Degradation Of Reactive Black Research Articles

Preparation of Mn-Ce oxide-loaded Al2O3 by citric acid-assisted impregnation for enhanced catalytic ozonation degradation of dye wastewater

The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support. In this study, citric acid (CA) was used as a modifier to prepare Al2O3 supported Mn-Ce oxides (Mn-Ce/CA-Al2O3) by the impregnation-calcination method. The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support, rendering Mn-Ce/CA-Al2O3 with a larger specific surface area and abundant surface hydroxyl groups, thereby providing more reaction sites for catalytic ozonation. The Mn-Ce/CA-Al2O3 exhibited excellent catalytic ozonation performance in degrading Reactive Black 5 (RB5) dye. It achieved nearly complete decolorization of RB5 within 60 min, with a COD removal efficiency of 60%, which was superior to the sole ozonation (30%). Furthermore, the Mn-Ce/CA-Al2O3 system demonstrated significant degradation of RB5 over a wide pH range of 3 to 11. Based on the XPS and EPR analysis results, a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al2O3 was proposed. The redox cycle of Mn3+/Mn4+ and Ce3+/Ce4+ effectively accelerated the electron transfer process, thus promoting the generation of reactive oxygen species (ROS) and improving the degradation of RB5. Meanwhile, the Mn-Ce/CA-Al2O3 exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.

Role of surfactants in the degradation and sustainable dyeing for reactive dyeing wastewater

To enhance the decolorization rate of thermally activated sodium persulfate in dye wastewater, C.I. Reactive Black 5 (RB5) was investigated in this study, which was evaluated by the decolorization of the dye solution. The effect of surfactant concentration (including anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant Tween 80 (TW-80) and amphoteric surfactant (BS-12)), SPS concentration, and reaction temperature on the degradation of RB5 was studied. Furthermore, the relationship between free radicals and RB5 degradation was investigated. The results showed that the addition of SDS and TW-80 would inhibit the decolorization of RB5. Correspondingly, the effect would enlarge as the surfactant concentration increased. Nevertheless, the addition of BS-12 wouldn’t affect the final decolorization of RB5 dye solution, despite it could increase the decolorization rate in the initial stage. After 10 min of decolorization, compared to the dye liquor without BS-12, the decolorization could increase by 9.07 % and 0.69 %, respectively, after adding 0.5 and 1.0 CMC of BS-12. Besides, when reactive dyes were degraded by thermally activated sodium persulfate, the SO4-· and ·OH would work together, and SO4-· played a major role while ·OH played an auxiliary part. When the treated wastewater was used for dyeing, the addition of BS-12 could effectively regulate the dyeing rate. The fixation and K/S value were increased by 1.1 % and 0.20, respectively. Furthermore, the dyed fabrics also exhibited improved uniformity, with negligible differences in color fastness. The effects of adding SDS were similar to BS-12, while it decreased the exhaustion and fixation rate of RB5. In addition, non-ionic TW-80 was unfavorable to dyeing. This work provides a new way for efficient treatment of dyeing wastewater as well as reuse, opening an environmentally friendly treatment concept.

Enhancing Biodegradation Efficiency of Reactive Black-5 Dye using Bacillus wiedmannii strain NAF4: Optimization of Degradation Parameters via Response Surface Methodology (RSM)

