Reactive Brilliant Red X3B Research Articles

Internal cycling of Fe3+/Fe2+ within Fe3O4 on cathode promotes green degradation of reactive brilliant red X-3B on anode

ABSTRACT Reactive brilliant red X-3B (RBRX-3B) wastewater is difficult to decolourise, not readily biodegradable, and large in quantity. Therefore, the efficient removal of RBRX-3B is crucial. In this paper, a green and efficient electrochemical-electro-Fenton system with Fe3O4-modified carbon felt bag cathode (ECEF-Fe3O4) was set up to degrade RBRX-3B wastewater. Experiments confirmed that the removal of RBRX-3B by ·OH or H2O2 is quite low, and RBRX-3B can be completely oxidised and degraded directly on the anode. Long-cycle experimental data further shows that the degradation efficiency of RBRX-3B on the anode is 100% at 70 min at the reaction rate constants (k) of 0.071 min−1 in ECEF-Fe3O4 while that of RBRX-3B on the cathode is only 16.8 ± 0.9%. The generation of ·OH is mainly catalysed through the internal cycling of Fe3+/Fe2+ within Fe3O4 on the cathode, and the generation and annihilation of ·OH on the cathode enhance the oxidation efficiency of the anode, achieving the green and effective removal of RBRX-3B by the anode in ECEF-Fe3O4.

Effective degradation of organic pollutants by CuFe@C composite derived from bimetallic MOFs synthesized through stepwise feeding method

In this work, Cu-Fe bimetal-embedded carbonaceous CuFe@C materials were prepared by high-temperature pyrolysis of CuFe-MOFs precursors synthesized through a facile two-step feeding approach. Through adjusting the reaction time of each feeding step, CuFe-MOFs of uniform dispersed crystals with controlled sizes were obtained. The carbonized composites were then applied to activate persulfate (PMS) for Reactive Brilliant Red X-3B (RBRX-3B) degradation in water. The removal rate of RBRX-3B was up to 98% in 40 min in the CuFe@C600/PMS system, indicating that the CuFe@C600 catalyst showed excellent sulfate radical-based oxidation (SR-AO) activity in the degradation process. The effects of PMS dosage, initial pH, RBRX-3B concentration on the degradation efficiency were investigated in detail. Based on quenching experiments, a possible mechanism for the CuFe@C600/PMS system was proposed. The catalyst had good reusability, in which the removal rate of RBRX-3B could attain 82% after 5 times of repeated recycling. It also showed satisfactory removal effect on other organic pollutants, i.e. Congo red, Methyl orange, Reactive blue and p-nitrophenol. This study provided a valuable strategy for the treatment of wastewater containing organic pollutants using MOFs-derived materials.

Effects of ZSM‐5 Treatment on the Properties of Gd2Ti2O7‐nHZSM‐5 Composites for RBR‐X3B Degradation

AbstractGd2Ti2O7‐nHZSM‐5 (GTO‐nZ) composites are prepared using HZSM‐5 zeolite via a sol–gel route. The hydrochloric acid concentration in zeolite treatment can affect the properties of GTO‐nZ composites. GTO has a typical pyrochlore phase Gd2Ti2O7, and HZSM‐5 zeolite does not have noticeable influences on GTO crystal formation. The bandgap energies are 3.77, 3.73, 3.67, 3.65, and 3.64 eV for GTO‐nZ composites when hydrochloric acid concentration is 0, 0.2, 0.3, 0.5, and 1 mol L−1, respectively. The isotherms of GTO‐nZ composites are classified as IUPAC type IV of mesoporous material, while the adsorbed nitrogen quantities on GTO‐nZ composites are much larger than the nitrogen quantity on GTO. The small amount of HZSM‐5 zeolite can improve the porosity of GTO in the composites, and the surface area of GTO in the composites is significantly enlarged. The hydrochloric acid concentration has an apparent influence on the photocatalytic degradation efficiency of GTO‐nZ composites. RBR‐X3B (Reactive Brilliant Red‐X3B) degradation efficiency is enhanced with increasing hydrochloric acid concentration to the maximum value at 0.3 mol L−1. The reaction rate constants are 2.03 × 10−2, 9.1 × 10−3, and 3.1 × 10−3 min−1 for GTO‐0.3Z, GTO‐0Z, and GTO, respectively.

