Acid Black Research Articles

Enhanced removal of acidic dyes (AB1 and MO) from binary systems using anion exchange membrane BII: kinetic, isotherm, and thermodynamic analyses.

In the current work, the adsorption of acid black 1 (AB1), a hair dye, and methyl orange (MO) on anion exchange membrane BII (AEM-BII) in a binary system was studied experimentally. The effects study for contact time, adsorbent's and adsorbates' concentration, and temperature of aqueous media on the AB1 and MO removal, AEM-BII recovery, and reusability were also investigated. The highest removal was observed at optimum conditions, 150-min contact time and 5g L-1 of adsorbent for AB1 (91.2%) and MO (83.4%). Adsorption kinetics was estimated by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetics. The experimental findings were fitted well by PSO kinetics with an adsorption capacity of 19.45 ± 0.93 and 19.34 ± 0.84mgg-1 for ABI and MO, respectively. Moreover, the adsorption isotherm study confirmed that AB1 and MO adsorption by AEM-BII from the binary system was followed by Langmuir isotherms. Adsorption thermodynamics revealed that adsorption of both AB1 and MO by AEM-BII was endothermic and spontaneous. Moreover, the desorption phenomenon of ABI and MO from the loaded AEM-BII showed that dye removal from AEM-BII was found to be 74.95%, demonstrating AEM-BII can be considered as good adsorbent for acidic dyes from the binary system.

Enhanced visible light photocatalytic and electrochemical performance of Au modified zinc oxide nanocolumns

Research on the treatment of Acid Black 1 as an azo dye is significant because it is toxic and can have adverse effects on both human health and the ecosystem if not properly treated. The purpose of the research was the preparation and application of Au-ZnO nanocolumn (Au-ZnO NCs) photocatalysts to treat the azo dye Acid Black 1 (AB1) in industrial wastewater when it was exposed to light. The structural, electrochemical, and optical properties of prepared photocatalysts were analyzed. Results of structural analyses using SEM and XRD indicated that the surfaces of the ZnO NCs were successfully coated with Au nanoparticles to produce a large effective surface area. Results of electrochemical experiments showed that depositing conductive Au nanoparticles on the surface of ZnO nanocrystals significantly increased the charge transfer rate, implied a longer lifetime for photo-generated electrons, and increased the separation efficiency of Au-ZnO NCs. Results of optical studies showed that the band gap energies of ZnO NCs and Au-ZnO NCs could be measured to be 3.19 eV and 2.96 eV, respectively, which demonstrated that Au nanoparticles narrowed the band gap energy and caused the absorption to extend to the visible range. Results of studies on photocatalytic degradation showed that Au-ZnO NCs, as opposed to ZnO NCs, removed AB1 photocatalytically more quickly. After 20, 30, 45, 50, and 100 min of visible-light illumination, respectively, the total degradation of AB1 was 10, 25, 100, 125, and 300 mg/L. The Au-ZnO NCs' ability to treat 200 ml of a 100 mg/L AB1 solution using a real industrial wastewater sample and deionized water was studied. The results showed that because there are more pollutants in industrial wastewater, the total treatment of the real sample required more time. The results thus showed that AB1 from actual industrial wastewater was successfully photocatalytically treated in an Au-ZnO NCs photocatalyst.

A bottom-up approach to select microbes from textile wastewater for detoxification of aromatic amine and azo dye in a single stage

Biological processes show great promise for treating textile wastewater, but the complexity and high energy needs limit their industrial applications. Complete dye degradation involves physiologically distinct bacteria in a two-stage process. First, anaerobic bacteria cleave azo dyes into hazardous aromatic amines, whereas its further degradation requires aerobic bacteria. We propose strategic microbial selection based on their physiological capabilities while developing a bioremediation design to detoxify aromatic amines and dyes in a single stage. Bacillus firmus PM1, the amine degrader, and Serratia liquefaciens PM2, the helper strain, were isolated from textile wastewater. B. firmus PM1 completely degraded 4-Nitroaniline (4-NA), a common dye intermediate, under a range of physicochemical conditions prevalent in textile effluent viz. varying pH (7–11), oxygen availability (static/shaking), temperature (30–40 °C), and 4-NA concentrations (200–1000 μM). Along with 4-NA degradation (100 %), B. firmus PM1 could also efficiently degrade co-contaminants, aniline (35 %), and phenols (45 %). UPLC, FTIR, and LC-MS analysis suggested that when B. firmus PM1 is used in co-culture with S. liquefaciens PM2, it efficiently mineralizes 4-NA (95 %) and reduces Acid Black 1 (AB1) (80 %) dye both in synthetic and the real textile effluent. Further, the co-culture could also significantly reduce 4-NA and AB1 mixture induced phytotoxicity/cytogenotoxicty in Vigna mungo and Allium cepa. Thus, the study demonstrates a novel bottom-up approach that relies on isolating bacteria degrading the penultimate toxic dye metabolite and developing a co-culture for degrading the parent dye. The study demonstrates that detoxification-centric use of specialized microbes has potential to evolve sustainable industrial practices.

