Dye Degradation Research Articles

Comparative study of anodized TNTs and S-TNTs on Ti plates for effective methylene blue degradation under UV LED and direct sunlight

The key findings of this research are focused on enhancing the degradation of methylene blue dye with titania nanotubes acting as catalysts under benign UV LED and sunlight. By comparing pristine and sulfur-doped titania, the study reveals that the doped-titania with anatase phase demonstrates a superior photocatalytic activity than pristine titania with mixed phases, achieving a remarkable 98 % degradation of dye within 120 min under direct sunlight with a small amount of hydrogen peroxide. This enhanced performance is attributed to the 10.7 μm longer and well-arranged nanotubes, effective surface area, better bandgap of 2.39 eV, effective anatase phases, and a lower 20 nm crystallite size. The study underscores the importance of anodization and sulfur doping using titanium plates to tailor the properties of the resultant nanotubes. Also, it indicates a cost-effective dye removal method without secondary pollution, offering a practical and optimistic solution to environmental challenges. The effective titania nanotubes for photocatalytic application in environmental remediation were identified through field emission scanning electron microscope, energy dispersive X-ray analysis, X-ray diffraction analysis, and diffuse reflectance analysis, providing valuable insights and inspiring future research and application in this field.

Photocatalytic activity of molybdenum-doped LOS- zeolite for efficient dye degradation and hydrogen production

This research investigates the synthesis and application of Losod-zeolite (LOS-Z), a crystalline hydrated sodium aluminosilicate (Na12Al12Si12O48.xH2O) as a potential photocatalyst for dye degradation and H2 production from dye-degraded water. The photocatalytic properties are enhanced by impregnating molybdenum (Mo) into LOS-Z (Mo@LOS-Z). XRD, FTIR, SEM, EDX, and elemental mapping were used to study the physicochemical properties of synthesized materials while UV–vis and PL were employed to explore the optoelectronic properties. The photocatalytic activities for dye degradation and H2 production were evaluated using methylene blue (MB) under visible light irradiation. An enhancement in the efficiency of dye degradation (56%–82%) and H2 production rate was demonstrated due to the competitive photocatalytic performance of 10% Mo@LOS-Z compared to the pristine LOS-Z and CFA-BFA blend. It exhibited 2.5 times higher (∼1200 μmol g−1h−1) H2 production than the LOS-Z (∼480 μmol g−1h−1) due to the synergistic effects of narrowed band gap and recombination rate. This study could pave the way forward into the synthesis of waste-derived photocatalysts for efficient dye degradation and H2 production.

Box-Behnken design optimization of 2D Ti3C2Tx MXene nanosheets as a microwave-absorbing catalyst for methylene blue dye degradation

The 2D MXene Ti3C2Tx was synthesized from the precursor MAX phase Ti3AlC2 by etching the Al layer using hydrofluoric acid. Different Characterization techniques were employed to investigate the properties of the synthesized Ti3C2Tx. The degradation of methylene blue (MB) dye under microwave irradiation in the presence of the prepared 2D MXene was studied. It was found that the synthesized Ti3C2Tx was an excellent microwave catalyst for MB dye degradation, and results obtained were promising. Using this approach, the dye was almost wholly degraded with a degradation efficiency of 99.85 % in only 10 min without adding any oxidant. The degradation was found to follow the pseudo-first-order kinetic model, and the rate constants obtained varied from 0.10 and reached up to 0.67 min−1. The effect of pH, initial MB concentration and catalyst dosage on the MB dye degradation rate has been studied. It was found that carrying out the reaction at pH values ranging from 2 to 10 did not obviously affect its rate. On the other hand, lower initial MB dye concentrations and higher catalyst dosages significantly increased the degradation rate. The high degradation efficiency was found to be maintained for up to five successive catalytic cycles, ensuring the high stability of the synthesized 2D MXene Ti3C2Tx as a catalyst. Optimization of parameters affecting the degradation process was studied using response surface methodology (RSM). According to the Box-Behnken design, the optimal degradation efficiency (99.92 %) could be achieved by adding 21.24 mg of 2D Ti3C2Tx MXene catalyst and using an initial MB dye concentration of 53.06 ppm (mg/L) during a reaction time of 11.93 min.

