Eriochrome Black T Research Articles

β-CD-Induced Precipitation of Eriochrome Black T Recovered via CTAB-Assisted Foam Fractionation for Adsorption of Trace Cu(II).

In order to remove and reuse the ecotoxic dye Eriochrome black T (EBT) from dyeing wastewater, we used a process called cetyltrimethylammonium bromide (CTAB)-assisted foam fractionation. By optimizing this process with response surface methodology, we achieved an enrichment ratio of 110.3 ± 3.8 and a recovery rate of 99.1 ± 0.3%. Next, we prepared composite particles by adding β-cyclodextrin (β-CD) to the foamate obtained through foam fractionation. These particles had an average diameter of 80.9 μm, an irregular shape, and a specific surface area of 0.15 m2/g. Using these β-CD-CTAB-EBT particles, we were able to effectively remove trace amounts of Cu2+ ions (4 mg/L) from the wastewater. The adsorption of these ions followed pseudo-second-order kinetics and Langmuir isotherm models, and the maximal adsorption capacities at different temperatures were 141.4 mg/g at 298.15 K, 143.1 mg/g at 308.15 K, and 144.5 mg/g at 318.15 K. Thermodynamic analysis showed that the mechanism of Cu2+ removal via β-CD-CTAB-EBT was spontaneous and endothermic physisorption. Under the optimized conditions, we achieved a removal ratio of 95.3 ± 3.0% for Cu2+ ions, and the adsorption capacity remained at 78.3% after four reuse cycles. Overall, these results demonstrate the potential of β-CD-CTAB-EBT particles for the recovery and reuse of EBT in dyeing wastewater.

A donor-acceptor self-assembled graphitic carbon nitride based EB-T photocatalytic system for generation and regeneration of C(sp3) F bond and NADH under sunlight

As most promising organic semiconductors, and polymeric materials have concentrated much attention due to their thermochemical stability, chemical inertness, non-toxicity, excellent photoelectrical properties, low cost, and abundance of raw materials. However, the light-harvesting polymeric material graphitic carbon nitride (g-C3N4) has a limited ability to absorb light in the region below 420 nm because of its wide optical band gap. As one method to enhance the character of light harvesting and optical properties, such as EB-T (Eriochrome Black-T) has been used, and easy to prepare g-C3N4 based EB-T (g-C3N4@EB-T) composite photocatalyst, which has tuned the energy gap of pristine g-C3N4. In this article, we synthesized a new classic type of g-C3N4@EB-T composite photocatalyst by the copolymerization method. The EB-T moieties serve as external photosensitizing components in this composite photocatalyst. Compared to the initial materials, the g-C3N4@EB-T composite photocatalyst shows exceptional yields in the regeneration and formation of NADH and C(sp3)F bond.

Synthesis and characterization of Ag doped ZnO nanomaterial as an effective photocatalyst for photocatalytic degradation of Eriochrome Black T dye and antimicrobial agent

Doped ZnO nanomaterials are a type of material that can be used for photocatalysis and antibacterial applications. The metal dopant improves the overall performance of the photocatalyst by lowering the band gap energy and lowering electron–hole recombination. Likewise, metal dopants result in a significant increase in antimicrobial potential. Premised on these compelling viewpoints, we present a straightforward co-precipitation approach for synthesizing ZnO and 5% Ag modified ZnO (5% Ag/ZnO), as well as their applicability in photocatalysis and antibacterial study. The synthesized ZnO and 5% A/ZnO nanomaterials are well characterized by Ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. From the UV-Vis analysis, it has been established that silver doping resulted in a decline in the band gap of ZnO. The XRD investigations indicated hexagonal wurtzite structure for ZnO and 5% Ag/ZnO with average nanoparticle sizes of 25.37 and 20.23 nm, respectively. The porous morphology of produced nanomaterials was shown by FE-SEM analysis, while the elemental composition was validated by EDAX. The ZnO and 5% Ag-ZnO were successfully employed for the photocatalysis of Eriochrome Black T (EBT) dye and antimicrobial screening. Various parameters like catalyst dose, the effect of contact dye, and the effect of initial dye concentration were investigated which proved that 5% Ag/ZnO is more proficient in the degradation of EBT dye than ZnO. Besides, the radical scavenging study was to explore the presence of reactive oxygen species in photocatalytic degradation. The kinetic study revealed the involvement of Pseudo first-order kinetics. Furthermore, the 5% Ag/ZnO was recycled and reused for multiple cycles which indicated its stability and reusability performance. The antibacterial studies of ZnO and 5% Ag/ZnO against S.aureas, B. subtilis, K. pneumoniae and E. coli and antifungal studies against A. niger and C. albicans were investigated. The antibacterial and antifungal screening clearly emphasized that silver doping has an excellent effect on the augmentation of the antimicrobial performance of ZnO.