Rapid microwave fabrication of new nanocomposites based on Tb-Co-O nanostructures and their application as photocatalysts under UV/Visible light for removal of organic pollutants in water

Herein, a novel and stable Tb-Co-O nanocomposite photocatalyst is fabricated through a one-pot microwave route for 2 min (600 W, 20 s On, 60 s Off), which is introduced as UV/Visible light active catalysts in wastewater treatment. Employing various combined parameters of Tb:Co ratio, pH adjustment agents, chemical and natural templates, the resulting nanostructures displayed the intrinsic structure nature, narrow size distribution, good optical properties, and excellent photocatalytic efficiency. The formation of Tb-Co-O nanostructures and their features were verified via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and ultraviolet–visible diffuse reflection spectroscopy (DRS) technologies. Detailed physic-chemical measurements exhibited that all as-prepared nano-photocatalysts possesses both cubic (TbO1.81) and orthorhombic (TbCoO3) crystal structures. Furthermore, optical characterization by DRS developed light-sensitive channelization with band-gap energies at approximately 2.95 and 3.20 eV for Tb-Co-O nanocomposites. Finally, the photocatalytic studies of the resulting nanocomposites were compared by determining the elimination of Erythrosine (EY), Acid Violet 7 (AV7), and Acid Black 1(AB1) under UV and Visble light illumination. As a results, the TbCoO3/TbO1.81 nanocomposties with molar ratio of 1:3 (Tb:Co), valerian distillate as natural directing agent and ethylenediamine (en) as alkaline template yielded the optimum degradation percentage of 88 % for EY dye under the reaction condition of 10 ppm dye concentration in the presence UV light toward other pathways. Also, we proposed a mechanistic insight of photodegradation based on the radical scavengers, which revealed that h+ did the important role, and OH• and •O2− represented an irrelevant role in the degradation of EY. The current study offer an effective way for development of a high-efficiency Tb-Co-O photocatalyst in eliminating dyes from contaminant water.

Stability of Acid Black 210 dye in Tannery Industry Effluent in Aqueous Solution Is Limited and Generates Harmful Subproducts

The present work investigates the occurrence of the Acid Black 210 (AB210) dye and its subproducts in the tannery industry by analytical techniques. The AB210 is an important dye characterized by three azo groups as a chromophore and is one of the most used azo dyes in the tannery industry. The stability of AB210 in front of chlorination, sunlight exposition, and ambient conditions was investigated, as well as its occurrence and degradation products in the tannery wastewater. The stability study of AB210 showed a decrease in dye concentration of up to 45% after 14 days at room temperature. The exposure of the AB 210 by a solar simulator for 3 h showed discoloration of the dye. Furthermore, the chlorination of the AB210 caused a reduction of 25% in the intensity of the absorption band at the visible region after 300 s of treatment with sodium hypochlorite (NaClO). Studies based on high-performance liquid chromatography (HPLC-DAD), liquid chromatography-mass spectrometry (LC-MS/MS), and nuclear magnetic resonance (NMR) have indicated the occurrence of several harmful compounds such as benzene, cresol, naphthalene, phenol, 2-naphthylamine, and phenylacetic acid, and three aromatic amines, 2-naphthylamine, 2,6-dimethylaniline and 4-nitroaniline from the tannery industry. The cytotoxicity assay showed toxicity for the samples stored for a long period. Thus, the immortalized human keratinocyte (HaCAT) and 3T3 cells assays for the AB210 stored for 14 days showed 70% cell death in both strains evaluated. Our results demonstrated that the AB210 degradation is a great environmental concern due to increased toxicity for the body of living beings, especially for humans, as their biotransformation produces harmful compounds such as amines, which have been widely condemned by the International Agency for Research on Cancer.