Reactive Black 5 (RB-5) dye is extensively used in industries such as textile, paper, and leather, raising environmental concerns due to its persistence and adverse effects. This study aimed to develop efficient and eco-friendly strategies for RB-5 dye removal from industrial wastewater. RB-5 dye-degrading bacteria, namely NAF1, NAF2, NAF3, and NAF4, were isolated from soil contaminated with textile effluents. Evaluation of their decolorization potential revealed NAF4 as the most effective, achieving a decolorization percentage of 89%, followed by NAF3 and the co-culture at 75% and 73%, respectively. NAF2 exhibited the lowest decolorization potential. The isolate NAF4 showed significant production of tyrosinase and laccase enzymes, with lower quantities of lignin peroxidase and azoreductase. Phylogenetic analysis confirmed the identities of the isolates as Bacillus, Pseudomonas, Escherichia, and Citrobacter. The decolorization potential exhibited by Bacillus wiedmannii NAF4 has instigated the investigation of its capacity to secrete degradative enzymes implicated in the breakdown of azo dyes. Substantial enzyme production was observed over a duration of 192 hours. The biodegradation potential of B. wiedmannii strain NAF4 for RB-5 dye was assessed using Surface Response Optimization (SRO) modeling. The optimized conditions for RB-5 degradation were determined to be an agitation speed of 115.777 rpm, pH of 7.449, inoculum size of 12.255, and temperature of 29.74°C. The SRO model exhibited high statistical significance with an F-value of 53.30 and low p-values (<0.0001), as well as a correlation coefficient (R2) value of 0.9813. Validation studies confirmed the adequacy and precision of the model. The maximum RB-5 degradation achieved was 90.2291%. Three-dimensional plots visually represented the validated optimum conditions of variables and responses. The successful application of Response Surface Methodology (RSM) as an optimization tool highlights its effectiveness in enhancing degradation processes. This study provides insights into the potential applicability of RSM for optimizing degradation processes in various contexts. The developed eco-friendly strategies offer promising solutions for RB-5 dye removal from industrial wastewater, mitigating its environmental impact.In conclusion, the application of Response Surface Methodology (RSM) as an optimization tool proved effective in maximizing the degradation process by optimizing the degradation parameters. The success of this approach suggests its potential applicability in other contexts to enhance degradation processes.

Rice husk-derived cobalt silica as effective peroxymonosulfate activator for degradation of organic pollutants

In this study, mesoporous silica was synthesized from rice husks, and subsequently used to prepare a cobalt silica (Co/SiO2) catalyst via a simple sol–gel approach. The synthesized Co/SiO2 catalyst was thoroughly characterized. The analysis of the scanning electron microscopy (SEM) images revealed silica particles with sizes of nearly 20 nm. Energy-dispersive X-ray analysis showed a good Co dispersion on the catalyst surface with a Co content of 7.7 %. The Co/SiO2 catalyst was then utilized as a peroxymonosulfate (PMS) activator to degrade reactive black 5 (RB5). Furthermore, the impact of various parameters on RB5 degradation was analyzed. The Co/SiO2 catalyst demonstrated excellent performance and completely degraded RB5 within 8 min with a rate constant of 5.5 × 10−1 min−1 at an extremely low dosage of 0.05 g/L. Furthermore, the degradation rate increased with temperature, and the activation energy was 51.5 kJ/mol. The analysis of the quenching and electron paramagnetic resonance experiments showed that SO4• −, HO•, 1O2, and O2• − were produced, with 1O2 being the predominant reactive species. Notably, the catalyst remained effective when tested in actual water environments and could degrade various other dyes and tetracycline. To facilitate catalyst recovery through filtration, Co/SiO2 was embedded in crosslinked chitosan beads. The bead catalyst demonstrated comparable performance to pristine Co/SiO2 and could be reused for five cycles.

Accelerated mineralization of textile wastewater under 222 nm irradiation from Kr/Cl2 excilamp: an environmentally friendly and energy efficient approach

