Methylene Blue Aqueous Solution Research Articles

Boosting the photocatalytic activity of bismuth vanadate (BiVO4) via optimization of the internal polarization

Photocatalytic performance can be improved by optimizing the morphology and surface texture of the photocatalyst or forming different p-n and/or n-n heterojunctions. Although the heterojunction system enhances photocatalytic property; however, an internal spontaneous polarization electric field may be much more effective due to the separation of electron-hole pairs when the polarization field forces them to move in different directions. The present study demonstrated this insight where the BiVO4 synthesis condition and polarization field forces were controlled via homogeneous precipitation in the presence of polyvinylpyrrolidone (PVP). The as-synthesized BiVO4 photocatalysts' structure and morphology were investigated using XRD, SEM, Raman, DRS, and PL. The result revealed that the increase of PVP concentration reformed the shaping to the truncated bipyramid-like shape and creates a spontaneous internal polarization that enhanced BiVO4 photocatalytic performance. The photocatalytic activity of BiVO4 was evaluated by monitoring the photocurrent enhancement using chronoamperometry, electrochemical impedance spectra and the photodegrading of methylene blue (MB) aqueous solution to harmless compounds in the presence of light. The spontaneous polarization between the different facets of BiVO4 crystal enhances the e−/h+ separation during internal facets homojunction and leads to four times photocurrent enhancement and the MB photocatalytic degradation rate increased from 0.43 to 1.92 min−1.

Synthesis of stannite Cu2CoSnS4 and its use as photocatalyst for degradation of pollutants

We report the synthesis of p-type stannite Cu2CoSnS4 (CCTS) powder by direct fusion, and its use as a photocatalyst for the degradation of methylene blue (MB) under solar irradiation. Structural analysis by X-ray diffraction and Raman spectroscopy revealed that the prepared powder is polycrystalline and has preferential orientation along the (112) plane, characteristic of the stannite phase. Scanning electron microscopy (SEM) images show agglomerated nanoparticles. Compositional analysis by energy dispersive spectroscopy shows that the composition of the prepared CCTS powder approaches the theoretical 2:1:1:4 stoichiometry. The oxidation state of the constituent elements in CCTS powder were investigated by X-ray photoelectron microscopy (XPS), which reveals that the valence states of the constituent elements present in the CCTS sample are: Cu+, Co2+, Sn4+and S2−. Optical analysis through diffusion reflectance and photoluminescence (PL) spectroscopy were used to estimate the bandgap, which was found to be about 1.4 eV. Upon visible light illumination, CCTS powder exhibits an excellent photocatalytic performance. The apparent reaction rate constant k found to be k = 13.10−3 min−1, which suggests that the p-type stannite CCTS powder would be a promising candidate of photocatalyst for the degradation of MB in aqueous solution.

Broadband and strong visible-light driven photocatalytic enhancement utilizing two-dimensional plasmonics of Au/Cu-modified SrTiO3 perovskite nanostructures

Addressing limited access to clean drinking water demands innovative solutions to energy and environmental crises. Photocatalysis offers promise without eliciting secondary pollution, yet traditional metal oxide semiconductor photocatalysts encounter impediments in solar energy utilization and charge carrier recombination rates. To overcome these limitations, we present for the first time, a novel design, fabrication, and characterization of two-dimensional plasmonic noble metal/perovskite nanostructure hybrids for photocatalysis, combining Au as the plasmonic material with Cu-modified SrTiO3 as the semiconductor, fabricated on elastomeric polydimethylsiloxane substrates. Integrating localized surface plasmon resonance and Schottky junction-related band-bending significantly extends optical absorption into the ultraviolet-visible-infrared bands and enhances the effective carrier lifetimes, ensuring state-of-the-art photocatalytic efficiency. Exceptional photocatalytic performance in a 5-ppm aqueous methylene blue solution can be attained with 72.69-wt% Cu incorporation in the perovskite oxide, reaching a visible light-mediated photodegradation efficiency of 26% - an astounding 62.5-% efficiency increase compared to previous experiments without Cu modification. This advancement underscores the synergistic potential of noble metals and photocatalytic semiconductors in managing water purification challenges.

