Azo Dye Acid Research Articles

WS2-Assisted Electrochemical Activation of Peroxymonosulfate for Eliminating Organic Pollutant in Water

Advanced oxidation process based on heterogeneous activation of peroxymonosulfate (PMS) has received significant attention in wastewater remediation. Herein, a facile and effective electrochemical method was introduced in a tungsten sulfide (WS2)-activated PMS process for the removal of a typical azo dye Acid Orange 7 (AO7) in aqueous solution. It was found that the electrochemical activation could remarkably promote the removal of organic pollutants by coupling with WS2/PMS system. The elimination of AO7 in the electro-assisted WS2-activated PMS (E/WS2/PMS) system achieved 95.8% of AO7 removal in 30 min, with the optimal conditions of 1.0 g/L WS2, 1.0 mM PMS, current density of 1.0 mA/cm2 and initial pH of 6.5. Based on quenching experiments and EPR techniques, mechanistic studies confirmed that hydroxyl radical (•OH) and singlet oxygen (1O2) are the primary reactive oxygen species for the oxidation of pollutants. In addition, the influences of pH, WS2 dosage, PMS concentration, current density, common anions and humic acid on the AO7 removal are also investigated in detail. Furthermore, the system exhibited resistance to aqueous matrices, verifying the accepted applicability in real water (i.e., Yangtze River water and Shahu Lake water). In summary, this study demonstrates a green system for the effective removal of contaminants in water, holding significant implications for practical application.

Investigating the efficacy of Palladium Doped Ceria for the Photodegradation of Azo Dyes

Ceria (CeO2) was prepared by microwave assisted precipitation method while sonothermal method was utilized for the synthesis of palladium doped ceria (Pd-CeO2) photocatalyst. HR-TEM analysis confirms the face centered cubic geometry (FCC) of CeO2. The particle size of Pd-CeO2 calculated from HR-TEM analysis (7.6±2.18 nm) is in close relation with XRD (8.25±0.25 nm). The SAED pattern of Pd-CeO2 shows the poly crystallinity where the d-spacing was 0.31 and 0.30 nm which corresponds to CeO2 and Pd crystal facets 111 and 100 respectively. The amount of dopant and existence of Pd, Ce and O was confirmed from EDX spectra and elemental mapping. BET surface area analysis of CeO2 (64.45 m2/g), Pd-CeO2 (60.20 m²/g) revealed that the decrease in the surface area of CeO2 due to Pd loading which is confirmed by pore volume (0.079 cm³/g) for CeO2 and pore volume for Pd-CeO2 (0.073 cm³/g). The photocatalytic activity of Pd-CeO2 was screened against a model azo dye Acid red-4 (AR-4). The fluctuation of the rate of photodegradation (PD) of AR-4 was observed under different reaction conditions. Therefore, the reaction parameters were optimized to achieve best catalytic activity up to PD; 98%. The kinetic study suggests that the PD of AR-4 follows 1st order kinetics with regression coefficient (R2=0.973) and rate constant (k=0.024/min). Recycling study revealed the prolong use of catalyst without significant loss of activity. DFT study and experiments revealed the synergism of Pd on the photo response of CeO2. Perhaps this synergistic effect due to metal support interaction, causes redistribution of charges and Fermi energy levels. The synthesized catalyst showed potential application for the treatment of textile industrial effluents.

Heterogeneous Photo-Fenton Degradation of Azo Dyes over a Magnetite-Based Catalyst: Kinetic and Thermodynamic Studies

Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the azo dyes Acid Red 18 (AR18), Acid Red 66 (AR66), and Orange 2 (OR2) using magnetite as a catalyst. The magnetic catalyst was synthesized via a hydrothermal process at 150 °C. Experiments were conducted at room temperature, investigating the effect of catalyst dosage, pH, and initial concentrations of H2O2 and AR18 dye. Kinetic and thermodynamic studies were performed at 25, 40, and 60 °C for the three azo dyes (AR18, AR66, and OR2) and the effect of the dye structures on the degradation efficiency was investigated. At 25 °C for 0.33 mmolL−1 of dye at pH 3.0, using 1.4 gL−1 of the catalyst and 60 mgL−1 of H2O2 under UV radiation of 16.7 mWcm−2, the catalyst showed 62.3% degradation for AR18, 79.6% for AR66, and 83.8% for OR2 in 180 min of reaction. The oxidation of azo dyes under these conditions is spontaneous and endothermic. The pseudo-first-order kinetic constants indicated a strong temperature dependence with an order of reactivity of the type OR2 > AR66 > AR18, which is associated with the molecular size, steric hindrance, aromatic conjugation, electrostatic repulsion, and nature of the acid–base interactions on the catalytic surface.

