Methylation of hemoglobin to enhance flocculant performance

Abstract

AbstractBACKGROUNDSynthetic organic polymer flocculants can be highly effective at clarifying suspensions, but these substances may also have negative environmental and health effects. Relatively few studies have been done using biobased flocculants, which are more environment friendly. Hemoglobin (Hb) has previously been demonstrated to be a promising flocculant of kaolin and lignin suspensions. This study examines the methylation of Hb side chain carboxyl groups for the purpose of improving its flocculation performance at near‐neutral pH.RESULTSPotentiometric titration of methylated Hb (MeHb) showed an approximately 28% degree of methylation when the Hb was suspended in methanol with 0.8 mol L−1 HCl for 48 h. Under some conditions, MeHb clarified suspensions of kaolin at one‐quarter the dose that was required for Hb. Furthermore, MeHb exhibited flocculant activity over a wide pH range, compared with Hb. The percentage of original turbidity removed was 37% for Hb while 60% of the original turbidity was removed for MeHb at near‐neutral pH (pH = 6.8).CONCLUSIONSVery small doses of methylated hemoglobin (MeHb) rapidly clarify suspensions of kaolin. The potential of MeHb as a biobased flocculant for the clarification of water for industrial or municipal use was demonstrated. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.