Efficient Adsorption of Methylene Blue Using a Hierarchically Structured Metal-Organic Framework Derived from Layered Double Hydroxide.

The growing concerns about environmental pollution, particularly water pollution, are causing an increasing alarm in modern society. One promising approach to address this issue involves engineering existing materials to enhance their effectiveness. A one-step solvothermal reconstruction approach was used to build an eco-friendly two-dimensional (2D) AlNiZn-LDH/BDC MOF composite. The characterizations confirm the formation of a metal-organic framework (MOF) at the layered double hydroxide (LDH) surface. The resulting synthesized material, 2D AlNiZn-LDH/BDC MOF, demonstrated remarkable efficacy in decontaminating methylene blue (MB), a model cationic dye found in water systems. The removal performance of 2D AlNiZn-LDH/BDC MOF was significantly higher than that of pristine 2D AlNiZn-LDH. This improvement shows the potential to increase the adsorption capabilities of nanoporous LDH materials by incorporating organic ligands and integrating meso-/microporosity through MOF formation on their surfaces. Furthermore, their kinetic, isothermal, and thermodynamic studies elucidated the adsorption behavior of this composite material. The results of synthesized MOF showed excellent removal efficiency (92.27%) of 10 ppm of MB aqueous solution as compared to pristine LDH. Additionally, the as-synthesized adsorbent could be regenerated for six successive cycles. This method holds promise for the synthesis of novel and highly effective materials to combat water pollution, laying the groundwork for potential advancements in diverse applications.

High-performance of ZnO/TiO2 heterostructured thin-film photocatalyst fabricated via atomic layer deposition

Oxide semiconductor is one of the most promising candidates for photocatalysts due to its light absorption ability, electronic properties, and stability. It is used in various applications such as solar-energy conversion, CO2 reduction, and water splitting. In this research, ZnO, TiO2, and ZnO/TiO2 heterostructured thin films are fabricated via atomic layer deposition (ALD), and their photocatalytic performances are evaluated. The film thickness can be controlled using ALD, and surface reactions can easily occur in thin films owing to the short distances between the active sites and charge carriers. In addition, unlike a powder catalyst, the bilayer photocatalyst is fixed in the solution; therefore, it does not make the solution turbid or disturb the light penetration. Diethylzinc and titanium tetraisopropoxide are used as precursors for Zn and Ti, and the thin films are deposited on soda-lime glass substrates at 150 °C using H2O as the reactant gas. The photocatalytic activity and stability are evaluated through photodegradation tests using methylene blue aqueous solution. The ZnO single-substance thin film exhibits a high degradation rate, but its performance significantly decreases after three consecutive experiments. The TiO2 single-substance thin film exhibits a relatively low degradation rate, but high reusability, exhibiting characteristics opposite to that of ZnO. Therefore, a TiO2 thin film is coated on ZnO to leverage both these advantages. The thin films are heat-treated at 400 °C for 10 min after deposition in a vacuum atmosphere. The surface morphology, crystal structure, and electrical characteristics of the photocatalyst specimens are analyzed through high-resolution scanning electron microscopy, Cs-corrected scanning transmission electron microscopy, and x-ray diffraction analysis. Their photocatalytic performances under ultraviolet (UV) irradiation are measured through UV–visible spectroscopy. The heat-treated ZnO/TiO2 heterostructured thin film exhibits a photodegradation rate exceeding 80%, with little degeneration after three cycles, indicating enhanced photodegradation performance and stability.

Fabrication and Characterization of Electrospun Cu-Doped TiO2 Nanofibers and Enhancement of Photocatalytic Performance Depending on Cu Content and Electron Beam Irradiation.

