One-Pot Method Synthesis of Bimetallic MgCu-MOF-74 and Its CO2 Adsorption under Visible Light

A magnesium-based metal-organic framework (Mg-MOF-74) exhibits excellent CO₂ adsorption under ambient conditions. However, the photostability of Mg-MOF-74 for CO₂ adsorption is poor. In this study, Mg _x Cu_1-x -MOF-74 was synthesized by using a facile "one-pot" method. Furthermore, the effects of synthesis conditions on the CO₂ adsorption capacity were investigated comprehensively. X-ray diffraction, Fourier transform infrared, scanning electron microscopy, thermo gravimetric analysis, inductively coupled plasma atomic emission spectroscopy, ultraviolet-visible spectroscopy and photoluminescence spectroscopy, and CO₂ static adsorption-desorption techniques were used to characterize the structures, morphology, and physicochemical properties of Mg _x Cu_1-x -MOF-74. CO₂ uptake of Mg _x Cu_1-x -MOF-74 under visible light illumination was measured by the CO₂ static adsorption test combined with the Xe lamp. The results revealed that Mg _x Cu_1-x -MOF-74 exhibited excellent photocatalytic activity. Furthermore, the CO₂ adsorption capacity of Mg _x Cu_1-x -MOF-74 was excellent at a synthesis temperature and time of 398 K and 24 h in dimethylformamide (DMF)-EtOH-MeOH mixing solvents, respectively. Mg _x Cu_1-x -MOF-74 retained a crystal structure similar to that of the corresponding monometallic MOF-74, and its CO₂ uptake under visible light was superior to that of the corresponding monometallic MOF-74. Particularly, the CO₂ uptake of Mg_0.4Cu_0.6-MOF-74 under Xe lamp illumination for 24 h was the highest, up to 3.52 mmol·g^-1, which was 1.18 and 2.09 times higher than that of Mg- and Cu-MOF-74, respectively. The yield of the photocatalytic reduction of CO₂ to CO was 49.44 μmol·g_cat ^-1 over Mg_0.4Cu_0.6-MOF-74 under visible light for 8 h. Mg²⁺ and Cu²⁺ functioned as open alkali metal that could adsorb and activate CO₂. The synergistic effect between Mg and Cu metal strengthened Mg _x Cu_1-x -MOF-74 photostability for CO₂ adsorption and broadened the scope of its photocatalytic application. The "bimetallic" strategy exhibits considerable potential for use in MOF-based semiconductor composites and provides a feasible method for catalyst design with remarkable CO₂ adsorption capacity and photocatalytic activity.

Spinning disc photoreactor based visible-light-driven Ag/Ag2O/TiO2 heterojunction photocatalyst film toward the degradation of amoxicillin

The presence of antibiotics in waste and drinking water is causing increasing concern around the world, thereby an advanced sustainable technology needs to be developed to eliminate the antibiotics from water resources. Hence, an efficient spinning disc photoreactor (SDPR) equipped with visible light-activated Ag/Ag₂O/TiO₂ heterostructure thin film photocatalyst was assessed for the degradation of amoxicillin (AMX) as a typical antibiotic. The surface morphology, optoelectronic and structural features of Ag/Ag₂O/TiO₂ heterojunction were characterized by TEM, BET, mott Schottky, FESEM, EDS, AFM, XRD, UV-Vis-DRS, and contact angle measurements. Results confirm that Ag and Ag₂O have a significant effect on the photocharge carrier separation and transfer of the as-developed photocatalyst system. The operative variables including illumination time, rotational speed, solution flow rate, aeration rate, pH, and initial AMX concentration were optimized by CCD. The results displayed the maximum AMX photodegradation (97.91%) could be achieved at optimal conditions involving illumination time of 80 min, a rotational speed of 225 rpm, the solution flow rate of 0.6 L/min, aeration rate of 20 L/min, pH = 6, and initial AMX concentration of 20 mg/L. Interestingly, more than 79% COD and 64% TOC were removed under optimum conditions during 80 min illumination time, respectively. Active species tests confirmed the dominant role of ·OH and ·O₂^- in AMX degradation. finally, the XRD pattern confirmed that the reusability assessments of the heterojunction film could successfully retain its stability for six consecutive photocatalytic degradation runs. This work demonstrates the feasibility of utilizing visible-light-driven thin-film photocatalysts in spinning disc photoreactors in treating the tenacious antibiotic pollutants.

Evaluation of the multifunctional activity of silver bionanocomposites in environmental remediation and inhibition of the growth of multidrug-resistant pathogens

Imperata cylindrica cellulose supported Ag bionanocomposites purified industrial water and controlled the contagious diseases with high potential activity.

A new 3D 8-connected Cd(ii) MOF as a potent photocatalyst for oxytetracycline antibiotic degradation

1 exhibits the best photocatalytic decomposition efficiency towards antibiotic OXY. The plausible photocatalytic mechanism has been explained with the help of the density of states calculations and Hirshfeld surface analysis.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.

Immobilizing Ag/Cu2O on cotton fabric to enhance visible light photocatalytic activity

Ag/Cu₂O composites were prepared by the solvothermal and photo-reduction method.