Decolourisation of Metal-azo Dyes in Wastewaters by Sodium Peroxodisulphate: A Template for Experimental Investigations

Background: It has long been recognized that the presence of azo metal complex dyes and their non-complexed counterparts in wastewaters, which is due to their manufacturing and use in the textile industries, renders natural waterways intensely coloured, and is therefore aesthetically unacceptable. Azo dye moieties are also known to be precursors of human carcinogenicity. Objective: This work aimed at the decolourisation of metal-azo dyes present in wastewaters so that pollution of natural bodies of water can be prevented. Decolourisation is indicative of the destruction of the metal-ligand complex, allowing the retrieval of transition metal ions, which are also water contaminants. Fracturing of the azo bond itself minimizes the potential for the carcinogenicity of these dyes. Methods: Decolourisation is achieved by the oxidative action of free radicals furnished by Na2S2O8, the sodium salt of peroxodisulphuric acid (Marshall’s acid). Raman spectroscopy characterizes the dye (ligand) known as “Eriochrome Black T (EBT)” by a peak at 1425 cm-1. Dismantling of its molecular structure by peroxodisulphate will lead to decolourisation accompanied by the collapse of the peak. Concomitantly, as EBT ligands fracture and cease to chelate, metallic ions are released, oxidized to a higher oxidation state, and precipitated as insoluble compounds in alkaline media. Results: The concentration of metallic ions in the aqueous phase has been found to be substantially reduced. The successfully treated dye solutions are mostly clear and colourless; their Beer-Lambert absorbances are in the range of 0.02 ≤ absorbance ≤ 0.05. The treatment of Ni(II), Co(II) and Fe(II)-EBT solutions is straightforward; the Cu(II) and Cr(III)-EBT solutions require additional treatment to be included in the above absorbance range. The Cr(III)-EBT is the least responsive to treatment. Fracturing of the azo bond is evinced by Raman Spectroscopy. Conclusion: A template to investigate the feasibility of decolourisation of metal-complex dye solutions is pioneered and recommended.

Seamless architecture of porous carbon matrix decorated with Ta2O5 nanostructure-based recyclable photocatalytic cartridge for toxicity remediation of industrial dye effluents

Dye waste management via renewable stratagem as well as understanding the nature of degraded products are highly essential for controlling the water purification process. Decoration of the photoactive heterostructure on top of a porous, chemically stable, nontoxic and rigid template is a real challenge for practical designing of low-cost cartridge for industrial waste management. Herein, the porous, high surface carbon-based Melamine Foam-Graphene-Carbon Nanotubes decorated Tantalum oxide (MF-Gr-CNTs-Ta2O5) heterostructure is successfully synthesized. The oxygen vacancies in Ta2O5lattice evident in X-ray Photoelectron Spectroscopy (XPS) analysis and facile interface in CNTs-Ta2O5observed in Transmission Electron Microscopy (TEM) imaging, promote the effective way of photogenerated charge carrier separation. The excellent photocatalytic performance is observed against Eriochrome Black T (EBT) with 95% of degradation efficiency within 100 min of photo exposure. The rate constant increases from 0.00624 to 0.03059 min-1for bare Ta2O5 to heterostructure, owing to faster kinetics involved in the generation of reactive oxygen species (ROS) for rapid photodegradation of dye. The effect of scavenger shows that superoxide radical participation is dominant in reaction kinetics with respect to other reactive species. The Total Organic Carbon (TOC) removal efficiency is achieved to be ∼ 93.45% which is remarkably high in photocatalytic degradation process. Liquid Chromatography-Mass Spectroscopy (LCMS) are performed to elucidate the non-toxic end-products evaluated via Toxicological analysis on glial cell line (C6) which shows cellular viability of 72% as compared to that of 38% for bare EBT (800 μg/ml).The photocatalyst has shown reusability till 8 cycles at a loss of ∼ 8% efficiency revealing the potential applicability towards developing cartridge technology. Knowing the porous and stable carbon-based heterostructure, a smart strategy has been adopted to demonstrate a filter-prototype setup. This study paves the way to design a cost-effective, reusable, cartridge material adopting an environmentally benign technique for waste-water purgation.

