Recycling Experiments Research Articles

A double-chain based metallomicellar catalyst for aerobic oxidative synthesis of benzimidazoles in water.

The oxomolybdenum complexes Mo1, Mo2 and Mo3, which share a common ONO donor ligand backbone but differ in their peripheral substituents, were explored to study their reactivity in organic transformations in water. The ligand backbones of Mo1 and Mo2 were covalently linked to a methyl group and a single hydrophobic n-hexadecyl chain via an ether linkage, respectively. The complex Mo3 was found to possess two n-hexadecyl chains attached to the ligand backbone via a common amine-N. Complexes Mo2 and Mo3 formed metallomicelle when dispersed in water due to the surfactant presence in their structures, enabling them to uptake organic substrates. The catalytic potential of the complexes was evaluated for the oxidative coupling of benzylamine with 1,2-diaminobenzene to synthesize benzimidazole in neat water using open air as the sole oxidant. The double-chain surfactant-type catalyst Mo3 displayed superior activity compared to the single-chain surfactant-type complex, Mo2. A wide variety of benzimidazoles were synthesized in good to excellent yields under environmentally benign conditions using Mo3 as the catalyst. The practical utility of the process was validated through multi-gram scale-up reactions and recyclability experiments. A plausible mechanism was proposed based on several controlled experiments and literature support.

Defect-regulated and amino-functionalized UiO-67 for efficient removal of tetracycline hydrochloride from aqueous solutions

There is notable interest in the development of the efficient removal technologies for antibiotic contaminants in aqueous environments. In this study, L-cysteine was introduced into a UiO-67 precursor solution, and the defective amino-functionalized adsorbent UiO-67-HAc-NH2 was synthesized via a hydrothermal method. This adsorbent was used for the adsorption of tetracycline hydrochloride (TCH) from aqueous solutions. The characterization results confirmed the successful incorporation of amino groups into the adsorbent through L-cysteine and indicated that the defective structure, resulting from competitive interactions with organic ligands, significantly increased the specific surface area. UiO-67-HAc-NH2 demonstrated a maximum adsorption capacity of 605 mg/g for TCH and a notable enhancement in the specific surface area from 704.1 m2/g for pristine UiO-67–2858.7 m2/g. The adsorption mechanism was governed by the synergistic interplay of coordination, acid-base interactions, π–π conjugation, and weak noncovalent interactions. Recycling and regeneration experiments indicated that UiO-67-HAc-NH2 retained a regeneration recovery rate exceeding 90 %, highlighting its excellent reusability as an adsorbent. This result indicates the significant potential of defective amino-functionalized metal-organic framework (MOFs) materials for antibiotic adsorption applications.

Synthesis, Structural Aspects, Magnetic, and Adsorption Properties of a Dinuclear Cu (II) Complex Derived From Mixed Ligand Approach

ABSTRACTA dinuclear copper complex, [Cu2(teaH)(pNBA)2(H2O)2]·MeOH·pNBH (1) (where teaH3 = triethanolamine, pNBH = 4‐nitro‐benzoic acid, and pNBA = 4‐nitro‐benzoate) has been prepared and structurally characterized. In 1, there is an interesting intermolecular structure that is shown as a tetramer copper connected in chain‐like motif. In the UV‐Vis spectrum, higher absorbance at 267 nm is referred to n → π* transition, coupled with a weak peak at 500 nm, indicating another transition, which is specified as metal‐to‐ligand charge transfer. The higher intensity peak in the photoluminescence spectrum is marked as the absorption of energy required for the excitation of electrons, whereas lower intensity peaks show the emission of energy, which describes d‐d transitions of Cu (II) electrons due to d9 configuration. Complex 1 was explored for the adsorption of methylene blue (MB) dye, with the maximum adsorption as 101.07 mg/g, whereas the removal efficiency was estimated to be 81.05%. In conformity with the kinetic studies, the adsorption process proceeded via a Pseudo‐first‐order kinetic model. The incorporation of mixed ligands such as teaH3 and pNBH in 1 tends to increase the dimensionality that led to increased MB adsorption. The plausible mechanism behind the adsorption was favored by hydrogen‐bonding, electrostatic, π–π, and n–π* interactions, operating between the dye and complex 1. Further, the H‐bonding and these interactions provided stability to the complex, and an improved dye adsorption was observed even during the 2nd and 3rd recyclability experiments. Additionally, complex 1 corroborated remarkable stability after dye adsorption, allowing for up to four recycling turns. The magnetic study revealed antiferromagnetic coupling between the two magnetic centers with a singlet ground state (S = 0).

