ZnO-based Cu metal-organic framework (MOF) nanocomposite for boosting and tuning the photocatalytic degradation performance

Although metal-organic frameworks (MOFs) are a viable choice for photocatalysts with large surface area and tunable pore structure, the rapid recombination of excited photogenerated charges results in low activity towards photodegradation. Aiming at improving the photocatalytic activities of MOFs, different strategies to incorporate MOF with light-harvesting semiconductors have been developed. In this research, we report an effective photocatalyst designed by incorporating Cu-MOF with ZnO for the photocatalytic degradation of Rose Bengal exhibiting excellent degradation efficiency of 97.4% in 45 min under natural sunlight with catalyst dosage of 320 mg/L. The optical, morphology and surface characteristics of the prepared nanocomposite were studied using scanning electron microscopy (SEM-EDX), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric (TGA) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and ultraviolet diffused reflectance spectroscopy (UV-DRS) techniques. Further studies showed that the degradation followed first-order kinetics with a rate constant of 0.077869 min-1. The degradation mechanism was investigated by photoluminescence (PL) study, XPS, zeta potential and quenching experiment in presence of different scavengers. Meanwhile, the fabricated composite displayed good recovery and reuse properties up to 5 cycles as revealed by XRD analysis proving itself a potential MOF-based photocatalyst towards environmental remediation process.

Nanoscale designing of metal organic framework moieties as efficient tools for environmental decontamination

Environmental pollutants, being a major and detrimental component of the ecological imbalance, need to be controlled. Serious health issues can get intensified due to contaminants present in the air, water, and soil. Accurate and rapid monitoring of environmental pollutants is imperative for the detoxification of the environment and hence living beings. Metal-organic frameworks (MOFs) are a class of porous and highly diverse adsorbent materials with tunable surface area and diverse functionality. Similarly, the conversion of MOFs into nanoscale regime leads to the formation of nanometal-organic frameworks (NMOFs) with increased selectivity, sensitivity, detection ability, and portability. The present review majorly focuses on a variety of synthetic methods including the ex situ and in situ synthesis of MOF nanocomposites and direct synthesis of NMOFs. Furthermore, a variety of applications such as nanoabsorbent, nanocatalysts, and nanosensors for different dyes, antibiotics, toxic ions, gases, pesticides, etc., are described along with illustrations. An initiative is depicted hereby using nanostructures of MOFs to decontaminate hazardous environmental toxicants.

Ce(ΙΙΙ) and La(ΙΙΙ) ions adsorption through Amberlite XAD-7 resin impregnated via CYANEX-272 extractant

The goal of this paper is to investigate the ability of Amberlite XAD-7 (AXAD-7) resin impregnated with CYANEX-272 (di-2,4,4-trimethylpentyl phosphonic acid) to remove cerium (Ce(ΙΙΙ)) and lanthanum (La(ΙΙΙ)) ions from aqueous solutions in the batch scheme. The prepared adsorbent material was determined utilizing FTIR, SEM-EDX, and BET methods. The impact of three individual process variable factors involving feed solution pH (2-6), adsorbent dose (0.05-0.65), and process temperature (15-55 °C) on the simultaneous removal of Ce(ΙΙΙ) and La(ΙΙΙ) ions was evaluated via response surface methodology (RSM) according to the central composite design (CCD). The modeling of Ce(ΙΙΙ) and La(ΙΙΙ) ions adsorption was performed using the quadratic model and was evaluated using a coefficient of determination for both ions. The optimization data revealed that the adsorption amount of Ce(ΙΙΙ) and La(ΙΙΙ) ions removal under optimal conditions were 99.75% and 69.98%, respectively. Equilibrium and kinetic investigations were also conducted to define the removal performance of the calculated adsorbent for Ce(ΙΙΙ) and La(ΙΙΙ) ions removal. Various isotherms models such as Langmuir, Freundlich, Temkin, and Sips were examined at 25 °C to analyze the equilibrium isotherm data. The data revealed that the Sips approach is compatible with the experimental data. The highest adsorption capacity of the resin for Ce(ΙΙΙ) and La(ΙΙΙ) ions were 11.873 mg g^-1 and 7.324 mg g^-1, correspondingly. The kinetic study of the Ce(ΙΙΙ) and La(ΙΙΙ) adsorption process was conducted via pseudo-first-order, pseudo-second-order, and intraparticle diffusion models(IDMs). Based on the data obtained, kinetic data were fitted well to a pseudo-second-order rate correlation. According to the obtained results, the (AXAD-7) resin impregnated with CYANEX-272 performed well in removing both Ce(ΙΙΙ) and La(ΙΙΙ) ions from aqueous solutions with well stability during several adsorption-desorption cycles and well regeneration and excellent metallic ions recovery.