The textile dyeing and manufacturing industry is the major producer of significant amounts of wastewater that contain persistent substances such as azo dyes that require adequate remediation measures. Far ultraviolet at 222 nm light may provide an advantage for contaminants degradation as compared to conventional UV sources (254 nm). In this paper, the degradation of reactive black 5 (RB5) in artificial wastewater has been performed using a 222 nm Kr/Cl2 excimer source under direct photolysis and an advanced oxidation process using TiO2/H2O2. The solution pH, catalyst concentration, 222 nm intensity, initial concentration of dye, and addition of H2O2 influence the degradation rate constant. The molar absorption coefficient, quantum yield of RB5 at 222 nm and the electrical energy per order (EEO) from different treatment methods have been reported. RB5 shows 1.26 times higher molar absorption at 222 nm than at 254 nm. The EEO for excimer-222/H2O2 (∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 13 kWh/m3) is five times lower than that of the excimer-222/TiO2 process, which makes the process energy efficient. The degradation of wastewater has been carried out at three distinct pH values (2, 6, and 10), and the pH level of 10 exhibited the highest degree of degradation. The degradation rate in the alkaline medium is 8.27 and 2.05 times higher than in the acidic or ambient medium. Since textile effluent is highly alkaline, this result is significant, as no neutralization of the wastewater is required, and direct treatment is possible. A possible degradation pathway has been established based on Fourier transform infrared spectroscopy (FTIR) and high resolution mass spectroscopy (HRMS) analysis. The phytotoxicity of the treated wastewater has also been evaluated for its suitability for reuse in agriculture. The study reveals that the excimer-222/H2O2 treated wastewater significantly enhanced the germination percentage of Raphanus sativus seed (97%) compared to dye wastewater-grown seeds (75%). This work offers crucial information for future studies on the direct and indirect photolysis of azo dyes, as well as insight into the process of RB5 degradation under Kr/Cl2 excimer radiation.

Degradation of Reactive Black 5 by potassium ferrate(VI)

Degradation of Reactive Black 5 by potassium ferrate(VI)

Efficient Photocatalytic Luminous Textile for Simulated Real Water Purification: Advancing Economical and Compact Reactors.

The growing worldwide problem of wastewater management needs sustainable methods for conserving water supplies while addressing environmental and economic considerations. With the depletion of freshwater supplies, wastewater treatment has become critical. An effective solution is needed to efficiently treat the organic contaminants departing from wastewater treatment plants (WWTPs). Photocatalysis appears to be a viable method for eliminating these recalcitrant micropollutants. This study is focused on the degradation of Reactive Black 5 (RB5), a typical contaminant from textile waste, using a photocatalytic method. Titanium dioxide (TiO2) was deposited on a novel luminous fabric and illuminated using a light-emitting diode (LED). The pollutant degrading efficiency was evaluated for two different light sources: (i) a UV lamp as an external light source and (ii) a cold LED. Interestingly, the LED UV source design showed more promising results after thorough testing at various light levels. In fact, we note a 50% increase in mineralization rate when we triple the number of luminous tissues in the same volume of reactor, which showed a clear improvement with an increase in compactness.

Visible-light photocatalytic degradation of two textile dyes by recyclable ZnO-Perlite: kinetic models and cost analysis

ABSTRACT Zinc oxide (ZnO), as an n-type semiconductor photocatalyst, is often selected due to its excellent photocatalytic performance and is supported on commercial expanded perlite (EP) to enhance interfacial charge separation efficiency under visible LED light. The structure and photocatalytic properties of the synthesised photocatalyst via the co-precipitation route were studied through XRD, FT-IR, SEM, EDX and pHpzc analyses. The photocatalytic response was evaluated by studying the degradation of two toxic and refractory azo dyes, reactive black 5 (RB5) and acid red 14 (AR14). Azo dyes (20 mg L−1) were completely degraded in the studied system, which occurred at pH 7 and 3, with catalyst amounts of 2 and 1 g L−1, and in the presence of H2O2 at 2 and 10 mM under LED light (15 W) within 2 h for RB5 and AR14, respectively. The degradation of RB5 and AR14 followed first-order kinetics with Kobs values of 0.0218 and 0.0169 min−1 and R2 values of 0.9271 and 0.8325, respectively. The assessment of energy consumption (EEO) and total operation cost (OC) confirmed that the supported ZnO offered the lowest power and cost requirements to transform selected pollutants into the acquired effluent, with values of 20.65 and 25.13 kWh m−3 and 3.11 and 3.205 USD kg−1 for RB5 and AR14, respectively, compared to using only VIS/ZnO, VIS/EP and VIS. Furthermore, the catalyst exhibited stability without the need for any additional chemicals for up to 10 h (5 reuse cycles). Additionally, the presence of major anions (sulphate, chloride and alkalinity) reduced the degradation efficiency in a real water matrix (1.74 and 1.47 times for RB5 and AR14, respectively) compared to that in distilled water.