Sonochemical synthesis and characterization of Ho-Cu-O nanostructures and their application as photocatalyst for degradation of water-soluble organic pollutants under UV light

Water pollutants have been a significant concern in recent years. It is essential to use advanced materials that effectively reduce these pollutants. This work introduces Ho2Cu2O5/Ho2O3 nanocomposites as a novel catalyst for photodegradation of various water-soluble organic pollutants. First, Ho2Cu2O5/Ho2O3 nanocomposites were prepared via a simple and fast ultrasonic-assisted route. The chemical and morphological features of the as-synthesized sample were determined using VSM, FTIR, XRD, EDS, SEM, and TEM analysis. Also, the optical bandgaps and pore diameter were determined to be 3.1, 3.6 eV, and 12.74 nm via ultraviolet–visible diffuse reflectance spectroscopy and Brunauer-Emmett-Teller (BET) for Ho2Cu2O5 and Ho2O3, respectively. The findings revealed that the prepared nanocomposite could act as a photocatalyst for removing various organic pollutants from water. 93.01% and 92% of Eriochrome black T (ECBT) and Acid yellow (AY) were degraded under UV irradiation at optimum conditions after 120 min (0.03 g of photocatalyst and 10 ppm of pollutants). The kinetics of the ECBT removal was studied through the Langmuir-Hinshelwood model, and the apparent rate of the pseudo-first-order reaction (k = 0.03465 min−1) was obtained. The use of different scavengers made it clear that formation •O2– species were primarily responsible for the photodegradation of pollutants.

Simple sonochemical synthesis, characterization of TmVO4 nanostructure in the presence of Schiff-base ligands and investigation of its potential in the removal of toxic dyes

Thulium vanadate (TmVO4) nanorods were successfully prepared by a simple sonochemical approach using Schiff-base ligands. Additionally, TmVO4 nanorods were employed as a photocatalyst. The most optimal crystal structure and morphology of TmVO4 have been determined and optimized by varying Schiff-base ligands, the molar ratio of H2Salen, the sonication time and power, and the calcination time. A Eriochrome Black T (EBT) analysis revealed that the specific surface area was 24.91 m2/g. A bandgap of 2.3 eV was determined by diffuse reflectance spectroscopy (DRS) spectroscopy, which makes this compound suitable for visible photocatalytic applications. In order to assess the photocatalytic performance under visible light, two anionic dyes (EBT) and cationic dyes (Methyl Violet (MV)) were used as models. A variety of factors have been studied in order to improve the efficiency of the photocatalytic reaction, including dye type, pH, dye concentration, and catalyst loading. Under visible light, the highest efficiency was achieved (97.7%) when 45 mg TmVO4 nanocatalysts were present in 10 ppm Eriochorome Black T at pH = 10.