Titanium dioxide (TiO₂) is a widely studied material with many attractive properties such as its photocatalytic features. However, its commercial use is limited due to issues such as deactivation in the visible spectrum caused by its wide bandgap and the short lifetime of photo-excited charge carriers. To overcome these challenges, various modifications could be considered. In this study, we investigated copper doping and electron beam treatment. As-spun TiO2 nanofibers were fabricated by electrospinning a TiO2 sol, which obtained viscosity through a polyvinylpyrrolidone (PVP) matrix. Cu-doped TiO2 nanofibers with varying dopant concentrations were synthesized by adding copper salts. Then, the as-spun nanofibers were calcined for crystallization. To evaluate photocatalytic performance, a photodegradation test of methylene blue aqueous solution was performed for 6 h. Methylene blue concentration was measured over time using UV-Vis spectroscopy. The results showed that Cu doping at an appropriate concentration and electron-beam irradiation showed improved photocatalytic efficiency compared to bare TiO2 nanofibers. When the molar ratio of Cu/Ti was 0.05%, photodegradation rate was highest, which was 10.39% higher than that of bare TiO2. As a result of additional electron-beam treatment of this sample, photocatalytic efficiency improved up to 8.93% compared to samples without electron-beam treatment.

Facile construction of robust superhydrophobic ZIF‐8@pulp/cellulose nanofiber (CNF) membrane for multifunctional applications

Given the increasing contamination of freshwater supplies, it is essential to effectively treat industrial wastewater. However, treating industrial wastewater using a single method is challenging due to the presence of complex contaminants like petroleum, organic dyes, bacteria, and other complex contaminants. In this study, we present a straightforward and scalable approach to prepare multifunctional nanocellulose-based membranes (NM) that exhibit superhydrophobicity, self-cleaning, oil/water separation, photocatalysis, and anti-bioadhesion properties. To begin with, we created NM by extruding fiber slurry onto a stencil and drying it. Next, we built a polyurethane (PU)/ZIF‐8/1H, 1H, 2H, 2H‐perfluorooctyltriethoxysilane (POTS)-based superhydrophobic layer by spraying it over the NM's surface. By employing the aforementioned processes, we successfully integrated multiple functions into a single superhydrophobic NM. Our results demonstrate that the NM-PU/ZIF-8/POTS membrane exhibits superior hydrophobicity performance, with a high-water contact angle (166.8 ± 0.8°) and a low rolling angle (5 ± 0.3°). Moreover, these samples retain high-water contact angles and low rolling angles even in harsh environments such as acid and alkali solutions, high temperatures, abrasion resistance, UV aging resistance, bending and folding, tape peeling, and self-cleaning. The NM-PU/ZIF-8/POTS membrane also exhibits high and stable oil-water separation performance, with a separation efficiency of 94.6% and a relatively high separation flux (133.2 L·m−2·h−1). At the same time, the NM-PU/ZIF-8/POTS membrane exhibits water-in-oil emulsion separation ability. The membrane’s stability, effectiveness, and reusability were demonstrated through ten repetitions of degradation experiments using aqueous methylene blue solution, with the NM-PU/ZIF-8/POTS membrane exhibiting an excellent degradation rate (>94%). Finally, the bioadhesion resistance test indicated a reduction of 69.1% in the adhesion rate of the NM-PU/ZIF-8/POTS membrane. Overall, the creation of the NM-PU/ZIF-8/POTS membrane serves as a useful inspiration for the practical application of superhydrophobic NM in multifunctional integration, while also broadening the scope of membrane applications.