Synergistic adsorption and photocatalytic degradation of persist synthetic dyes by capsule-like porphyrin-based MOFs

The synergistic effects involving surface adsorption and photocatalytic degradation commonly play significant roles in the removal of persistent synthetic organics from wastewater in the case of porous semiconductors. Inspired by the visible-light harvesting advantages of porphyrin-based MOFs, a capsule-like bimetallic porphyrin-based MOF (PCN-222(Ni/Hf)) has been successfully constructed through a facile hydrothermal method. In which, the Hf (IV) ions were exactly bonded to the carboxyl groups substituted on the porphyrin rings, meanwhile the Ni (II) ions were finely bonded to the −N inside the porphyrin rings. The adsorption/photocatalytic performances were assessed by using four persistent dyes including rhodamine B (RhB), basic violet 14 (BV14), crystal violet, and acid black 210 (AB210) as the target substances, and enhanced total removal efficiency was obtained by the bimetallic PCN-222(Ni/Hf) in comparison with that of single PCN-222(Hf). The electrochemical analyses and the sacrificial agent capture experiments were carried out to elucidate the photocatalytic mechanism, and the adsorption/photocatalytic stability of PCN-222(Ni/Hf) is also investigated. The work has broadened the applications of porphyrin-based MOFs in the removal of organics by combining their excellent surface adsorption capacity and photocatalytic activities.

Optimization of MCM-41 Mesoporous Material Mixed Matrix Polyethersulfone Membrane for Dye Removal.

The aim of this work is the optimization of the operating conditions under which MCM-41-mesoporous material can be incorporated into polyethersulfone (PES)/MCM-41 membranes for nanofiltration (NF) applications. MCM-41 mesoporous material mixed matrix PES membranes have the potential to reduce membrane fouling by organic dye molecules. Process optimization and modeling aim to reduce wasted energy while maintaining high flow during the operation to handle the energy efficiency problems membranes often have. An optimization technique was applied to obtain optimum values for some key parameters in the process to produce a certain amount of flux above the desired values. Response surface methodology (RSM) and analysis of variance (ANOVA) were used as mathematical and statistical analyses to improve the performance of the process on a larger scale. This work investigated the influence of the operating parameters, such as the feed pH values (3–11), MCM-41 content (0–1 wt.%), and the feed dye concentration (10–100 ppm) for each of the two studied dyes, acid black 210 (AB-210) and rose bengal (RB), and their interactions on the PES membrane permeability. The results showed that the PES membrane had the best performance at 64.25 (L·m−2·h−1·bar-1) and 63.16 (L·m−2·h−1·bar-1) for the AB-210 and RB dyes, respectively. An MCM-41 content of nearly 0.8 wt.% in the casting solution, feed dye concentration of 10 ppm for the studied dyes, and feed pH of 3 for the RB dye was found to be the optimal parameters for eliciting the response. The pH had no significant influence on the response for the AB-210 dye, while the pH shows some minor effects on response with the RB dye, and the Pareto chart of the standardized effects on the permeation flux of both dyes using statistically significant at the 5% significance level support these results.

"MALDI-CSI": A proposed method for the tandem detection of human blood and DNA typing from enhanced fingermarks

Matrix Assisted Laser Desorption Ionization Mass Spectrometry Profiling and Imaging (MALDI MSP and MALDI MSI), in combination with bottom up proteomics, have proven to successfully detect and map blood-derived peptide signatures in blood fingermarks, with high specificity and compatibility with a number of blood enhancement techniques (BET). In the present study, the application of MALDI MSP and MSI to blood marks has been investigated further. In particular, the MALDI based detection and visualisation of blood has been explored in tandem with DNA typing. This investigation has been undertaken in a scenario simulating blood fingermarks on painted walls. In the present study, two sets of marks were analysed with each set comprising of a depletion series of four marks deposited on a surface treated to simulate painted walls: Set I - developed with Ninhydrin (NIN) and Set II- developed with Acid Black-1 (AB-1). For both sets, the application of MALDI MSP was successful in detecting haem and human specific haemoglobin peptide markers. MALDI MSI also provided molecular images by visualising haem on the ridge pattern enhanced by BET. The feasibility of successful and subsequent DNA profiling from the recovered fingermarks was also assessed for marks that had undergone enzymatic in situ digestion and MALDI MSI; it was observed that in 73% of the samples analysed, a DNA profile suitable for comparison was obtained. Based on these results, a possible operational workflow has been proposed incorporating the use of a MALDI MS based approach as a confirmatory test for human blood enabling subsequent DNA typing.