Histology of skin, gill, liver, and kidney of tilapia Oreochromis niloticus exposed by azo dyes acid red 88.

Abstract Coloring is one of the main process in textile production. Using azo dyes type are the first pick of textile industries. Therefore, the disposal of dye waste containing high levels of azo can increase the toxicity level also impact the fish. Acid Red 88 is an azo type dye which provides a red color as the basic color for coloring textile products. Acid Red 88 are left behind as much as 60% of textile waste. the textile factories wastewater in Indonesia contains an average of 750 mg/L suspended solids. The aim of this study was to determine the effect of azo dye Acid Red 88 exposure to tilapia by the histology of its skin, gills, liver and kidneys. The method used was experimental method with 4 different exposure concentrations of Acid Red 88 P0 (0 mg/L), P1 (75 mg/L), P2 (150 mg/L), P3 (225 mg/L), and P4 (300 mg/L). The damage is identified on the histology of the organs and then measured using a scoring method. The results showed that several damages were found such as epithelial erosion, edema, hyperplasia, telangectasis, hemorage, fatty degeneration, congestion and necrosis.

Degradation of acid black 210 Na AZO dye through electro-oxidation with graphite electrodes

Dyes are widely used substances, however, if disposed of incorrectly in the environment, they can cause numerous problems. To degrade them, it is possible to use advanced oxidative processes (AOP) methods, such as electro-oxidation. This technique was used to degrade the azo dye Acid Black 210 Na. Four treatments were applied (A, B, C, and D) with electric current densities of 4, 12, 20, and 30 mA.cm−2 for 10 min, and the degradation was evaluated by molecular absorbance spectroscopy. Using ANOVA, it was verified that the most suitable condition for degradation corresponds to an electric current density of 20 mA.cm−2 (treatment C), obtaining degradation around 87 % for 459 nm and 95 % for 609 nm, since the degradation at 319 nm follows second-order kinetics, with a rate constant (K) of 0.561 and R² of 0.978. There was an increase in the toxicity of the samples, through the germination and growth of Lactuca sativa radicles and the test with Daphnia magna, after the treatments, possibly due to the presence of chlorine, since the absorbance analysis in the infrared region did not indicate the formation of toxic intermediates.

Removal of acid red dye 1 from textile wastewater by heterogenous photocatalytic ozonation employing titanium dioxide and iron zeolite

Clean water is a necessity for all life to survive and flourish. However, natural waters are being continuously contaminated due to the release of waste streams in water. Hence, it is important to remove pollutants from wastewater to fulfill human needs. Conventional treatment methods are neither efficient nor economical for wastewaters that especially contain refractory toxic pollutants. This requires novel techniques like Advanced oxidation processes (AOPs), that may successfully degrade persistent micropollutants more efficiently. In this study, an azo dye Acid Red 1 was removed by three AOPs, namely Photocatalytic oxidation, Ozonation and Photocatalytic Ozonation, by employing heterogenous catalysts. TiO2 was used as photocatalyst, whereas Fe-Zeolite has been further added as Ozonation catalyst. The study revealed that photocatalysis degraded only 28% Acid red dye after 15 min, whereas for ozonation, the degradation percentage was 95% in same time. In combined photocatalytic ozonation process using TiO2, 95% degradation was achieved in just 9 min and treatment time further reduced to 5 min when Fe-zeolite was added. Optimization studies for initial concentration, UV intensity and catalyst loading were performed. Finally, rate constants and Electrical Energy per Order (EEO) values were determined for all AOPs, and mechanism was proposed.