Preparation of mesoporous anatase titania with large secondary mesopores and extraordinarily high photocatalytic performances

A mesoporous titania (SN2) with three-dimensional (3D) large secondary mesopores (6.2 nm) highly connecting the mesochannels was prepared employing the method of first synthesizing an ordered 2D hexagonal mesoporous titania-silica nanocomposite (SN1) via “synchronous-assembly” of inorganic precursors with surfactant molecules, then “extracting silica”. Our tactic adopts a large amount of silica, a high crystallization temperature and mild silica extraction. The 3D interconnectivities of the resultant mesochannels are quite high, but the mesostructures are retained intact. Titania is fully anatase crystalline with uniform nanocrystals size (11.2 nm) and a high specific surface area (∼ 174 m2 g−1). This strategy is gentle, simple and easily reproducible. SN2 presents extremely-high photocatalytic degradation activities to anionic azo dyes like acid red 1 and reactive brilliant red X3B, which reach 55.9 and 51.1 times that of commercial P25 photocatalyst, even up to 87.0 and 84.7 times that of SN1, respectively; and far higher than that of the contrast sample (CS) possessing 3D small secondary mesopores (2.7 nm). Additionally, SN2 also displays a very high activity to microcystin-LR, which is much higher than that of P25 and CS, respectively. Our results clearly indicate that the large secondary mesopores play a key role in the great increases of activities. Moreover, our photocatalyst is considerably stable and reusable. Such results have hitherto not been seen in the literature. Furthermore, this method would pave the way for the rational design and preparation of ordered mesoporous other metal-oxides with large secondary mesopores and unexpected performances.

Enhanced mineralization of reactive brilliant red X-3B by UV driven photocatalytic membrane contact ozonation

The partial oxidation on refractory organics in ozonation process and the poor performance of mass transfer between ozone (O3) phase and liquid phase by common O3 distribution techniques inhibit the practical application of O3. To overcome these defects, hollow fiber membrane was applied in membrane contact ozonation (MCO)-UV process for the reactive brilliant red X-3B (RBRX-3B) degradation. The efficiency of mass transfer was guaranteed due to the enormous gas/liquid contact area supplied in this bubble-less O3 transfer process. UV photolysis not only significantly improved the O3 utilization efficiency but also accelerated the mineralization of RBRX-3B by promoting O3 to decompose to hydroxyl radicals (OH). When 15 mg/L of O3 was supplied at flow rate of 0.2 L/min, and a liquid velocity of 0.453 m/s, the chemical oxygen demand (COD) removal and total organic carbon (TOC) removal reached 90 % and 77 %, respectively. The rate constant for TOC removal in the MCO-UV process (7.89 × 10−3 min−1) was 3.08 and 6.12 times higher than that in MCO and UV photolysis processes, respectively. Furthermore, the mineralization efficiency (ΔCOD/ΔO3 = 0.84 mg/mg) and electrical energy per mass (EEM = 4.7 kW h/kg) were calculated and these results indicated a promising future for the MCO-UV process.

Sequential Production of Xylose, Levulinic Acid and Activated Carbon from Pine Wood

AbstractIn this work, a sequential production of bioenergy platform intermediates (i. e., xylose and levulinic acid (LA)) and carbon materials from pine wood was developed by a three‐step conversion technology. Firstly, the hemicellulose in pine wood was hydrolyzed, obtaining 12.8 wt% xylose and 68.9 wt% solid products containing cellulose and lignin. Secondly, the solid products were hydrolyzed, obtaining 30.6 wt% LA and 42.0 wt% solid residues containing humins and lignin. Thirdly, the solid residues were used for activated carbon (AC) production through potassium hydrate (KOH) activation followed by pyrolysis from 400–800 oC. An AC obtained at a pyrolysis temperature of 800 oC had a high Brunauer‐Emmett‐Teller (BET) surface area of 2436 m2/g and pore volume of 0.91 cm3/g, which exhibited an excellent reactive brilliant red X‐3B (RBRX‐3B) adsorption capacity of 892 mg/g. As a case, 1000 g of pine wood finally produced 128 g xylose, 211 g LA and 39 g high‐performance activated carbon.