The Development and Synthesis of a CdZnS @Metal–Organic Framework ZIF-8 for the Highly Efficient Photocatalytic Degradation of Organic Dyes

The development of photocatalysts for organic degradation is a hot research topic. In this study, CdZnS was selected as the carrier, and ZIF-8 was combined with it to explore the photocatalytic performance of the composite. In addition, the compound material, CdZnS@ZIF-8, was used as a photocatalyst for the decomposition of methylene blue dye, and the performance of pure CdZnS and pure ZIF-8 was compared. The photocatalytic efficiency of CdZnS@ZIF-8 was significantly higher than that of the other two. In the experimental reaction, the amount of catalyst was 0.04 g, the pH value was 7, the initial concentration of methylene blue aqueous solution was 20 mg/L, and the degradation of methylene blue in 50 mL aqueous solution could reach 99.5% under visible light irradiation for 90 min, showing excellent photocatalytic efficiency in the visible light range. It demonstrated excellent photocatalytic function in the visible light region, and the electron transfer phenomenon at the interface occurred in the het-junction and the separation of the photo-generating electron–hole as an electron acceptor of ZIF-8 further promoted the photocatalytic effect.

A Fresh Perspective on the Impact of ZnTiO3 Coupling on the Microstructure and Photocatalytic Properties of TiO2 Fabricated at Varied Temperatures.

ZnTiO3/TiO2 composite photocatalysts were synthesized via the sol-gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO2 undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO3 engenders a reduction in the TiO2 grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO3. In contrast, for pure TiO2, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min-1. Interestingly, the ZnTiO3/TiO2 composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO2 across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO3 coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.

Nanocomposites of Nb2O5 and ZnO with reduced graphene oxide for heterogeneous photocatalysis of dyes

Nanocomposites of Nb2O5 and ZnO with reduced graphene oxide for heterogeneous photocatalysis of dyes

Enhancing photocatalysis through annealing: Unveiling the role of physical properties in photocatalytic behavior

Using spray pyrolysis, silver-doped In2S3 thin films were deposited on pre-heated glass substrates, with varying doping concentrations. Subsequently, these films underwent vacuum annealing at 400 °C for a duration of 2 h. A comprehensive study of their structural, morphological, and optical properties was conducted, revealing homogeneous, compact, crack-free films with polycrystalline tetragonal-phase of In2S3. Among the set of the analyzed films the best parameter values, including crystallite size, dislocation density, micro-strain, grain size, and root mean square (RMS) roughness, were achieved when maintaining a Silver-to-indium (|Ag|/|In|) ratio of 4 % in the precursors for both as-deposited and annealed samples. The annealing process had a discernible impact on the grain size distribution, resulting in a significant increase in crystallite and grain size, along with RMS roughness, for most doped films. The optical analysis of these films unveiled their transparency in the visible and near-infrared regions, coupled with substantial absorption in the UV region. Higher Ag concentration in the as-deposited films led to an increased band gap energy in the annealed samples. The roughness peaked at |Ag|/|In| = 4 %, resulting in a noteworthy enhancement of photocatalytic activity, achieving 95 % photodegradation of a methylene blue aqueous solution. This underscores the critical role of surface properties in determining performance. Future research intends to explore other applications for these thin films, including potential usage in gas sensors, capitalizing these films' promising characteristics.

Integrated adsorption and photocatalytic removal of methylene blue dye from aqueous solution by hierarchical Nb2O5@PAN/PVDF/ANO composite nanofibers

This work presents the development of hierarchical niobium pentoxide (Nb2O5)-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue (MB) pollutants from aqueous solutions. The Nb2O5 nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate (V) oxalate hydrate (Nb2O5@PAN/PVDF/ANO). They were characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) analysis, and Fourier transform infrared (FTIR) spectroscopy. These composite nanofibers possessed a narrow optical bandgap energy of 3.31 ​eV and demonstrated an MB degradation efficiency of 96 ​% after 480 ​min contact time. The pseudo-first-order kinetic study was also conducted, in which Nb2O5@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29 ​× ​10−2 ​min−1 and 0.30 ​× ​10−2 ​min−1 for adsorption and photocatalytic degradation of MB aqueous solutions, respectively. These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb2O5 nanostructures. Besides their outstanding photocatalytic performance, the developed membrane materials exhibit advantageous characteristics in recycling, which subsequently widen their practical use in environmental remediation applications.