Decolorization, degradation, and detoxification of textile dye and efficient hydrogen production by highly-stable MIL-177-LT@NiFe-LDH photoelectrocatalyst: Mechanism and economical studies

Combining organic compounds with inorganic layers leads to the development of innovative organic-inorganic hybrid materials with specific functional properties, opening up possibilities for advanced applications that go beyond current technological limits. In the present study, Ti-MOF (MIL-177-LT) was decorated with NiFe layered double hydroxide (NiFe-LDH) to fabricate a heteroatom electrocatalyst (MIL-177-LT@NiFe-LDH). The synthesized electrode included capable electron transportation, long-term stability, and high specific surface area. Photoelectrocatalytic degradation of the Azo dye (Acid Red 18) from water was studied with respect to the influence of pH, bias potential, temperature, and dye concentration. It was found that hydrogen evolution reaction (HER) has minimized overpotentials, i.e., 130 and 182 mV corresponding to the current densities of 400 and 1000 mA cm−2, respectively. High stability was also observed when a current density of 5000 mA cm−2 was applied to the modified electrode for 500 h. The layered architecture of the MIL-177-LT@NiFe-LDH composite provides high surface points for the degradation of dye molecules and water splitting for HER. The electrocatalyst showed great stability in the degradation process. The experiment was powered by solar cells, reducing the need for electricity and resulting in cost savings. Additionally, the treatment process was analyzed in terms of costs. Therefore, a promising approach is suggested in this study for developing high-performance organic-inorganic hybrid materials with exceptional electrochemical and photocatalytic properties.

Formulation of silver phosphate/graphene/silica nanocomposite for enhancing the photocatalytic degradation of trypan blue dye in aqueous solution

Photocatalytic degradation of several harmful organic compounds has been presented as a potential approach to detoxify water in recent decades. Trypan Blue (TB) is an acidic azo dye used to distinguish live cells from dead ones and it's classified as a carcinogenic dye. In this study, silver phosphate (Ag3PO4) nanoparticles and novel Ag3PO4/graphene/SiO2 nanocomposite have been successfully prepared via simple precipitation method. Afterward, their physical properties, chemical composition, and morphology have been characterized using SEM, EDS, TEM, SAED, BET, XRD, FTIR and UV–VIS spectroscopy. The specific surface area of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite were reported to be 1.53 and 84.97 m2/g, respectively. The band gap energy of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite was measured to be 2.4 and 2.307 eV, respectively. Photocatalytic degradation of Trypan blue (TB) was studied at different parameters such as pH, catalyst dosage, initial concentration, and contact time. The results showed that, at initial dye concentration of 20 ppm, pH = 2, and using 0.03 g of Ag3PO4/G/SiO2 as a photocatalyst, the degradation percent of TB dye in the aqueous solution was 98.7% within 10 min of light exposure. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the photocatalytic degradation kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order kinetic model. Finally, the possible photocatalytic performance mechanism of Ag3PO4/G/SiO2 was proposed.

Red-emitting 4-methyl coumarin fused barbituric acid as an electrochemical sensor for catechol detection and probe for latent fingerprints.

Herein, we have reported a red-emitting 4-methyl coumarin fused barbituric acid azo dye (4-MCBA) synthesized byconventional method. Density functional theory (DFT) studies of tautomer compounds were done using (B3LYP) with a basis set of 6-31G(d,p). NLO analysis has shown that tautomer has mean first-order hyperpolarisabilities (β) value of 1.8188 × 10-30 esu and 1.0470 × 10-30esu for azo and hydrazone forms, respectively, which is approximately nine and five times greater than the magnitude of urea. 4-MCBA exhibited two absorption peaks in the range of 290-317 and 379-394 nm, and emission spectra were observed at 536 nm. CV study demonstrated that the modified 4-MCBA/MGC electrode exhibited excellent electrochemical sensitivity towards the detection of catechol and the detection limit is 9.39 μM under optimum conditions. The 4-MCBA employed as a fluorescent probe for the visualisation of LFPs on various surfaces exhibited Level-I to level-II LFPs, with low background interference.

Rapidly chemical preparation of Mn doped ZnO nanostructures for photocatalysis efficiency based on UV light system and mechanism insights

Through a facile chemical precipitation process, pure zinc oxide (ZnO) and various ratio of Mn-doped zinc oxide (Zn1-xMnxO) nanostructured materials were synthesized. The degradation of an azo dye acid orange 2 (AO-2) solution under UV light was investigated using the synthesized materials as photocatalysts. XRD, FTIR, DLS, FESEM, EDS, PL, BET, magnetic, TGA and UV–vis techniques were used to elucidate the structural, functional, particle, elemental, morphological, and optical aspects of the catalysts. The XRD and FESEM analysis showed the hexagonal ZnO structure and spherical shape of the ZnO nano-photocatalyst, respectively. The crystal sizes of Zn1-xMnxO are 27.40–38.31 nm. The optical band gap energy of Zn1-xMnxO are 2.53–3.10 eV. Under UV irradiation for 60 min, MZ-25 NPs demonstrated better degradation (100.0%) of AO-2 dye. The effect of various factors such as catalyst quantity, and pH of the dye solution on the rate removal was investigated. After 60 min of UV light irradiation, dye removal was obtained under ideal conditions (with catalyst loading of 3 mgL−1, and pH 4). The rate constant values of MZ-25 sample are determined to be 0.0219 min−1. The scavenging test reveals that ∙O2 − and ∙OH are responsible for the photo-degradation of AO-2 dye.