In Situ Preparation of MnO2 on the Catechol/Silane-Coated Polypropylene Nonwoven Fabrics for Effective Removal of Cationic Dyes.

Previous studies have confirmed that MnOx removes heavy metal ions and organic pollutants from water with dual effects of adsorption and oxidation coupling, significantly improving the ability to remove impurities. Nanometal oxides have a highly reactive surface but tend to agglomerate during preparation and are challenging to recycle after use. A common method is to combine nano-MnO2 with Fe3O4 to prepare magnetic materials for easy recycling. Our previous research has confirmed that catechol (CA) and (3-aminopropyl) triethoxysilane (KH550) can be co-deposited on the surface of polypropylene nonwovens to form a stable CK coating under alkaline conditions. In addition, the coating has many active groups, including hydroxyl groups, amino groups, etc. This study further investigates the secondary reactivity of CK coatings. The coordination of catechol groups and metal ions was used to anchor manganese ions to the coating. Meanwhile, the hydroxyl and amino groups were used to reduce manganese ions to Mn4+ in situ to prepare PP-(CK-MnO2). We found that the sample had an excellent decolorization effect on cationic dyes but was limited to anionic dyes. The decolorization mechanism of cationic dyes was further discussed. The results showed that the decolorization of cationic dyes had a dual effect of adsorption and oxidative degradation. Under acidic conditions, its oxidation properties were enhanced. It can be used as a highly effective decolorizing agent for cationic dyes, and the decolorization behavior is consistent with the first-order kinetics. As the pH increases, its oxidation properties gradually decrease. Although the electrostatic adsorption effect was enhanced, the overall decolorization performance was significantly reduced. Recycling experiments have proved that it can maintain >90% removal rate after five cycles. This study also demonstrated that the CK coating has dopamine-like properties, which can coordinate with metal ions to prepare metal-organic hybrid materials.

Spherical magnetic MgO-CeO2-Fe3O4@JB heterojunction for enhanced photodegradation of pesticide and complex anionic dyes: Understanding the degradation process and diverse water systems

Clothianidin (CLO) is a widely utilized pesticide recognized as an emerging pollutant capable of contaminating surface and subsurface water sources. Utilizing nanoparticles for photodegradation is a very ecological and cost-effective method for water treatment. This study involves the creation of a MgO-CeO2-Fe3O4@JB (Jute-Biochar) heterojunction with a mesoporous structure using hydrothermal process. The purpose of this design is to explore its potential for photocatalytic applications. PXRD (Powder X-ray Diffraction), FTIR (Fourier Transform Infrared), UV–DRS (Ultraviolet–Visible Diffuse Reflectance Spectroscopy), PL (Photoluminescence), TEM (Transmission Electron Microscopy), EDX (Energy Dispersive X-ray), XPS (X-ray Photoelectron Spectroscopy), VSM (Vibrating Sample Magnetometry), BET (Brunauer Emmett Teller), and SEM (Scanning Electron Microscopy) analysis confirmed the formation of a mesoporous MgO-CeO2-Fe3O4@JB heterojunction with preferred interface between MgO, CeO2, and Fe3O4 phases, extending the light-absorption insights to 700 nm. The photocatalytic performance of MgO-CeO2-Fe3O4@JB heterojunction was evaluated under visible-light using CLO as the target molecule. The degradation performances of CLO on MgO-CeO2-Fe3O4@JB were determined to be 95.24 ± 1.18 % after 35 min of exposure to light. The calculated rate constants for the degradation of CLO in presence of light using the MgO-CeO2-Fe3O4@JB composite were determined to be 0.0924 min−1. Furthermore, two complex dyes, Niagara Blue (NB) and Reactive Red (RR), photodegrade to 99.45 ± 1.24 % and 97.23 ± 1.41 % within 25 and 30 min, respectively. The excellent photocatalytic characteristics of the MgO-CeO2-Fe3O4@JB heterojunction was suggested to be primarily caused by the larger photo-response, aligned band-structure, and useful use of the photo-induced charge carriers of the photocatalyst. In addition, the recycling experiments have verified the exceptional photostability of the MgO-CeO2-Fe3O4@JB photocatalyst due to incorporation of nanoparticles into the biochar matrix. This leads to a synergistic mechanism for effectively eliminating these pollutants.