Fabrication of recyclable magnetic carbon material adsorbent from waste ion exchange resin

Recently, the circular economy aiming at recycle of waste as the raw material of new valuable products has attracted great interest. In this study the carbon material (CM) was obtained by carbonization of waste ion exchange resin (WIER) and the magnetic carbon material (MCM) was prepared by mixing CM with an aqueous Fe3+/Fe2+ solution followed by the NaOH treatment. Surface structure and charges of CM and MCM were characterized by SEM, XRD, FTIR and potentiometric titration. The surface charge analysis showed that surfaces of CM and MCM were negatively charged in the alkaline condition. The characteristic peaks of magnetite on MCM can be found in XRD patterns and FT-IR spectra. Adsorption capabilities of CM and MCM was tested in the methylene blue (MB) aqueous solution. MCM adsorption efficiency is 97.7 %, while 81.1 % of CM. MCM adsorption capacity is 13.9 mg/g, better than 10.33 mg/g of CM. Nearly 96 % MB was degraded in the Fenton-Like process by MCM. MCM reusability was verified in the adsorption/ desorption test conducted for five cycles, in which the adsorption efficiency remained 83.6 % at the fifth cycle. The experimental data were fitted by adsorption isotherms, showing that MB adsorption on CM and MCM were more consistent with Langmuir model. In the adsorption kinetic analysis, the pseudo-first order model fitted better for CM sorption, while the pseudo-second order model for MCM. This work revealed that WIER is a proper precursor of carbon adsorbent for MB dye, which would specifically reduce the environmental cost of waste disposal.

Enhancing adsorption capacity of magnetic magnesium-aluminum layered double hydroxide by surface modification with sodium dodecyl sulfate for efficient removal of organic contaminants

A magnetic magnesium-aluminum layered double hydroxide (Mag-MgAl) was prepared, and its surface was modified using surfactant sodium dodecyl sulfate (SDS) and utilized as adsorbents for antibiotic ciprofloxacin (CIP) and dyes ponceau red (PR) and methylene blue (MB). Mag-MgAl/SDS demonstrated twice the adsorption capacity for CIP compared to Mag-MgAl, confirming that the surface modification by SDS aided the adsorption capacity. At pH 3.5, Mag-MgAl removed CIP and PR, attributed to electrostatic effect and hydrogen bonding, whereas it did not interact with MB. Conversely, Mag-MgAl/SDS successfully removed both MB and CIP, suggesting that SDS micelles acted as nanoreactors attracting cationic contaminants. The PR removal efficiency was low, possibly due to electrostatic repulsion. A binary dye system adsorption assessment was performed by mixing MB and PR aqueous solutions with Mag-MgAl and Mag-MgAl/SDS as selective adsorbents. Mag-MgAl removed around 80% of PR and 45% of MB, whereas Mag-MgAl/SDS removed less than 40% of PR and 80% of MB. SDS remains adsorbed on the surface of Mag-MgAl/SDS after the adsorption process of CIP, MB, or PR. The inversion in the affinity for the target molecules suggests that the surface of the composite can be adjusted to modulate the behavior of the adsorbent toward organic contaminants.

Causes of adverse outcomes in acute intestinal obstruction.

