon).
Carbon Content: Implications
IBI Classifies biochar based on organic carbon content:
Class 1: Corg > 60 wt%
Class 2: 30% > Corg > 60 wt%
Class 3: 10% > Corg > 30 wt%
Ronsse, Frederik, et al. "Production and characterization of slow pyrolysis biochar: influence of feedstock type and pyrolysis conditions." Gcb Bioenergy 5.2 (2013): 104-115.
10/29/2018
6
Ultimate Analysis: Measurement
Carbon Combustion Analyzer:
• Combusts sample of known weight at known gas flow of oxygen
• Chromatograph measures the concentration of C, H and N (O by difference; can also add S)
https://www.labcompare.com/553-Carbon-Analyzer-Carbon-Combustion-Analyzer/1247-CHN628-Series-Carbon-Hydrogen-Nitrogen-Determinator/
Ultimate Analysis: Implications
Physical degradation occurs via dissolution (high O:C, low H:C ratio materials dissolve with saturation cycles)
IBI says that H/Corg ratio should be used to determine stability.
Materials with H/Corg > 0.7 (atomic basis) are not classified as biochar by IBI.
Enders, Akio, et al. "Characterization of biochars to evaluate recalcitrance and agronomic performance." Bioresource technology 114 (2012): 644-653.
10/29/2018
7
Biochar pH & EC Measurement
• Mix 1:20 solution of biochar:deionized water (1 gram biochar, 20 mL/20 g DI water)
• Allow to equilibrate for at least 90 minutes while shaking
• Measure pH and EC with calibrated instrument
Torres, Ariana P., Michael V. Mickelbart, and Roberto G. Lopez. "Leachate volume effects on pH and electrical conductivity measurements in containers obtained using the pour-through method." HortTechnology 20.3 (2010): 608-611.
pH & Electrical Conductivity: Implications
• pH and surface basicity tends to increase with pyrolysis temperature
• Salinity of biocharstends to increase with pyrolysis temperature
Enders, Akio, et al. "Characterization of biochars to evaluate recalcitrance and agronomic performance." Bioresource technology 114 (2012): 644-653.
10/29/2018
8
IBI Standards – Category B (Required)
https://www.biochar‐international.org/wp‐content/uploads/2018/04/IBI_Biochar_Standards_V2.1_Final.pdf
Parameter Range of Max Thresholds
Test Method
Germination Inhibition Assay
Pass/Fail OECD Methodology (3 species)
Polycyclic Aromatic Hydrocarbons (sum of 16 EPA Priority Pollutants)
6‐300 mg/kg dry weight
USA EPA 8270 with 100% toluene as extracting solvent
Dioxins/Furans (PCDD/Fs)
17 ng/kg dry wt US EPA 9280
Polychlorinated Biphenyls (PCBs)
0.2‐1 mg/kg dry Test Methods for the Examination of Composting and Compost (TMECC; US Composting Council and US Dept. of Ag., 2001)
Range of Heavy Metals (Varies by metal) TMECC (2001)
Germination Inhibition Assay
• Lettuce widely recommended species to use in germination assessments due to sensitivity
• Results should be reported as “fail” if seedling does not germinate in biochar‐blend soils but does in unamended soil
• Results reported as “pass” if there is no difference of germination success between biochar‐blend soils or where biochar‐blend soils are preferred
http://www.waldeneffect.org/blog/Seed_germination_test_in_flats/ Rogovska, Natalia, et al. "Germination tests for assessing biochar quality." Journal of environmental quality 41.4 (2012): 1014-1022.
Kwapinski, Witold, et al. "Biochar from biomass and waste." Waste and Biomass Valorization 1.2 (2010): 177-189.
10/29/2018
9
Organic Content (ex: PAH): Measurement
EPA Methods 8270 (solvent extraction to GCMS or HPLC), 8275 (thermal desorption to GCMS)
https://orgspectroscopyint.blogspot.com/2014/11/gas‐chromatography‐mass‐spectrometry‐gc.html;http://www.restek.com/chromatogram/view/LC_EV0469
Total Ion Count
Gas Chromatogram Mass Spectrum of Anthracene [8]
Organic Content (PAH): Implications
McGrath, Thomas E., W. Geoffrey Chan, and Mohammad R. Hajaligol. "Low temperature mechanism for the formation of polycyclic aromatic hydrocarbons from the pyrolysis of cellulose." Journal of Analytical and Applied Pyrolysis 66.1-2 (2003): 51-70.
