Flocculation of kaolin and lignin by bovine blood and hemoglobin

Abstract

BACKGROUND The kaolin flocculant activities of bovine blood (BB) and hemoglobin (HEM) at different salt and pH values were determined. Lower limit concentration (LLC), window of application (WA), and degrees of clarification (DC) values for BB and HEM were determined and compared with those of the synthetic polymeric flocculants poly(diallydimethylammonium chloride) (PDADMAC), cationic polyacrylamide (PAM), and anionic PAM. BB flocculation of lignin, a bioproduct of biomass conversion to bioethanol, was demonstrated. RESULTS Flocculation of kaolin by BB and HEM increased at acidic pH and in the presence of NaCl. LLC values of HEM and BB were similar to LLC values of cationic and anionic PAM. LLC values of HEM and BB were 18–20-fold higher than that of PDDMAC. WA values of BB and HEM were similar to those of PDADMAC, cationic PAM, and anionic PAM. For lignin flocculation, the ratio of LLC for BB/PDADMAC was 20–38, but the ratio of WA for BB/PDADMAC was > 3.6. For kaolin and lignin flocculation, DC values were similar for all flocculants. CONCLUSIONS The renewable flocculants BB and HEM rapidly settle kaolin and lignin suspensions; BB and HEM could be used in the process to separate lignin from other biomass components. Published 2014. This article is a U.S. Government work and is in the public domain in the USA