Visible light-driven selective oxidative transformation of vicinal diols using ZnS-based photocatalyst in the presence of molecular oxygen

The heterogeneous photocatalysis for the oxidative cleavage of C–C bond is significant to the transformation of biomass feedstock. In this work, a heterojunction photocatalyst based on the conductor ZnS and C3N4 (CN) material is prepared and employed in the aerobic oxidative cleavage reaction of vicinal diol under visible light irradiation. As a result, it is found that 3ZnS/CN catalyst obtained by a mechanical grinding method shows a high photocatalytic activity. In the photocatalytic oxidative cleavage process of 1-phenyl-1,2-glycol, more than 98.7% conversion of substrate with a 96.2% selectivity of benzaldehyde was attained using O2 as oxidant. In addition, the photocatalyst recycling experiments exhibited that the 3ZnS/CN catalyst still kept a good activity and stability even after being recycled for 5 times. Finally, the active reaction intermediates were investigated by the control experiments and the relative electron paramagnetic resonance (EPR) detection. According to the obtained results and photocatalytic principle, the mechanism for the selective oxidative transformatioin of 1-phenyl-1,2-glycol has been proposed. It gives a promising approach for the catalytic utilization of biomass-based lignin and cellulose.

Influence of transition metal (Cu) and rare earth metal (Dy) co-doping on spinel zinc ferrite (Cu0.1Dy0.08Zn0.9Fe1.92O4) for improved photocatalytic degradation of industrial effluents

In the present era, design and development of novel, highly stable, easily and magnetically separable, cost effective, and visible light driven catalytic material for the removal of harmful industrial effluents is of great importance. In this context, facile co-precipitation route was adopted for the synthesis of ZnFe2O4 (ZFO), Cu0.1Zn0.9Fe2O4 (CZFO), Dy0.08ZnFe1.92O4 (DZFO), and Cu0.1Dy0.08Zn0.9Fe1.92O4 (CDZFO) and their fabrication was confirmed by XRD, FTIR, SEM, and UV-Visible spectroscopy. The phase analysis of all designed materials exhibits that there is an increment in the crystallite size of co-doped zinc ferrite (CDZFO) i.e. 11.51 nm as compared to ZFO (10.74 nm), CZFO (10.92 nm), and DZFO (11.41 nm). The optical study shows a significant decrease in bandgap of CDZFO i.e. 1.82 eV as compared to DZFO (1.89 eV), CZFO (2.0 eV), and ZFO (2.14 eV). This decrease in optical bandgap and increase in crystallite size of the CDZFO is due to the quantum confinement effect. The photocatalytic efficiency of pure, doped, and co-doped samples was investigated against organic dye (Congo red), pharmaceutical drug (ibuprofen), and colorless organic compound (benzoic acid). The photocatalytic results reveal that CDZFO showed about ∼90 % degradation of Congo red while ZFO, CZFO, and DZFO showed only 59 %, 70 %, and 79 % respectively. Moreover, CDZFO also showed highest photocatalytic removal efficiency against ibuprofen (88 %) and benzoic acid (74 %) out of all other synthesized materials. The remarkable photodegradation ability of CDZFO for all targeted pollutants could be attributed to the generation of crystal defects in its lattice, its small bandgap, and higher absorption in visible region. Furthermore, the recyclability experiment confirmed the stability and reusability of the prepared sample.

A novel molecularly imprinted solid phase based on SiO2-Ag2O double-nucleation doped with graphene oxide for extraction and determination of flavonoids from Acanthaceae ebracteatus via HPLC-MS/MS