Synthesis, spectroscopic, DFT, TD-DFT, and dyeing studies of 2-amino-3-cyano thiophene-based azo dyes on wool and nylon

This study presents the design, synthesis, and application of eight novel thiophene-based acid azo dyes featuring benzoic and salicylic acid acceptors. The synthesized dyes demonstrate versatile light absorption properties, spanning the near UV, visible, and deep red regions. Notably, the thiophene acid azo dyes containing benzoic acid acceptor unit (AB series dyes) exhibited red-shifted absorption, while their salicylic acid counterparts (SR series dyes) displayed blue-shifted absorption. The influence of increased donor strength at position 4 of the thiophene ring on absorption properties is systematically explored. Theoretical findings from Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) substantiate the experimental results. Moreover, the dyes are applied to wool and nylon fabrics, displaying excellent dyeability with % exhaustion properties above 70%. The dyed fabrics manifest rich shades, ranging from blue-black to deep orange. Enhanced K/S values are observed for wool-dyed fabrics in the case of SR series dyed fabrics, whereas the AB series dyes show superior results for nylon-dyed fabrics. The dyed fabrics exhibit remarkable light, wash, and rubbing fastness. Notably, nylon-dyed fabrics outperformed wool-dyed fabrics in light and wash fastness. UV protection studies reveal the fabrics’ potential to block harmful UV-A and UV-B radiation with excellent UPF ratings.

Impact of Additive Hydrophilicity on Mixed Dye-Nonionic Surfactant Micelles: Micelle Morphology and Dye Localization.

The nonionic surfactant pentaethylene glycol-monododecylether C12E5 forms micelles in aqueous solutions with a lower critical solution temperature. This characteristic solution behavior of C12E5 is independent of the pH. Such micelles are used to solubilize a large variety of active guest molecules like for instance dyestuffs. An example is an acidic azo dye termed Blue used as a hair colorant. Depending on the pH, Blue gradually changes its hydrophilicity from the protonated BlueH at pH = 2 to the bivalent anion Blue2- at pH = 13 while keeping the shape and size of Blue essentially unchanged. These features of C12E5 and Blue offer the unique chance to investigate the sole impact of a tunable hydrophilicity of a guest molecule on the solution behavior of mixed micelles of the guest and C12E5. Accordingly, the present work establishes a phase diagram of Blue-C12E5 micelles and analyzes their morphology including the spatial distribution of Blue in the micelles as a function of the hydrophilicity of Blue. Small angle neutron scattering reveals the size and shape of the micelles, and detailed contrast matching of the C12E5 supported by 1H NMR with NOESY provided insight into the localization of Blue within the micelles as its hydrophilicity changes.

Acid Violet 3: A Base-Activated Water-Soluble Photoswitch.

Acidic azo dyes are widely used for their vibrant colors. However, if their photophysics were better understood and controllable, they could be integrated into many more applications such as photosensing, photomedicine, and nonlinear optics. Here, the proton-controlled photophysics of a widely used acid, hydrazo dye, acid violet 3 (AV3) is explored. Density functional theory is used to predict the ground- and excited-state potential energy surfaces, and the proposed photoisomerization mechanism is confirmed with spectroscopic experiments. The ground-state and first two excited-state surfaces of the three readily accessible protonation states, AV3-H, AV3, and AV3+H, are investigated along both the dihedral rotation and inversion coordinates. The deprotonated AV3-H undergoes photoisomerization with blue light (λex = 453 nm) through a dihedral rotation mechanism. Upon the formation of the cis-isomer, the reversion of AV3-H is predicted to occur through a mixed rotational and inversion mechanism. In contrast, AV3 and its protonated form, AV3+H, do not undergo photoisomerization because there is no driving force for either the rotation or inversion of the azo bond in the excited state. In addition, when the azo bond is acidic, the ground-state dihedral rotation reversion mechanism barrier is lower. The mechanistic insights gained here through the combination of theory and experiment provide a roadmap to control the reactivity of AV3 across 11 orders of magnitude of proton concentration, making them interesting candidates for a range of pharmaceuticals.

