Effect of co-doping of bismuth, copper and cerium in zinc ferrite on the photocatalytic degradation of bisphenol A

Structural/surface characterization of transition metal element-doped H-ZSM-5 adsorbent for CH3SH removal: identification of active adsorption sites and deactivation mechanism

CH3SH is a potential hazard to both chemical production and human health, so controlling its emissions is an urgent priority. In this work, a series of transition metal-loaded H-ZSM-5 adsorbents (Si/Al = 25) (Cu, Fe, Co, Ni, Mn, and Zn) were synthesized through the wet impregnation method and tested for CH3SH physicochemical adsorption at 60 °C. It was shown that the Cu-modified H-ZSM-5 adsorbent was much more active for CH3SH removal due to its abundant strong acid sites than other transition metal-modified H-ZSM-5 adsorbents. The detailed physicochemical properties of various modified H-ZSM-5 adsorbents were characterized by SEM, XRD, N2 physisorption, XPS, H2-TPR, and NH3-TPD. The effects of metal loading mass ratio, calcination temperature, and acid or alkali modification on the performance of the adsorbent were also investigated, and finally 20% Cu/ZSM-5 was found to have the best adsorption capacity after calcined at 350 °C. Additionally, the Cu/ZSM-5 adsorbent modified by sodium bicarbonate could expose more active components, which improved the adsorbent's stability. However, the consumption and reduction of the active component Cu2+ and the accumulation of sulfate during the adsorption process are the main reasons for the deactivation of the adsorbent. In addition, the simultaneous purging of N2 + O2 can effectively restore the adsorption capacity of the deactivated adsorbent and can be used as a potential strategy to regenerate the adsorbent.

Noble metals (Pd, Ag, Pt, and Au) doped bismuth oxybromide photocatalysts for improved visible light-driven catalytic activity for the degradation of phenol

The doping of noble metals onto the semiconductor metal oxides has a great impact on the intrinsic properties of the materials. This present work reports the synthesis of noble metals doped BiOBr microsphere by a solvothermal method. The various characteristic findings reveal the effective incorporation of Pd, Ag, Pt, and Au onto the BiOBr and the performance of synthesized samples was test for the degradation of phenol over visible light. The Pd-doped BiOBr material showed enhanced phenol degradation efficacy, which is ∼4-fold greater than pure BiOBr. This improved activity was on reason of good photon absorption, lower recombination rate, and higher surface area facilitated by surface plasmon resonance. Moreover, Pd-doped BiOBr sample displayed good reusability and stability after 3 cycles of run. A plausible charge transfer mechanism for phenol degradation is disclosed in detail over Pd-doped BiOBr sample. Our findings disclose that the incorporation of noble metal as the electron trap is a feasible approach to enhance visible light activity of BiOBr photocatalyst used in phenol degradation. This work represents new vision interested in the outline and development of noble metal doped semiconductor metal oxides as a visible light material for the elimination of colorless toxins from untreated wastewater.

Dual function Mg-doped binary metal ferrite: Photocatalytic degradation of trichlorophenol, bactericidal activity and molecular docking analysis

A new Mg-doped Zn_0.5Ni_0.5Fe₂O₄ (Mg-FZN) photocatalyst was synthesised using a simple co-precipitation-doping technique to develop a dual-function material with the ability to degrade hazardous and refractory pollutants and inactivate bacterial strains. The characterization results revealed that Mg-FZN is an n-type semiconductor with a conduction band of -0.413 eV, an average pore width of 2.32 nm, and a crystal size of 31.45 nm. The photocatalytic activity of Mg-FZN was assessed based on the degradation of 2,4,5-trichlorophenol and achieved 83.8% degradation efficiency under optimised conditions. The radical quenching results revealed that h⁺ significantly contributed to the photodegradation process while ^•OH, and ^•O₂^- played key roles. Additionally, within 60 min, 25 mg of Mg-FZN had bactericidal effects on the bacteria E. coli and S. aureus in both the presence and absence of UV light. Mg-FZN showed H-bonding, electrostatic, and metal-contact interactions with the amino acid residues of the bacterial protein with high binding scores (-4.711 kcal/mol and -5.872 kcal/mol), according to molecular docking.