Note: PAH are presents, but their lability in soil is NOT well understood…
Before large scale biochar addition to soils is adopted, future work is needed to address the dynamic between sorbent saturation and microbial activity and how this relates to the concentration of PAHs in soil solution and their persistence in the environment.Quilliam, Richard S., et al. "Is biochar a source or sink for polycyclic aromatic hydrocarbon (PAH) compounds in agricultural soils?." Gcb Bioenergy 5.2 (2013): 96‐103.
However, very little or no attention have been paid to the fact that biochars can give simultaneous impact on PAH fate processes, such as volatilization, sorption and biodegradation.Anyika, Chinedum, et al. "The impact of biochars on sorption and biodegradation of polycyclic aromatic hydrocarbons in soils—a review." Environmental Science and Pollution Research 22.5 (2015): 3314‐3341.
10/29/2018
10
Elemental Analysis: Measurement
Digest biochar in nitric acid
Run sample in elemental analyzer (eg: AAS; ICPMS; ICPOES)
http://www.jsg.utexas.edu/icp‐ms/icp‐ms/. https://crustal.usgs.gov/laboratories/icpms/intro.htmlhttps://www.emdmillipore.com/CA/en/water‐purification/learning‐centers/applications/inorganic‐analysis/icp‐ms/_e2b.qB.s7QAAAFAniQQWTtN,nav
Elemental Analysis: Implications
IBI Range of Maximum
Allowed Thresholds:
Element Max. Range (mg/kg dry wt)
Arsenic 13 – 100
Cadmium 1.4 – 39
Chromium 93 – 1200
Cobalt 34 – 100
Copper 143 – 6000
Lead 121 – 300
Mercury 1‐ 17
Molybdenum 5 – 75
Nickel 47 – 420
Selenium 2 – 200
Zinc 416 – 7400
Boron, Chlorine, Sodium
Declaration
Soil Implications:• Reduced soil fertility• Modifications of microbial
populations and processes• Changes to carbon mineralization• Anomalous nitrogen transformationPlant Implications:• Induced oxidative damage• Genetic modification• Changes in signaling pathways• Abnormal reproductive responseHuman Health Implications:• Impacts of respiratory system• Potential for kidney damage• Loss of bone density• Reproductive system damage• Cancer
10/29/2018
11
Elemental Analysis: Implications
• pH and elemental analysis also impact the cation exchange capacity
• Depending on pH, the hydroxyl, carboxylate and carbonyl groups can chelate metals (bind Fe+3 and Al +3
strongly; Mg+2 weakly)
Lee, James W., et al. "Characterization of biochars produced from cornstovers for soil amendment." Environmental science & technology 44.20 (2010): 7970-7974.
IBI Standards – Category C (Optional)
https://www.biochar‐international.org/wp‐content/uploads/2018/04/IBI_Biochar_Standards_V2.1_Final.pdf
Parameter Unit Test Method
Mineral (available) Nitrogen (ammonium and nitrate)
mg/kg 2M KCl extraction followed by spectrophotometry
Total Phosphorus and Potassium
mg/kg Modified dry ashing followed by elemental analysis
Available Phosphorous mg/kg 2% formic acid followed by spectrophotometry
Total Calcium, Magnesium, Sulfur
mg/kg 1 M HCl extraction followed by elemental analysis
Volatile Matter % dry mass (See Proximate Analysis)
Total Surface Area m2/g ASTM D6566 via Nitrogen Adsorption
10/29/2018
12
Surface Area: Implications
Soil surface area influences all aspects of soil fertility: water, air, nutrient cycling, microbial activity.• Micropores are important for
molecular transport and nutrient storage
• Macropores are important for root movement and microbe habitat*
Surface Area (m2/g)
Pore volume (cm3/g)
Micropores 750 – 1500 0.2 – 0.5
Macropores 50 – 150 0.6 – 1.0
* Surface area measurement described is for micro to mesopores… Brewer, Catherine E., et al. Biomass and Bioenergy 66 (2014): 176-185.
