Selected Chloro-Organic Detoxifications by Polychelate (Poly(acrylic acid)) and Citrate-Based Fenton Reaction at Neutral pH Environment

Abstract

The use of chelating agents to modify the Fenton reaction is well-documented in the literature. Polymeric chelates (such as poly(acrylic acid), PAA) provide multiple binding sites and can complex iron ion (ferrous/ ferric ion) and prevent ferric hydroxideprecipitation even at neutral pH environment. In this study, it was proven that poly(acrylic acid) could act as a polychelate in the modified Fenton reaction for the oxidation of chlorinated organic compounds (such as 2,2′-dichlorobiphenyl and biphenyl) at neutral pH environment. Numerical simulation based on the kinetic model developed from the well-known Fenton reaction and ironchelate chemistry fits the experimental data well for both standard and chelate-based modified Fenton reactions without pollutant. This is the first reported confirmation of the dechlorination of carbon tetrachloride from the aqueous phase by superoxide radical anion using both monomeric (citrate) and polymeric (PAA) chelatebased modified Fenton reactions. The main purpose of this research is to understand and model a chelatebased modified Fenton reaction in a homogeneous phase. The oxidation reactions involving immobilized iron on PAA-functionalized solid support (silica particles and PVDF membrane) were also explored.

Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

“…In addition to the speciation of iron, the [L]:[Fe] ratio plays an important role in determining the rate of H 2 O 2 degradation. This rate decreases as this molar ratio is increase from 1:1 to 4:1 and, in conjunction with other findings, indicates Fe–citrate complexes are nonreactive with H 2 O 2 when compared to uncomplexed iron (Li et al , 2007b). Increasing the L:Fe ratio increases the efficiency of H 2 O 2 consumption by reducing the rate of hydroxyl radical production.…”

“…The use of a chelate for remediation in aerobic environments minimizes Fe(II) oxidation by O 2 . Li et al (2007b) demonstrated that dissolved oxygen has no effect on the degradation of trichlorophenol (TCP) by the chelate-modified Fenton reaction using polyacrylic acid (PAA) as the chelating agent. Sun and Pignatello (1992) documented the interactions of dozens of chelating agents, such as EDTA and catechol, with Fe(III) as well as their effect on the reactivity of the Fe(III)–chelate complexes with H 2 O 2 for 2,4-D oxidation.…”

A new green approach to Fenton’s chemistry using tea dregs and coffee grounds as raw material

“…The use of a chelate for remediation in aerobic environments minimizes Fe 2+ oxidation by O 2 . Dissolved oxygen has no effect on the degradation of trichlorophenol by the chelate-modified Fenton's reaction using polyacrylic acid as the chelating agent [14]. Most of the tested chelates for Fenton's reaction in the literature are of …”

Influence of Chelating Agents on Fenton-Type Reaction Using Ferrous Ion and Hypochlorous Acid

“…However, industrial wastewater often contains chelating agents such as detergents, stabilizers, and masking agents for metallic ions, which have a potential to inhibit the iron-based advanced oxidation process through masking of iron. Li et al (2007b) demonstrated that chelating agents of citrate and poly(acrylic acid) constrained the Fenton reaction by lowering free Fe…”