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Structure and performance of soy hull carbon adsorbents as affected by pyrolysis temperature
Author(s) -
Gnanasambandam Ravin,
Mathias M.,
Proctor A.
Publication year - 1998
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-998-0074-z
Subject(s) - pyrolysis , adsorption , fourier transform infrared spectroscopy , carbon fibers , chemistry , muffle furnace , activated carbon , scanning electron microscope , specific surface area , materials science , chemical engineering , organic chemistry , composite material , catalysis , calcination , composite number , engineering
Soy hulls were evaluated as a source of adsorbent carbon for vegetable oil processing. Soy hull carbon was prepared by burning ground soy hulls (<100 mesh) at 300, 400, 500, or 700°C in a muffle furnace. The structure of the soy hull carbon was studied by scanning electron microscope (SEM), X‐ray diffraction (XRD), and Fourier‐transform infrared spectroscopy (FTIR). Crude soy oil was processed with the soy hull carbon products at 2% (w/w) in the laboratory under commercial bleaching conditions. Free fatty acids (FFA), peroxide value, phospholipid phosphorus (PLP), and lutein content of the treated samples were determined. SEM of the samples revealed particle size ranging from 1 to 2 mm. Increasing the pyrolysis temperature resulted in expansion and disruption of cellular structure. FTIR spectra of the carbon samples showed major differences in peak intensities at 3600 to 3200, 1600, and 1450 cm −1 due to pyrolysis temperature. XRD revealed a predominantly amorphous structure with increasing pyrolysis temperature, which also resulted in an increased alkaline surface. Soy hull carbon decreased the FFA content of oil samples compared to that of crude oil, with the exception of carbon that was prepared at 300°C ( P <0.05). A similar trend was observed in the adsorption of peroxides; however, no trends were observed in the adsorption of PLP or lutein. Higher pyrolysis temperature decreased randomness of the carbon and imparted a certain degree of structural order. This may be beneficial in providing physical access of the adsorbate molecule to the adsorbent surface.