Development of mesoporous activated carbon from waste tires rubber via one-step activation using a blend of ZnCl2/FeCl3 and its application in Eriochrome Black T and Cr(VI) removal from aqueous phase

ABSTRACT A mesoporous activated carbon (MAC) was synthesized from waste tires rubber (WTR) via a one-step ZnCl2/FeCl3 activation route, and the typical sample was implemented in eliminating Eriochrome Black-T (EBT) dye and Cr(VI) from their synthetic effluents. The impact of the impregnation ratio of ZnCl2/FeCl3, the activation temperature, and the activation period was optimized . The best AC was created at 750°C for 60 minutes using a 2:1 ZnCl2/FeCl3:WTR impregnation ratio. This AC was analyzed for its BET surface area and pore volume, Fourier Transform Infra-Red spectroscopy (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), Boehm titration, and pHPZC. The outcomes disclosed that it had a surface area of 122.68 m2/g with a mean pore diameter of 8.53, indicating its mesoporosity. It also exhibited an acidic surface due to its pHPZC, which amounted to 4.80. The highest elimination of EBT (99.33%) and Cr ions (98.05%) from thier aqueous phases was achieved using 0.35 g dosage of MAC, a pH = 2.0 at 40°C for 210 minutes. The EBT and Cr(VI) isothermal and kinetics studies disclosed that the Langmuir and pseudo-2nd-order models best described their adsorption over the said AC. Thermodynamic functions showed that the MAC adsorption for EBT and Cr(VI) was endothermic and spontaneous. Reusability tests suggested that the regenerated AC could be utilized four times with reasonable efficiency. In conclusion, the application of the MAC described above because of its high efficiency in eliminating EBT and Cr(VI) from synthetic samples can be assessed in future studies to be applied in actual scales.

Fe3S4/biochar catalysed heterogeneous Fenton oxidation of organic contaminants: Hydrogen peroxide activation and biochar enhanced reduction of Fe (III) to Fe (II)

Greigite and biochar are two important materials recently gaining importance in Fenton catalysis to remove organic contaminants. Each material, however, has significant drawbacks. For instance, biochar is challenging to remove from reaction media despite having good Fenton activities, whereas greigite (FS) exhibits limited Fenton activities in the absence of light. To make both materials useful, we prepared Fe3S4/ biochar (FSBC) composite to enhance the reactivity, stability, and reusability, which could be used for large-scale applications in organic pollutant degradation. At room temperature, the developed catalysts demonstrated good Fenton degradation efficiency toward cationic and anionic dyes as well as phenols. About 90.2 % of Eriochrome Black T (EBT) degradation was accomplished at pH 4 within 1 h without light irradiation. The activation of H2O2 to generate hydroxyl radicals was enhanced by the addition of biochar to the Fe3S4 for the degradation of pollutants. The electrons produced by the biochar and the S-generated specie on the Fe3S4 surface boost the surface iron redox cycle with the regeneration of Fe2+ ions. The biochar has a crucial role in enhancing the activity by 10 % in 1 h in the presence of magnetic Fe3S4 with a rate constant of 0.0372 min−1.The biochar provides stability to the Fe3S4/ biochar composite with minimum Fe leaching and is recovered magnetically from the reaction mixture by using external magnets, which can be used for five catalytic cycles without significant loss of catalytic activity. The reported catalyst, which overcame the individual limitations of both the FS and biochar to improve catalyst activity and magnetic separation, will serve as the foundation for creating novel catalyst systems for the future degradation of organic pollutants.

Decolourisation of Metal-Azo Dyes in Wastewaters by Sodium Peroxodisulphate: A Template for Experimental Investigations

Background It has long been recognized that the presence of azo metal complex dyes and their non-complexed counterparts in wastewaters, which arise from their manufacturing and their use in the textile industries, renders natural waterways intensely coloured, and is therefore aesthetically unacceptable. Azo dye moieties are also known to be precursors of human carcinogenicity. Objective This work aimed at the decolourisation of metal-azo dyes present in wastewaters so that pollution of natural bodies of water can be prevented. Decolourisation is indicative of the destruction of the metal-ligand complex, allowing the retrieval of transition metal ions, which are also water contaminants. Fracturing of the azo bond itself minimizes the potential for carcinogenicity of these dyes. Methods Decolourisation is achieved by the oxidative action of free radicals furnished by Na2S2O8, the sodium salt of peroxodisulphuric acid (Marshall’s acid). Raman spectroscopy characterizes the dye (ligand) known as “Eriochrome Black T (EBT)” by a peak at 1425 cm-1. Dismantling of its molecular structure by peroxodisulphate will lead to decolourisation accompanied by the collapse of the peak. Concomitantly, as EBT ligands fracture and cease to chelate, metallic ions are released, oxidized to a higher oxidation state, and precipitated as insoluble compounds in alkaline media. Results The concentration of metallic ions in the aqueous phase has been found to be substantially reduced. The successfully treated dye solutions are mostly clear and colourless; their Beer-Lambert absorbances are in the range of 0.02 ≤ absorbance ≤ 0.05. The treatment of Ni(II), Co(II) and Fe(II)-EBT solutions is straightforward; the Cu(II) and Cr(III)-EBT solutions require additional treatment to be included in the above absorbance range. The Cr(III)-EBT is the least responsive to treatment. Fracturing of the azo bond is evinced by Raman Spectroscopy. Conclusion A template to investigate the feasibility of decolourisation of metal-complex dye solutions is pioneered and recommended.