(Objectives) A novel method was developed for extracting and determining flavonoids from marine mangrove medicinal plants. This approach utilizes surface molecular imprinting to increase selectivity. Graphene oxide doped with a SiO2–Ag2O dual core structure served as a scaffold for synthesizing multilayer surface-imprinted polymers. The surface of the SiO2-Ag2O@GO composite was modified through self-polymerization. (Methods) Acacetin molecularly imprinted polymers (AMIPs) were created via surface-initiated precipitation polymerization with acacetin as the template. These AMIPs were synthesized and characterized via ultraviolet (UV) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Recycling experiments demonstrated the stability of the AMIPs. Analysis of the adsorption mechanism via the Langmuir and Freundlich models indicated that the Langmuir model was more suitable for predicting AMIPs. (Results) Scatchard plots showing two different binding sites of AMIPs for acacetin adsorption at various concentrations. The class selectivity of AMIPs for flavonoids was found in Acanthaceae ebracteatus. Compared with other analogs, competitive binding experiments revealed that the polymer had greater selectivity for acacetin. After AMIP solid-phase extraction (AMISPE), the linearity, LOD, LOQ, intraday and interday variabilities, recovery, and repeatability of AMIPs combined with HPLC–MS/MS were validated, confirming the method’s selectivity, precision, accuracy, and reproducibility. The contents of acacetin, apigenin, kaempferol, luteolin, quercetin, and genistein in Acanthaceae ebracteatus were determined. (Conclusions) These results indicate that AMISPE coupled with HPLC–MS/MS is a new, simple, and practical method for extracting, purifying, and enriching flavonoids from complex samples, such as those of herbs and other natural marine plants.

Defining quality by quantifying degradation in the mechanical recycling of polyethylene

Polyolefins have a multitude of uses across packaging, automotive and construction sectors. Their resistance to degradation during reprocessing enables recyclability, but variability in recycled polymer feedstocks renders it difficult to assure their manufacturing suitability. The lack of quality control methods has disabled circular economy pathways; product failure is costly, wasteful and time-intensive. Using rheology-simulated and extrusion-based recycling experiments, we explore the degradation pathways of high-density polyethylene (HDPE). Chain scission dominates during the initial degradation of HDPE, and increasing exposure to O2 shifts the dominant mechanism to long-chain branching. Importantly, extending this method to post-consumer recyclate (PCR), the results show potential as a methodology to assess recyclate quality to enable a circular plastics economy. In this study, we establish the validity of this rheology simulation to define a characteristic degradation parameter, relating it to the structural evolution under different environments defined for virgin HDPE and post-consumer recyclate (PCR).

Designing highly porous three-dimensional triazine-bearing covalent organic polymers as prominent adsorbents of carbon dioxide and iodine

A new class of triazine-containing covalent organic porous polymers TCOP1-3 were made using a versatile one-pot [3 + 2] cyclocondensation reaction revealing remarkable robustness as proven by their thermal stability which disclosed a 10 % weight loss temperature ≥400 °C. Investigation of the intrinsic microporosity properties of TCOP1-3 using nitrogen adsorption experiments disclosed salient Brunauer–Emmett–Teller (BET) surface areas ranging from 725 to 932 m2 g−1 with average pore volumes in the range of 0.52–0.65 cm3 g−1. TCOP1-3 exhibited high CO2 uptakes attaining 120 mg g−1 at 273K and low pressure whereas iodine capture tests demonstrated significant results achieving a maximum adsorption of 4.02 g g−1. Recycling experiments confirmed the potential for these polymers to be restored even after a multitude of concurrent iodine adsorption-desorption cycles.

Enhanced photocatalytic degradation of Reactive Green 19 dye using earthworms like T-ZnO-CuO nano-composite material as a S-scheme heterojunction photocatalyst

Due to increasing organic dye pollution in the water environment, green and efficient photocatalyst are urgently needed to solve this problem. This study hypothesizes that green-synthesized nanocomposites, using plant leaf extracts, will significantly enhance the efficiency of organic dye degradation without the environmental drawbacks associated with traditional methods. Herein, enhanced degradation of Reactive Green 19 (RG 19) dye using earthworm like T-ZnO-CuO (TZC) nano-composite was reported. T-ZnO (TZ) and TZC nano-composite were synthesized using leaves extract of Thevetia peruviana plant. In the synthesis process, Thevetia peruviana leaves extract acts as a capping, stabilising and reducing agent, and additionally create a unique surface morphology of TZC nano-composite. The establishment of TZ and TZC nano-composite samples were investigated using FT-IR, XRD, FE-SEM with EDX, HR-TEM and UV–VIS DRS spectroscopy. Furthermore, band gap energy of TZ and TZC nano-composites were calculated using Tauc’s plot. The band gap energy of TZC2 nano-composite was determined to be 2.80 eV. The nano-composite photocatalyst (TZC) was utilised in the degradation of RG 19 dye with 96.89 % efficiency in 150 min at 20 mg/L dye concentration, pH=7.5, and 0.6 g/L catalyst dose. In order to investigate the tentative photocatalytic mechanism, scavenging study, recyclability experiment, and stability were also investigated. The findings show that O2− and OH radical species have higher degree of involvement in the degradation process. The kinetics of the degradation of RG 19 dye follows pseudo-first-order kinetics.