Sequential reduction/oxidation of azo dyes in a three-dimensional biofilm electrode reactor

By combining sequential anaerobic-aerobic reactor and penetrable cathode-anode operation, a novel anaerobic/aerobic sequencing three-dimensional biofilm electrode reactor (3D-BER) was developed to evaluate the degradation of azo dye reactive brilliant red X-3B (RBRX-3B). In the bottom cathodic region, anaerobic reductive conditions and H2 were produced for the bioreduction of azo dyes; in the top anodic region, aerobic oxidative conditions and O2 were produced for the mineralization of dye intermediates. Due to the supply of electrical power, electrons could be mediated via electrolysis of water or directly transfer between electrodes and microbe cells. The biofilm immobilized on the surface of the cathode utilized electrode or H2 as electron donors and accelerated the rate of RBRX-3B reduction, and the decolorization rate was significantly increased 2.6–3.7 fold, reaching at 2.52–3.39 mol/m3/d at an energy consumption of 0.15 kWh/mol RBRX-3B. RBRX-3B was reductively cleaved into aromatic amines at the biocathode and these amines were effectively removed at the bioanode. Acute toxicity tests showed that the intermediates of RBRX-3B were more toxic when compared with the initial influent, and the 3D-BER effluent exhibited much lower toxicity (5% inhibition of bioluminescence of Vibrio fisheri) than the electrochemical and biological effluent (65% and 30% inhibition, respectively). These findings suggest the novel 3D-BER may provide a promising alternative to remove azo dyes in dyeing wastewater.

Sol-gel Synthesis of χTiO2/HZSM-5 Composite Photocatalyst on Degradation of Reactive Brilliant Red X3B

Background: Different kinds of materials have been tried to support TiO2. The possible interactions between the supporting materials and the photocatalyst might put effect on photocatalytic activity. Synthesized zeolite with porous structure and large surface area has a long industrial history as adsorbent and catalyst. Photocatalytic degradation of Reactive Brilliant Red-X3B on χTiO2/HZSM-5 regarding TiO2 loading percentage and reaction time were investigated. Keywords: Sol-gel, TiO2, HZSM-5, photocatalytic, supporting, degradation.

Degradation pathway and mechanism of Reactive Brilliant Red X-3B in electro-assisted microbial system under anaerobic condition

The degradations of Reactive Brilliant Red X-3B (RBRX-3B) in an electric-assisted microbial system (EAMS), a microbial system (MS) and an electrochemical system (ECS) were compared. The degradation efficiency of RBRX-3B in EAMS (99.8%) was 10.8% higher than the sum in MS (61.9%) and ECS (27.1%) at 24h at the optimal voltage of 0.4V, indicating that there was a synergistic effect between the electrode reaction and the biodegradation. The RBRX-3B degradation in EAMS followed first-order kinetic model. The activation energy of RBRX-3B degradation in EAMS was calculated to be 60.53kJmol−1 by the Arrhenius equation, showing that the degradation rate of RBRX-3B mainly depended on bio-chemical reaction. RBRX-3B was degraded to both low-strength toxic compounds and nontoxic compounds in EAMS and those intermediates were easier to be further degraded. The pathway of RBRX-3B degradation in EAMS was different from that in MS.