Synergistic degradation of toxic azo dyes using Mn-CuO@Biochar: An efficient adsorptive and photocatalytic approach for wastewater treatment

Congo red (CR) and Eriochrome Black T (EBT) is a toxic azo dye with a complex structure which represents a serious Ecotoxicological hazards for aquatic bodies. This research investigates the synergistic effects of Corn plants biochar and manganese (Mn)-composited copper oxide (CuO) in the adsorptive and photocatalytic degradation of toxic anionic dyes i.e. CR and EBT. The acquired materials were characterized by FTIR, XRD, SEM-EDX, XPS, TEM, BET, ZP, and pHZc test. The experiment demonstrated that Mn-CuO@BC composite exhibited a remarkable adsorption of ∼ 98 % and ∼ 95 % and photocatalytic degradation of 92 % and 88 % for CR and EBT respectively. It was further found that coupling of the H2O2 with Mn-CuO@BC enhances the photocatalytic efficiency of catalyst for CR and EBT i.e. upto ∼ 98 % and 96 % respectively possibly owing to the efficient ●OH radical. Adsorption kinetics followed a pseudo 2nd order model, indicating predominant chemisorption, and adsorption isotherms fit well with the Langmuir model. Further, toxicity degradation products of EBT were examined through ECOSAR indicated a reduced ecological impact. In general, this work highlight the dual functional advantages of the Mn-CuO@BC composite, providing an efficient and versatile approach for wastewater treatment involving complex dye pollutants.

Exploring the photocatalytic activity of doped novel SrMoO4 nanoparticles in dye degradation: catalyzing change

To avert future energy crises, it is crucial to pursue sustainable energy sources nonstop. Due to its purity, sustainability, and dependability, solar energy stands out among the variety of evolving options. The utilization of solar energy for the generation of chemical energy has captured considerable attention, presenting the prospect of providing dependable and adaptable energy solutions. In this work, Sol-Gel method is used to synthesize extremely effective novel photocatalysts in the form of Strontium Molbydate (SM), 2.5 % Cerium doped Strontium Molbydate (SM2.5), and 5 % Cerium doped Strontium Molbydate (SM5) nanoparticles. The investigation includes a thorough examination of the photocatalytic study, structural analysis, and morphology of pure and doped samples. X-ray Diffraction (XRD) analysis of all the samples exhibit tetragonal structures, before and after degradation of dye. Scanning electron microscopy (SEM) was used to examine the morphology of each sample. To find out the functional groups present in the samples, Fourier Transform Infrared Spectroscopy (FT-IR) is employed. Liquid Chromatography Mass Spectrometry (LCMS) of the samples have also been done to find out the degradation product. The Mott-Schottky curves for SM, SM2.5, and SM5 exhibited positive slopes, indicating n-type semiconductor behavior. To determine the ecotoxicity of by-products of the CR ECOSAR program was operated. Ultraviolet visible spectroscopy (UV–Vis) results indicated the band gap for SM, SM2.5, and SM5 is 4.12 eV, 3.92 eV, and 3.74 eV, respectively. We employed the degradation of methylene blue (MB) in the presence of UV light irradiation to evaluate the photocatalytic activity. SM5 nanoparticles had the highest photocatalytic activity, reaching 95.5 % in 150 min. Pseudo second order kinetid model is best fitted, and the rate of reaction is 0.0021 (g mg⁻1 min⁻1), 0.0038 (g mg⁻1 min⁻1), 0.00413 (g mg⁻1 min⁻1) for SM, SM2.5, and SM5 respectively.

