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Flocculation of wheat straw soda lignin by hemoglobin and chicken blood: effects of cationic polymer or calcium chloride

Piazza, George J, Lora, Jairo H, Garcia, Rafael A
Journal of chemical technology and biotechnology 2017 v.92 no.4 pp. 793-800
biomass, blood, byproducts, calcium chloride, cations, chemical oxygen demand, chickens, feeds, flocculants, flocculation, hemoglobin, lignin, neutralization, solubility, wheat straw, zeta potential
BACKGROUND: Lignin is the largest byproduct of biomass processing. Flocculation could replace strong acid used in lignin recovery and be useful for the cleanup of lignin from residual processing waters. Commercial nonrenewable flocculants are known to be effective with lignin, but the investigation of renewable lignin flocculants has received little attention. RESULTS: Methods were developed to economize on the use of biobased flocculant for wheat straw lignin flocculation. Thus, 43% less hemoglobin (HEM) and 39% less chicken blood (CB) were needed when the Zeta potential was increased by the co‐addition of poly (diallydimethylammonium chloride) (pDADMAC). Supernatant chemical oxygen demand (COD) was reduced by 78% with optimal pDADMAC and CB. Up to 94% less HEM was needed for lignin flocculation with the co‐addition of CaCl₂. CONCLUSION: Charge neutralization promoted lignin flocculation with coflocculants pDADMAC/HEM or pDADMAC/CB. Some lignin flocculation was noted at higher levels of CaCl₂ due to reduced lignin solubility. Charge neutralization contributed to lignin flocculation at lower CaCl₂ levels and high HEM. A novel finding was that divalent cation bridging promoted lignin flocculation in the presence of CaCl₂ at lower levels of HEM. Lignin flocculated with HEM‐CaCl₂ is possibly useful as a protein‐enriched animal feed. © 2016 Society of Chemical Industry