Modification of Cellulose Acetate Microfiltration Membranes Using Graphene Oxide-Polyethyleneimine for Enhanced Dye Rejection.

Pressure-based membrane processes represent excellent water resource recovery prospects from industrial waste streams. In contrast with conventional pretreatment technologies, studies have shown that membrane pretreatment applications, such as microfiltration (MF), are more cost-effective and improve the results of the overall treatment processes. Hence, enhancing rejection efficiency of MF will enhance the performance of any downstream treatment processes. In this study, 0.45 µm cellulose acetate (CA) microfiltration membranes were modified by vacuum filtration-assisted layer-by-layer deposition of bilayers composed of negatively charged graphene oxide (GO) and positively charged polyethyleneimine (PEI). The performance of 1-, 2-, and 4-bilayer GO-PEI-modified membranes were investigated for their dye-rejection of anionic eriochrome black T (EBT) dye and cationic methylene blue (MB) dye in a cross-flow membrane module. As the number of bilayers on the membrane increased, the membrane thicknesses increased, and the deionized (DI) water flux through the membranes decreased from 4877 LMH/bar for the control (no bilayer) membrane to 2890 LMH/bar for the 4-bilayer membrane. Conversely, the dye-rejection performance of the modified membranes increased as increasing bilayers of GO-PEI deposited on the membranes. The anionic EBT dye saw superior rejection (~90% rejection) compared to the cationic MB dye (~80% rejection), which can be attributable to the electrostatic repulsion between the negatively charged GO surface and anionic EBT dye. After 50% recovery of the saline and dye-laden feed water, there was an observed drop in DI water fluxes of ~40-41% and 36%, respectively. There was also a slight increase in EBT dye-rejection during the composite feed-water experiments, attributed to the precipitation of salts on the membrane feed side or pore spaces, which subsequently reduce the membrane pore sizes.

Preparation of barium ferrate from mill scale and degradation study of aqueous Eriochrome black – T

This present study involves the utilization of mill scale, an iron rich steel industry waste, to synthesize barium ferrate. Ferrate with iron in +(VI) oxidation state is a green chemical with promising oxidation, disinfection and coagulation properties. The X-Ray diffraction(XRD) analysis of mill scale indicates the presence of iron in three forms hematite, magnetite and wustite. Mill scale was dissolved in concentrated HCl. The metallic composition of dissolved mill scale was determined by Inductively Couple Plasma Mass Spectroscopy(ICP-MS). Barium ferrate was synthesized using the dissolved mill scale by the wet oxidation method. The resulting crude ferrate was washed with different organic solvents to remove the impurities. The product thus obtained was analyzed by chromite method and characterized by Fourier Transform Infrared Spectroscopy(FTIR). Degradation of aqueous Eriochrome Black – T(EBT) with barium ferrate was studied at different pH, time and concentration. The degradation of the dye was monitored by UV-Visible spectroscopy and chemical oxygen demand. The degradation products of the aqueous EBT were characterized by Gas Chromatography-Mass Spectroscopy(GC-MS) and Proton Nuclear Magnetic Resonance (1H-NMR). Computational studies were performed to compare the stability of barium ferrate with that of potassium ferrate. The 1H-NMR calculations were performed to compare the degradation products obtained experimentally.