Poly(N-isopropylacrylamide)-chitosan nanogels for nanotechnological and catalytic applications

Polymer nanogels consisting of poly(N-isopropylacrylamide) and chitosan [P(NC)] were synthesized using a free radical precipitation polymerization technique in an aqueous environment. This process involved the polymerization of N-isopropylacrylamide (NIPAAM) with chitosan (CS) and a cross-linker. These P(NC) nanogels were utilized as nano-reactors for the synthesis of gold nanoparticles (AuNPs), which were formed within the polymeric network through an in-situ reduction process using chloroauric acid [H(AuCl4)] as precursor salt and sodium borohydride (NaBH4) as the reductant. Various analytical methods, including transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), ultraviolet–visible spectroscopy (UV–Vis), and Fourier transform infrared spectroscopy (FTIR), were employed to confirm the formation of P(NC) nanogels and the incorporation and durability of AuNPs within the P(NC) nanogels. The AuNPs loaded P(NC) nanogels were utilized as catalysts for the reduction of 4-nitrophenol (4-NiP) into 4-aminophenol (4-AmP) in the presence of NaBH4. This system was also used to degrade a number of dyes including methylene blue (MB), methylene orange (MO), Rhodamine B (RhB), brilliant blue (BB) and eosin Y ((EY) by using NaBH4 as reducing agent. The Au-P(NC) catalyst exhibited remarkable efficiency, facilitating the fast reduction of 4-NiP and degradation of dyes within a very short interval of time. This system stands out for its economic usage, as even a small quantity of it can efficiently reduce toxic pollutants like 4-NiP and dyes. The results of the reactions highlighted exceptional yield, emphasizing the effectiveness and recyclability of the Au-P(NC) hybrid nanogels as highly capable catalysts.

Degradation of Dyes Using Biologically Synthesized Nanoparticles by Aloe barbadensis Leaves Extract

AbstractNanotechnology has enormous, economic, social, and environmental ramifications. Due to their capacity to survive in complex processes, inorganic nanomaterials like metal/metal oxides have received substantial study during the past decade. Nanoparticles have antibacterial, magnetic, electrical, and catalytic characteristics due to their greater surface area. There are several methods to develop nanoparticles but environment friendly behavior with no toxic byproducts attracts researchers toward biological process of nanoparticles. This work synthesizes copper oxide (CuO) nanoparticles and zinc oxide (ZnO) with Aloe barbadensis (Aloe vera) leaves extract and successfully characterizes them with different analytical techniques. The catalytic activity of such nanoparticles tests over different cationic and anionic dyes like methylene blue (MB), methyl orange (MO), and methyl red (MR) for different intervals of time and reveals. The degradation efficiency of CuO nanoparticles for MB, MO, and MR dyes are 59.92%, 73.48%, and 73.10% respectively, and for ZnO nanoparticles it is 81.44%, 76.46%, and 63.30% for MB, MO, and MR dyes respectively under the exposure of sunlight for 8 h. The present work successfully develops an ecofriendly process of dye degradation by biologically synthesized nanoparticles.

Purification of textile wastewater by collective degradation using nanorods of cesium titanium bromide (CsTiBr3) perovskite

The present work recommends a sustainable environmentally safe method for the removal of textile dyes in an economically viable way.The wastewater expelled from the textile dying units contains a mixture of dyes. Here we address the challenge of using a single catalyst for the collective photocatalytic degradation of mixture of six dyes and two samples of textile effluents collected from a local dying unit under direct sunlight. The lead-free perovskite of CsTiBr3 nanorods prepared via the solvothermal process is effective in the collective photocatalytic degradation of dye mixture containing toxic dyes like congo red, crystal violet, malachite green, methylene blue, rhodamine, and methyl orange. The six-dye mixture turned colorless within three hours of direct sunlight exposure. The collective photocatalytic degradation ability of CsTiBr3 perovskite nanorods is successfully exploited for the degradation of the textile effluents. The chemical oxygen demand (COD) analysis guarantees the degradation of dye into non-toxic components. The recycling of wastewater is made possible by the removal of CsTiBr3 catalysts through adsorption using biochar derived from invasive plants. The biochars are extracted from invasive plants such as Acrostichum Aureum, Alternanthera bettzickiana, cyclosorus interrupts, and Quisqualis indica in which Acrostichum Aureum showed maximum adsorption. The scavenger studies using isopropyl alcohol (IPA), ethylene diamine tetra acetic acid (EDTA), and silver nitrate (AgNO3) suggest that holes control the photocatalysis mechanism.

