Fe-based metallic glass catalyst with nanoporous surface for azo dye degradation

Electrospun cellulose acetate/activated carbon composite modified by EDTA (rC/AC-EDTA) for efficient methylene blue dye removal

The present study fabricated regenerated cellulose nanofiber incorporated with activated carbon and functionalized rC/AC3.7 with EDTA reagent for methylene blue (MB) dye removal. The rC/AC3.7 was fabricated by electrospinning cellulose acetate (CA) with activated carbon (AC) solution followed by deacetylation. FT-IR spectroscopy was applied to prove the chemical structures. In contrast, BET, SEM, TGA and DSC analyses were applied to study the fiber diameter and structure morphology, the thermal properties and the surface properties of rC/AC3.7-EDTA. The CA was successfully deacetylated to give regenerated cellulose nanofiber/activated carbon, and then ethylenediaminetetraacetic acid dianhydride was used to functionalize the fabricated nanofiber composite. The rC/AC3.7-EDTA, rC/AC5.5-EDTA and rC/AC6.7-EDTA were tested for adsorption of MB dye with maximum removal percentages reaching 97.48, 90.44 and 94.17%, respectively. The best circumstances for batch absorption experiments of MB dye on rC/AC3.7-EDTA were pH 7, an adsorbent dose of 2 g/L, and a starting MB dye concentration of 20 mg/L for 180 min of contact time, with a maximum removal percentage of 99.14%. The best-fit isotherm models are Temkin and Hasely. The outcome of isotherm models illustrates the applicability of the Langmuir isotherm model (LIM). The maximal monolayer capacity Q_m determined from the linear LIM is 60.61 for 0.5 g/L of rC/AC3.7-EDTA. However, based on the results from error function studies, the generalized isotherm model has the lowest accuracy. The data obtained by the kinetic models' studies exposed that the absorption system follows the pseudo-second-order kinetic model (PSOM) throughout the absorption period.

Enhanced degradation performance of Fe75B12.5Si12.5 amorphous alloys on azo dye

The Fe₇₅B_12.5Si_12.5 and Fe₇₅B_12.5C_12.5 amorphous alloy ribbons were prepared by the melt spinning method. The decolorization performances of these ribbons were investigated in details. It is found that the Fe₇₅B_12.5C_12.5 amorphous ribbons and Fe₇₅B_12.5Si_12.5 annealed ribbons only adsorbed the azo dye molecules, with no chemical degradation process. However, the Fe₇₅B_12.5Si_12.5 amorphous ribbons can reduce -N = N- to -NH₂ because of their high reactivity and the local galvanic effect that occurred during the reaction to accelerate electron transfer. The reaction rate constant k_obs is 0.0872 min^-1, 0.0474 min^-1, and 0.0064 min^-1 for Fe₇₅B_12.5Si_12.5 amorphous ribbons, Fe₇₅B_12.5C_12.5 amorphous ribbons, and Fe₇₅B_12.5Si_12.5 annealed ribbons in the same condition, respectively. Fe₇₅B_12.5Si_12.5 amorphous ribbons can effectively degrade Acid Orange II (AO II) azo dyes and achieve decolorization by breaking azo bonds in the dye in a short time, indicating the prominent capacity of Fe₇₅B_12.5Si_12.5 ribbons on the degradation of AO II. Furthermore, the influence of chemical factors such as ribbons thickness, reaction temperature, initial pH, and AO II concentration of the solution on the reaction rate constant k_obs of Fe₇₅B_12.5Si_12.5 amorphous ribbons had also been studied. The k_obs can reach 0.177 min^-1 under optimal conditions. In addition, all the degradation processes in this work were fitted well with the pseudo-first-order kinetic model. The results are guidance for the practical applications, and they have important implications in developing Fe-based amorphous alloys for functional application materials in the field of wastewater treatment.

Nanomaterials as a Sustainable Choice for Treating Wastewater: A Review

The removal of dyes from textile effluents utilizing advanced wastewater treatment methods with high efficiency and low cost has received substantial attention due to the rise in pollutants in water. The purpose of this work is to give a comprehensive analysis of the different treatments for removing chemical dyes from textile effluents. The capability and potential of conventional treatments for the degradation of dyeing compounds in aqueous media, as well as the influence of multiple parameters, such as the pH solution, initial dye concentration, and adsorbent dose, are presented in this study. This study is an overview of the scientific research literature on this topic, including nanoreductive and nanophotocatalyst processes, as well as nanoadsorbents and nanomembranes. For the purpose of treating sewage, the special properties of nanoparticles are currently being carefully researched. The ability of nanomaterials to remove organic matter, fungus, and viruses from wastewater is another benefit. Nanomaterials are employed in advanced oxidation techniques to clean wastewater. Additionally, because of their small dimensions, nanoparticles have a wide effective area of contact. Due to this, nanoparticles' adsorption and reactivity are powerful. The improvement of nanomaterial technology will be beneficial for the treatment of wastewater. This report also offers a thorough review of the distinctive properties of nanomaterials used in wastewater treatment, as well as their appropriate application and future possibilities. Since only a few types of nanomaterials have been produced, it is also important to focus on their technological feasibility in addition to their economic feasibility. According to this study, nanoparticles (NPs) have a significant adsorption area, efficient chemical reactions, and electrical conductivity that help treat wastewater effectively.

