title: Hydrothermal carbonization (HTC) of wheat straw: influence of feedwater pH prepared by acetic acid and potassium hydroxide.
abstract: In this study, influence of feedwater pH (2-12) was studied for hydrothermal carbonization (HTC) of wheat straw at 200 and 260°C. Acetic acid and KOH were used as acidic and basic medium, respectively. Hydrochars were characterized by elemental and fiber analyses, SEM, surface area, pore volume and size, and ATR-FTIR, while HTC process liquids were analyzed by HPLC and GC. Both hydrochar and HTC process liquid qualities vary with feedwater pH. At acidic pH, cellulose and elemental carbon increase in hydrochar, while hemicellulose and pseudo-lignin decrease. Hydrochars produced at pH 2 feedwater has 2.7 times larger surface area than that produced at pH 12. It also has the largest pore volume (1.1 × 10(-1) ml g(-1)) and pore size (20.2 nm). Organic acids were increasing, while sugars were decreasing in case of basic feedwater, however, phenolic compounds were present only at 260°C and their concentrations were increasing in basic feedwater.
authors.affiliation: APECS Group, Leibniz Institute for Agricultural Engineering (ATB), Max-Eyth-Allee 100, Potsdam 14469, Germany; Department of Chemical and Materials Engineering, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA. Electronic address: toufiq_reza_unr@yahoo.com.
authors.forename: M Toufiq
authors.initials: MT
authors.lastname: Reza
authors.affiliation: Institute of Earth and Environmental Science, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Erwin
authors.initials: E
authors.lastname: Rottler
authors.affiliation: APECS Group, Leibniz Institute for Agricultural Engineering (ATB), Max-Eyth-Allee 100, Potsdam 14469, Germany.
authors.forename: Laureen
authors.initials: L
authors.lastname: Herklotz
authors.affiliation: APECS Group, Leibniz Institute for Agricultural Engineering (ATB), Max-Eyth-Allee 100, Potsdam 14469, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wirth
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D056804:Biofuels; D001709:Biotechnology / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry; D005662:Furaldehyde / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010636:Phenols / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014908:Triticum / Q000737:chemistry*
chemical_list: D056804:Biofuels; D006878:Hydroxides; D010636:Phenols; D017680:Potassium Compounds; D002244:Carbon; D002482:Cellulose; D005662:Furaldehyde; D019342:Acetic Acid; C029943:potassium hydroxide
keywords: Fiber analysis; HTC biochar; Hydrothermal carbonization; Pore analysis; pH