Anchoring TiO2 and CuO nanoparticles on SnO2 nanotube arrays to construct ternary heterostructure for visible-light-driven photocatalytic degradation of green malachite dye

Designing and constructing heterostructure photocatalysts is necessary to facilitate the long-term separation of photogenerated charge carriers and enhance photocatalytic efficiency. Herein, a ternary nanocomposite photocatalyst based on SnO2, TiO2 and CuO semiconductors was successfully synthesized and employed as a highly effective photocatalyst for the malachite green (MG) dye degradation under visible light irradiation. According to the results, the ternary SnO2/TiO2/CuO nanocomposite demonstrated impressive photocatalytic activity (98.4 %) compared to pristine SnO2 nanotubes (40.3 %), binary SnO2/TiO2 (76 %) and SnO2/CuO nanocomposites (88 %), when exposed to 90 min of visible illumination. The photoreaction rate constant of SnO2/TiO2/CuO nanocomposite (0.0482 min−1) was found to be ∼8.5 times faster than SnO2 nanotubes (0.0057 min−1) against MG dye. This enhancement in photocatalytic performance can be attributed to the introduction of TiO2 and CuO which effectively suppress the recombination of photogenerated electron-hole pairs, accelerate the transfer of charge carriers, increase the active sites, and improve the optical absorption properties. Scavengers were used to elucidate the photocatalytic mechanism, exhibiting the pivotal role of •O2− and h+ in the photodegradation process. Besides, recyclability tests showed acceptable results after four cycles, confirming the stability and durability of the SnO2/TiO2/CuO nanocomposite against RhB dye degradation.

Evaluation of azo dyes degradation potential of Staphylococcus strains: A strategy for dye-waste management

The current investigation aimed to identify the bacterial isolates that could prove helpful in the degeneration of harmful azo dyes from wastewater. The bacterial strains 1b, 1 m, and 4v could decolorize azo dyes up to 81 %, 79 %, and 87 % within 5 days. The degraded products by thin layer chromatography (TLC) showed Rf values of 0.89, 0.95, 0.90, 0.92, and 0.98 while the control showed an Rf value of 0.94. The comparison of the retention time of control and treated samples by the high-performance liquid chromatography (HPLC) system convinced that remarkable decolorization had occurred by the bacterial strains. The Fourier transform infrared spectroscopy (FTIR) analysis of the control and degraded samples was proof that the bond stretching occurred in the treated samples due to the action of bacterial strains. The release of compounds by bacteria i.e., 3-Aminobutanoic acid, pyrrolo pyrazine-1, 4-dione, and palmitic acid was inspected by Gas Chromatography-Mass Spectroscopy (GC-MS) analysis. No clear zones showed that the bacterial dye-degraded wastewater had no harm to the normal flora. At last, phytotoxicity was studied on Vigna radiata which had negative results. Given their pollutant degrading capabilities, these bacterial isolates are a good bioresource for green chemistry to exterminate azo dyes from the environment.

Studies of pure TiO2 and CdSe doped TiO2 nanocomposites from structural, optical, electrochemical, and photocatalytic perspectives

A low temperature hydrothermal method is employed in this study to synthesize CdSe doped TiO2 nanocomposites. Further characterization and studies of the synthesized particles were carried out. As part of this study, the sample was examined by X-ray diffraction to determine its structure, crystallite size, strain, and crystallinity. Molecules were analyzed by energy dispersive X-ray spectroscopy to determine their chemical composition. By using fourier transform infrared spectroscopy spectroscopy, we were able to observe the presence of functional groups as well as the types of bonds. By analyzing the scanning electron microscopy spectra, we were able to determine the particle size while by analyzing the photoluminescence spectra, we could determine the bandgap energy. To determine the nature of materials and their effective photocatalytic behavior, optical bandgap energies were observed in the ultra-violet visible spectrum of synthesized particles. For determining the charge transfer mechanism and specific capacitance, electrochemical studies were conducted using electrochemical impedance spectroscopy and cyclic voltammetry analysis. The degradation of malachite green and Rhodamine-B dyes with CdSe doped TiO2 nanocomposites in the visible region was studied for photocatalytic activity, degradation efficiency, and rate constant. According to the results, doped nanoparticles increased the efficiency of RhB dye degradation by ~ 4% and MG dye degradation by ~ 20% over pure nanoparticles.