Review of Thermoplastic Drawing with Bulk Metallic Glasses

This study summarizes the recent progress in thermoplastic drawing of bulk metallic glasses. The integration of drawing with templated embossing enables the fabrication of arrays of high-aspect-ratio nanostructures whereas the earlier drawing methodologies are limited to a single fiber. The two-step drawing can produce metallic glass structures such as, vertically aligned nanowires on substrates, nanoscale tensile specimens, hollow microneedles, helical shafts, and micro-yarns, which are challenging to fabricate with other thermoplastic forming operations. These geometries will open new applications for bulk metallic glasses in the areas of sensors, optical absorption, transdermal drug-delivery, and high-throughput characterization of size-effects. In this article, we review the emergence of template-based thermoplastic drawing in bulk metallic glasses. The review focuses on the development of experimental set-up, the quantitative description of drawing process, and the versatility of drawing methodology.

Middle-low-temperature oxidation and adsorption of arsenic from flue gas by Fe-Ce-based composite catalyst

Fe-Ce-based composite catalysts were prepared and used for As₂O₃ catalytic oxidation and adsorption. They were characterized by XRD, BET, H₂-TPR, Raman, SEM and XPS. The results suggests Fe, La and Zr can be partially doped into CeO₂ lattice to form solid solutions. Compared with pure Fe₂O₃, the composite catalysts have stronger low-temperature reducibility, especially La³⁺ doping is beneficial to the formation of more low-temperature active sites. Raman and XPS measurements disclose the presence of oxygen vacancy and surface adsorbed oxygen in composite catalysts and these are more prominent in FeCeLaO. Ce³⁺ ratio increases to 18.30% after reaction, which confirms part of Ce⁴⁺ can participate in As₂O₃ oxidation and be reduced to Ce³⁺. The oxidation and adsorption capacity for As₂O₃ were investigated at different temperatures and O₂ concentrations. The results show FeCeLaO exhibits excellent activity at middle-low-temperatures of 200-400 °C, the oxidation efficiency of As₂O₃ can reach 100%, the total adsorbed arsenic at 400 °C reaches 583.7 μg/g, which is 1.8 times of pure Fe₂O₃ at 600 °C. As₂O₃ oxidation mechanism over FeCeLaO with/without O₂ was proposed through the Mars-Maessen theory with the aid of surface-active oxygen. The abundant oxygen vacancy defects and active chemisorbed oxygen play important roles and guarantee an efficient As₂O₃ oxidation, which is also the essential reason why the composite catalysts can effectively oxidize and adsorb As₂O₃ at middle-low-temperature of 200-400 °C, while pure Fe₂O₃ can only be at high temperature of 600-700 °C.

Degradation performance and mechanism toward methyl orange via nanoporous copper powders fabricated by dealloying of ZrCuNiAl metallic glassy precursors

The catalyst of nanoporous Cu (NP-Cu) powders, with the chemical composition of Cu_79.63Ni_6.85O_13.53(at%), was successfully fabricated by dealloying of Zr-Cu-Ni-Al metallic glassy precursors. The as-prepared NP-Cu powders, co-existing with Cu₂O phase on Cu ligament surface, had a three-dimensional network porous structure. The NP-Cu powders/H₂O₂system showed superior catalytic degradation efficiency toward azo dyes in both acidic (pH 2) and neutral (pH 7) environments. Moreover, the cyclic tests indicated that this powder catalyst also exhibited good durability. A novel degradation mechanism of NP-Cu powders/H₂O₂was proposed: the high degradation performance in acidic environment was mainly derived from heterogeneous reaction involved with a specific pathway related to Cu³⁺to produce HO·, while in neutral environment it was primarily resulted from homogeneous reaction with the generation of HO· from the classical Cu-based Fenton-like process. This work indicates that the NP-Cu powders have great potential applications as catalysts for wastewater treatments.

