Use of chemical and physical characteristics to investigate

Use of chemical and physical characteristics to investigate trends in biochar feedstocks Fungai Mukome, Xiaoming Zhang, Lucas C. R. Silva, Johan Six, and Sanjai J. Parikh University of California, Davis US Biochar Conference, Rohnert Park, CA July 2012

What is Biochar? Walnut shell Fly ash carbon-negative. us Wood chips Rice Husks Manure Corn stover Orange peels Wood

All biochars are not created equal…. (Mc. Laughlin et al. 2009) • Differ on – Cation exchange capacity (CEC) – p. H – H/C ratio – Surface area – C/N ratio – Ash content – Water holding capacity • All a function of pyrolysis temperature (highest treatment temperature-HTT), pyrolysis method, residence time and feedstock

Objectives 1. To characterize physical and chemical properties of various biochars (mostly commercially available) 2. To determine if trends exist for biochar properties that can be related to feedstock material, which can serve to develop guidelines for biochar use.

Objectives 1 Twelve biochars were analyzed • Physical properties: • Chemical properties: – Moisture content – Elemental content – Ash content – H and C content – BET Surface area – p. H – Surface – Cation exchange capacity morphology – Surface basicity and acidity – Surface functionality (ATR-FTIR and Raman)

Physical properties Char Source Material BC_ A BC_Bb Turkey litter Walnut shell 700 -800 900 64 40. 4 21. 8 227. 1 BC_C Inoculated material unavailablec 15. 5 95. 9 Ps. II (H 4) BC_D Soft wood 600 -700 2. 4 25. 2 Ps. II (H 4) BC_E Wood + Algal digestate Wood chips Wood chips 600 -700 510 410 500 -650 unavailable 6. 4 3 2. 6 17 5 2. 8 5. 5 4. 2 2 165. 8 2. 8 4. 9 164. 1 153. 1 154. 4 301. 6 Ps. II (H 3) Ps. II (H 4) BC_F BC_G BC_H BC_I BC_J BC_K BC_L Ps. II = Pseudo Type II b Unknown, not willing to provide or proprietary c Not commercially available a Ash (wt %) Type BET Surface Area (m 2/g) (Hysteresis) Pyrolysis Temp (°C) a. Ps. II (H 3) Ps. II (H 4) Wood Non-wood

Scanning Electron Microscopy analysis a) BC_G 60µm b) BC_F 100µm c) BC_B 10µm SEM images of three biochars showing a) a char with type H 3 hysteresis loop b) a char with type H 4 hysteresis loop and c) a char with high ash content. Type II isotherms - capillary non-porous or macroporous adsorbents and represent monolayer-multilayer adsorption. Lower surface areas (BC_J, BC_H, BC_A and BC_G) - Type H 3 hysteresis loops lack of microporosity, plate-like particles and slit shaped pores. Higher surface area - (BC_L, BC_K, BC_J, BC_I, BC_F) - Type H 4 hysteresis loopsnarrow slit-like pores

Chemical properties Char C N H O PO 4 -P K (wt %) (wt %) S (ppm) Fe (ppm) p. Hw (1: 2) Acidity Basicity cmol/kg (meq/g) CECa BC_A 15. 6 0. 78 0. 83 4. 4 6. 61 7. 05 10720 9191 10. 9 24. 4 0. 08 4. 92 BC_Bb 55. 3 0. 47 0. 89 1. 6 0. 64 9. 32 940 1981 9. 7 33. 4 - 11. 71 BC_C 53. 3 1. 96 3. 7 24. 3 0. 47 1. 2 5920 1109 6. 8 44. 5 1. 22 1 BC_D 68. 2 0. 51 3. 66 26. 8 0. 13 0. 26 370 1934 7. 5 26. 2 1. 24 1. 02 BC_E 58. 1 0. 41 4. 16 31. 7 0. 08 0. 19 685 3370 6. 8 67 1. 56 1. 22 BC_F 83. 9 0. 36 1. 88 19. 8 0. 02 0. 13 110 505 7. 3 12 0. 27 0. 93 BC_G 65. 7 0. 21 4. 38 23. 5 0. 02 0. 12 50 248 7. 1 10 0. 83 0. 4 BC_H 71. 2 0. 91 2. 88 11. 6 0. 08 0. 72 480 3517 7. 9 3. 2 0. 79 1. 01 BC_I 87. 3 0. 59 2. 15 7. 4 0. 07 0. 85 140 203 9. 2 9. 1 0. 41 0. 84 BC_J 88 0. 44 2. 55 14. 8 0. 02 0. 33 60 79 9. 5 14. 9 0. 49 0. 87 BC_K 85. 4 0. 55 2. 37 8. 9 0. 07 0. 48 140 606 8. 8 3. 6 0. 94 BC_L 82. 5 0. 49 1. 64 5. 6 0. 06 1. 02 160 473 9. 5 16. 5 0. 36 1. 21 a. CEC = Cation exchange capacity b Not commercially available Wood Non-wood

FTIR: Fourier Transform Infrared Spectroscopy Aromatic C=C C-H Aliphatic/Functionalized C-O, C-H C-O C=O Greater aromaticity in wood derived biochar

x. Aromatic Char C-H (744 cm-1) x. Aliphatic ether (1029 cm-1) x. Aliphatic CH 3 (1417 cm-1) x. Aromatic C=C (1587 cm-1) x. Aromatic carbonyl (1690 cm-1) BC_A - 2. 9 1 0. 21 0. 02 BC_B - 1. 1 2. 2 - - BC_C 0. 53 3. 6 0. 38 0. 69 0. 39 BC_D 0. 63 2. 67 2. 46 2. 6 1. 2 BC_E 0. 27 2. 83 2. 2 2. 05 0. 94 BC_F 1. 2 2. 09 1. 7 2. 3 0. 28 BC_G 1. 2 2. 16 0. 83 1. 5 0. 4 BC_H 1. 12 1 1. 78 0. 41 BC_I 1 1. 2 1. 83 1. 98 0. 38 BC_J 0. 71 1. 67 0. 27 1. 41 0. 36 BC_K 1. 05 1. 17 1. 6 1. 9 0. 36 BC_L 1. 1 1. 05 1. 22 0. 12 x. Ratios of peak intensities relative to the aromatic C-H stretch at 870 cm-1 common to all spectra