Bioengineered Nickel Oxide Nanofabrication for Energy Storage Systems, Degradation of Refractory Water Toxicity, and Antibacterial Study

AbstractNickel oxide (NiO) nanoparticles were synthesized using a green method involving Pterolobium hexapetalum flower extract as the reducing agent. Synthesized nickel oxide nanoparticles (NiO NPs) were thoroughly characterized using X‐ray diffraction, UV–vis spectroscopy, Fourier‐transform infrared spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The XRD analysis confirmed the pure formation of NiO NPs. TEM and SEM images revealed the size, shape, and surface morphology of the nanoparticles. BET analysis indicated a high surface area, making these nanoparticles suitable for various applications. The NiO NPs were further investigated for their potential in supercapacitor applications, demonstrating excellent electrochemical performance. NiO@rGO electrode with graphene proportion showed a maximum specific capacity of 1266 Fg−1 at 1 Ag−1. Moreover, following the 3000‐cycle assessment, the specific retention of 98.2% confirmed that the electrode had high cyclic stability. Additionally, their effectiveness in dye degradation was evaluated, showing promising results in removing organic dyes from wastewater. The antibacterial activity of the NiO nanoparticles was also assessed, indicating significant inhibition against various bacterial strains. These multifaceted studies suggest that NiO NPs synthesized from plant extract hold great promise for applications in energy storage, environmental remediation, and antimicrobial treatments.

Synergistic impacts of novel tantalum doping in BiVO4 for effective photocatalytic applications, antimicrobial activity, and antioxidant aspect

This paper reports the production of pure and Ta-doped (1 %, 2 %, 3 %, and 4 %) BiVO4 nanoparticles (NPs) for MB dye degradation. UV–Vis, FTIR, SEM, PL, and XRD techniques were used to analyze the samples. Photocatalysts (BiVO4, Ta-doped BiVO4) NPs have been used to study the photocatalytic activity of these materials for the degradation of methylene blue (MB) in response to visible light. The band gap reduction from 2.7 to 1.98 eV and the photogeneration of electron-hole pairs have also been demonstrated by UV–visible and PL spectroscopy. According to FTIR spectroscopy analysis, Bismuth, Tantalum, Vanadium, Oxygen, and Carbon are all present in the synthesized material. As the dopant concentration rises, the XRD data show that the crystallite size decreases. The crystallite size of the optimal (4 % Ta-doped BiVO4) is 23 nm, whereas the crystallite size of the 2 % Ta-doped BiVO4 is 39 nm. The SEM image shows that particle size reduces when dopant concentration rises. In comparison to previous synthesized materials, the 4 % Ta-doped BiVO4 NPs have a smaller band gap, crystalline size, and recombination rate. Therefore, using the co-precipitation process, 4 % Ta-doped BiVO4 NPs degrade the MB dye (86 %) in 120 min, making them an ideal material. The findings of this study will be applied to wastewater treatment.