Effects of calcination temperature on sol-gel synthesis of porous La2Ti2O7 photocatalyst on degradation of Reactive Brilliant Red X3B

AbstractThe effects of calcination temperature on properties of porous lanthanum titanate using PEG4000 template in a sol-gel route were studied. Photocatalytic degradation of Reactive Brilliant Red X3B on the materials was evaluated. Monoclinic La

Effects of calcination temperature on characterization and photocatalytic activity of La2Ti2O7 supported on HZSM-5 zeolite

The effects of calcination temperature on properties of 70%La2Ti2O7/HZSM-5 prepared by sol-gel method were studied. Photocatalytic degradation of Reactive Brilliant Red X3B on the materials was measured. The supported La2Ti2O7 tends to disperse on the surface of HZSM-5 particles in 70%La2Ti2O7/HZSM-5 composites. The majority phase of lanthanum titanate, monoclinic La2Ti2O7, forms in the material at 800 °C, while a small amount of orthorhombic La4Ti9O24 appears at 900 °C. The crystallite sizes of La2Ti2O7 are 24.5, 29.9 and 42.0 nm in the samples calcinated at 800, 900 and 1000 °C, respectively. The band gaps of 70%La2Ti2O7/HZSM-5 is gradually reduced with the increase of calcination temperature up to 900 °C, due to the quantum size effect along with crystal growth at high temperature. BET surface area of the composite gradually decreases with rising calcination temperature. The maximum photocatalytic acitvity is found on 70%La2Ti2O7/HZSM-5 calcinated at 800 °C, which is in accordance to production of hydroxyl radical under irradiation. 73.7% of the initial photocatalytic activity is still retained when the material is reused for the fifth time.

Effect of pH, inoculum dose and initial dye concentration on the removal of azo dye mixture under aerobic conditions

Biodegradation of mixture of three dyes namely, reactive brilliant red X-3B (RBRX-3B), direct blue-6 (DB-6) and direct black-19 (DB-19) in a batch shake flask was investigated in this study. Mixed microbial culture isolated from the sludge procured from a local common effluent treatment plant was used to degrade the dyes. Acclimatization of the bacterial culture was done prior to the experiment to obtain a culture with effective degradation ability. Batch kinetic studies were done and modelled using Monod and Michaelis-Menten models. The effects of process parameters, namely pH (5–9), inoculum dosage (5–15%) and initial dye concentration (20–100 mg l−1) on the biodegradation of dye mixture were studied systematically and optimized using response surface methodology (RSM). The maximum removal efficiencies obtained for RBRX-3B, DB-6 and DB-19 were 31.2%, 71.5% and 87.6% respectively. The model equations generated by RSM were found to be statistically significant and the optimized values of process parameters were experimentally validated. The error between experimental values and model prediction was found to be less than 10% for all the three dyes.

Enhancement of Catalytic Activities of a Biomimetic Catalyst FePz(dtnCl2)4 for the Wet Oxidation of Brilliant Red X3B through the Synergetic Effect of Heat and Light Irradiation

In this study, catalytic wet oxidation of Reactive Brilliant Red X3B (abbreviated as X3B) was studied using hydrogen peroxide as oxidant in the presence of a biomimic catalyst, iron(II) tetra(5,6-dichloro-1,4-dithiin)porphyrazine [abbreviated as FePz(dtnCl2)4]. Important factors including the solution pH, H2O2 concentration, and reaction temperature were investigated in detail to optimize the catalytic activity for the removal of X3B. Under the optimal conditions, X3B was degraded by 97.0% at pH = 2 for 240 min. Activation energy and rate constants at different reaction temperatures were calculated for the degradation of X3B in both the dark reaction and photoreaction. These results demonstrated that the catalytic activities of FePz(dtnCl2)4 for the wet oxidation of X3B could be efficiently enhanced through the synergetic effect of heat and light irradiation. Through fluorescence technology, hydroxyl radical (HO•) was detected as the main reactive oxidative species for the oxidative degradation of X3B.