Char Aliphatic ether (1029 cm-1) BC_A BC_B BC_C BC_D BC_E BC_F BC_G BC_H BC_I BC_J BC_K BC_L 2. 9 1. 1 3. 6 2. 67 2. 83 2. 09 2. 16 1 1. 2 1. 67 1. 17 1. 01 y. Raman Id/Ig 0. 4 0. 34 0. 76 0. 58 0. 65 0. 4 0. 25 0. 83 0. 68 0. 72 0. 59 0. 71 y. Ratio of peak intensities of the Carbon D (1350 cm 1) and G (1690 cm -1) bands in Raman spectra D band (aromatic) G band (aliphatic & olefinic) • ID - sp 2 disordered C atoms in aromatic ring structures • IG - sp 2 disordered C atoms in aliphatic and olefinic molecules • Approximates sp 2: sp 3 ratio in amorphous carbon

Objective 2 A algae G grass L hull M manure N nutshell P pomace W wood n= 85 van Krevelen diagram of a) selected biochar (from literature) and b) 12 study biochar (inset) 1. Sharma et al. Fuel 2004, 83, 1469 -1482. 2. Keiluweit et al. Environmental Science & Technology 2010, 44, 1247 -1253. 3. Zheng et al. Journal of Hazardous Materials 2010, 181, 121 -126. 4. Cao, X. et al. Bioresource Technology 2010, 101, 5222 -5228. 5. Özçimen et al. Renewable Energy 2010, 35, 13191324. 6. Jindarom et al. Chemical Engineering Journal 2007, 133, 239 -246. 7. Chan et al. Soil Research 2008, 46, 437 -444. 8. Azargohar et al. Applied Biochemistry and Biotechnology 2006, 131, 762 -773. 9. Wu et al. Industrial & Engineering Chemistry Research 2009, 48, 10431 -10438. 10. Toles et al. Bioresource Technology 2000, 71, 8792. 11. Van Zwieten et al. Plant and Soil 2010, 327, 235246. 12. Chen, B. and Chen, Z. Chemosphere 2009, 76, 127 -133. 13. Major et al. Plant and Soil 2010, 333, 117 -128. 14. Argudo, M. et al. Carbon 1998, 36, 1027 -1031. 15. Hammes et al. Applied Geochemistry 2008, 23, 2113 -2122. 16. Chun et al. Environmental Science & Technology 2004, 38, 4649 -4655. 17. Mahinpey et al. Energy & Fuels 2009, 23, 27362742. 18. Rondon et al. Biology and Fertility of Soils 2007, 43, 699 -708. 19. Abdullah, H. and Wu, H. Energy & Fuels 2009, 23, 4174 -4181. 20. Cheng, C. -H and Lehmann, J. Chemosphere 2009, 75, 1021 -1027. 21. Spokas et al. Chemosphere 2009, 77, 574 -581. 22. Steiner et al. J. Environ. Qual. 2009, 39, 12361242. 23. Busscher et al. Soil Science 2010, 175, 10 -14. 24. Brewer et al. Environmental Progress & Sustainable Energy 2009, 28, 386 -396. 25. Novak et al. Annals of Environmental Science 2009, 3, 195 -206. 26. Novak, J. M. and Reicosky, D. C. Annals of Environmental Science 2009, 3, 179 -193. 27. Singh et al. J. Environ. Qual. 2010, 39, 1224 -1235.

Change in ash content as a function of pyrolysis temperature of biochar derived from hard and softwood

Change in the C/N ratio as a function of pyrolysis temperature of biochar derived from hard and softwood.

Change in the surface area as a function of pyrolysis temperature of biochar Change in surface area as a function of pyrolysis temperature of biochar derived from hard and softwood

Box plots showing differences in a) ash content and b) C/N ratios, but not in c) surface area across the different feedstocks. The grey boxes show the range from first to third quartiles, with the median dividing the interquartile range, into two boxes for the second and third quartiles. Letters show significant differences (p<0. 05) according to a one-way ANOVA followed by Tukey (HSD) multiple means comparison

Suggested guidelines Property Agroecosystem consideration Ash content Hydrophobicity and retention of agrochemicals C/N ratio Initial Immobilization of soil N Sorption of pesticides, herbicides and heavy metals, sites for fungal and microbial colonization Surface area Characteristic Suggested guideline Ash content grass ≈ manure >> nut shells, pomace and wood (hard wood > soft wood) C/N ratio Surface area wood >> grass> pomace> manure (soft wood > hard wood) temperature dependent (soft wood > hard wood)

Acknowledgements Xiaoming Zhang Lucas C. R. Silva Johan Six Sanjai J. Parikh UC Davis Agricultural Sustainability Institute (ASI) Junior Faculty Award • David and Lucile Packard Foundation • • • Email: fmukome@ucdavis. edu

Effects of biochar • Improves – – – water holding capacity nutrient retention soil fertility agricultural yield greenhouse emission (GHG) mitigation • However many other studies have shown – no increase in crop yields, – increased GHG emissions, – unintended “liming” of soils. • Results often linked to the properties of the biochar used, application rate, soil type and climate.