Advancements in visible light responsive MOF composites for photocatalytic decontamination of textile wastewater: A review

Heterogeneous photocatalysis using metal-organic frameworks (MOFs) is expected to provide a pivotal solution for the remediation of toxic dyes and heavy metals from textile wastewater. However, MOFs often suffer from a low removal efficiency, due to the rapid recombination between holes and electrons, generated upon photoexcitation. Additionally, the MOFs exhibit poor water stability, which restricts their large-scale application. In this regard, various approaches (i.e. doping of metal nanoparticle, semiconductor, quantum dot, and ligand functionalization) have been adopted for the formation of multifunctional composites. The MOF-composites possess suitable photochemical, surface, optical, and electronic properties, resulting in enhanced water stability, visible light absorption, and reduced recombination between photogenerated species. This comprehensive review targets to provide an insight into the synthesis and subsequent application of various MOF composites for photocatalytic removal of organic contaminants (dyes) and inorganic (Cr(VI)) contaminants from water. MOFs/graphene oxide composites possess improved surface area and reusability whereas noble metal incorporated MOFs composites suffer from photocorrosion and are relatively costly. Zr and Ti based MOFs exhibit tuning from UV to visible light response and surpass the poor water stability upon binary/ternary composite formation. The role of the dopants in enhancing the efficiency of the composites; the effect of influencing factors such as solution pH, pollutant concentration; the mechanism, and the kinetics of reactions have been outlined. In spite of many advancements, the article also summarizes some roadblocks that need to be unraveled to achieve the energy-water-environment nexus and scope for future breakthrough research in this field.

MOF-Hosted Enzymes for Continuous Flow Catalysis in Aqueous and Organic Solvents

Fully exploiting the potential of enzymes in cell‐free biocatalysis requires stabilization of the catalytically active proteins and their integration into efficient reactor systems. Although in recent years initial steps towards the immobilization of such biomolecules in metal–organic frameworks (MOFs) have been taken, these demonstrations have been limited to batch experiments and to aqueous conditions. Here we demonstrate a MOF‐based continuous flow enzyme reactor system, with high productivity and stability, which is also suitable for organic solvents. Under aqueous conditions, the stability of the enzyme was increased 30‐fold, and the space–time yield exceeded that obtained with other enzyme immobilization strategies by an order of magnitude. Importantly, the infiltration of the proteins into the MOF did not require additional functionalization, thus allowing for time‐ and cost‐efficient fabrication of the biocatalysts using label‐free enzymes.

Hybrid metal organic frameworks as an Exotic material for the photocatalytic degradation of pollutants present in wastewater: A review

In this world, water is considered as the Elixir for all living creatures. Human life rolls with water, and every activity depends upon water. Worldwide water resources are being contaminated due to the elevation in the population count, industrialization and urbanization. Ejection of chemicals by industries and domestic sewages remains the major reason in the destruction of natural water resources. Contaminated water with harmful microbes, chemical dyes, pesticides, and carcinogens are the root cause of many diseases and deaths of living species. In this scenario, researchers engaged in producing ultra components to remove the contaminants. Metal organic frameworks (MOF) are the desired combination of organic and inorganic materials to achieve the required target. MOFs possess unique characteristics like tunable internal structure, porosity, crystallinity and high surface area which enable them for energy and environmental application. For the past years, MOFs are concentrated more as a photocatalyst in the treatment of polluted water. These research studies discuss the improvement of photocatalytic performance of MOF by the incorporation of metals, metal coupled with nanoparticles like polymers, graphene, etc., into it to achieve the enhanced photocatalytic activity by scavenging entire chemicals and harmful microbes to retain the quality of water. The target of this review article is to focus on the state of the art research work on MOFs in photocatalytic water treatment technique.