Interaction of catalyst nanoparticles and pollutant molecules in photocatalytic wastewater treatment: Novel characterization via dynamic surface properties

In photocatalytic processes for wastewater treatment, the degradation reactions mainly occurs at the surface of the catalyst and nearby regions. Therefore, understanding of the interactions between the catalyst and pollutant in a photocatalytic degradation system is of utmost importance, determining the affinity of the pollutant molecules to be attracted or repulsed from the photocatalyst particles. The aim of this experimental study is to get a better insight about the interactions between the catalyst nanoparticles and pollutant molecules via a novel characterization method based on dynamic surface phenomena analysis. Drop profile analysis tensiometry (PAT) is used for this purpose for dynamic surface tension and elasticity measurements of dye solutions (as pollutants), and in mixed solutions with catalyst particles at different pH conditions. The results demonstrate that the cationic dye Malachit Green (MG) has a low surface activity at pH 6.5, with an equilibrium surface tension about 69 mN/m. While it becomes much more surface active at pH 9 and surface tension is decreased to 59 mN/m. Adding TiO2 nanoparticles to MG solution at pH 9 causes a significant increase in surface tension, with much slower dynamics of adsorption at air/water interface. These results indicate a significant attraction and attachment of MG molecules to the surface of TiO2 nanoparticles, creating MG-TiO2 complexes, which have mobility much slower than the free MG molecules. This observation is in a good correlation with observed higher efficiency of MG degradation around pH 9. The capability of this novel experimental protocol is also examined for the anionic dye Eriochrom Black-T (EBT). According to the results, a significant interaction between TiO2 nanoparticles and EBT exist at pH 3, which is also well in accordance with reported higher efficiency of EBT degradation around pH 3. The elasticity measurements performed in this work, also support these results as an important characterization parameter for estimation of the molecular interactions in mixed adsorbed layers.

Adsorption of anionic and cationic dyes from aqueous solutions on fly ash-based porous geopolymer

<p>Fly ash, solid waste from coal-fired power plant, had been utilized as raw material for porous geopolymer by alkaline activation and addition of hydrogen peroxide (H2O2) blowing agent. Porous geopolymer had higher surface area and total pore volume compared to fly ash and geopolymer without blowing agent, namely 45.511 m2 g-1 and 0.05131 cc g-1, respectively. Porous geopolymer was applied as adsorbent for anionic dyes Eriochrome Black T (EBT) and cationic dyes Methyl Violet (MV) from aqueous solutions. In this paper, factors affecting adsorption process such as adsorbent dosage, pH, time, and initial concentration were studied, in addition to adsorption kinetics and isotherm studies. Adsorbent dosage, time, and initial concentration factors had the same effect on the adsorption process for both EBT and MV dyes. The optimum removal efficiency was obtained at adsorbent dosage of 2 g L-1 and adsorption time of 90 minutes. The increase of the initial concentration of dyes would decrease the removal efficiency. For pH factor, adsorption of EBT dyes was better at pH of 2, while adsorption of MV dyes was better at pH of 10. Both adsorption of EBT and MV dyes by porous geopolymer followed pseudo-second-order kinetics model and Langmuir isotherm model with maximum adsorption capacity of 45.454 mg g-1 and 49.261 mg g-1, respectively.</p>

A Comparative Study on Visual Detection of Mycobacterium tuberculosis by Closed Tube Loop-Mediated Isothermal Amplification: Shedding Light on the Use of Eriochrome Black T.

Loop-mediated isothermal amplification is a promising candidate for the rapid detection of Mycobacterium tuberculosis. However, the high potential for carry-over contamination is the main obstacle to its routine use. Here, a closed tube LAMP was intended for the visual detection of Mtb to compare turbidimetric and two more favorable colorimetric methods using calcein and hydroxy naphthol blue (HNB). Additionally, a less studied dye (i.e., eriochrome black T (EBT)) was optimized in detail in the reaction for the first time. Mtb purified DNA and 30 clinical specimens were used to respectively determine the analytical and diagnostic sensitivities of each method. The turbidimetric method resulted in the best analytical sensitivity (100 fg DNA/reaction), diagnostic sensitivity and specificity (100%), and time-to-positivity of the test (15 min). However, this method is highly prone to subjective error in reading the results. Moreover, HNB-, calcein-, and EBT-LAMP could respectively detect 100 fg, 1 pg, and 1 pg DNA/reaction (the analytical sensitivities) in 30, 15, and 30 min, while the diagnostic sensitivity and specificity were respectively 93.3% and 100% for them all. Interestingly, EBT-LAMP showed the lowest potential for subjective error in reading the results. This report helps judiciously choose the most appropriate visual method, taking a step forward toward the field applicability of LAMP for the detection of Mtb, particularly in resource-limited settings.