Synthesis and characterization of Graphene Oxide-Ammonium Ferric Sulfate composite for the removal of dyes from tannery wastewater

The leather processing industry is currently facing numerous environmental pollution challenges. Dyes are known as one of the most significant causes for water pollution. Thus, the present work is designed to tackle this issue via preparation of different composite comprising both graphene oxide and ammonium ferric sulfate, donated as GO-AFS. Results obtained via FTIR, TGA, XRD and SEM tools confirmed the facile preparation of GO-AFS composite having good thermal stability and exhibited rough and porous surface with no clear edges. The adsorption efficiency of the as-prepared GO-AFS composite was successfully examined against two commercial dyes, namely anionic dye Basic Black 7 (BB7) and cationic dye Acid Black 210 (AB210) together with specific tannery dye wastewater. The findings also ascertained that the color removal for BB7 was noticed to be mostly 100% within 2 min by GO-AFS adsorbent at 10 mg (0.1 g/L), while the color removal concentration at pH~7 was up to 700 ppm. In addition, the color removal performance of AB210 was also detected at approximately 100% by 12 mg (0.12 g/L) of GO-AFS within 3 min when the dye concentration at pH~4 was up to 400 ppm. Regarding the removal of real tannery dye from wastewater, it was also observed that the efficacy of GO-AFS as adsorbent reached 100%. Within the second cycle, the adsorption potential of recycled GO-AFS was restored by nearly 100% and this percentage decreased to 95.4% in the third cycle. In view of these findings, it can be concluded that the prepared GO-AFS composite can be considered as an excellent candidate for eradication of pollutants or contamination from tannery wastewater instead of the conventional high-cost adsorbents.

Chemical and Plant Mediated Synthesis of La2O3 Nanoparticles and Comparison of their Structural, Antibacterial, Photocatalytic and Optical Properties

The La2O3 nanoparticles have been synthesized successfully with a chemical and biosynthesized method. The optical bandgap energy and of chemically synthesized or biosynthesized (M. oppositifolia and T. portlacaustrum leaf extract) La2O3 nanoparticles was calculated from UV-visible absorption between 5.10, 4.26 and 4.46 eV. The good polycrystalline cubic nature of synthesized La2O3 nanoparticles was evident from the bright circular SAED pattern, consistent with the XRD outcome. It is clear that the non-polar extracts could function as stabilizers for La2O3 nanoparticles through attachment to the counterions. The La2O3 nanoparticles have been used as efficient photocatalyst to degrade acid black 1 dye under sunlight irradiation. Besides, this biocatalyst showed excellent ability to degrade biosynthesized La2O3 nanoparticles (T. portlacaustrum) under visible light irradiation 87%. Synthesis of La2O3 nanoparticles by green chemistry process presented good antibacterial activity against Gram-negative and Gram-positive bacteria.

Removal of acid black 1 by Acacia Concinna; adsorption kinetics, isotherm and thermodynamic study

In the present research, batch adsorption of anionic dye such as Acid Black 1 (AB1) in aqueous solution onto biosorbent Acacia concinna was investigated at room temperature. The effect of various physico-chemical parameters such as contact time, adsorbent dosage, initial dye concentration and temperature on the percentage removal of dye were investigated. Adsorption kinetics was investigated using linear and nonlinear form of pseudo first-order and pseudo-second-order kinetic models but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna was fitted well to pseudo-second order model with maximum value of regression coefficient (0.9995). Linear and nonlinear forms of Langmuir, Freundlich, Tempkin, and Dubinin– Radushkevich (D–R) were used to reveal experimental data but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna fitted well to the Langmuir isotherm model with adsorption capacity 3.21✕10-4 Adsorption thermodynamic study showed that adsorption of AB1 dye onto adsorbent Acacia concinna was endothermic and spontaneous process. This study revealed that biosorbent Acacia concinna was good biosorbent for removal of dyes from aqueous solution.

