Search

Horseradish peroxidase (HRP) is a highly specific enzyme with great potential for use in the decolorization of synthetic dyes. A comprehensive study of HRP immobilization using various techniques such as adsorption and covalent immobilization on the novel carrier Purolite® A109 with a special focus on enzymatic decolorization and toxicity of artificially colored wastewater. The immobilized preparations with an activity of 156.21 ± 1.41 U g -1 and 85.71 ± 1.62 U g -1 after the HRP adsorption and covalent immobilization, respectively, were obtained. Stability and reusability of the immobilized preparations were also evaluated. A noteworthy decolorization level (~90%) with immobilized HRP was achieved. Phytotoxicity testing using Mung bean seeds and acute toxicity assay with Artemia salina has confirmed the applicability of the obtained immobilized preparation in industrial wastewater plants for the treatment of colored wastewater., (© 2020 American Institute of Chemical Engineers.)

Two anthraquinonic dyes, C.I. Acid Blue 225 and C.I. Acid Violet 109, were used as models to explore the feasibility of using the horseradish peroxidase enzyme (HRP) in the practical decolorization of anthraquinonic dyes in wastewater. The influence of process parameters such as enzyme concentration, hydrogen peroxide concentration, temperature, dye concentration, and pH was examined. The pH and temperature activity profiles were similar for decolorization of both dyes. Under the optimal conditions, 94.7% of C.I. Acid Violet 109 from aqueous solution was decolorized (treatment time 15 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.4 mM, dye concentration 30 mg/L, pH 4, and temperature 24°C) and 89.36% of C.I. Acid Blue 225 (32 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.04 mM, dye concentration 30 mg/L, pH 5, and temperature 24°C). The mechanism of both reactions has been proven to follow the two substrate ping-pong mechanism with substrate inhibition, revealing the formation of a nonproductive or dead-end complex between dye and HRP or between H2O2 and the oxidized form of the enzyme. Both chemical oxygen demand and total organic carbon values showed that there was a reduction in toxicity after the enzymatic treatment. This study verifies the viability of use of horseradish peroxidase for the wastewaters treatment of similar anthraquinonic dyes.

A macroporous copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate, poly(GMA-co-EGDMA), with various surface characteristics and mean pore size diameters ranging from 44 to 200 nm was synthesized, modified with 1,2-diaminoethane, and tested as a carrier for immobilization of horseradish peroxidase (HRP) by two covalent methods, glutaraldehyde and periodate. The highest specific activity of around 35 U g(-1) dry weight of carrier was achieved on poly(GMA-co-EGDMA) copolymers with mean pore diameters of 200 and 120 nm by the periodate method. A study of deactivation kinetics at 65 °C and in 80 % dioxane revealed that periodate immobilization also produced an appreciable stabilization of the biocatalyst, while stabilization factor depended strongly on the surface characteristics of the copolymers. HRP immobilized on copolymer with a mean pore diameter of 120 nm by periodate method showing not only the highest specific activity but also good stability was further characterized. It appeared that the immobilization resulted in the stabilization of enzyme over a broader pH range while the Michaelis constant value (K (m)) of the immobilized HRP was 10.8 mM, approximately 5.6 times higher than that of the free enzyme. After 6 cycles of repeated use in a batch reactor for pyrogallol oxidation, the immobilized HRP retained 45 % of its original activity.

The problem of environmental pollution day by day becomes more worrisome, primarily due to the large amounts of wastewater contaminated with various harmful organic compounds, discharged into the environment untreated or partially clean. Feasibility of use of horseradish peroxidase (Amoracia rusticana) in the synthetic dyes decolorization was approved by many researchers. Among a number of supports used for the immobilization, it was found that natural clay, kaolin has excellent features which are a precondition for obtaining biocatalysts with the excellent performances. For this reason, a horseradish peroxidase was immobilized onto kaolin using glutaraldehyde as a cross-linking agent. Obtained biocatalyst was applied in the decolorization of anthraquinone dye C. I. Acid Violet 109. Under determined optimal conditions (pH 4.0, hydrogen peroxide concentration 0.6 mM, dye concentration 30 mg L-1, temperature 24ºC) around 76 % of dye decolorization was achieved. Reusability study showed that resulting biocatalyst was possible to apply four times in the desired reaction with relatively high decolorization percentage. [Projekat Ministarstva nauke Republike Srbije, br. III-46010 i br. 172013]

Two anthraquinonic dyes, C.I. Acid Blue 225 and C.I. Acid Violet 109, were used as models to explore the feasibility of using the horseradish peroxidase enzyme (HRP) in the practical decolorization of anthraquinonic dyes in wastewater. The influence of process parameters such as enzyme concentration, hydrogen peroxide concentration, temperature, dye concentration, and pH was examined. The pH and temperature activity profiles were similar for decolorization of both dyes. Under the optimal conditions, 94.7% of C.I. Acid Violet 109 from aqueous solution was decolorized (treatment time 15 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.4 mM, dye concentration 30 mg/L, pH 4, and temperature 24°C) and 89.36% of C.I. Acid Blue 225 (32 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.04 mM, dye concentration 30 mg/L, pH 5, and temperature 24°C). The mechanism of both reactions has been proven to follow the two substrate ping-pong mechanism with substrate inhibition, revealing the formation of a nonproductive or dead-end complex between dye and HRP or between H2O2 and the oxidized form of the enzyme. Both chemical oxygen demand and total organic carbon values showed that there was a reduction in toxicity after the enzymatic treatment. This study verifies the viability of use of horseradish peroxidase for the wastewaters treatment of similar anthraquinonic dyes. [ABSTRACT FROM AUTHOR]