Decolorization of acid orange 7 in moving bed biofilm reactor packed with polyhydroxyalkanoate/activated carbon

Moving bed biofilm reactor (MBBR) using various carrier medium has been widely employed in wastewater treatment. This study aimed to investigate the feasibility of polyhydroxyalkanoate (PHA) and activated carbon (AC) composite (PHA/AC) as biofilm carrier to enhance MBBR treatment of azo dye acid orange 7 (AO7). Each PHA/AC carrier had a height of 0.40 cm and a cylindrical diameter of 1.25 cm. The biofilm on PHA/AC carrier was characterized using microscopic and chemical analysis. AO7 decolorization efficiency and kinetics were evaluated. The incorporation of AC in PHA was found to promote biofilm growth. Mature biofilm of 2075 ± 79.30 μm was successfully formed on PHA/AC carrier. Compared to a control reactor, the MBBR with 5 % (v/v) PHA/AC exhibited improved decolorization, with decolorization efficiency and first-order rate constant, kAO7, increasing from 78.2 % and 9.90 × 10−4 min−1 to 95.0 % and 1.70 × 10−3 min−1, respectively. The enhancement of decolorization in MBBR was attributed to the presence of anoxic zone within the biofilm that favored the azo bond cleavage. Batch studies on the effects of suspended activated sludge (AS) and biofilm amounts showed an additive effect on decolorization efficiency when combined. The combined suspended AS and biofilm also resulted a 3–4 folds increase in kAO7 value compared to AS alone. The results indicate that PHA/AC was an effective carrier and its biofilm exhibited high decolorizing ability for AO7. The enhancement provided by the PHA/AC biofilm makes it advantageous for developing efficient and environmentally-friendly wastewater treatment systems with compact design and minimal sludge production.

Biosynthesis and Stabilization of Nanosilver Using Houttuynia Extract for Degradation of Azo Acid and Mordant Dyes

Silver nanoparticles (AgNPs) are promising candidates for environmental remediation due to their exceptional catalytic properties. However, their tendency to aggregate during formation undermines their stability, posing challenges for large-scale production. This study presents a one-step biosynthesis method of AgNPs using Houttuynia plant (Houttugniae herba) extract, where the plant biomolecules act as both reducer and stabilizer. The bioreduction kinetics were meticulously optimized using the one-factor-at-a-time (OFAT) approach, establishing the ideal synthesis conditions as follows: 1.0 mM AgNO3, 0.1 ml Houttuynia plant extract, heated at 80 °C for 45 minutes, with the medium at pH 9. Morphological characterization revealed the formation of spherical, well separated, and highly crystalline (d-spacing = 0.237 nm) AgNPs with an average particle size of 7.756 ± 2.372 nm. The synthesized AgNPs exhibited remarkable catalytic activity in reducing azo dyes, achieving degradation rates of approximately 98% for both acid red 1 (AR1) and mordant blue 9 (MB9) within 4 and 20 minutes, respectively. This eco-friendly and cost-effective method can be an excellent alternative for treating industrial effluents.

Treatment of textile wastewater using the Co(II)/NaHCO3/H2O2 oxidation system

Textile wastewater (TWW) is one of the most hazardous wastewaters for ecosystems when it is discharged directly into water streams without adequate treatment. Some organic pollutants, such as dyes in TWW, are considered refractory compounds that are difficult to degrade using conventional chemical and biological methods. The bicarbonate-activated peroxide (BAP) system is an advanced oxidation process (AOP) based on applying H2O2, which has been demonstrated to be a clean and efficient technology for dye degradation, with the advantage of operating under slightly alkaline pH conditions. In this study, response surface methodology (RSM) based on a central composite design (CCD) was used to optimize the degradation of TWW contaminated with the azo dye Acid Black 194 using the BAP system catalyzed with cobalt ions in solution (Co2+). The analysis of variance (ANOVA) technique was applied to identify significant variables and their individual and interactive effects on the degradation of TWW. The optimum reagent concentrations for degrading TWW at 25 °C and with 45 μM Co2+ were 787.61 and 183.34 mM for H2O2 and NaHCO3, respectively. Under these conditions, complete decolorization (≥99.40), 32.20 % mineralization, and 52.02 % chemical oxygen demand removal were achieved. Additionally, the acute toxicity of textile wastewater before and after oxidation was evaluated with guppy fish (Poecilia reticulata), showing a total reduction in mortality after treatment with the Co2+–BAP system. The Co2+–BAP oxidation system is a potential method for textile wastewater treatment, which, in addition to achieving complete decolorization and partial mineralization, improves biodegradability and reduces the toxicity of the treated water.