Photo-Fenton-like activity of Fe/ZnO structure applied as a heterogeneous catalyst for the methylene blue dye removal in aqueous matrices

This work developed efficient heterogeneous catalysts for the methylene blue (MB) dye degradation under photo-Fenton-like conditions. The material was modified to incorporate Fe(III) into ZnO, creating Fe/ZnO strucuture, and applied as heterogeneous catalysts at various pH levels. SEM analysis revealed an agglomerated and plate-like morphology of the synthesized catalysts. The enhanced structure facilitated a removal efficiency of 96.2% for MB dye when employing the photo-Fenton-based process using 5.0% Fe/ZnO catalyst. The high removal efficiency is attributed to the synergy between ≡Fe(III) and ≡Zn(II), which promotes the generation of photoradical species through the Fenton effect. Real water matrices served as a source of MB dye contamination, exhibiting minimal interference and achieving ∼100 % of removal. Scavenger studies indicate that •OH and e⁻ are the primary contributors to the high MB dye degradation efficiency. Additionally, the by-products formed after photo-Fenton process exhibit minimal toxicity towards Lactuca sativa L. No Fe(II) ions were leached at the end of the process. Eight cycles of degradation did not cause significant spectral changes in the FTIR analysis, as well as in the XRD patterns, indicating the material efficient and stable structure.

Copper-PANI-graphite HB2 composite for eco-friendly efficient degradation of textile dyes: Advancements in wastewater treatment enhanced by solar radiation

This research aimed to assess the potential of Cu50PANI@UG composite for sunlight drive photocatalytic dye degradation, targeting specifically Thymol Blue (TB) and Black NT (BNT) dyes and their mixture (DM). The Cu50PANI@UG composite was successfully synthesized via electropolymerization in acetonitrile/sulfuric acid mixture under atmospheric conditions. Photocatalytic experiments were conducted by exposing aqueous dye solutions to sunlight. N,N-dimethyl-p-nitrosoaniline (RNO) served as a molecular probe for detecting hydroxyl radicals (•OH). Additionally, experiments capturing free radicals were performed to identify active components, with a concomitant proposal of plausible degradation reaction mechanism for the Photo-Fenton-Like degradation into the Cu50PANI@UG composite + H2O2 + hv reaction system. Various operating parameters affecting dye degradation were evaluated, including catalyst dosage (from 0.27 to 0.67 g L−1), H2O2 concentration (from 16 to 64 mM), pH (from 3.0 to 9.0), and dye concentration (from 25 to 100 mg L−1). Optimization of key parameters such as pH, catalyst dosage, and H2O2 concentration was conducted. The highest degradation efficiency, ca. 100% of DM dye, was achieved within 35 min under optimized conditions, using Cu50PANI@UG composite as a catalytic precursor. These conditions were determined as follows: Catalyst dosage = 0.67 g L−1, pH = 3.0–6.0, H2O2 = 32–64 mM, and irradiation time of 35 min. The degradation percentage under the Response Surface Methodology (RSM) was utilized as a statistical tool to correlate influential parameters. Four consecutive reusability trials were performed to assess catalyst stability.

Structural, electronic and optical properties of SrMnO3 photocatalyst for dye degradation; experimental and DFT study

Perovskite oxides (PO) are versatile multi-functional materials with wide range of applications. In current study, highly-crystalline perovskite manganite (PM) SrMnO3 has been synthesized via ultrasonic method followed by calcination at 600 °C. Morphology of PM with irregular shape and size was assessed by FESEM and hexagonal geometry with a crystallite size of 13.67nm was determined by XRD studies. As-synthesized PM was further tested as photocatalyst for its dye degradation potential against malachite green (MG) and methylene blue (MB). In the presence of synthesized perovskites, degradation of both the dyes MG and MB was achieved in 12min and 4.5min with the percentage degradation of 80.26% and 89.35% respectively. The factors including pH and temperature affecting degradation of both the dyes were also studied. Additionally, calculations based on simulated DFT (density function theory) have been employed to explore the optical, electronic and structural attributes of SrMnO3 PM through generalized gradient approximation (GGA). The total and partial density of states have been evaluated by GGA confirms the Fermi level (Ef) characteristics of metallic Sr and Mn and found that ‘d’ and ‘p’ orbitals of Sr, Mn and O were responsible for the band formation. The results of the current study advocate the synthesis of PM and related compounds followed by their successful applications as catalyst for dye degradation as well as many other fields involving the use of nanomaterials.