Engineering of the ferrite-based support for enhanced performance of supported Pt, Pd, Ru, and Rh catalysts in hydrogen generation from NaBH4 hydrolysis

A series of M/NiCo-Ferrite (M: Pt, Pd, Ru, and Rh) nanoparticles were successfully synthesized, through a facile sol–gel auto-combustion followed by impregnation-reduction approach, as a catalyst for hydrogen generation from hydrolysis of NaBH4. All synthesized samples were characterized by XRD, N2 adsorption–desorption method, ICP-OES, FE-SEM, and EDX analysis. Compared to the other samples, it was observed that the Rh/NiCo-Ferrite sample exhibited higher particle distribution and surface area. To evaluate the hydrogen generation rate, the hydrolysis was carried out at a temperature of 35 °C, with an aqueous solution containing 5 wt.% NaBH4 and 3 wt.% NaOH. The experimental findings indicate that the Rh/NiCo-Ferrite sample exhibited a superior rate of hydrogen generation, with an average value of 11,667 mL/min.gcat, compared to the other samples studied. Enhanced catalytic properties may be responsible for its high activity. In addition, the activation energy of hydrolysis of sodium borohydride over the Rh/NiCo-Ferrite sample was 54.5 kJ/mol which is lower than the activation energy of many Ferrite-based catalysts. Moreover, the re-usability test of the Rh/NiCo-Ferrite sample denoted a decline in the catalytic activity after 4 recycling experiments due to the alterations in morphology and the reduction in the quantity of active phase.

Construction of ZnCo2O4/Ag3PO4 composite photocatalyst for enhanced photocatalytic performance

AbstractIn this study, ZnCo2O4/Ag3PO4 composite catalyst was prepared by the precipitation method, and their performance in the photocatalytic degradation of methyl orange (MO) was studied. The catalysts were characterized by scanning electron microscopy, high‐resolution transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, selected area electron diffraction, X‐ray photoelectron spectroscopy, and UV‐Vis diffuse reflectance spectroscopy. The results indicate that the 0.1 ZnCo2O4/Ag3PO4 composite system has good photocatalytic activity in the degradation of methyl orange. Under simulated sunlight conditions, the degradation rate can reach 94% after 30 min. The maximum reaction rate constant of 0.1 ZnCo2O4/Ag3PO4 was 0.05301 min−1, which is 3 times and 52 times the rate constant of pure Ag3PO4 and pure ZnCo2O4, respectively. In catalyst recycling experiments, 0.1 ZnCo2O4/Ag3PO4 still degraded methyl orange at a rate of 84.4% after three cycles. Trapping experiments showed that holes and superoxide radicals mostly contributed to the photocatalytic degradation of methyl orange by the catalyst, while hydroxyl radicals played a partial role. The energy level structure of ZnCo2O4/Ag3PO4 is conducive to the effective separation of photogenerated electrons and holes, improving the lifespan of photogenerated charges. In the investigated catalyst series, 0.1 ZnCo2O4/Ag3PO4 demonstrated the best photocatalytic performance.

Core-Shell Structured Cobalt Sulfide/C. I. Pigment Yellow 53 Photocatalysts with Abundant Sulfur Vacancies for Efficient Photocatalytic Co-Production of Xylonic Acid and CO.