The purpose of this study is to analyse the effectiveness of methods of diagnosis and treatment of patients with acute intestinal obstruction. A total of 123 patients were examined, who were diagnosed based on history, an overview X-ray of the abdominal cavity, a contrast examination of the intestine, and contrast marks according to Yu. L. Shalkov and irrigoscopy. 57.4 % of patients had all typical aspects of the disease, 17.7 %- indolent aspects, and 4.8 %- atypical. In the case ofcolonic obstruction, the method of irrigoscopy is informative. To restore intestinal function, patients with acute intestinal obstruction of the small intestine are indicated with a Yu. L. Shalkov nasogastroenteral tube or a double-drainage nasointestinal tube. And with the colonic form ofthe disease, it is necessary to perform a Hartmann-type operation and establish a Maidl-type anastomosis. It was noted that with indolent or atypical aspects of the disease, patients received medical care late. It is shown that in the case of resection of necrotic areas of the intestine, it is informative to determine the resection boundary using the vasoscopy method using a 1 % aqueous solution of methylene blue. It was found that the optimal distance from the edge of the resection is 3 cm. The results of this study are of interest to clinicians who are engaged in the diagnosis and treatment of patients with acute intestinal obstruction.

Synthesis and characterization of enhanced visible light-driven C-doped ZnO-2D GO/g-C3N4 heterojunction photocatalyst

Well-designed 2D graphene oxide-modified polymeric graphitic carbon nitride composite nanosheets (GO/g-C3N4) as desirable sensitizers and catalytic substrates for optimising the visible light-driven photocatalytic performance of ZnO-based photocatalysts have been investigated. Herein, 2D GO/g-C3N4 composite nanosheets are first developed by ultrasonic and hydrothermal methods, and then coupled with ZnO nanoparticles to prepare a series of ternary GO/g-C3N4-ZnO heterojunction composites with vary GO loading concentrations. Characterization of the photocatalysts was carried out by SEM, TEM, XPS, XRD, DRS, photoluminescence (PL) spectroscopy; evaluation of the visible light photocatalytic activity was performed by degrading an aqueous methylene blue (MB) solution. XPS studies showed that the formation of a ZnC bond in 15 % GO/g-C3N4-ZnO is due to the replacement of oxygen by carbon, indicating the construction of a hybrid heterojunction composed of C-doped ZnO and visible light sensitive GO/g-C3N4 composite nanosheets. The photodegradation performance of 15 % GO/g-C3N4-ZnO is 5.3, 2.9, and 2.2 times higher than that of pure ZnO, g-C3N4, and g-C3N4-ZnO, respectively. Due to the increase of GO loading in GO/g-C3N4 composite nanosheets, some characteristics of efficient visible light photocatalysis, such as a wider light absorption range, fluorescence quenching in the PL spectrum, excellent optical response in photocurrent measurement, and good stability，were confirmed and can be attributed to the electronic interaction between heterostructures and the effective transfer of photogenerated electrons in these ternary nanocomposites. This work may provide a new promising pathway for the construction of easily prepared 2D GO/g-C3N4 hybrid-modified nanocomposites, which is a hopeful material for wastewater control.

Constructing CQDs/MIL-101(Fe)/g-C3N4 photocatalyst and its enhancement to the photocatalytic activity

In this work, CQDs/MIL-101(Fe)/g-C3N4 photocatalyst was facilely fabricated, which exhibited prominent photocatalytic properties for the degradation of methylene blue (MB) aqueous solution. The photocatalytic degradation rate of MB by CQDs/MIL-101(Fe)/g-C3N4 composite material was found to be 124.7 times higher than that of MIL-101(Fe) and 1.3 times higher than that of MIL-101(Fe)/g-C3N4. Based on the different positions of CQDs in the structure, it is proposed that both Type-II and Z-scheme heterostructure models may exist simultaneously in the CQDs/MIL-101(Fe)/g-C3N4 composite material. The enhancement mechanism of CQDs in promoting the migration and separation of visible light-generated carriers in the ternary composite material is under discussion.

Spectrophotometric thermodynamic analysis of methylene blue aggregation in water by chemometrics; what comes in the presence of different cyclodextrins?