Comparative Analysis for Bioremediation of Plastic and Dye Degradation

The leading environmental risk factor for disease and premature death is pollution, with plastic and dye pollutants being the most common in developing countries. The global textile industry contributes to pollution by releasing contaminated wastewater into water bodies, leading to a decline in water quality. Plastic pollution is a widespread issue affecting various environments, emphasizing the urgent need for a global response to combat the adverse effects of pollution on human health and the environment. Anoxybacillus sp. PDR2 is a soil bacterium possessing natural competence. By nature, it is a thermophile, capable of biodegrading industrial dyes. Pseudomonas sp. B10, Gram-negative bacteria, is a strain capable of degrading Polyethylene Terephthalate (PET) plastic. To detect the genome-level mutations, comparative genomic analysis was performed using a free and open source software, Galaxy. Using five different variant callers (Samtools, Varscan, Freebayes, Sniffles, Ivar), mutations were detected at various loci resulting in the modifications of the genes. The primary goal of this investigation was to perform a comparative analysis of the whole genome sequencing of two bacterial species, along with their reference strains. The purpose was to identify potential solutions for the degradation of plastics and industrial dyes. By examining the genetic composition of these bacteria, this analysis had provided valuable insights into the genetic makeup of these bacteria and their ability to break down PETs and dyes.

Chiral FeNC single-atom nanozymes with multi-enzyme activity for dye degradation

The application of single-atom nanozymes in the removal of organic dye pollution by advanced oxidation process (AOPs) have been widely concerned. However, the application of single-atom nanozymes in AOPs is rarely reported. In this work, a kind of Fe-and nitrogen-codoped carbon (Fe-N-C) with peroxidase-like and laccase-like activities was prepared by calcining Fe-doped MOF, then the chiral peptides were introduced into single-atom nanozymes, and chiral single-atom nanozymes (L-Au@FeNC) were successfully prepared. The L-Au@FeNC can effectively activate PMS to degrade different kinds of organic dyes and also shows high cycle stability. In addition, the results of quenching experiment and electron paramagnetic resonance (EPR) test show that 1O2 produced during PMS activation plays an important role in the degradation of organic dyes, and O2·-, ·OH, and SO4·- are also produced during PMS activation, suggesting that the degradation of selected organic dyes include radical and non-radical pathways. It should be noted that L-Au@FeNC showed higher activity than D-Au@FeNC in enzyme-like activity (laccase-like and peroxidase-like) experiment and organic dye degradation, the results of molecular docking simulation indicated that it may be due to the better binding force of L peptide to the substrate of enzyme-like reaction and organic dye than D peptide. This chiral single-atom nanozymes provide a new idea for the application of organic dye degradation and enzyme-like catalysis design.

Synergistic removal of malachite green and Cr(Ⅵ) using ethylenediamine disuccinic acid functionalized silica gel