Mono and binary mixture removal of eriochrome black T and Cr(VI) from water by SiO2/polyaniline composite

The combined uptake of heavy metals and dyes from wastewater discharged by different sectors is a challenging concept. For this reason, this study investigated the uptake of hexavalent chromium Cr(VI) and eriochrome black T (EBT) dye over SiO2/polyaniline composite in a single and binary mixture. The prepared composite was examined by FTIR, XRD, and SEM-EDX to provide evidence of the successful synthesis and the enhanced properties compared to the polyaniline polymer (PAni). In a batch system, various factors affecting the adsorption were studied. Kinetic investigations revealed that Cr(VI) and EBT adsorption in both systems suited the pseudo second order kinetic model. The hybrid Langmuir-Freundlich isotherm correlated with the obtained findings in the mono and binary systems. The prepared composite showed a higher affinity toward Cr(VI), with a monolayer capacity of 285.5 mg g−1, than EBT dye with a capacity of 90.23 mg g−1. However, Cr(VI) capacity decreased to 149 mg g−1 in the binary mixture, indicating the antagonist effect between the adsorbate and the inhibitory impact of EBT dye. However, the EBT adsorption capacity in the mixture was 89.23 mg g−1, which is almost equivalent to the single system. The calculated thermodynamic parameters indicated that Cr(VI) and EBT uptake in the mono and binary systems was endothermic, favorable, and spontaneous, with physical adsorption as the governing mechanism.

Fluorinated covalent organic framework materials for photocatalytically driven benzylamine coupling and azo dyes degradation

Covalent organic frameworks (COFs) with pre-designed structures and superior photophysical properties have attracted significant attention due to their applications in photocatalysis. In this research, an imine-linked fluorinated 2D-COF (TFA-TTA-COF) material was feasibly fabricated from polycondensation of 2,3,5,6-tetrafluoroterephthalaldehyde (TFA) and 4,4′,4′'-(1,3,5-triazine-2,4,6-triyl)trianiline (TTA) in solvent-thermal methods. The TFA-TTA-COF material exhibited excellent crystallinity, high Brunauer-Emmett-Teller surface area of 1504 m2·g−1, and superior thermal and chemical stability. Considering the advantages of enhanced light absorption, effective charge separation and charge transfer, the prepared TFA-TTA-COF was employed as photocatalyst for the degradation of dyes. The degradation efficiencies of Eriochrome Black T (EBT) and Eriochrome Black A (EBA) dye in water could attain 89 % and 82 %, respectively. Furthermore, TFA-TTA-COF was found to show satisfactory photocatalytic performance with high conversion and selectivity in the photo-driven oxidative coupling of benzylamines. This work demonstrated the important contributions to the development of heterogeneous COFs-based photocatalysts.

Removal of Eriochrome Black T dye from aqueous solution using base activated typha grass (Typha latifolia) as an adsorbent

Adsorption of Eriochrome Black T (EBT) dye from aqueous solution by activated typha grass (T. latifolia) was studied using batch system. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) methods, as well as the point of zero charge (PZC). Adsorption parameters including effect of contact time, adsorbent dose, initial dye concentration and pH were studied and the adsorption capacity (qe) was found to be 47.619mg/g. The adsorption isotherm for the adsorption processes were also modelled and evaluated and the data fitted Freundlich isotherm model with R2 of 0.9943 relative to other models tested. The kinetic data were best described by pseudo-second order model with R2 values of 0.999 and rate constant (k) of 6.30mol-1dm3s-1 out of the four models tested. The thermodynamic quantities of the adsorption process including the entropy change (ΔS) which describe the degree of disorderliness of the dye-adsorbent interphase was found to be 2.108Jmol- 1K-1 indicating an increase in the interphase disorderliness, the enthalpy change (ΔH) describing the nature of energetic interaction between the dye molecules and the adsorbent surface has a value of -9.223kJmol-1 proving an exothermic process and the Gibbs free energy change (ΔG) of the range -8.563 to -8.718kJmol-1 were obtained indicating the process to be feasible and spontaneous in nature. Hence, the activated carbon produced from typha grass can be a potential adsorbent for the removal of hazardous dyes such as Eriochrome Black T from industrial effluent.

