Decolorization of Remazol Brilliant Blue R using a novel acyltransferase-ISCO ( in situ chemical oxidation) coupled system

Magnetic Biochar Prepared with Rosa roxburghii Residue as Adsorbents for Congo Red Removal

In this work, magnetic biochars (MBCs) were produced with the chemical coprecipitation method. The resulting materials were dried at 50 °C for 12 h and characterized via SEM-EDS, XRD, FT-IR, BET, TGA, and VSM techniques to evaluate their efficacy in removing Congo red (CR). The effects of solution pH, CR concentration, MBC1:1 mass, and a variety of ions on the adsorption performance were systematically examined. According to the experimental results, for 200 mL of 50 mg/L CR, the highest adsorption capacity of 20 mg MBC1:1 was 172.88 mg/g in a 2 h period at pH 7. Additionally, the pseudo-second-order (PSO) model-based kinetic analysis exhibited that the process of adsorption adhered to this model. Furthermore, the interaction between MBC1:1 and CR was best described by Langmuir multilayer adsorption, according to isotherm analysis. All of these theoretical and practical findings point to the great potential of MBC1:1 as adsorbents for the applications of wastewater treatment.

Pseudo-water-soluble Fe2O3 as Nanozyme catalyzed chemiluminescent reaction for detection of brilliant blue in gelatin and beverages

Converting solid iron oxide nanoparticles into a "pseudo-water-soluble" form before applying them to chemiluminescent reactions leads to enhance the chemiluminescence intensity. Using 8-hydroxyquinoline as a colloidal agent, a new, fast, and simple method of synthesizing pseudo-water-soluble Fe2O3 nanoparticles was developed. SEM, VSM, SAED, HRTEM, XRD, FTIR, and EDS techniques were used to characterize the synthesized Fe2O3 nanoparticles. Fe2O3 nanoparticles synthesized in this study have superior peroxidase-like activity (POD-like) and are stable under a wide range of pH and temperature. The chemiluminescence reaction of luminol-H2O2 is intensified and accelerated by a colloidal solution of Fe-nanoparticles/8-hydroxyquinoline. Reverse-flow injection analysis was employed to determine brilliant blue. A chemiluminescent sensing method based on iron oxide nanozymes was utilized for sensitive detection of the brilliant blue synthetic dye, achieving a limit of detection of 0.06 mg/L and a dynamic linear range of 0.1 to 50 mg/L. The recovery and relative standard deviations of real samples were found to be 97.83-99.93% and 0.09-3.07%, respectively. An analysis of a sample, from injection to obtaining the maximum peak, could be performed in less than one minute.

DC magnetic field-assisted improvement of textile dye degradation efficiency with multi-capillary air bubble discharge plasma jet

Axial DC magnetic field-assisted multi-capillary underwater air bubble discharge plasma jet has been used to study the productions of reactive oxygen species. Analyses of optical emission data revealed that the rotational (T_r) and vibrational temperatures (T_v) of plasma species slightly increased with magnetic field strength. The electron temperature (T_e) and density (n_e) increased almost linearly with magnetic field strength. T_e increased from 0.53 to 0.59 eV, whereas n_e increased from 1.03 × 10¹⁵ cm^-3 to 1.33 × 10¹⁵ cm^-3 for B = 0 to B = 374 mT, respectively. Analytical results from the plasma treated water provided that the electrical conductivity (EC), oxidative reduction potential (ORP), and the concentrations of O₃ and H₂ O₂ enhanced from 155 to 229 µS cm^-1, 141 to 17 mV, 1.34 to 1.92 mg L^-1, and 5.61 to 10.92 mg L^-1 due to the influence of axial DC magnetic field, while [Formula: see text] reduced from 5.10 to 3.93 for 30 min treatment of water with B = 0 and B = 374 mT, respectively. The model wastewater prepared with Remazol brilliant blue textile dye and the plasma treated wastewater studied by optical absorption spectrometer, Fourier transform infrared spectrometer, and gas chromatography mass spectrometer. The results show that the decolorization efficiency increased ~ 20% after 5 min treatment for the maximum B = 374 mT with respect to zero-magnetic field and, power consumption, and electrical energy cost reduced ~ 6.3% and ~ 4.5%, respectively, due to the maximum assisted axial DC magnetic field strength of 374 mT.

Activated Carbon with Ultrahigh Specific Surface Derived from Bamboo Shoot Shell through K2FeO4 Oxidative Pyrolysis for Adsorption of Methylene Blue

To effectively remove methylene blue (MB) from dye wastewater, a novel activated carbon (BAC) was manufactured through co-pyrolysis of bamboo shoot shell and K₂FeO₄. The activation process was optimized to a temperature of 750 °C and an activation time of 90 min based on its excellent adsorption capacity of 560.94 mg/g with a yield of 10.03%. The physicochemical and adsorption properties of BACs were investigated. The BAC had an ultrahigh specific surface area of 2327.7 cm²/g and abundant active functional groups. The adsorption mechanisms included chemisorption and physisorption. The Freundlich model could be used to describe the isothermal adsorption of MB. The kinetics confirmed that the adsorption of MB belonged to the pseudo-second-order model. Intra-particle diffusion was the main rate-limiting step. The thermodynamic study showed that the adsorption process was endothermic and temperature was beneficial for the improvement of adsorption property. Furthermore, the removal rate of MB was 63.5% after three cycles. The BAC will have great potential for commercial development for purifying dye wastewater.