Fly ash-based nanocomposites: a potential material for effective photocatalytic degradation/elimination of emerging organic pollutants from aqueous stream

Fly ash is readily available and cheaply generated as 47a by-product of the combustion of organic matter. A tremendous amount of fly ash is generated worldwide, and its disposal has imposed 47a severe environmental concern. Its good adsorption capacities attracted several researchers to study the use of fly ash as 47a support for photocatalysts for the degradation of contaminants from wastewater. Undoubtedly the photocatalysts supported on fly ash have represented excellent degradation efficiencies due to the synergistic effect of adsorption and photocatalytic capacity. The utilization of fly ash as 47a precursor has solved the problem of disposal and added value to the waste by-product. Various preparation techniques for fly ash-based nanocomposites such as the sol-gel method, hydrothermal method, solvothermal method, precipitation and co-precipitation, modified metalorganic decomposition, electrospinning, incipient impregnation, and wet chemical synthesis, along with 47a brief study of their characterization using scanning electron microscopy, X-ray diffraction technique and Fourier transform infrared (FTIR) spectroscopy, and the mechanism of photodegradation of dyes have been discussed in this paper. The literature shows that SiO₂, TiO₂, and Al₂O₃ present in fly ash play an essential role in the photodegradation of dyes. Factors affecting the degradation of dyes, their kinetic studies, and methods to enhance photodegradation efficiency have also been discussed.

Ce/Eu redox couple functionalized HKUST-1 MOF insight to sono-photodegradation of malathion

The Ce/Eu redox pair-functionalized HKUST-1 MOF, as an innovative environmentally friendly and recyclable sono-photocatalyst, was hydrothermally mixed and fully characterized by XRD, PL, EIS, FE-SEM, EDS, Mott-Schottky, chronoamperometry, and DRS techniques. The obtained chemical and optical characteristics of the n-type Ce/Eu-HKUST-1 MOF showed that the transfer of additional 4f orbital electrons in the Ce/Eu redox pair improves the sono-photocatalytic activity. The performance of Ce/Eu-HKUST-1 MOF for the sono-photodegradation of Malathion (MA) was evaluated in the aqueous media in the simultaneous presence of blue light and ultrasonic irradiation. The optimization of the process was cross-examined using the response surface methodology as a function of the MA concentration (15-35 mg·L^-1), Ce/Eu-HKUST-1 mass (10-30 mg), pH (4-12), and ultrasonic wave irradiation duration (10-30 min). The maximum sono-photocatalytic degradation capacity was found to be 99.99% under the optimum conditions set as 25 mg·L^-1, 20 mg, 8, and 25 min for the concentration of Malathion, photocatalyst mass, pH, and irradiation duration, respectively. These findings were attributed to the suppression of electron-hole pair recombination, increased life-time of charge carriers, enhanced visible light absorption, and prominent proportion of hydroxyl and peroxide radicals formed.

Metal organic framework-derived C-doped ZnO/TiO2 nanocomposite catalysts for enhanced photodegradation of Rhodamine B

A series of C-doped ZnO/TiO₂ composites with various molar ratios of ZnO to TiO₂ were synthesized by one-step controllable pyrolysis of Zn/Ti bimetallic metal-organic frameworks (Zn/Ti-MOF). The Zn/Ti-MOF was prepared using a facile microwave hydrothermal method. Electron microscopic analysis proved that the composites presented regularity cubic morphology with an edge length of about 1 μm and the C atoms were successfully doped into ZnO/TiO₂ composites. X-ray photoelectron spectroscopy (XPS) measurement results confirmed the C-doping in the ZnO/TiO_2. Comparative experimental studies showed that 2% ZnO/TiO₂ composites prepared with the calcination temperature of 600℃ displayed the best photocatalytic degradation efficiency (94%) of RhB under the simulated sunlight irradiation. Cyclical experiment indicated the high stability and reusability of 2% ZnO/TiO₂ composites. Electron spin resonance (ESR) and trapping experiments illustrated that the produced O₂^- served as the main active species for the efficient RhB removal. This work provides an efficient way for preparing C-doped bimetal oxides composites, which would have an important application prospect in the photocatalytic degradation of organic pollutants in environmental water.