Comparing biofilm reactors inoculated with Shewanella for decolorization of Reactive Black 5 using different carrier materials.

This study assessed the performance of biofilm reactors inoculated with azo dye degrading Shewanella for the decolorization of Reactive Black 5 (RB5), using three different carrier materials, namely almond shell biochar, moving bed biofilm reactor (MBBR), and polypropylene carrier (PPC). The reactors were fed with low-nutrient artificial wastewater containing RB5, and all three carriers showed good RB5 decolorization performance, with varying efficiencies. Liquid Chromatography-Mass Spectrometry analysis revealed distinct RB5 degradation pathways associated with each carrier, influenced by carrier materials and microbial communities. The MBBR carrier exhibited good stability due to its rough surface and microbial aggregates. Sequencing results highlighted differences in the microbial community structures among the carriers. Shewanella predominated the functional bacteria in the MBBR and PPC carriers, while the biochar carrier fostered highly efficient degrading microbial communities. The physicochemical properties of carrier materials significantly influenced the microbial community and RB5 degradation efficiency. These findings provide valuable insights for optimizing biofilm reactors for dye-containing wastewater treatment.

Bioremediation, Biosorption and Biodegradation of the Textile Dye Reactive Black 5 by Life Cultures of Trichoderma asperellum LBKURCC1

Reactive black 5 (RB5) is an azo dye widely used in the textile industry for dyeing fabrics. It is categorized as a recalcitrant dye that is hard to degrade and an environmental pollutant. Therefore, textile waste effluents containing this dye must be treated to remove or degrade the dye, before being released into the environment. One method that can be used to degrade synthetic dyes such as RB5 is to use biological methods, by directly using live fungal cells or using laccase enzymes. Trichoderma asperellum LBKURCC1 is a filamentous fungus isolated from cacao plantation soil in Riau, Indonesia, and it is a laccase enzyme producer. To be able to determine the ability of T. asperellum LBKURCC1 life cultures to decolorize RB5 dye, several RB5 dye removal tests were carried out. Incubation of 50 ppm RB5 with life cultures of T. asperellum LBKURCC1 at room temperature (30°C, pH 6.5) for 24 hours resulted in 22% bioremediation, 3.2% biosorption and 19.1% biodegradation of the RB5 dye. The results of this study show that the live culture of T.asperellum LBKURCC1 is capable of biodegrading RB5. This is indicated by the degradation of RB5 by extracellular enzymes produced by these filamentous fungi.

Anaerobic biodegradation of azo dye reactive black 5 by a novel strain Shewanella sp. SR1: Pathway and mechanisms

The efficiency of microbial populations in degrading refractory pollutants and the impact of adverse environmental factors often presents challenges for the biological treatment of azo dyes. In this study, the genome analysis and azo dye Reactive Black 5 (RB5) degrading capability of a newly isolated strain, Shewanella sp. SR1, were investigated. By analyzing the genome, functional genes involved in dye degradation and mechanisms for adaptation to low-temperature and high-salinity conditions were identified in SR1. The addition of co-substrates, such as glucose and yeast extract, significantly enhanced RB5 decolorization efficiency, reaching up to 87.6%. Notably, SR1 demonstrated remarkable robustness towards a wide range of NaCl concentrations (1–30 g/L) and temperatures (10–30 °C), maintaining efficient decolorization and high biomass concentration. The metabolic pathways of RB5 degradation were deduced based on the metabolites and genes detected in the genome, in which the azo bond was first cleaved by FMN-dependent NADH-azoreductase and NAD(P)H-flavin reductase, followed by deamination, desulfonation, and hydroxylation mediated by various oxidoreductases. Importantly, the degradation metabolites exhibited reduced toxicity, as revealed by toxicity analysis. These findings highlighted the great potential of Shewanella sp. SR1 for bioremediation of wastewaters contaminated with azo dyes.