Spectrophotometry has been utilized to characterize the thermodynamic/dynamic properties of self-aggregation of methylene blue (MB) in water, particularly while interacting with a modulator like different cyclodextrins (α-, β-, hydroxypropyl-β- (HP-β-), and γ-CDs). These systems comprise many interactions that make such chemical systems sophisticated. We developed a mathematical modeling-fitting analysis for the simultaneous quantitative analysis of thermodynamic parameters of chemical reactions, relying on the fitting algorithm. Through analyzing simulated photometric titration data, we demonstrate the simultaneous determination of thermodynamic parameters of the different guest/host interactions. This first has brought the need for the calculation of the visible-light absorption spectrum and the thermodynamic parameters for the pure dimerization system. Therefore, the multiwavelength spectral-mole ratio data of aqueous solutions of MB over a concentration range of 2.5 × 10−5 to 4.5 × 10−5 M while temperature is changing; or being titrated with CDs solutions at various temperatures were collected, augmented, and then have been fed to solid mathematical routines to determine the potential existence of dimeric aggregates. The results of thermodynamics indicated that the positions of the monomer/dimer equilibria do not alter by the presence of α-CD. The apparent dimerization was suppressed upon addition of β- or HP-β-CDs, while the addition of γ-CD enhanced the dimerization.

Supercritical CO2‐assisted formation of metal–organic framework‐loaded porous polystyrene membranes for dye removal

AbstractMetal–organic frameworks (MOFs) are efficient adsorbents for the removal of hazardous materials. An MOF based on 1,3,5‐benzenetricarboxylic acid (BTC), Cu3(BTC)2, is prepared via phase separation using supercritical CO2 (scCO2) as a nonsolvent for the polymer solution. The prepared MOF is then loaded onto microporous polystyrene membranes. To evaluate the performance of Cu3(BTC)2‐loaded microporous polystyrene membranes for pollutant removal from water, they are tested for the separation of methylene blue (MB) dye from an aqueous solution. Prior to the preparation of the Cu3(BTC)2‐loaded microporous polystyrene membranes, Cu3(BTC)2 is activated with scCO2. After the activation with scCO2, the internal surface area of Cu3(BTC)2 and its MB adsorption increase. A toluene solution of polystyrene containing Cu3(BTC)2 particles is prepared, and scCO2 is introduced to induce the phase separation of the polymer solution. A Cu3(BTC)2‐loaded microporous polystyrene membrane is obtained without the collapse of the structure after the release of the CO2 pressure. MB can be readily and rapidly removed from aqueous solutions using Cu3(BTC)2‐loaded microporous polystyrene membranes. The removal efficiencies for aqueous MB solution were high, and removal efficiencies reached 92.8%.

Adsorption and Degradation of Methylene Blue Aqueous Solution by Fe‐based Amorphous Alloy

Fe‐based amorphous ribbons with the brand name 1K101 can adsorb methylene blue (MB) solution. The adsorption reaction is multilayer adsorption, in which chemical adsorption plays a major role. There are also some processes like physical adsorption, liquid phase diffusion, and internal diffusion of particles. The adsorption reaction is exothermic and spontaneous, which is more favorable at low temperatures. During the adsorption process, the entropy value decreases, the degree of disorder and freedom of the solution decreases, and the structure also changes. What's more, H2O2, pH, ribbons's dosage, dye's concentration, and temperature affect the degradation performance of 1K101 on MB. Degradation reactions are mainly controlled by surface chemical reactions, including chemical reduction reactions and adsorption. When c(H2O2) is 15 mm, pH is 2, ribbons’ dosage is 0.9 g, c(MB) is 20 mg L−1, temperature is 338 K, the degradation effect is the best. The optimal conditions with lowest overall cost obtained under the orthogonal experiment are: c(H2O2) = 20 mm, pH = 2, ribbons's dosage = 0.7 g, c(MB) = 20 mg L−1, and T = 338 K. Overall, 1K101 amorphous ribbon can be utilized to treat MB solution, and its degradation effect is better than adsorption effect, which can provide new ideas for the reuse of waste amorphous ribbon and the treatment of azo dye wastewater.