Silver embellished PANI/CNT nanocomposite for antimicrobial activity and sequestration of dye based on RSM modelling

Silver doped PANI/CNT (Ag-PANI/CNT) nanocomposite was synthesized and investigated as adsorbent for its possible application in the elimination of organic dye Brilliant Blue G (BBG). The morphological characteristics of Ag-PANI/CNT were studied using Fourier transform infrared, scanning electron microscopy, elemental mapping, transmission electron microscopy and X-ray diffraction. The response of operational parameters given as adsorbent dosage, concentration, pH and contact time for dye removal were investigated by using Response Surface Methodology (RSM). The results from RSM suggested that the efficiency of BBG elimination is 98.7 under the optimum conditions of experimental factors. The adsorption studies showed that the equilibrium data fitted well with Langmuir isotherm model compared to Freundlich. Finally, the antimicrobial activities of Ag-PANI/CNT were tested against bacterial strain Escherichia coli and Salmonella typhi and fungal strains Aspergillus niger.

Microwave Hydrothermally Synthesized Metal-Organic Framework-5 Derived C-doped ZnO with Enhanced Photocatalytic Degradation of Rhodamine B

C-doped ZnO particles have been successfully prepared by the calcination using microwave hydrothermally prepared metal-organic framework-5 (MOF-5) as the precursor. MOF-5 was turned into C-doped ZnO through calcination at 500 °C, and its cubic shape was well-maintained. X-ray photoelectron spectroscopic studies confirmed the C-doping in the ZnO. The as-prepared C-doped ZnO demonstrated a Rhodamine B (RhB) degradation efficiency of 98% in 2 h under an solar-simulated light irradiation, much higher than that of C-doped ZnO derived from MOF-5 synthesized by the ordinary hydrothermal method. The trapping experiment revealed that the crucial factors in the RhB removal were photogenerated h⁺ and •O₂^-.

Electrostatically controlled plasmonic effects of gold nanoparticles with indigo-carmine functionation for rapid and straightforward colorimetric detection of Cu2+ ions

A colorimetric sensor is fabricated for effective on-site monitoring of Cu²⁺ ions content based on the distance-dependent optical properties of gold nanoparticles-polyvinyl alcohol-citrate (Au-NPs-PVA-Cy) which plasmonic effect electrostatically was controlled by PVA-Cy stabilizing indigo-carmine (IC) functionalizing. The surface-modified gold nanoparticles were extremely stable with a strong affinity toward Cu²⁺ ions. Citrate ion was employed as a cross-linking agent for pairs of Au-NPs-PVA-Cy and IC for stabilizing coordination between Cu²⁺ ion and IC. The active materials were characterized by UV-Vis, SEM, DLS, XRD, FT-IR, and EDS analyses. The sensor response toward Cu²⁺ ion was found to be linear in the range of 0.0974 to 3.27 μM with the limit of detection and quantification values of 0.021 and 0.07 μM, respectively. The sensor represents good sensitivity and stability, promisingly suggesting this device for the accurate and repeatable determination of Cu²⁺ in real water samples. The effect of different foreign ions on the selectivity of the sensor was checked. The sensor has a long shelf life in comparison to other similar colorimetric sensors. Also, it shows a repeatable response with RSD% of 2.02%. Thus, the sensing of Cu²⁺ ions based on the electrostatically control plasmonic of Au-NPs-PVA-Cy was developed with proper signaling based on the color change from dark blue to light blue as readily seen by the naked eye. Furthermore, the efficient environmental applicability of this simple and rapid determination of the Cu²⁺ sensor is proved.

Colorimetric determination of F-, Br- and I- ions by Ehrlich's bio-reagent oxidation over enzyme mimic like gold nanoparticles: Peroxidase-like activity and multivariate optimization

Citrate and polyvinyl alcohol capped gold nanoparticles (PVA-GNPs) were synthesized via chemical reduction technique and fully characterized by DLS, SEM, EDS, XRD, UV-Vis and FT-IR analysis. A simple and practical colorimetric sensor based on red-ox reaction of p-dimethylaminobenzaldehyde (DABA) as ehrlich's bio-reagent and Au(III) with H₂O₂ on PVA-GNPs mimic catalyst with enzyme-like activity, has been fabricated for determination of F^-, Br^- and I^- halide anions. Prepared PVA-GNPs, can simultaneously catalyze the disintegration of H₂O₂, that used to reduce Au(III) ions into co-doped Au-NPs and oxidation of p-dimethylaminobenzaldehyde ehrlich's bio-reagent while in the presence of halide ions Au-X complex can be formed and improved sensor selectivity. Halide ions (F^-, Br^- and I^-) effectively diminishes the catalytic activity of GNPs to disintegrate oxygenated water by the interaction among Au⁺ and Au⁰ and suppressing oxidation of p-dimethylaminobenzaldehyde ehrlich's bio-reagent. In this system which contains PVA-GNPs, H₂O₂, p-dimethylaminobenzaldehyde ehrlich's bio-reagent, and Au(III), increasing the halide ions (F^-, Br^- and I^-) concentration show color changes from deep green to red. In view of this rule, in this work, a novel colorimetric technique for sensitive determination of F^-, Br^- and I^- was developed. This method has the detection limits of 2.60 × 10^-6 M, 6.64 × 10^-8 M and 9.93 × 10^-9 M and linear ranges between 1.98 × 10^-5-1.22 × 10^-3 M, 1.99 × 10^-6-2.0 × 10^-4 M and 1.07 × 10^-7- 2.86 × 10^-5 M for F^-, Br^- and I^-, respectively. Assays are highly selective over other ions. They effectively applied to detection of halide ions in real water samples.

