This study evaluates the potential of the enzyme horseradish peroxidase in the decolorization of one common industrial azo dye, naphthol blue black. Studies are carried out to understand the process parameters such as pH, temperature and reaction time. The enzymatic decolorization of the dye was examined by UV-Vis spectrophotometer and LC-MS measurements. Temperature and pH conditions were optimized for obtaining high azo-dye decolorization. Azo-dye removal at a pH range 4-6 was found to be the highest for all temperatures. After 5 minutes of treatment, the color removal of dye was ca. 80-90%. The LC-MS and spectrophotometric analyses indicated that the decolorization of the azo dye with enzyme was due to the reduction of the azo bonds. This study verifies the viability of the use of the horseradish peroxidase in the decolorization of naphthol blue black.
In this study, poly(lactic acid) (PLA)/pistachio shell (PS) biocomposites were fabricated by melt functionalization through a one-step compatibilization process in varying PS filler rates (0–30%). To enhance interfacial adhesion, alkaline-silane pre-treatment was applied to PS, and PLA was grafted with maleic anhydride (MA). The effect of filler ratio, pre-treatment, and maleation steps on the mechanical, thermal, and morphological properties of biocomposites was investigated. The tensile and flexural analysis showed that composites with optimum mechanical properties were obtained by blending 20% of pre-treated PS with maleated PLA. Mechanic and thermal analyses were performed to examine fiber/matrix surface compatibility. The mechanical analysis of biocomposites, such as tensile/flexural strength and modulus were determined with a universal testing machine. Thermal analysis and thermal degradation of biocomposites were determined by using Differential Scanning Calorimetry and TG/DTG. Morphological analysis performed by SEM proved that the composites prepared by maleated PLA and pre-treated PS showed better adhesion between the fiber and the matrix.
In this study, covalent immobilization of the horseradish peroxidase (HRP) onto various polysulfone supports was investigated. For this purpose, different polysulfones were methacrylated with methacryloyl chloride, and then, nonwoven fabric samples were coated by using solutions of these methacrylated polysulfones. Finally, support materials were immersed into aquatic solution of HRP enzyme for covalent immobilization. Structural analysis of enzyme immobilization onto various polysulfones was confirmed with Fourier transform infrared spectroscopy, atomic force microscopy, and proton nuclear magnetic resonance spectroscopy. Decolorization of textile diazo (Acid Black 1) and anthraquinone (Reactive Blue 19) dyes was investigated by UV-visible spectrophotometer. Covalently immobilized enzyme has been used seven times in freshly prepared dye solutions through 63 days. Dye decolorization performance of the immobilized systems was observed that still remained high (70%) after reusing three times. Enzyme activities of immobilized systems were determined and compared to free enzyme activity at different conditions (pH, temperature, thermal stability, storage stability). Enzyme activities of immobilized systems and free enzyme were also investigated at the different temperatures and effects of temperature and thermal resistance for different incubation time at 50 °C. In addition, storage activity of free and immobilized enzymes was determined at 4 °C at different incubation days.
Aim: Fenolic compounds are major of pollutants in medicine, food and local matrixe. The enzyme peroxidase is known for its capacity to remove phenolic compounds and aromatic amines from aqueous solutions and also to decolorize textile effluents. In this study, decolorization of anthraquinone dye, Reactive Blue 19 (RB 19), large quantities of which used in textile and other industries was investigated using Horseradish peroxidase (HRP) at different conditions. In addition, decolorization efficiency of dye by enzyme was studied in the presence of denaturing agent urea and salt in synthetic wastewater. Material and Methods: Horseradish peroxidase and Reactive Blue 19 were obtained by commercial way. The enzymatic decolorization of the dye was examined by UV-Vis spectrophotometer measurements. Decolorization studies were performed by varying parameters such as enzyme and dye concentrations, pH, temperature, incubation time, presence of H 2 O 2 , salt and urea. Results: Optimum pH value for dye decolorization was determined as 5.0. Maximum dye was removed within 5 min after the beginning for every experiment. After 5 minutes of treatment, the color removal of dye was ca. 90-95% at pH 5.0 and all temperatures. Furthermore, the higher concentrations of dye, H 2 O 2 and NaCl did not exhibit inhibition effect but the initial decolorization rate decreased with increasing the urea concentration. The kinetic constants of enzyme were determined for dye.
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