Photocatalytic Degradation of Diazo Dye over Suspended and Immobilized TiO2 Catalyst in Swirl Flow Reactor: Kinetic Modeling

The degradation kinetics of Direct Blue 15 (DB15), a diazo dye, were studied over a suspended and immobilized TiO2 catalyst. For all experiments, the kinetics experiments were performed in a swirl flow photoreactor under the influence of UV light. The effect of different parameters: dye concentration, catalyst loading, and light intensity, on the DB15 kinetics was investigated. The kinetic rates were assessed using apparent (ka) approach, a single value of reaction rate (kr) and adsorption constant (K), and approach of kr as of variable. The DB15 mineralization was discussed as well. Using a dip-coating device, the P25 catalyst was deposited on a Pyrex glass. The thin film surface characterization was examined. The coated catalyst was evaluated by checking the effect of two variables: initial dye concentration and light intensity on the DB15 kinetics. In terms of the ka approach, the results demonstrated that DB15 degradation is described by the pseudo first-order kinetics model. The Langmuir-Hinshelwood (L-H) model was fitted well with the experimental data for the number of process variables. L-H constant kr was determined as a function of three parameters: initial dye concentration, catalyst loading, and light intensity. The ka values were evaluated and compared with experimental results. In terms of three variables, ka can be expressed as ka=0.15 [C]o−0.69 [W]0.73 I0.91 1+0.17 [C]o  while the empirical model results in the following expression, ka=0.77 [C]o−1.65 [W]0.73 Io0.89. It was observed that 83.64% mineralization was achieved after a period of 16 hrs. In terms of immobilized catalyst, the DB15 degradation kinetics was described by a pseudo first-order model for different dye concentrations. Meanwhile, a power-law model described the impact of light intensity on dye kinetics. In addition, the coated catalyst was successfully reusable with high efficiency for up to four cycles.

The catalytic performance of Cu46Zr47-xAl7Yx amorphous ribbons in the degradation of AO II dye wastewater

Metallic glasses (MGs) with unique disordered atomic stacking structures exhibit excellent catalytic performance in wastewater treatment. The catalytic degradation of Orange II (AO II) aqueous solutions by four CuZr-based MG ribbons under such processing parameters as pH values, the dosage of ribbons, and temperature was investigated in this paper. The catalytic performance of the MG ribbons was characterized by using the degradation efficiency of the dye wastewater. The phase constituent, surface morphology, and chemical valence state of elements on the surface of MG ribbons before and after use were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the Cu₄₆Zr₄₂Al₇Y₅ MG ribbon has the best catalytic performance among the Cu₄₆Zr_47-xAl₇Y_x (x = 0, 1, 3, 5) MGs in the degradation process, and the dye in the wastewater can almost be completely decolorized within 60 min under the conditions of pH = 2, the dosage of ribbons being 1.8 g/L and water bath temperature of 313 K, with the degradation efficiency and chemical oxygen demand removal being 96.05% and 51.73%, respectively. Furthermore, the Cu₄₆Zr₄₂Al₇Y₅ MG ribbon still shows superior structural stability and degradation performance after repeated use, and the corrosion pits on the MG surface promote the physicochemical reaction between the wastewater and the ribbons.

Excellent dye degradation performance of FeSiBP amorphous alloys by Fenton-like process

Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure. They possess excellent degradation efficiency, stability and reusability. In this work, Fe₈₀Si₁₀B₁₀ and Fe₈₃Si₅B₈P₄ amorphous ribbons exhibited advanced catalytic performance for the degradation of Methyl Blue (MB) and Rhodamine B (RhB) dyes, and the color removal reach nearly 100% within 11 min for both the dyes. Compared with the Fe₈₀Si₁₀B₁₀ amorphous ribbon, the Fe₈₃Si₅B₈P₄ ribbon showed higher degradation efficiency due to its lower reaction activation energy, higher electron transfer ability and higher Fe content, and the formation of the galvanic cell between the strong Fe-P bonds and the weak Fe-B bonds. It also exhibited high stability and reusability. The degradation efficiency was improved when the appropriate concentration of H₂O₂ is added. As regards the pH, high degradation efficiency was observed in acidic MB solution, but it decreased as the pH increased up to pH 7. The application of the electro-Fenton-like process is discussed, which can effectively improve the degradation performance in a nearly natural solution. This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.

Modeling of Degradation of Diazo Dye in Swirl-Flow Photocatalytic Reactor: Response Surface Approach

Photocatalytic degradation of Direct Blue 15 (DB15), an azo dye, was studied using a swirl-flow monolithic reactor under UV irradiation. The degradation reactions were carried out to investigate effects of initial dye concentration, catalyst loading, and light intensity at an optimal pH. The experiments were designed and mathematically modelled by CCD-RSM (central composite design-response surface methodology) approach. It was found that the selected parameters significantly affect DB15 degradation. In terms of the linear term, catalyst loading and light intensity had a synergistic effect, while dye concentration registered the opposite effect. Strong interaction was observed between catalyst loading and both light intensity and initial dye concentration compared with the interaction of light intensity and initial dye concentration. Based on the experimental results, a quadratic model was developed to predict the percentage removal of DB15. The predicted values of the model were in good agreement with the experimental values (R2 = 0.987), indicating the model fits well for the parameter space for which experiments were performed. According to diagnostic plots, the model credibility was valid because its residuals were distributed normally and exhibited a random pattern based on their examination versus the predicted values. The results revealed that the initial dye concentration and catalyst concentration have a significant effect on the mineralization time.