Multifunctional Ternary NLP/ZnO@l-cysteine-grafted-PANI Bionanocomposites for the Selective Removal of Anionic and Cationic Dyes from Synthetic and Real Water Samples.

The development of competent adsorbents based on agro-waste materials with multifunctional groups and porosity for the removal of toxic dyes from aqueous solutions is still a challenge. Herein, a bionanocomposite made up of neem leaf powder (NLP), zinc oxide (ZnO), and amino acid (l-cysteine)-functionalized polyaniline (PANI), namely, NLP/ZnO@l-cysteine-grafted-PANI (NZC-g-PANI), has been prepared by an in situ polymerization method. The as-prepared bionanocomposite was tested for the adsorptive removal of three anionic dyes, namely, methyl orange (MO), amido black 10B (AB 10B), and eriochrome black T (EBT), as well as three cationic dyes, namely, brilliant green (BG), crystal violet (CV), and methylene blue (MB), from synthetic aqueous medium. The morphological and structural characteristics of the NZC-g-PANI nanocomposite were examined with the help of HR field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopy. FTIR and Raman studies show that the formulated NZC-g-PANI have an ample number of functional moieties such as carboxyl (-COOH), hydroxyl (-OH), amines (-NH2), and imines (-N=), thus demonstrating outstanding dye removal capacity. C-S linkage helps to attach l-cysteine with polyaniline. Moreover, the predominance of chemisorption via ionic/pi-pi interaction and hydrogen bonding between the NZC-g-PANI nanocomposite and dyes (BG and MO) has been realized by FTIR and fitting of kinetics data to the PSO model. For both BG and MO dyes, the biosorption isotherm was precisely accounted for by the Langmuir isotherm with q max values of up to 218.27 mg g-1 for BG at pH 6 and 558.34 mg g-1 for MO at pH 1. Additionally, thermodynamic studies revealed the endothermic and spontaneous nature of adsorption. NZC-g-PANI showed six successive regeneration cycles for cationic (MO: from 96.3 to 90.4%) and anionic (BG: from 94.7 to 88.7%) dyes. Also, batch adsorption operations were validated to demonstrate dye biosorption from real wastewater, such as tap water, river water, and laundry wastewater. Overall, this study indicates that the prepared NZC-g-PANI biosorbent could be used as an effective adsorbent for the removal of various types of anionic as well as cationic dyes from different aqueous solutions.

Transformation of used aluminium foil food container into AlOOH nanoflakes with high catalytic activity in anionic azo dye reduction

Synthesis of aluminium-based nanomaterials from aluminium-waste has received huge attention in current scientific research. Herein, an attempt was made to convert aluminium foil food container into aluminium oxyhydroxide (AlOOH) nanoparticles by a precipitation method. X-ray diffraction (XRD), spectroscopic and electron microscopic studies were employed to characterize impure AlOOH (containing sodium chloride, NaCl) and pure AlOOH samples. The band gap (Eg) of AlOOH nanoparticles was found to be 4.5 eV. The catalytic potential of AlOOH samples was evaluated using reduction of methyl orange (MO) and Eriochrome black T (EBT) dyes. Impure AlOOH nanoparticles could reduce 99.8% of MO and EBT dye within 4 min and 3 min respectively. Effect of the AlOOH dosage and NaBH4 concentration on catalytic reduction was determined. Used aluminium foil food container-derived AlOOH nanoparticles will become a low-cost and sustainable catalyst in the catalytic treatment of azo dye contaminated waters.