Excellent photocatalytic degradation activities of ordered mesoporous anatase TiO2–SiO2 nanocomposites to various organic contaminants

Ordered 2-D hexagonal mesoporous TiO2–SiO2 nanocomposites consisted of anatase TiO2 nanocrystals and amorphous SiO2 nanoparticles, with large mesochannels and high specific surface areas, have been extensively and detailedly evaluated using various cationic dyes (methylene blue, safranin O, crystal violet, brilliant green, basic fuchsin and rhodamine-6G), anionic dyes (acid fuchsin, orange II, reactive brilliant red X3B and acid red 1) and microcystin-LR. We use mesoporous 80TiO2–20SiO2-900 for the degradation of cationic dyes and MC-LR, due to the dominant adsorption of SiOH groups and synergistic role of coupled adsorption and photocatalytic oxidation. For anionic dyes, due to the adsorption results predominantly from TiOH groups, our strategy realizes the enhanced photocatalytic oxidation by strong surface acids and larger available specific surface area. Based on this, we prepared 90TiO2–10SiO2-700 to degrade them. The results show that our samples exhibit excellent degradation activities to all the contaminants, which are much higher than that of P25 photocatalyst. The dyes are not only decolorized promptly but degraded readily as well. It is strongly indicated that our mesoporous nanocomposites are considerably stable and reusable. These results demonstrate that our mesoporous TiO2–SiO2 nanocomposites present extensive and promising application in the fast and highly efficient degradation of various organic pollutants.

Adsorption Properties of MgO(111) Nanoplates for the Dye Pollutants from Wastewater

Nanoplates of MgO possessing the polar (111) facet as the primary surface were studied as adsorbents for dye pollutants removal from wastewater. The thickness of the MgO(111) nanoplates is (3 to 5) nm, with an average specific surface area (SSA) of 198 m2·g−1. Congo red and reactive brilliant red X3B are used as model azo dyes, and their adsorption is studied at different dye concentrations, solution pH, salt concentration, and temperatures in a batch reactor. The experimental results indicate that the MgO nanoplates with polar (111) surfaces exhibited much more favorable adsorption properties than a conventionally decomposition prepared MgO powder (CP-MgO, SSA = 30 m2·g−1) and activated carbon (SSA = 1500 m2·g−1) for Congo red solution with the initial concentration of 100 mg·L−1 in 30 min. The maximum adsorption capability of Congo red on MgO (111) nanosheets reached 131.3 mg·g−1 in 30 min, while the maximum adsorption capabilities of Congo red on CP-MgO and activated carbon were only (61.9 and 17.7) mg...

Synergistic effects of hollow structure and surface fluorination on the photocatalytic activity of titania

To study the synergistic effects of hollow structure and surface fluorination on the photoactivity of TiO(2), TiO(2) hollow microspheres were synthesized by a hydrolysis-precipitate method using sulfonated polystyrene (PS) as templates and tetrabutylorthotitanate (TBOT) as precursor, and then calcined at 500 degrees C for 2h. The calcined samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N(2) sorption. Photocatalytic activity was evaluated using reactive brilliant red X3B, an anionic organic dye, as a model pollutant in water. The results show that the photocatalytic activity of TiO(2) hollow microspheres is significantly higher than that of TiO(2) nanoparticles prepared in the same experimental conditions. At pH 7 and 3, the apparent rate constants of the former exceed that of the latter by a factor of 3.38 and 3.15, respectively. After surface fluorination at pH 3, the photoactivity of hollow microspheres and nanoparticles further increases for another 1.61 and 2.19 times, respectively. The synergistic effect of surface fluorination and hollow structure can also be used to prepare other highly efficient photocatalyst.

Synthesis and characterization of ZnO and TiO 2 hollow spheres with enhanced photoreactivity

To study the relationship between the morphology and the photoreactivity of the catalyst, hollow spheres of two semiconductors of ZnO and TiO 2 were synthesized by using sulfonated polystyrene (PS) as template. The catalyst samples were then characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), diffuse reflectance spectra (DRS), transmission electron microscopy (TEM) and N 2 sorption. Reactive brilliant red X3B, an anionic organic dye, was used in this study as a model chemical with the aim of organic pollutants control. The results show that, whatever the catalyst was, both the adsorptive ability and photoreactivity of the hollow spheres were much higher than that of nanoparticles. The adsorption and photoreactivity of ZnO hollow spheres increased by a factor of 7.36 and 4.66, respectively compared with ZnO nanoparticles, while 3.74 times increased in adsorption and 3.41 times increased in photoreactivity for TiO 2 hollow spheres compared with TiO 2 nanoparticles. Correlations between adsorption and photoreactivity reflected the importance of adsorption in the enhanced photoreactivity of ZnO and TiO 2 hollow spheres.