Alkaline-thermal hydrolysate of waste activated sludge as a co-metabolic substrate enhances biodegradation of refractory dye reactive black 5

Aromatic azo dyes possess inherent resistance and are known to be carcinogenic, posing a significant threat to human and ecosystems. Enhancing the biodegradation of azo dyes usually requires the presence of co-metabolic substrates to optimize the process. In addressing the issue of excessive waste activated sludge (WAS) generation, this study explored the potential of utilizing alkaline-thermal hydrolysate of WAS as a co-metabolic substrate to boost the degradation of reactive black 5 (RB5) dyes. The acclimated microbial consortium, when supplemented with the WAS hydrolysate obtained at a hydrolysis temperature of 30 °C, achieved an impressive RB5 decolorization efficiency of 90.3% (pH = 7, 35 °C) with a corresponding COD removal efficiency of 45.0%. The addition of WAS hydrolysate as a co-substrate conferred the consortium with a remarkable tolerance to high dye concentration (1500 mg/L RB5) and salinity levels (4–5%), surpassing the performance of conventional co-metabolic sugars in RB5 degradation. 3D-EEM analysis revealed that protein-like substances rich in tyrosine and tryptophan, present in the WAS hydrolysate, played a crucial role in promoting RB5 biodegradation. Furthermore, the microbial consortium community exhibited an enrichment of dye-degrading species, including Acidovorax, Bordetella, Kerstersia, and Brevundimonas, which dominated the community. Notably, functional genes associated with dye degradation and intermediates were also enriched during the RB5 decolorization and biodegradation process. These findings present a practical strategy for the simultaneous treatment of dye-containing wastewater and recycling of WAS.

Decolorization of reactive azo dye using novel halotolerant yeast consortium HYC and proposed degradation pathway

The presence of high salinity levels in textile wastewater poses a significant obstacle to the process of decolorizing azo dyes. The present study involved the construction of a yeast consortium HYC, which is halotolerant and was recently isolated from wood-feeding termites. The consortium HYC was mainly comprised of Sterigmatomyces halophilus SSA-1575 and Meyerozyma guilliermondii SSA-1547. The developed consortium demonstrated a decolourization efficiency of 96.1% when exposed to a concentration of 50 mg/l of Reactive Black 5 (RB5). The HYC consortium significantly decolorized RB5 up to concentrations of 400 mg/l and in the presence of NaCl up to 50 g/l. The effects of physicochemical factors and the degradation pathway were systematically investigated. The optimal pH, salinity, temperature, and initial dye concentration were 7.0, 3%, 35 °C and 50 mg/l, respectively. The co-carbon source was found to be essential, and the addition of glucose resulted in a 93% decolorization of 50 mg/l RB5. The enzymatic activity of various oxido-reductases was assessed, revealing that NADH-DCIP reductase and azo reductase exhibited greater activity in comparison to other enzymes. UV-Visible (UV–vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC-MS) were utilized to identify the metabolites generated during the degradation of RB5. Subsequently, a metabolic pathway was proposed. The confirmation of degradation was established through alterations in the functional groups and modifications in molecular weight. The findings indicate that this halotolerant yeast consortium exhibits promising potential of degrading dye compounds. The results of this study offer significant theoretical basis and crucial perspectives for the implementation of halotolerant yeast consortia in the bioremediation of textile and hypersaline wastewater. This approach is particularly noteworthy as it does not produce aromatic amines.