Removal of acid black 1 by Acacia Concinna; adsorption kinetics, isotherm and thermodynamic study

In the present research, batch adsorption of anionic dye such as Acid Black 1 (AB1) in aqueous solution onto biosorbent Acacia concinna was investigated at room temperature. The effect of various physico-chemical parameters such as contact time, adsorbent dosage, initial dye concentration and temperature on the percentage removal of dye were investigated. Adsorption kinetics was investigated using linear and nonlinear form of pseudo first-order and pseudo-second-order kinetic models but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna was fitted well to pseudo-second order model with maximum value of regression coefficient (0.9995). Linear and nonlinear forms of Langmuir, Freundlich, Tempkin, and Dubinin– Radushkevich (D–R) were used to reveal experimental data but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna fitted well to the Langmuir isotherm model with adsorption capacity 3.21✕10-4 Adsorption thermodynamic study showed that adsorption of AB1 dye onto adsorbent Acacia concinna was endothermic and spontaneous process. This study revealed that biosorbent Acacia concinna was good biosorbent for removal of dyes from aqueous solution.

Synergistic photocatalytic performance of chemically modified amino phthalocyanine-GPTMS/TiO2 for the degradation of Acid Black 1

A novel functional material, Zinc (II) tetra-[α-(p-amino)benzyloxyl]phthalocyanine (ZnPc) upon covalent integration with glycidoxypropyltrimethoxy silane modified TiO2 (GPTMS/TiO2) is prepared here for the first time in order to improve the visible photocatalytic activity of TiO2. The photocatalytic property of obtained ZnPc-GPTMS/TiO2 hybrid was investigated by carrying out the photodegradation of di-anionic azo dye Acid Black 1 (AB1) in aqueous solution under visible light irradiation. The results revealed that the ZnPc-GPTMS/TiO2 hybrid photocatalyst greatly enhanced the photodegradation efficiency compared to that of the pure TiO2. Particularly, 0.2 wt% ZnPc-GPTMS/TiO2 photocatalyst showed the highest photocatalytic activity with a degradation ratio of 95.4% of AB 1 after 120 min irradiation. The synergistic effect between ZnPc and TiO2 was responsible for the enhanced photocatalytic activity of the ZnPc-GPTMS/TiO2 hybrid, due to the efficient charge separation with electron injection from ZnPc to TiO2. The photocatalytic mechanism was proposed preliminarily.

Adsorption of Acid Black 210 and Remazol Brilliant Blue R onto magnetite nanoparticles

Adsorption behavior of Acid Black 210 (AB210) and Remazol Brilliant Blue R (RBBR) from aqueous solutions onto magnetite nanoparticles (MNPs) was studied. Affecting parameters such as solution pH, contact time, adsorbent amount, and initial concentration of the dyes on the adsorption process were studied. Analysis of the kinetic data indicated that the adsorption process follows pseudo-second-order kinetics. The adsorption equilibrium data were analyzed by Langmuir and Freundlich isotherm models. The adsorption capacities for AB210 and RBBR were 70.80 and 74.40 mg g−1, respectively. This study suggested MNPs as effective and reusable adsorbent to remove the dyes from aquatic solutions.

Ultra-morphology of the scale as an indicator of the stress of Acid Black-1 (AB-1, CI: 20470) and zinc (Zn).