Magnetic BiFeO3 decorated UiO-66 as a p–n heterojunction photocatalyst for simultaneous degradation of a binary mixture of anionic and cationic dyes

Magnetic UiO-66/BiFeO₃ composite for simultaneous photodegradation of a binary mixture of anionic and cationic dyes.

Recent advances in MOF-based photocatalysis: environmental remediation under visible light

Highly photoactive MOFs can be engineered via various strategies for the purpose of extended visible light absorption, more efficient generation, separation and transfer of charge carriers, as well as good recyclability.

Enhanced visible light photocatalytic degradation of dyes in aqueous solution activated by HKUST-1: performance and mechanism

HKUST-1 is a copper-based metal–organic framework (MOF) and potential photocatalyst, but minimal research has addressed the performance and mechanism of HKUST-1 in the visible light photocatalytic degradation of dyes. In the present work, HKUST-1 was applied as a photocatalyst to activate peroxomonosulfate (PMS) under visible light (Vis) for dye removal in aqueous solution. The results showed that the removal efficiency of two cationic dyes [rhodamine B (RhB) and methylene blue (MB)] was greater than 95% within 120 min. Free radicals such as SO₄⁻˙, ·OH were present in the degradation process, with SO₄⁻˙ playing a dominant role. Zeta potential, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy data were used to investigate the degradation mechanism. In the degradation process, surface charge attraction between HKUST-1 and cationic dyes promotes removal efficiency, with the degradation efficiency of cationic dyes (MB and RhB) more than 50% higher than for anionic dyes [acid orange 7 (AO₇) and methyl red (MR)]. On the other hand, HKUST-1 has been proved to activate PMS by conducting photoelectrons, which accelerated the degradation of dyes. Compared with the reaction conditions of PMS/Vis, when the HKUST-1 was present (HKUST-1/PMS/Vis), the degradation rates of MB and RhB increased by 62.7 and 63.2%, respectively.

HKUST-1 is a copper-based metal–organic framework (MOF). The HKUST-1/PMS/Vis system can effectively degrade RhB and MB but accomplish poor removal of AO₇ and MR, which is attributed to the repulsion between surface charges.

Sonochemical synthesis and characterization of four nanostructural nickel coordination polymers and photocatalytic degradation of methylene blue

Four nanostructural nickel(II) coordination polymers {[Ni(ttpa)(1,4-ndc)(H₂O)₂]·2H₂O}_n (1), {[Ni(ttpa)(1,3-bda)]·2H₂O·DMF}_n (2·2H₂O·DMF), {[Ni(ttpa)(1,4-bdc)]·H₂O}_n (3) and {[Ni(ttpa)(aip)(H₂O)]·3H₂O}_n (4·3H₂O) were synthesized using hydrothermal and sonochemical methods (ttpa = tris(4-(1,2,4-triazol-1-yl)phenyl)amine, 1,4-ndc = 1,4-naphthalenedicarboxylate, 1,3-bda = 1,3-benzenediacetate, 1,4-bdc = 1,4-benzenedicarboxylate, aip = 5-aminoisophthalate), and characterized by elemental analysis, IR spectra, scanning electron microscopy, single-crystal and powder X-ray diffraction analysis, optical band gaps, VB XPS spectra and luminescence. The effects of sonication power, time and frequency on the size and morphology of nano-sized 1-4 have been studied. 1 exhibits an unusual 2D + 2D → 3D inclined polycatenated motif based on the (3,3)-coordinated 6³-hcb topology. 2 shows a (3,4)-coordinated 2D network of the bey topology. 3 presents a rare example of the 4-fold interpenetrating array of (3,5)-coordinated 3D network belonging to the 35T1 topology type. 4 displays an unusual 2D → 3D polythreaded network based on 2D sql networks. 1-4 exhibit luminescent emissions at 409, 399, 413 and 402 nm, respectively. 1-4 are semiconducting in nature, with E_g of 2.12 eV (1), 2.34 eV (2), 2.32 eV (3), and 2.47 eV (4). 1-4 are good catalysts for the degradation of MB under visible light irradiation. The effects of the size and morphology of nano-sized 1-4 on the photocatalytic efficiencies were studied. The higher sonication frequency obtains uniform and smaller nano-sized coordination polymers which have higher catalytic efficiencies.