As common industrial raw materials, malachite green (MG) and Cr(Ⅵ) generally coexist in waste liquids discharged from the paper printing, leather, and textile industries, causing serious harm to humans and the environment. Therefore, developing an effective method for the synergistic removal of MG and Cr(Ⅵ) from aquatic environments is of great research value. In this work, the non-homogeneous Fenton-like catalysts, namely, EDDS-Silica and EDDS-Co2+-Silica were successfully prepared using ethylenediamine disuccinic acid (EDDS) and silica gel (Silica) as raw materials, and a non-homogeneous Fenton-like catalytic method was developed for the efficient and synergistic removal of MG and Cr(Ⅵ) from wastewater. EDDS-Silica and EDDS-Co2+-Silica were analyzed using Fourier infrared spectroscopy and X-ray photoelectron spectroscopy to determine their structural composition and elemental contents. The catalytic degradation and removal effects of these materials in an MG single-waste system were also investigated. The results demonstrated that the incorporation of both materials can overcome the limitation of the conventional Fenton reaction, which is its applicability to acidic environments only. Moreover, EDDS-Co2+-Silica showed better degradation effects on MG than EDDS-Silica. Quantitative calculations based on density functional theory were used to predict the optimal coordination forms between Co2+and EDDS-Silica as well as the MG structure. The lowest unoccupied and highest occupied molecular orbitals of the catalysts were then used to predict the active sites on which MG tends to capture or release electrons during the degradation reaction. The optimal conditions for the synergistic removal of MG and Cr(Ⅵ) from a binary system using EDDS-Co2+-Silica were further investigated under different influencing factors. The results showed that EDDS-Co2+-Silica still had excellent catalytic effect on the degradation rate of MG in the range of pH 3-7, and the optimal conditions were as follows: solution pH, 7; degradation time, 1 h; temperature, 25 ℃; H2O2 concentration, 20 mmol/L; and the initial mass concentration of Cr(Ⅵ), 25 mg/L. Under the above conditions, the degradation rate was increased from 87.25% to 96.67% compared with that in the MG monosystem. Obvious enhancements in degradation effect and efficiency confirmed that the incorporation of EDDS-Co2+-Silica was favorable for the synergistic removal of MG and Cr(Ⅵ) in the binary system. Strongly oxidizing Cr(Ⅵ) can participate in the Fenton reaction, thus promoting MG degradation over a wide pH range. Thus, a positive synergistic effect exists between MG and Cr(Ⅵ). Considering that a large number of metal ions remained in the solution after the degradation reaction, EDDS-Silica was added to the degradation solution, and adsorption experiments were performed for 4 h at 30 ℃to adsorb and remove Cr and Fe via the strong chelating property of EDDS. The total residual mass concentrations of Cr and Fe were 4.96 and 1.02 mg/L, respectively, which meet national emission standards. These findings indicate that EDDS-Silica has good effects on the removal of residual metal ions after the nonhomogeneous Fenton reaction. As heterogeneous Fenton-like catalysts, the aminopolycarboxylic acid-modified materials proposed in this study can simultaneously promote the Fenton reaction and remove residual metal ions, thereby effectively removing MG and Cr(Ⅵ) from the binary system while ensuring that the content of residual metal ions in the system meets environmental emission standards. This study has broad application prospects in dye degradation and heavy-metal-ion wastewater treatment, and provides a reference value and theoretical basis for the development of other similar ligand-modified materials.

Nano-synthesis, characterization, theoretical, biological and catalytic studies of Mn(II), Cu(II), Cd(II), and Th(IV) complexes based on antipyrine azo dye ligand

The design and detailed characterization of the azo dye ligand obtained from the reaction of 4-aminoantipyrine diazonium salt with 3-hydroxybenzaldehyde (HL) and its novel metal chelates with Mn2+, Cu2+, Cd2+ and Th4+ ions have been presented. Utilizing modern spectroscopic and analytical techniques, these complexes were found to adopt an octahedral geometry, demonstrate inner sphere d2sp3 hybridization for Th(IV) complex and outer sphere sp3d2 hybridization for other complexes. Particle sizes calculated using the Debye-Scherrer equation on XRD patterns were 32.05 nm for Mn(II), 34.07 nm for Cu(II), 30.90 nm for Cd(II), and 22.05 nm for Th(IV). These substances' anticancer activity was assessed on human lung cancer cells (A-549) and pancreatic carcinoma cell lines (PANC-1). Cd(II) complex exhibited higher cytotoxicity against the A-549 cell line than the reference drug vinblastine sulfate which revealing its potential application as a new anticancer agent. Quantum chemical computations using the DMOL3 module's density functional theory (DFT) and molecular docking studies with the Schrödinger suite demonstrated significant inhibitory effects of the free organic compound and Cu(II) chelate on the FGFR1 protein, crucial for cell development and differentiation. Additionally, the study examined the catalytic activity of HL and its metal chelates in the oxidative degradation of methyl violet 2B dye in presence of H2O2. The order was followed by the pseudo-first-order rate constants: Th(IV) chelate (0.9556 min⁻¹) > HL (0.4911 min⁻¹) > Cu(II) chelate (0.5979 min⁻¹) > Mn(II) chelate (0.2645 min⁻¹) > Cd(II) chelate (0.2280 min⁻¹).