Degradation of Reactive Black 5 Dye (RB5) using Iron Electrode (Fe.S) Derived from Iron Sludge Steel Waste via Electrochemical Method

A study has been performed on the degradation of Reactive Black 5 (RB5) as pollutant using iron electrode (Fe.S) derived from iron sludge steel waste via electrochemical method. The Fe.S and titanium graphite electrodes were applied as anode and cathode respectively during the studied. The studied operating parameters were the effect of current density, initial pH, initial concentration, and the reusability of the Fe.S electrode. The experiment was carried out for 120 minutes of electrolysis time. From results revealed that Fe.S could be used three times with complete degradation of RB5 from initial concentration of 50 ppm. A complete RB5 colour removal can be achieved in any pH range (3,6, and 9). The current density at 4 mA/cm2 showed a faster RB5 degradation compared to at 2, 6,8, and 10 mA/cm2.

Synthesis of copper‐oxide nanoparticles from Euphorbia antiquorum extract and evaluation of its dye degradation capacity

AbstractDye discharge from industrial textile effluent is hazardous to the environment. Hence, the removal of dye has become important as it affects both human and aquatic life, even if it is present in minimal amounts. In comparison to the physio‐chemical technique, photocatalytic degradation of the dye using nanoparticles that are generated biologically provides a feasible method for the breakdown of environmental pollutants. Unlike other metal oxides, Copper oxide nanoparticles (CuONPs) have attracted the attention of many researchers due to their potential to act as photocatalyst and also because of their enormous surface area. Euphorbia antiquorum (triangular spurge) is a common thorny succulent found all over peninsular India, primarily in dry areas. The aqueous extract of the selected plant was employed to synthesis CuONPs, which were then analyzed using SEM‐EDX, FTIR, XPS, and XRD. The present study describes how CuONPs derived from the extract of E. antiquorum degrade major commercial dyes such as Congo Red (CR), Coomassie Brilliant Blue (CBB R‐250 dye, and Reactive Black (RB). The photocatalytic degradation efficiency of synthesized CuONPs has been demonstrated for a wide range of dyes used in the textile industry. Dye degradation of RB using synthesized CuONPs showed 93% efficiency.

Removal of Reactive Black 5 Azo Dye from Aqueous Solutions by a Combination of Reduction and Natural Adsorbents Processes

In this study, a combined process of reduction and adsorption for the degradation of azo dye with nanocrystalline Fe80Si10B10 powder as a reducing agent is analyzed. A mechanical alloying technique produced the powdered alloys needed for the redox process. The synthesized nanocrystalline structure favors the efficiency of the reduction step of Reactive Black 5 (RB5) azo dye. According to the UV-Vis analysis, the reductive process alone allowed for nearly complete color removal after 3 min of reaction. In this regard, the nanocrystallized FeSiB powder has excellent application potential in the first step of the reduction processes for degrading azo dye solutions. Indeed, the nanocrystalline FeSiB powder outperforms commercial Fe powders in terms of degradation efficiency because of the formation of multiple micro-batteries between the α-Fe solid solution and the Fe3Si nanocrystalline phases, favoring the loss of electrons from iron and exhibiting different corrosion resistance. In the second step, the adsorption process, the efficient removal of intermediate undesired compounds from the reduction processes, principally aromatic amines, is analyzed. Different adsorbents, including wood, graphene oxide, activated carbon, and pine particles, were used. The results suggest that graphene oxide and activate carbon performed the best for secondary product adsorption following RB5 degradation. The current study could serve as a guide for environmental applications, such as industrial wastewater treatment, using metallic powders produced by high-energy mechanical alloying.