Photocatalytic biorefinery has been gaining increasing attention as a promising method for utilizing biomass and solar energy, yet it still faces the key challenge of designing stable, efficient, and cost-effective photocatalysts. In this study, cobalt sulfide/ C. I. Pigment Yellow 53 composite photocatalysts (CoS/PY53-CSx) with a core-shell structure, which has abundant sulfur (S) vacancies, are developed using a simple hydrothermal method. The CoS nanocage with S vacancies not only offers numerous active sites but also enhances the light-trapping performance of PY53. Moreover, the internal electric field within the core-shell CoS/PY53-CSx further enhances charge separation/transfer efficiency while reducing electron transfer resistance, thereby boosting photocatalytic activity. Remarkably, 75.2% of xylonic acid and 22.8µmol of CO from xylose are obtained using CoS/PY53-CS0.1 in an air atmosphere. Recycling experiments demonstrate that CoS/PY53-CS0.1 exhibits excellent recyclability due to the strong bonding force between the core and shell. In addition, electron spin resonance characterization combined with poisoning experiments suggests that h+ and ·O2 - serve as the main oxidation active species during this system. This work presents a simple and cost-effective method for efficient photocatalytic biorefinery.

Heterogeneous Acetalization of Benzaldehyde over Lanthanide Oxalate Metal-Organic Frameworks.

Lanthanides (Ln) from the f-blocks of the periodic table have gained significant interest due to their unique characteristics, including magnetism, photoluminescence, and catalysis. In this study, a series of lanthanide metal-organic frameworks [Ln-MOFs, Ln = Eu(III), Tb(III), Nd(III), Er(III), Ho(III), Gd(III), Pr(III), and Dy(III)] were constructed based on oxalic acid and lanthanide metals as the building blocks. These MOFs were comprehensively characterized using various analytical and spectroscopic techniques, including powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, nitrogen adsorption-desorption, and Raman spectroscopy. The magnetic properties of the investigated materials were examined, revealing both antiferromagnetic and ferromagnetic interactions within the Ln-Ox MOFs. The catalytic activities of Ln-Ox MOFs were evaluated through the heterogeneous acetalization of benzaldehyde with methanol. Reaction yields by the reported catalysts varied up to 90% depending on the MOF's metal center, and the product was confirmed by gas chromatography-mass spectrometry. Recycling experiments have confirmed the stable regeneration of Ln-Ox MOFs in which the product yields remained the same over four consecutive cycles. The hydrothermal synthesis of these MOFs paves the way for a diverse array of materials showcasing unique lanthanide properties, making them suitable for various applications.

Evolution of the different types of catalytic sites in aminosilica materials during recycle experiments in aldol chemistry

Aminosilica materials are promising for many applications, including as a catalyst for aldol chemistry. Whereas aminosilica catalysts are known to deactivate overtime, it is unclear how recent revelations about the different types of catalytic sites impact the understanding of the deactivation behavior. In this work, we investigate how the aminosilica catalyst activity decreases and affects the fraction and the type of active sites. After a single catalytic cycle, the catalyst activity decreases, but the fraction of active sites remains constant. The decrease in catalytic activity is consistent with the conversion of medium and high activity sites transfer to low activity sites that lack cooperative interactions. Additional catalytic cycles decrease the fraction of active sites but do not result in aminosilane leaching. The sites are inactive because of accumulation of organic content. Interestingly, the organic can be removed through washing with a dilute sodium carbonate solution. The washed material fully recovers to the catalytic activity of the fresh material. Overall, the catalytic sites evolve after each cycle, but this trend can be reversed, enabling aminosilica materials to be used as sustainable catalysts for aldol chemistry.

Photocatalytic Degradation of Organic Dyes by Magnetite Nanoparticles Prepared by Co-Precipitation.

Iron oxide nanoparticles were synthesized by co-precipitation using three different iron salt stoichiometric mole ratios. Powder X-ray diffraction patterns revealed the inverse cubic spinel structure of magnetite iron oxide. Transmission electron microscopic images showed Fe3O4 nanoparticles with different shapes and average particle sizes of 5.48 nm for Fe3O4-1:2, 6.02 nm for Fe3O4-1.5:2, and 6.98 nm for Fe3O4-2:3 with an energy bandgap of 3.27 to 3.53 eV. The as-prepared Fe3O4 nanoparticles were used as photocatalysts to degrade brilliant green (BG), rhodamine B (RhB), indigo carmine (IC), and methyl red (MR) under visible light irradiation. The photocatalytic degradation efficiency of 80.4% was obtained from Fe3O4-1:2 for brilliant green, 61.5% from Fe3O4-1.5:2 for rhodamine B, and 77.9% and 73.9% from Fe3O4-2:3 for both indigo carmine and methyl red. This indicates that Fe3O4-2:3 is more efficient in the degradation of more than one dye. This study shows that brilliant green degrades most effectively at pH 9, rhodamine B degrades best at pH 6.5, and indigo carmine and methyl red degrade most efficiently at pH 3. Recyclability experiments showed that the Fe3O4 photocatalysts can be recycled four times and are photostable.