High contents of azo dyes and heavy metals enter surface waters with the wastewater from dying and dye-manufacturing industries and pose serious threat to fish. In the present study, changes in the ultra-morphological features of the scale have been evaluated as indicators of the stress of lethal and sublethal concentrations of an azo dye Acid Black-1 (AB-1, CI 20470), zinc (Zn), and their mixture AB-1 + Zn to Labeo rohita. Fish were exposed for 96h to lethal concentration (LC) causing 0-70% mortality, i.e., LC0, LC20, LC50, and LC70 of AB-1 (4, 6, 8, and 10mg/L respectively) and Zn (25, 50, 55, and 60mg/L respectively) and LC0, LC50, and LC70 of AB-1 + Zn (2 + 15, 2 + 20, and 2 + 25mg/L respectively). Subchronic exposures of 150days were given to 1/12, 1/6, and 1/3 of 96h LC50 values of AB-1, Zn, and AB-1 + Zn. After each exposure, the fish were kept for a recovery period of 90days. Breakage of circuli, erosion and breakage of lepidonts, uprooting of tubercles, and disappearance of intercircular teeth were observed in all the fish, after 96h exposure to AB-1, Zn, and AB-1 + Zn. However, damage to focus and holes were common on the scales of Zn-exposed fish. The mixture AB-1 + Zn was more toxic than either of the two as loss of circuli, lepidonts, and intercircular teeth, and sloughing of surface were observed in the scales after 96h exposure to 2 + 25mg/L. Damage at this concentration was more than the damage at 8/10mg/L AB-1 and 55/60mg/L Zn. After 150days of exposure, damage due to sublethal concentrations was more than the damage due to allthe concentrations of 96h exposure. Irregular and sloughed circuli were common at 2 + 1.79 and 2 + 3.59mg/L AB-1 + Zn. Cracks all over the surface (2 + 7.18mg/L), calcium projections (2 + 3.59 and 2 + 7.18mg/L), and holes (2 + 7.18mg/L) hint towards synergistic toxicity of the mixture. It seems that the present dye and metal formed complexes with collagen and osteoblastic cells of the scale that caused an increase in damage during the post-exposure period. Scales of 2 + 7.18mg/L AB-1 + Zn exposed fish were completely devoid of the normal architectural pattern on the 90th day of the recovery period. Changes in the ultra-morphology of scales at LC0 (0% mortality) and sublethal concentrations show that these are early indicators of the stress of minute quantities of dyes and metals in water. This is a first report on the cumulative toxicity of the two most abundant components of textile industry effluents.

Simple microwave synthesis of TiO2/NiS2 nanocomposite and TiO2/NiS2/Cu nanocomposite as an efficient visible driven photocatalyst

Abstract Approximately 47% of solar-terrestrial radiation is visible. It is a great achievement to produce a highly efficient visible driven photocatalyst. Here TiO2/NiS2/Cu nanocomposite was prepared as a highly active visible driven photocatalyst. TiO2/NiS2/Cu nanocomposite was prepared by microwave method. It degrades 92%, 86%, 87%, and 88% of Rhodamine B (RhB), Methyl orange (MO), Acid Black 1 (AB1), and Acid Brown 214 (AB214), respectively. Adding NiS2 and Cu to TiO2 dramatically increased the degradation efficiency from 17% for bare TiO2 to 92% for TiO2/NiS2/Cu nanocomposite under visible light. As-prepared TiO2/NiS2/Cu nanocomposite was characterized by SEM, TEM, XRD, DRS, BET, and EDX.

Adsorption of anionic dye onto magnetic Fe3O4/CeO2 nanocomposite: Equilibrium, kinetics, and thermodynamics

In this study, a magnetically separable Fe3O4/CeO2 (Fe/Ce) nanocomposite is synthesized by sol-precipitation method and characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive spectrometer , vibrating sample magnetometer, atomic absorption spectrometer, and zeta potential measurements. The Fe/Ce is used as sorbent to adsorb anionic dye of Acid Black 210 (AB210) from aqueous solutions, and the maximum adsorption capacity is about 90.50 mg/g, which is six times higher than that of the commercial CeO2. Dependence of absorption performance on essential factors, such as initial dye concentration, temperature and initial pH, are experimentally examined. The result shows that the adsorption kinetic of Fe/Ce follows pseudo-second-order model and the adsorption isotherm is well described by the Langmuir adsorption model. Furthermore, the thermodynamic analysis indicates that the adsorption of Fe/Ce for AB210 is spontaneous and endothermic.