Surface Area: Measurement*
1. Degas with Heat/ Vacuum
2. – 5. Measurements Done in Liquid Nitrogen Bath
https://andyjconnelly.wordpress.com/2017/03/13/bet‐surface‐area/
Coverage of N2 on surface
Sample to beAnalyzed (less than 2 g)
10/29/2018
13
Beyond IBI: Biochar Properties
Beyond these IBI‐prescribed characteristics, there are many other potential properties that impact commercialization opportunities:
• Density
• Calorific Value
• Adsorption Capacity
• Thermal stability
• Weathering
• Biological Oxygen Demand
• Cumulative Respiration
• …
Density: Implications
• Solid Density = density on molecular level
• Bulk Density = density of material made up of multiple particles (including void space)
• Directly related to mechanical strength
• Biochar usually mechanically stronger than biomass, but subject to structural fracturing at lower strains
• Weathering of biochar reduces mechanical strength
https://www.biochar‐journal.org/en/ct/71
10/29/2018
14
Density ‐ Commercial Meanings
• Dry mass density = dry weight of the biomass/biochar divided by the volume of biomass/biochar in a full container
• Shipped density = same volume as bulk density but can include the weight of moisture and other non‐biochar materials in the container.
• Packed out density = weight divided by the volume of the material as it is “packed out” for loading onto a truck or train car.
Measuring Density
ASTM E873‐82: Standard Test Method for Bulk Density of Densified Particulate Biomass Fuels
12”*12”*12” (volume accurate to 1 in3)
1. Weigh and record the empty box weight within 100 g (0.22 lb).
2. Fill the box by pouring from a height of 610 mm (2 ft) above the top edge of the container.
3. Drop the box five times from a height of 150 mm (6 in.) on to a nonresilient surface to allow settling.
4. Add additional sample and strike off the excess sample level with the top edge.
5. Weigh the box and sample to within 100 g (0.22 lb) and record the total weight.
Bulk Density = (Weight of Box + Sample) – (Weight of Box)(Volume of Box)
10/29/2018
15
Higher Heating Value: Measurement
The higher heating value (aka gross calorific value or gross energy) = amount of heat released by fuel originally at 25°C, after it is combusted and the products have returned to 25°C (accounts for the latent heat of vaporization of water in the combustion products)
https://www.learner.org/courses/chemistry/text/text.html?dis=U&num=Ym5WdElUQS9PQ289&sec=YzJWaklUQS9OeW89
Higher Heating Value: Implications
• “Energy Dense” fuels have larger HHVS (higher heating values) – energy content of fuel
• Degree of carbonization, to an extent, increases HHV (unless too much volatile matter is lost…)
• More energy dense fuels command higher price (akin to higher rank coals)
0
5
10
15
20
25
30
35
40
Raw 10 min,450 °C
60 min,450 °C
10 min,600 °C
60 min,600 °C
Hig
her
hea
tin
g v
alu
e (
MJ
kg–1
db
)
Wood
Straw
Green waste
Algae
Fig. 6 The biochar higher heating value (MJ kg 1 – expressedon dry, i.e. ash-containing, biomass feedstock basis) of the dif-ferent feedstocks tested, with varying intensity of the slowpyrolysis process (residence time, HTT).
Ronsse, Frederik, et al. "Production and characterization of slow pyrolysis biochar: influence of feedstock type and pyrolysis conditions." Gcb Bioenergy 5.2 (2013): 104-115.
10/29/2018
16
Adsorption Capacity: Implications
• Adsorption governs bioavailability and environmental fate and transport performance of agriculture chemicals
• Biochar is an effective sorbent for soil‐applied pesticides reduces leaching to groundwater but may increase persistence in soil
• Accumulation of allelochemicals in the biochar inhibit growth of other plants, alter microbes
www.mawdoo3.com
Davidwallphoto.com
Adsorption Capacity : Measurement
Expose known amount of biochar to model contaminant mixtures of varying concentration (methylene blue dye is common) for known period of time (isotherm) and single concentration over time (kinetics) to measure uptake rate and maximum capacity
Gao and Goldfarb, unpublished data
10/29/2018
17
Surface Functional Groups & Adsorption
• Highly oxygenated surfaces are very reactive
• Certain groups (‐OH, ‐COOH, ‐CO, ‐NH2) enhance adsorption of organics; C=O increases adsorption of heavy metals
Gopu, Chitanya, et al. "Valorizing municipal solid waste: Waste to energy and activated carbons for water treatment via pyrolysis." Journal of Analytical and Applied Pyrolysis 133 (2018): 48-58.