A dual surface inorganic molecularly imprinted Bi2WO6-CuO/Ag2O heterostructure with enhanced activity-selectivity towards the photocatalytic degradation of target contaminants

The proposed mechanism reveals that under visible light, MG and AO dyes can be selectively degraded by produced radicals at the surface of the inorganic molecularly imprinted Ag₂O-CuO-Bi₂WO₆ heterojunction.

Enhanced visible light-active CeO2/CuO/Ag2CrO4 ternary heterostructures based on CeO2/CuO nanofiber heterojunctions for the simultaneous degradation of a binary mixture of dyes

CeO₂/CuO/Ag₂CrO₄ composite is fabricated using an electrospinning and precipitation. Also, composite can photodegrade RB and MB under visible light irradiation. CeO₂/CuO/Ag₂CrO₄ can enhanced photocatalytic activity due to formed heterojunction.

Syntheses, crystal structures, dye degradation and luminescence sensing properties of four coordination polymers

Four coordination polymers based on the pyridyl-carboxyl ligand have been solvothermally synthesized and characterized. The heterogeneous catalytic oxidation activities of 1–3 and luminescence titration experiments for 4 have been studied.

As(III) adsorption onto different-sized polystyrene microplastic particles and its mechanism

We systematically investigated the surface characteristics of polystyrene microplastic particles (PSMPs) prepared by ball milling to impart a porous surface structure and special surface characteristics, and studied the mechanism of adsorption of As(III) onto PSMPs. The sizes of the PSMPs prepared by ball milling for 2, 4, and 8 h were in the ranges of 0.1-1, 1-10, and 10-100 μm, respectively. That is, the longer the milling time is, the larger the specific surface area of the particles is. Moreover, the higher the point of zero charge is, the higher the adsorbed amount of As(III) is. The highest adsorption rate of As(III) onto PSMPs was found to be 1.12 mg g^-1. After 1200 min, the adsorption reached equilibrium, and a pseudo-second-order model better fitted the As(III) adsorption kinetics. The Langmuir and Freundlich models could well describe the adsorption isotherms. Furthermore, hydrogen bonds between As(III) and PSMPs were broken at high temperatures, resulting in a decrease in As(III) adsorption onto PSMP, which indicated that the adsorption process was exothermic. Increases in the pH and concentrations of interfering nitrate and phosphate ions in the solution led to inhibited As(III) adsorption of PSMPs. The electrostatic potential of most areas of the PSMP surface was positive, and the H atom on the carboxyl group exhibited a very large positive potential (+56.6 kcal/mol), and thus attracted arsenic oxyanions. Thus, it was determined that As(III) adsorbed to the surface of PSMPs through hydrogen bonding with the carboxyl group. Electrostatic forces and non-covalent interactions are the key mechanisms affecting the adsorption of As(III) onto PSMPs. This work provides a clear theoretical basis for the behavior of the PSMP as an arsenic carrier and might aid to improve the environmental toxicity of arsenic.

Facile synthesis of laccase mimic Cu/H3BTC MOF for efficient dye degradation and detection of phenolic pollutants

Herein, we report an effectual method for designing a novel form of nanozyme laccase mimic namely Cu/H3BTC, using copper ions and 1,3,5-benzene tricarboxylic acid (1,3,5-H3BTC). This Cu-based metal-organic framework (MOF) was synthesized through a simple procedure of mixing of two usual reagents at room temperature. Amido Black 10B (AB-10B) was chosen as a model dye for degradation consequences. Results showed that Cu/H3BTC MOF revealed significantly higher catalytic efficacy under certain conditions like high pH, extreme temperature and high salt conditions and it has long-term storage stability, which can lead to a significant decline in catalytic activity of laccase. In addition, the degradation of AB-10B was up to 60% after ten cycles, showing good recyclability of Cu/H3BTC MOF. The UV-visible spectral changes clearly showed that Cu/H3BTC MOF is an effective laccase mimic for the degradation of azo dye AB-10B, which was degraded more easily within the time duration of 60 min. The Cu/H3BTC MOF also possessed fundamental activities like laccase with regard to oxidation of the phenolic compounds. Moreover, a technique for the quantitative detection of epinephrine by Cu/H3BTC MOF was established. These findings help to understand the laccase-like reactivity and provide a basis for the future design and application of metal-based catalysts.

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.

A Review on the Synthesis and Characterization of Metal Organic Frameworks for Photocatalytic Water Purification

This review analyzes the preparation and characterization of metal organic frameworks (MOFs) and their application as photocatalysts for water purification. The study begins by highlighting the problem of water scarcity and the different solutions for purification, including photocatalysis with semiconductors, such as MOFs. It also describes the different methodologies that can be used for the synthesis of MOFs, paying attention to the purification and activation steps. The characterization of MOFs and the different approaches that can be followed to learn the photocatalytic processes are also detailed. Finally, the work reviews literature focused on the degradation of contaminants from water using MOF-based photocatalysts under light irradiation.

ZIF-8 derived ZnO/Zn6Al2O9/Al2O3 nanocomposite with excellent photocatalytic performance under simulated sunlight irradiation

The ZIF-8 derived ZnO/Zn₆Al₂O₉/Al₂O₃ nanocomposite exhibits an unprecedented photocatalytic degradation activity toward MO of high concentration.