Speciation of Sulfur in Biochar Produced from Pyrolysis and Gasification of Oak and Corn Stover

Abstract

The effects of feedstock type and biomass conversion conditions on the speciation of sulfur in biochars are not well-known. In this study, the sulfur content and speciation in biochars generated from pyrolysis and gasification of oak and corn stover were determined. We found the primary determinant of the total sulfur content of biomass to be the feedstock from which the biochar is generated, with oak and corn stover biochars containing 160 and 600–800 ppm sulfur, respectively. In contrast, for sulfur speciation, we found the primary determinant to be the temperature combined with the thermochemical conversion method. The speciation of sulfur in biochars was determined using X-ray absorption near-edge structure (XANES), ASTM method D2492, and scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS). Biochars produced under pyrolysis conditions at 500–600 °C contain sulfate, organosulfur, and sulfide. In some cases, the sulfate contents are up to 77–100%. Biochars produced in gasification conditions at 850 °C contain 73–100% organosulfur. The increase of the organosulfur content as the temperature of biochar production increases suggests a similar sulfur transformation mechanism as that in coal, where inorganic sulfur reacts with hydrocarbon and/or H2 to form organosulfur when the coal is heated. EDS mapping of a biochar produced from corn stover pyrolysis shows individual sulfur-containing mineral particles in addition to the sulfur that is distributed throughout the organic matrix.

Additive effects due to biochar and endophyte application enable soybean to enhance nutrient uptake and modulate nutritional parameters

“…The up-or down-regulation of both N and S limits the function of other nutrients (McGrath and Zhao, 1996). The application of BC may also serve as an additional balanced source of S and N provisions (Elad et al, 2011;Cheah et al, 2014;Waqas et al, 2014). The role of both nutrients is central and interrelated to amino acid biosynthesis and, hence, proteins (McGrath and Zhao, 1996).…”

Physico-chemical properties and nutrient content of some slow pyrolysis biochars produced from different feedstocks

“…High production temperature increases the pH value of biochars probably as a consequence of the relative concentration of non-pyrolyzed inorganic elements that are already present in the original feedstocks (Novak et al 2009). Biochar's alkalinity can be attributed to four broad categories: surface organic functional groups, carbonates, soluble organic compounds and other inorganic alkalis including oxides, hydroxides, sulfates, sulfides, and orthophosphates (Cheah et al 2014). Increased pH of biochar amended acid soils may help to reduce Al toxicity and increase P availability.…”

“…In this study sulfur content of pyrolyzed biochars varied from slightly over 0.5% (corn cob) to about 2% (water hyacinth and domestic organic waste). Cheah et al (2014) reported that pyrolyzed biochars (500 -600°C) mainly contain sulfate (77 -100%), organosulfur, and sulfide whereas gasification biochars contain 73 -100% organosulfur.…”

The Effect of Biomass Physical Properties on Top-Lit Updraft Gasification of Woodchips

“…Extensive work has been published on the individual production of biochar or syngas [19,20]. However, attempts to simultaneously produce biochar in biomass gasifier systems has been rare and challenging [21]. For instance, Qian et al [22] tested a fluidized bed gasifier for the production and characterization of biochar.…”