Preparation of biomass-derived porous biochar for efficient removal of iodized X-ray contrast media in water: Adsorption performance and underlying mechanism

Hydrophilic Iodized X-ray contrast medias (ICM) are difficult to separate from water. Here, a novel porous biochar (MBC) with a high specific surface area (1435.1 m2 g−1) was prepared by one-step pyrolysis, which showed excellent adsorption capacity for Iodized X-ray contrast media, including diatrizoic acid (95.1 mg g-1), iohexol (297.8 mg g-1), and iopamidol (298.9 mg g-1). The optimal pyrolysis temperature for MBC was 700 ℃, and the ratio of sodium hydroxide to sodium carbonate was 1:3. Adsorption kinetic was well fitted by the pseudo-second-order model. Adsorption isotherm was best fitted to the Freundlich model. Adsorption thermodynamics suggested that ICM adsorption was spontaneous and endothermic. Material characterizations demonstrated that good adsorption performance of MBC for ICM mainly depended on pore filling, π-π interaction. The density functional theory (DFT) showed that H-bonding between oxygen-containing functional groups on MBC and ICM further promoted adsorption. Recycling experiments showed that MBC had good reusability. The study indicated that one-step pyrolysis synthesis of alkaline substance pretreatment biochar could be a promising adsorbent for water purification.

Exploring the in‐situ Development of A 1 D/2 D Gadolinium Iron Oxide/Tungsten Disulfide Photocatalyst to Improve Tetracycline Degradation Mediated by Visible Light

AbstractIn the field of photocatalysis, heterojunction photocatalysts have garnered a lot of attention due to their high‐efficiency interfacial charge‐transfer property and their nanoarchitecture. Herein, GdFeO3/WS2 is successfully synthesized by the in‐situ growth method and holds significant catalytic properties and efficient degradation for tetracycline. Using WS2 as a co‐catalyst could reduce e‐ and h+ recombination, improving GdFeO3’s photocatalytic performance. The GdFeO3/WS2 possesses a bandgap of 1.9 eV, 178.9 m2 g−1 specific surface area, 0.2 nm pore size, and a lifespan of 6 ns. The optimal GdFeO3/WS2 photocatalyst exhibits a maximum removal of 96.2 % at a tetracycline concentration of 10 mg/L, a pH of 3, and 40 mg of photocatalyst in an irradiation time of 90 min. Tetracycline has a higher photocatalytic efficiency in visible light (96.2 %) than in sunlight (72.6 %). Trapping tests revealed that the major reactive species for tetracycline removal in an aqueous solution are ⋅⋅OH, and ⋅⋅O2‐. The recycle experiment shows no deactivation of the GdFeO3/WS2 photocatalyst after 5 recycles. This study sheds light on the rational design of the GdFeO3/WS2 photocatalyst as a potential material for treating wastewater.

Agro-waste derived sulfonated biochar material as a sustainable heterogeneous catalyst for conversion of fructose to 5-hydroxymethylfurfural

BackgroundDevelopment of biomass derived solid acid catalysts has the advantage to conform the green chemistry protocol for production of 5-hydroxymethylfurfural (HMF) by dehydration of fructose. MethodWe have reported waste cashew nut shell produced char as a biochar to prepare sulfonated biochar (SBC) catalyst by incorporating –SO3H group through treatment of concentrated sulfuric acid. Significant findingsDifferent methods of characterization including XRD, FT-IR, XPS, FESEM-EDS, TEM, TPD and BET analysis, were used to study the structure, morphology, chemical compositions, acidity and porosity of the produced SBC catalysts. The mesoporous nature of the material was confirmed by the powder X-ray diffraction patterns (PXRD), type IV isotherm (BET), and flakes-like structure was observed in TEM analysis. The catalyst showed high yield of HMF (92%) under optimum conditions of 120 °C in 60 min under biphasic solvent mixture of water and toluene (1:2). High yield could be explained by high acid strength of catalyst as observed by NH3-TPD analysis. Leaching test by Sheldon's method and recyclability experiment proved the need and heterogeneity of the present catalyst.