Synthesis of MMT−CuFe2O4 Composite as a Peroxymonosulfate Activator for the Degradation of Reactive Black 5

AbstractCopper ferrite nanoparticles loaded on montmorillonite (MMT−CuFe2O4) were prepared by co‐precipitation method and applied as catalyst for activation of peroxymonosulfate (PMS) in degradation of reactive black 5 (RB5). The maximum removal efficiency of RB5 completely depends on the operating parameters and the highest removal percentage was obtained at MMT−CuFe2O4 dosage of 250 mg/L, PMS concentration of 4 mM, initial RB5 concentration of 50 mg/L and time of 15 min. The presence of anions such as Cl−, NO3−, HCO3−, and SO42− showed a significant limitation in the degradation of RB5 in the MMT−CuFe2O4/PMS system. Trapping experiments showed that ⋅OH and SO4⋅− radicals were involved in the catalytic degradation of RB5, however ⋅OH is the major specie in the catalysis system. Consecutive cycles were considered for testing the reusability of MMT−CuFe2O4; its results showed the stability of five consecutive cycles. The toxicity test was evaluated using Daphnia magna and the results illustrated a substantial drop in the toxicity of the solution treated. The significant reduction of TOC during RB5 degradation and the production of SO42−, NH4+ and NO3− confirm the proper progress of pollutant mineralization. The high catalytic performance of the catalyst in a short time compared to other removal systems emphasizes that MMT−CuFe2O4 can be suggested as a promising catalyst for the degradation of RB5 from aqueous solutions.

Comparative Photocatalytic Activity and Total Organic Carbon Removal Efficiency of TiO2 And ZnO for Reactive Black 5 Photodegradation

AbstractThe photocatalytic performance of TiO2 and ZnO was comparatively studied for photocatalytic degradation of reactive black 5 (RB5) under artificial UVC irradiation. The effect of initial solution pH, catalyst concentration, initial RB5 concentration, purging oxygen rate, stirring rate, and process temperature on the degradation process by TiO2 and ZnO was investigated. In addition, total organic carbon (TOC) analysis has been employed for each parameter to detect the presence of organic intermediates and the photodegradation performance of catalysts simultaneously with the photocatalytic degradation process. The RB5 photodegradation was more rapid in the aqueous medium by TiO2 under UVC irradiation compared to the catalysis by ZnO. On the other hand, the slower photocatalysis by ZnO resulted in generating more organic intermediates. The structural and morphological analyses of photocatalysts TiO2 and ZnO were performed using XRD and FE‐SEM techniques. The UV‐vis spectroscopy measurements supported that the TiO2 demonstrated evidently better photocatalytic activity than ZnO for RB5 degradation.

Degradation of Reactive Black 5 by ultrasound-activated persulfate process: kinetics, mineralization, and by-products

Degradation of Reactive Black 5 by ultrasound-activated persulfate process: kinetics, mineralization, and by-products

Green route synthesis and characterization of β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 using Juglans regia L. shell aqueous extract and photocatalytic properties for the degradation of RB-5

BackgroundPhotocatalyst oxides added with silicon improve their photocatalytic properties. In this research, nanostructured β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 were obtained by means of a green method mediated by the using the aqueous extract of J. regia shell as the source of reducing biomolecules and as a natural source of plant silicon.MethodThe β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 nanostructures were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and photoluminescence spectroscopy. The photocatalytic activity was measured by the degradation of Reactive Black 5 dye (RB-5).ResultsFT-IR and XPS demonstrated the presence of plant silicon in the bismuth oxide photocatalysts. HR-TEM showed that the crystal size of the as-synthesized materials is ~ 25 nm and revealed that the β-Bi2O3 synthesized with ground shell extract and heat-treated at 300 °C contains the Bi2O2.75 phase. Good photocatalytic activity was found in all the studied materials; particularly, the heat-treated nanostructures showed excellent properties resulting in 92% degradation of RB-5 under UV–Vis light after 15 min of exposure, and 98% after 180 min.ConclusionsThe findings of this research suggest that the metabolites coating the Bi2O3, which generate a large amount of hydroxyl radicals, the plant silicon content, and the crystalline defects conferred by the synthesis medium, all contribute to the improved degradation of the azo dye, providing the nanostructures with better photocatalytic activity.