Synthesis and application of Fe-N-Cr-TiO2 nanocatalyst for photocatalytic degradation of Acid Black 1 under LED light irradiation

Azo dyes are a large group of dye compounds and their removal and treatment is very important because of their high stability and high carcinogenicity. The purpose of this study was to determine the photocatalytic efficiency of titanium dioxide nanoparticles doped with iron, chromium and nitrogen immobilized on a glass bed in the presence of visible light to remove organic dye from the aqueous solution. LED lamp with a power of 20 watts was used as a visible source. SEM, EDX, XRD, AFM, FTIR, DLS and Zeta-potential analyzes were performed to characterize the fabricated nanoparticle. The operating parameters of the dopant type, solution pH, nanoparticle dosage, initial dye concentration, light intensity, and contact time between the photocatalysts and the dye solution were studied. The results showed that the removal of dyes in acidic pH was higher than that in neutral and alkaline pH. Dye removal efficiency was increased as the nanoparticle amount, light intensity and contact time increased. It was increased from 39 to 98% as the nanoparticle amount increased from 0.5 to 10 mg/cm2. Moreover, the removal efficiency at 358 and 950 lx was 11 and 74.5%, respectively. When dye concentration was increased from 50 to 200 mg/l, the removal efficiency was decreased from 72 to 10.8%. The photocatalytic process in the presence of the visible light using a Fe-Cr-N-TiO2 nanoparticle immobilized on the glass bed has the potential to remove the Acid Black1 dye from the aqueous medium.

Heterogeneous catalytic degradation of organic compounds using nanoscale zero-valent iron supported on kaolinite: Mechanism, kinetic and feasibility studies

Abstract Herein, nano zero-valent iron (NZVI) particles were anchored on kaolinite (K) for preparation of a mesoporous heterogeneous catalyst (marked as NZVI@K) in Fenton-like oxidation of Acid Black 1 (AB1) dye. The properties of morphological, physico-chemical and textural of catalyst were characterized using powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectrometer (EDS) techniques. Results indicated that NZVI particles with 40–80 nm diameter were incorporated successfully on K surface and iron was predominantly in Feo form. Prior oxidation experiments, adsorption studies were performed to determine the equilibrium point and also modeling (kinetic and isotherm) of the process. Fenton-like oxidation showed a better performance in decolorization of AB1, compared to adsorption process. The excellent reusability and high stability were found for NZVI@K during four consecutive use cycles. Under optimum operational conditions (pH: 2.0, catalyst dose: 0.3 g/L, H2O2 amount: 4.0 Mm), over 98% of dye (30 mg/L) and 76% of TOC were removed within 120 min reaction. A tentative mechanism was proposed for decomposition of H2O2 and production of reactive oxidizing species, based on the results of quenching tests. Decreasing decolorization rate in the presence of anions obeys the order of bicarbonate > chloride > nitrate > sulfate. A significant synergistic effect was detected when NZVI@K were coupled with H2O2. Reducing removal efficiency and the scavenging effect were observed at excessive concentrations of both catalyst and oxidant. Integration of adsorption and oxidation processes using NZVI@K coupled with H2O2 can be introduced as a promising technique for efficient decolorization of wastewaters, due to high adsorption capacity, good catalytic activity and minimal iron leaching.

Molecular mechanism of anionic dyes adsorption on cationized rice husk cellulose from agricultural wastes

Cationized rice husk cellulose (CRHC) were designed and synthesized by introducing hydroxypropyloctadecyldimethylammonium group onto rice husk cellulose (RHC) molecular structure. Structure and morphology of samples were characterized by FTIR, XRD and SEM. The characterization results showed that the molecular structure and morphology of RHC have changed and the quaternary ammonium group was successfully grafted onto the RHC molecular structure. Adsorption studies were conducted to evaluate the adsorption performance and related mechanism of Diamine Green B (DG-B), Acid Black 24 (AB-24) and Congo Red (CR) onto CRHC. The adsorption process was well described by Pseudo-second-order and Langmuir models. The Langmuir maximum adsorption capacity of DG-B, AB-24 and CR on the CRHC was found to be 207.15, 268.88 and 580.09 mg g−1 at 303.15 K, respectively. The possible adsorption mechanism might be due to the combination of molecular structure characteristics of adsorbents and adsorbates, electrostatic attraction, hydrogen bonding, and the competition of OH– ions. CRHC has a good reusability and high adsorption performance for dye removal. The thermodynamic parameters indicated the adsorption process is a spontaneous and feasible purification process, increasing the temperature is conducive to the adsorption process.