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

Abstract

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

Hemoglobin–Laccase Modifications of Ligninsulfonate: A Promising Synergistic Stratagem for Lignin Biodegradation

“…However, it was difficult to tell whether the additional heat stemmed from either physical flocculation or chemical catalysis. [ 18,19 ]…”

“…[ 39 ] It should be noted that certain amounts of heats released in the hemoglobin system, which were much lower than the laccase‐catalyzed oxidation, indicating that hemoglobin interacted with the lignin substrate. We could not, however, distinguish whether the interaction was physical molecular recognition [ 18,19 ] or chemically catalytic behavior. Heat from the lignin–hemoglobin interaction was at least tenfold lower than heat of oxidation under the experimental conditions.…”

“…Besides its well-known oxygen carrying property -which has a peroxidase-like character and interacts with lignin -this readily available biomolecule from animal blood effectively flocculates lignin to economize the use of flocculant in biomass processing. [18,19] Hemoglobin is also used in multicomponent systems, functioning as an oxygen carrier and accelerating transmission of dioxygen molecules with various "chaperon" oxidoreductases such as terminal respiratory oxidase and oxygenase. [20][21][22] Kang and co-workers reported that hemoglobin promotes peroxide decomposition of recalcitrant organic pollutants like polycyclic aromatic hydrocarbons (PAHs), in which hemoglobin executes a peroxidase role, similar to manganese peroxidase and lignin peroxidase in ligninase.…”

Phosphorus recovery from simulated municipal wastewater (SMW) through the crystallization of magnesium ammonium phosphate hexahydrate (MAP)

“…The stability of a particles suspension depends strongly on their surface charge. The higher the surface charge or potential of the particles the stronger the repulsive forces and the more stable the suspension …”

“…The higher the surface charge or potential of the particles the stronger the repulsive forces and the more stable the suspension. 25,26 Measurements of the zeta potential of suspensions of MAP crystals as a function of the concentration of Mg 2+ , which is a potential determining ion for struvite are shown in Fig. 7.…”