Synergistic effects and kinetics of rGO-modified TiO2 nanocomposite on adsorption and photocatalytic degradation of humic acid

Graphene oxide was prepared using the modified Hummers method and reduced graphene oxide (rGO) - titanium dioxide (TiO₂) nanocomposite was synthesised using the one-step hydrothermal treatment. The synergistic effects on adsorption and photocatalytic properties of the rGO-TiO₂ nanocomposite for the humic acid removal were systematically investigated. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman and infrared (IR) spectroscopy indicate that GO was partially reduced to reduced graphene oxide (rGO) in the hydrothermal synthesis process and anatase TiO₂ nanoparticles uniformly grew on the surface of rGO. The photoelectron and photohole generated under visible light irradiation were effectively separated on the surface of rGO-TiO₂. The rGO-TiO₂ nanocomposite exhibited higher photocatalytic activity as a result of the synergistic effects of surface functional groups for adsorption and the excellent conductivity for photocatalytic reaction. The effect of rGO-TiO₂ nanocomposite dosage, light intensity and system temperature on the removal of humic acid solution was investigated. The results show that the removal efficiency of humic acid increased with system temperature and light intensity. When the dosage of rGO-TiO₂ nanocomposite was 1.2 g/L, the temperature, the light intensity and the pH of this system was 303 K, 4.37 Wm^-2 and 7, respectively, the removal efficiency of humic acid reached 88.7% under visible light irradiation.

Activated carbon/metal-organic framework nanocomposite: Preparation and photocatalytic dye degradation mathematical modeling from wastewater by least squares support vector machine

Herein, Kiwi peel activated carbon (AC), Materials Institute Lavoisier (MIL-88B (Fe), and AC/MIL-88B (Fe) composite were synthesized and used as catalysts to degrade Reactive Red 198. The material properties were analyzed by the FTIR, BET-BJH, XRD, FESEM, EDX, TGA, and UV-Vis/DRS. The BET surface area of AC, MIL-88B (Fe) and AC/MIL-88B (Fe) was 1113.3, 150.7, and 199.4 m²/g, respectively. The band gap values (E_g) estimated by Tauc plot method, were obtained 5.06, 4.19 and 3.79 eV for AC, MIL-88B (Fe) and AC/MIL-88B (Fe), respectively. The results indicated that the AC/MIL-88B (Fe) composite had higher photocatalytic activity (99%) than that of pure AC (79%) and MIL-88B (Fe) catalysts (87%). The decolorization kinetic was matched well with the second-order model. Moreover, the data were modeled using least squares support vector machine which optimized with Cuckoo optimization algorithm. The optimal parameters were found 0.837 and 3.49e+02 based on σ² and γ values, respectively. The mean square error (MSE) and correlation coefficient (R²) values were obtained 3.97 and 0.948. Therefore, the attained data, materials characterization and prediction of modeling validate the composite form of MIL-88B(Fe) with new AC, had better photocatalytic activity in comparison with the individual form.

Bi2WO6/Ag3PO4–Ag Z-scheme heterojunction as a new plasmonic visible-light-driven photocatalyst: performance evaluation and mechanism study

The Bi₂WO₆/Ag₃PO₄–Ag Z-scheme heterojunction, as a novel plasmonic visible-light-driven photocatalyst, was prepared by ultrasound assisted in situ precipitation and the hydrothermal method and was further characterized using multiple techniques.

