Impact of Peroxidase Addition on the Sorption−Desorption Behavior of Phenolic Contaminants in Surface Soils

Abstract

The impact of peroxidase addition on sorption-desorption of phenol, o-cresol, 2,4-dichlorophenol (DCP), and 1-naphthol was evaluated using two surface soils. Target chemicals were added to soils as single solutes or binary mixtures. Seven-day adsorption studies were followed by sequential fill-and-draw extractions with synthetic groundwater. Addition of horseradish peroxidase (HRP) with H2O2 was the primary treatment evaluated. HRP-mediated sorption enhancementwas related to contaminant solubility and increased in the order: naphthol < DCP < cresol < phenol. Little or no competition was observed in the presence of cosolutes. Contaminant desorption from soils was dramatically reduced upon HRP addition. Reduction in desorption was quantified using the Hysteresis Index and interpreted as attenuation of contaminant mobility. Desorption data predicted that mobility reductions followed the order: naphthol < DCP < cresol < phenol. It is believed that enzyme addition resulted in the production of hydrophobic polymers that, due to their low aqueous solubilities, readily partitioned on to the solid-phase. The adsorbed polymers were less likely to partition into the aqueous phase than the parent phenols resulting in a reduced risk to the environment.

New Approaches for Bioaugmentation as a Remediation Technology

“…17,223,262,266 Strong et al 223 bioaugmented atrazine-contaminated soil with a genetically engineered E. coli strain that overproduced the atrazine chlorohydrolase enzyme responsible for dechlorinating atrazine. The researchers chemically killed the genetically engineered microorganisms (GEMs) prior to addition to a field site reducing regulatory concerns.…”

Detoxification of phenol through bound residue formation by birnessite in soil: Transformation kinetics and toxicity

“…Since bound residues have different chemical structures from their parent molecules and are considered as a part of organic matter their biological and chemical availabilities decrease and thus their toxicity is also altered to a significant extent. [2][3][4][5][6][7][8][9][10][11][12][13] For this reason, studies have been conducted to make bound residues from soil pollutants as a remediation technology. [4,14] Bound residues are formed by oxidative coupling reaction, and the reaction is catalyzed by oxidoreductive enzymes, and so far, most studies have concentrated on using enzymes such as peroxidase and laccase as catalysts.…”

“…[4,14] Bound residues are formed by oxidative coupling reaction, and the reaction is catalyzed by oxidoreductive enzymes, and so far, most studies have concentrated on using enzymes such as peroxidase and laccase as catalysts. [2,3,6,8,10,11,15,16] Metal oxides are also known to have such catalytic activity. Unlike enzymes, they are stable and abundant in the nature, and reactions mediated by oxides do not require oxygen and/or peroxides as electron acceptors because metal oxides themselves act as electron acceptors as well as oxidation catalysts.…”

“…Other reports [3,7,9,11,16] are also available with phenol in soil, but they used enzymes for initiating the oxidative coupling reaction. Selig et al [13] studied the reaction between hydroxylated aromatics and birnessite, but they concentrated on sorption/desorption behavior and extractability.…”

Effects of oxidative coupling reaction of 4-chlorophenol with manganese oxide on the phenanthrene sorption

“…[5,8,9] These self-or cross-coupling reactions of chlorophenols result in the formation of polymeric byproducts distributed to aqueous and solid phase. [10,11] This polymerization process is considered as an alternative means of subsurface cleanup or water treatment, [12,13] implying that manganese oxide can be utilized as reactive media or barrier for the removal of phenolic contaminants.…”