Variation of peroxidase isoenzyme and biofilm of Phanerochaete chrysosporium in continuous membrane bioreactor for Reactive Brilliant Red X3-B treatment

The influence of a Reactive Brilliant Red X-3B (RBR X-3B) dye on the peroxidase isoenzyme of Phanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor (MBR) was also investigated by scanning electron microscope (SEM). The variation of peroxidase isoenzyme and the decolorization rate in the continuous MBR were evaluated. The results showed that the 100 mg/L RBR X-3B could stimulate the production of the peroxidase isoenzyme in the shaking-flask culture. In addition, two new peroxidase isoenzyme bands with relative mobility (Rf) value of 0.27 and 0.28 appeared, but the activity was lower than the blank control of 11 d. In the continuous MBR, the system worked stably during the first 60 d, the main peroxidase isoenzyme bands existed and three new bands with Rf value of 0.10, 0.27, and 0.28 appeared. Meanwhile, the biofilm grew well and the average decolorization rate could reach 90.6%. But the bands of peroxidase isoenzyme decreased rapidly at day 65, only two bands with Rf value 0.24 and 0.26 existed, and the decolorization rate decreased to 78.3%. Therefore, 5 bottles of P. chrysosporium mycelial pellet were added into the MBR, and then the activity of the peroxidase isoenzyme and the decolorization rate had a slight recovery. Finally, the decolorization rate finally decreased to 75.2%. These results contribute to a comprehensive understanding of the variation of peroxidase isoenzyme and biofilm in continuous MBR by white rot fungi.

Photocatalytic degradation of textile dye X3B by heteropolyoxometalate acids

Reactive brilliant red X3B, one recalcitrant textile dye, was decolorized in water by (Photo)-Fenton reactions and TiO 2 photocatalysis [Chemosphere 43 (2001) 1103]. Complementary to this study, the present work has shown the effectiveness of several Keggin-type heteropolyoxomatalates (POM) as a photocatalyst for X3B degradation in water at pH 1.0 under UV light ( λ⩾320 nm) irradiation. Among four POMs, the relative activity was observed to be H 3PW 12O 40 ≫ H 4SiW 12O 40 > H 4GeW 12O 40 > H 3PMo 12O 40. The reaction was dependent of pH, light intensity and the catalyst loading, but not obviously of the molecular oxygen dissolved in water. Compared to the photocatalyst of TiO 2 (Degussa p25), H 3PW 12O 40 was less efficient for the dye bleaching and mineralization. The mechanism study reveals that hydroxyl radicals are involved in the degradation of X3B (and Rhodamine B) by POM photocatalysis.

SYNERGIC DEGRADATION OF REACTIVE BRILLIANT RED X-3B USING THREE DIMENSION ELECTRODE-PHOTOCATALYTIC REACTOR

A new reactor, three dimension electrode-photocatalytic reactor, was designed and used to investigate the photoelectrochemical degradation of reactive brilliant red X-3B (RBRX) in simulated wastewater. The reactor was characterized by a series of parameters, the current change, decolorization ratio, COD removal and degradation ratio. It was found that the three dimensional electrode-photocatalytic reactor could effectively destroy the RBRX within a reaction time of 30 min. The results also showed that the photoelectrochemical process is more efficient than the single application of electrochemical oxidation or photocatalytic degradation. The degradation reactions of RBRX conformed to pseudo first order kinetics in the three processes, and an apparent synergic effect in the increase of the photocurrent and the disappearance of RBRX was observed by combining the electrochemistry with photocatalytic process in the three dimension electrode-photocatalytic reactor.