Location: Dairy and Functional Foods ResearchTitle: Flocculation performance and mechanisms of heme-removed and methylated bovine hemoglobin
|LIANG, CHEN - Oak Ridge Institute For Science And Education (ORISE)|
|LEE, CHANGHOON - Oak Ridge Institute For Science And Education (ORISE)|
Submitted to: Separation and Purification Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2022
Publication Date: 4/15/2022
Citation: Liang, C., Garcia, R.A., Qi, P.X., Lee, C. 2022. Flocculation performance and mechanisms of heme-removed and methylated bovine hemoglobin. Separation and Purification Technology. https://doi.org/10.1016/j.seppur.2022.121017.
Interpretive Summary: Flocculants are substances that aid in the removal of solid contaminants from water; they are critical for wastewater treatment and a number of industrial processes. Modern flocculants are very effective but they have disadvantages including being made from non-renewable resources, environmental persistence, and potential human health impacts. Past research has shown that it is possible to use the proteins from some agricultural by-products as substitutes for conventional flocculants. Hemoglobin protein from slaughterhouse blood is a particularly good flocculant substitute, but it suffers from the disadvantage of having an intense red color. In this research, it is shown that three different methods are effective at minimizing the color without compromising the flocculant performance. These findings remove a critical barrier to the commercial adoption of a substitute flocculant that is renewable, biodegradable, and less risky to health and the environment.
Technical Abstract: Bovine hemoglobin (Bh), a slaughterhouse by-product, has been reported as an adequate flocculant. In this study, the heme was removed or degraded by acidified acetone (AA), carboxymethyl cellulose (CMC), and hydrogen peroxide oxidation (H2O2) methods, resulting in apo-Hb. These heme-depleted Hb were further modified by methylation, yielding apo-MeHbs with considerably increased size (Rh ~ 85 - 130 nm) and isoelectric point (~10) compared to Hb and apo-Hbs (pI ~ 7). These decolorized flocculants showed significantly improved flocculation performance in terms of reduced dose (~15 mg/g kaolin) and broadened pH adaptability (pH 4.5 - 8.5). It is demonstrated that charge neutralization is the dominating factor in their exceptional flocculation properties. Evidence is shown that aggregated and crosslinked protein fractions may also contribute to flocculation by bridging suspended particles.