Natural Molecule‐Incorporated Magnetic Organic‐Inorganic Nanoflower: Investigation of Its Dual Fenton Reaction‐Dependent Enzyme‐Like Catalytic Activities with Cyclic Use

The functional organic‐inorganic hybrid nanoflowers (hNFs) have recently attracted considerable attention due to enhanced catalytic activity and stability. The main purpose of this study is to synthesize new Fenton reagents and investigate their catalytic activity, dye degradation performance and antimicrobial activity. This magnetic gallic acid nanoflowers (FeGANF) were self‐assembled via incorporating magnetic nanoparticles (Fe3O4 NPs) into gallic acid (GA) as organic part and copper(II) phosphate (Cu3(PO4)2) as inorganic parts. The FeGANF were characterized by SEM, EDX, FT‐IR and XRD. The peroxidase‐like activity and dye degradation performance of FeGANF and GANF based on Fenton reaction in the presence of H2O2 was studied toward guaiacol as substrate, using methylene blue (MB) and congo red (CR) as a cationic and anionic dyes, respectively. FeGANF shows much high catalytic activity and decoloration efficiency (97 % for MB and 99 % for CR) because of dual active center in Fenton reaction on the surface of FeGANF. FeGANF exhibited more antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, and Candida albicans ATCC 10231 than that of the GA and GANF. The results of these studies suggest that magnetic hNFs has proved to be promising Fenton reagents for biological and environmental applications including treatment of wastewater.

Enzymatic synthesis of 2-phenethyl acetate in water catalyzed by an immobilized acyltransferase from Mycobacterium smegmatis

Although water is an ideal green solvent for organic synthesis, it is difficult for most biocatalysts to carry out transesterification reactions in water because of the reversible hydrolysis reaction. 3D structural characteristics and the microenvironment of an enzyme has an important effect on its selectivity for the transesterification reaction over the hydrolysis reaction. A novel 2-phenethyl acetate synthesis technology was developed using acyltransferase (EC 3.1.1.2) from Mycobacterium smegmatis (MsAcT) in water. Firstly, MsAcT was entrapped in a tetramethoxysilane gel network and the immobilization process of MsAcT increased its selectivity for the transesterification reaction over the hydrolysis reaction by 6.33-fold. Then, the synthesis technology of 2-phenethyl acetate using the immobilized MsAcT in water was optimized as follows: vinyl acetate was used as acyl donor, the molar ratio of vinyl acetate to 2-phenylethyl alcohol was 2 : 1, and the water content was 80% (w/w). The reaction was carried out at 40 °C for 30 min and conversion rate reached 99.17%. The immobilized MsAcT could be recycled for 10 batches. The synthesis method of 2-phenethyl acetate using MsAcT as a biocatalyst in water is a prospective green process technology.

Screening of perhydrolases to optimize glucose oxidase-perhydrolase-in situ chemical oxidation cascade reaction system and its application in melanin decolorization

A novel glucose oxidase (GOD)-perhydrolase-in situ chemical oxidation (ISCO) cascade reaction system was designed, optimized, and verified the operation feasibility in this research. Among the determined four perhydrolases, acyltransferase from Mycobacterium smegmatis (MsAcT) displayed the highest specific activity for perhydrolysis reaction (76.4 U/mg) and the lowest K_m value to hydrogen peroxide (13.9 mmol/L). GOD-MsAcT cascade reaction system also displayed high catalytic efficiency. Under the optimal parameters (50:1 activity unit ratio of GOD to MsAcT, pH 8.0, 50 mmol/L of β-d-glucose, and 15 mmol/L of glyceryl triacetate), the melanin decolorization rate using GOD-MsAcT-ISCO cascade reaction system reached 86.8 %. Kinetics of GOD-MsAcT-ISCO cascade reaction system for melanin decolorization fitted the kinetic model of Boltzmann sigmoid. As a substitutive skin whitening technology, GOD-MsAcT-ISCO cascade reaction system displayed an excellent application prospect.

Treatment of wastewater containing Reactive Brilliant Blue KN-R using TiO2/BC composite as heterogeneous photocatalyst and adsorbent

Heterogeneous photocatalysis namely titanium dioxide (TiO₂) supported on coconut shell biochar (BC) was synthesized by sol-gel method (calcined at 450 °C) in the paper, which was innovatively applied to the decolorization of Reactive Brilliant Blue KN-R. The transmission electron microscopy (TEM) and X-ray diffraction patterns (XRD) results demonstrated that anatase TiO₂ film was firmly immobilized on the surface and pores of BC. The photocatalysis tests under UV high pressure xenon lamp (300 W) showed highest decolorization efficiency occurred at strong acid and alkali conditions (pH = 1 and 11) reached as 99.71% and 96.99% respectively within 60 min. Therefore, the TiO₂/BC composites demonstrated both photocatalytic and adsorption capacity on KN-R decolorized, and presented quite durable and reusable in regeneration cycles, indicating a widely application possibility in anthraquinones dyeing wastewater treatment.