Incorporating Antimicrobial Activity During Synthesis of New Acid-Azo Dyes: Thermal Stability and Application on Various Fabrics.

Textile materials are susceptible to microbial attack as they provide suitable conditions for their growth. The microbes grow with normal body secretions on garments. These microbes are responsible for the weakening, brittleness, and discoloration of the substrate. Furthermore, they cause many health issues to the wearer, including dermal infection, bad odour etc. They threaten the human health as well as create tenderness in fabric. Usually, antimicrobial textiles are prepared by applying antimicrobial finishes after dyeing, which is an expensive approach. Concerning these adversities, in the present study, a series of antimicrobial acid-azo dyes have been synthesized by incorporating antimicrobial sulphonamide moiety into the dye molecules during its synthesis. A commercially available sulphonamide-based compound, sulfadimidine Na-salt was used as a diazonium component and coupled with different aromatic amines to get desired dye molecules. Since dyeing and finishing are two separate energy-intensive processes, in the current research work, an approach to combine both processes in one step has been adopted that would be economical, time-saving, and environment friendly. Structures of the resultant dye molecules have been confirmed using different spectral techniques such as Mass spectrometry, 1H-NMR spectroscopy, FT-IR, and UV-Visible spectroscopy. Thermal stability of the synthesized dyes was also determined. These dyes have been applied to wool and nylon-6 fabrics. Their various fastness properties were examined using ISO standard methods. All the compounds exhibited good to excellent fastness properties. The synthesized dyes and the dyed fabrics were screened biologically against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 10536, resulting in significant antibacterial activities.

Optimal hybrid artificial intelligence models for predicting the adsorptive removal of dyes and phenols from aqueous solutions using an amine-functionalized graphene oxide/layered triple hydroxide nanocomposite

Water pollution is a serious environmental problem with a significant negative impact on human health and the ecosystem. Adsorption is an attractive process for water decontamination. Developing artificial intelligence models capable of predicting the adsorption performance of newly developed materials could save huge amounts of resources and efforts. In the present study, a novel polyethyleneimine/graphene oxide/layered triple hydroxide (PEI/GO/LTH) nanocomposite was synthesized, characterized, and applied to adoptively remove harmful phenolic (bisphenol A) and azo dye (acid red 1) from wastewater samples. The results revealed that the PEI/GO/LTH nanocomposite is highly effective in removing these two pollutants. The adsorption isotherms and kinetics of these two pollutants are best fitted by the Langmuir isotherm and pseudo-second-order models, respectively. Additionally, the synthesized nanocomposite is easily and highly regenerable with an insignificant loss in performance when repeatedly used. Besides the above investigations, the present study also employs support vector machines (SVM) and Bayesian optimization as tools for predicting the adsorptive removal of acid red 1 (AR1) dye and bisphenol A (BPA) from contaminated water samples by the synthesized PEI/GO/LTH nanocomposite. The models achieved promising results as the correlation coefficients, during the testing phase, reached 97.3 and 96.6 % for the AR1 and BPA data using BO-SVM models, respectively.

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.

Removal of Acid Orange G Azo Dye by Polycation-Modified Alpha Alumina Nanoparticles.

Highly positively charged poly(vinyl benzyl trimethylammonium chloride) (PVBMA) was successfully synthesized with approximately 81.8% of yield. The PVBMA was characterized by the molecular weight (Mw) of 343.45 g·mol-1 and the molecular weight distribution, (Đ) of 2.4 by 1H NMR and SEC measurements. The PVBMA was applied as an effective agent for α-Al2O3 surface modification in the adsorptive removal of the azo dye acid orange G (AOG). The AOG removal performance was significantly enhanced at all pH compared to without surface modification. The experimental parameters were optimal at pH 8, free ionic strength, 15 min of adsorption time, and 5 mg·mL-1 α-Al2O3 adsorbents. The AOG adsorption which was mainly controlled by the PVBMA-AOG electrostatic attractions was better applicable to Langmuir isotherm and pseudo-second kinetic model. The PVBMA-modified α-Al2O3 demonstrates a high-performance and highly reusable adsorbent with great AOG performances of approximately 90.13 % after 6 reused cycles.