Thermal Degradation
• Thermal stability often determined using thermogravimetric analysis
• Pyrolysis in TGA up to 900°C – reaction rate, total mass loss, and peak temperature indication of stability in soil
• Oxidation in TGA up to 900°C – reaction rate, mass loss, peak temperature – indicates ability to combust (e.g. as solid fuel), reactivity and susceptibility to oxidation
Goldfarb et al., unpublished data
10/29/2018
18
Water Extraction (Weathering)
Lin, Yun, et al. "Water extractable organic carbon in untreated and chemical treated biochars." Chemosphere 87.2 (2012): 151-157.
Biological Responses
Biological Oxygen Demand Cumulative Respiration
Ronsse, Frederik, et al. "Production and characterization of slow pyrolysis biochar: influence of feedstock type and pyrolysis conditions." Gcb Bioenergy 5.2 (2013): 104-115.
10/29/2018
19
Tips on Accessing Lab Facilities
• Certified lab tests can get very expensive if you are in a trial phase – a proximate analysis (carbon content) will start around $35/sample; elemental analysis will run around $85/sample
• In a commissioning or test phase, consider partnering with an academic researcher – let them publish results of characterization in exchange for information about how samples were made (and co‐authorship…)
• Benefit of working with academics: better equipment, little/no cost depending on research potential.
• Drawback of working with academics: can be slower paced, need to keep on target with project.
Summary: Biochar Characteristics
• Physical, Chemical, Biological Characteristics of biochars are starting to be standardized
• Characteristics will have strong influence on ability to use biochar as soil amendment
• Some very “simple” tests that can be done “at home” versus those that require extensive equipment and knowledge
• Characteristics will vary with feedstock and pyrolysis conditions
10/29/2018
20
Further Readings: Biochar Properties
• Enders, Akio, et al. "Characterization of biochars to evaluate recalcitrance and agronomic performance." Bioresource technology 114 (2012): 644‐653.
• Lee, James W., et al. "Characterization of biochars produced from cornstovers for soil amendment." Environmental science & technology 44.20 (2010): 7970‐7974.
• Lee, Yongwoon, et al. "Comparison of biochar properties from biomass residues produced by slow pyrolysis at 500°C." Bioresource technology 148 (2013): 196‐201.
• Lehmann, Johannes, and Stephen Joseph, eds. Biochar for environmental management: science, technology and implementation. Routledge, 2015.
• Lin, Yun, et al. "Water extractable organic carbon in untreated and chemical treated biochars." Chemosphere 87.2 (2012): 151‐157.
• Klasson, K. Thomas. "Biochar characterization and a method for estimating biochar quality from proximate analysis results." Biomass and Bioenergy 96 (2017): 50‐58.
• Kloss, Stefanie, et al. "Characterization of slow pyrolysis biochars: effects of feedstocks and pyrolysis temperature on biochar properties." Journal of environmental quality 41.4 (2012): 990‐1000.
• Ronsse, Frederik, et al. "Production and characterization of slow pyrolysis biochar: influence of feedstock type and pyrolysis conditions." Gcb Bioenergy 5.2 (2013): 104‐115.
• Sun, Yining, et al. "Effects of feedstock type, production method, and pyrolysis temperature on biochar and hydrocharproperties." Chemical Engineering Journal 240 (2014): 574‐578.
• Wu, Weixiang, et al. "Chemical characterization of rice straw‐derived biochar for soil amendment." Biomass and bioenergy47 (2012): 268‐276.
• Zhang, Shuping, et al. "Effects of torrefaction on yield and quality of pyrolysis char and its application on preparation of activated carbon." Journal of analytical and applied pyrolysis119 (2016): 217‐223.
• Zhao, Ling, et al. "Heterogeneity of biochar properties as a function of feedstock sources and production temperatures." Journal of hazardous materials 256 (2013): 1‐9.