A Bi2WO6/Ag2S/ZnS Z-scheme heterojunction photocatalyst with enhanced visible-light photoactivity towards the degradation of multiple dye pollutants

A novel visible-light-driven Z-scheme heterojunction, Bi₂WO₆/Ag₂S/ZnS, was synthesized and its photocatalytic activity was evaluated for the treatment of a binary mixture of dyes, and its physicochemical properties were characterized using FT-IR, XRD, DRS and FE-SEM techniques. The Bi₂WO₆/Ag₂S/ZnS Z-scheme heterojunctions not only facilitate the charge separation and transfer, but also maintain the redox ability of their components. The superior photocatalytic activity demonstrated by the Z-scheme Bi₂WO₆/Ag₂S/ZnS attributes its unique properties such as the rapid generation of electron–hole pairs, slow recombination rate, and narrow bandgap. The performance of the Bi₂WO₆/Ag₂S/ZnS was evaluated for the simultaneous degradation of methyl green (MG) and auramine-O (AO) dyes, while the influences of the initial MG concentration (4–12 mg L⁻¹), initial AO concentration (2–6 mg L⁻¹), pH (3–9), irradiation time (60–120 min) and photocatalyst dosage (0.008–0.016 g L⁻¹) were investigated through the response surface methodology. The desirability function approach was applied to optimize the process and results revealed that maximum photocatalytic degradation efficiency was obtained at optimum conditions including 6.08 mg L⁻¹ of initial MG concentration, 4.04 mg L⁻¹ of initial AO concentration, 7.25 of pH, 90.58 min of irradiation time and 0.013 g L⁻¹ of photocatalyst dosage. In addition, a possible photocatalytic mechanism of the Bi₂WO₆/Ag₂S/ZnS heterojunction was proposed based on the photoinduced charge carriers.

A Z-scheme Bi₂WO₆/Ag₂S/ZnS heterojunction was successfully synthesized as a novel visible-light-driven photocatalyst for the degradation of multiple dye pollutants.

A simple approach for the sonochemical loading of Au, Ag and Pd nanoparticle on functionalized MWCNT and subsequent dispersion studies for removal of organic dyes: Artificial neural network and response surface methodology studies

In this study, the artificial neural network (ANN) and response surface methodology (RSM) based on central composite design (CCD) were applied for modeling and optimization of the simultaneous ultrasound-assisted removal of quinoline yellow (QY) and eosin B (EB). The MWCNT-NH₂ and its composites were prepared by sonochemistry method and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis's. Initial dyes concentrations, adsorbent mass, sonication time and pH contribution on QY and EB removal percentage were investigated by CCD and replication of experiments at conditions suggested by model has results which statistically are close to experimented data. The ultrasound irradiation is associated with raising mass transfer of process so that small amount of the adsorbent (0.025 g) is able to remove high percentage (88.00% and 91.00%) of QY and EB, respectively in short time (6.0 min) at pH = 6. Analysis of experimental data by conventional models is good indication of Langmuir efficiency for fitting and explanation of experimented data. The ANN based on the Levenberg-Marquardt algorithm (LMA) combined of linear transfer function at output layer and tangent sigmoid transfer function at hidden layer with 20 hidden neurons supply best operation conditions for good prediction of adsorption data. Accurate and efficient artificial neural network was obtained by changing the number of neurons in the hidden layer, while data was divided into training, test and validation sets which contained 70, 15 and 15% of data points respectively. The Average absolute deviation (AAD)% of a collection of 128 data points for MWCNT-NH₂ and composites is 0.58%.for EB and 0.55 for YQ.

Sonochemical synthesis of amide-functionalized metal-organic framework/graphene oxide nanocomposite for the adsorption of methylene blue from aqueous solution

Graphene oxide-[Zn₂(oba)₂(bpfb)]·(DMF)₅ metal-organic framework nanocomposite (GO-TMU-23; H₂oba=4,4'-oxybisbenzoic acid, bpfb=N,N'-bis-(4-pyridylformamide)-1,4-benzenediamine, DMF=N,N-dimethylformamide) is prepared through a simple and large-scale sonochemical preparation method at room temperature. The obtained nanocomposite is characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Additionally, the absorption ability of GO-TMU-23 nanocomposite toward cationic dye methylene blue was also performed. Significantly, GO-TMU-23 nanocomposite exhibits remarkably accelerated adsorption kinetics for methylene blue in comparison with the parent materials. The adsorption process shows that 90% of the dye has been removed and the equilibrium status has been reached in 2min by using the nanocomposites as the adsorbent.