Bismuth and Vanadium-Substituted Yttrium Phosphates for Cool Coating Applications

Luminescent yttrium phosphate is engineered into an environmentally benign near infrared (NIR) reflective yellow pigment by the substitution of bismuth and vanadium metals in the host lattice. A series of YP_(1-x)V _x O₄ (x = 0, 0.05, 0.1, 0.15, 0.2, and 0.4), Y_(1-y)Bi _y PO₄ (y = 0.1 and 0.3), and Y_(1-y)Bi _y P_(1-x)V _x O₄ (x = y = 0.2, 0.4, and 0.6) were prepared by the precipitation method. Secondary phase was noticed at x = 0.2 and y = 0.2 while substituting vanadium and bismuth, respectively, due to high ionic radii of the dopant ions. Co substitution of vanadium and bismuth in the YPO₄ lattice enhanced both NIR reflectance and yellow color of all the fabricated materials. XPS spectra proved the presence of trivalent bismuth and pentavalent vanadium in Y_0.4Bi_0.6P_0.4V_0.6O₄. Due to the substitution effect, a more defined morphology was noticed, which enhanced the scattering co-efficient of the fabricated materials; hence, the NIR reflectance of the materials was increased from 68% (YPO₄) to 83% (Y_0.4Bi_0.6P_0.4V_0.6O₄). Chemical and thermal stability test of Y_0.4Bi_0.6P_0.4V_0.6O₄ confirmed the color and strength of the designed pigment. With good yellow hue (b* = +56.06), high NIR solar reflectance (R* = 83%), and good stability, Y_0.4Bi_0.6P_0.4V_0.6O₄ can act as an environmentally benign cool yellow pigment.

Integration of Mn-ZnFe2O4 with S-g-C3N4 for Boosting Spatial Charge Generation and Separation as an Efficient Photocatalyst

The disposal of dyes and organic matter into water bodies has become a significant source of pollution, posing health risks to humans worldwide. With rising water demands and dwindling supplies, these harmful compounds must be isolated from wastewater and kept out of the aquatic environment. In the research presented here, hydrothermal synthesis of manganese-doped zinc ferrites’ (Mn-ZnFe₂O₄) nanoparticles (NPs) and their nanocomposites (NCs) with sulfur-doped graphitic carbon nitride (Mn-ZnFe₂O₄/S-g-C₃N₄) are described. The samples’ morphological, structural, and bonding features were investigated using SEM, XRD, and FTIR techniques. A two-phase photocatalytic degradation study of (0.5, 1, 3, 5, 7, 9, and 11 wt.%) Mn-doped ZnFe₂O₄ NPs and Mn-ZnFe₂O₄/(10, 30, 50, 60, and 70 wt.%) S-g-C₃N₄ NCs against MB was carried out to find the photocatalyst with maximum efficiency. The 9% Mn-ZnFe₂O₄ NPs and Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs exhibited the best photocatalyst efficiency in phase one and phased two, respectively. The enhanced photocatalytic activity of the Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs could be attributed to synergistic interactions at the Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs interface that resulted in a more effective transfer and separation of photo-induced charges. Therefore, it is efficient, affordable, and ecologically secure to modify ZnFe₂O₄ by doping with Mn and homogenizing with S-g-C₃N₄. As a result, our current research suggests that the synthetic ternary hybrid Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs may be an effective photocatalytic system for degrading organic pollutants from wastewater.

Construction of a Well-Defined S-Scheme Heterojunction Based on Bi-ZnFe2O4/S-g-C3N4 Nanocomposite Photocatalyst to Support Photocatalytic Pollutant Degradation Driven by Sunlight

Currently, organic dyes and other environmental contaminants are focal areas of research, with considerable interest in the production of stable, high-efficiency, and eco-friendly photocatalysts to eliminate these contaminants. In the present work, bismuth-doped zinc ferrite (Bi-ZnFe2O4) nanoparticles (NPs) and bismuth-doped zinc ferrites supported on sulfur-doped graphitic carbon nitride (Bi-ZnFe2O4/S-g-C3N4) (BZFG) photocatalysts were synthesized via a hydrothermal process. SEM, XRD, and FTIR techniques were used to examine the morphological, structural, and bonding characteristics of the synthesized photocatalysts. The photocatalytic competence of the functional BZFG nanocomposites (NCs) was studied against MB under sunlight. The influence of Bi (0.5, 1, 3, 5, 7, 9, and 11 wt.%) doping on the photocatalytic performance of ZnFe2O4 was verified, and the 9%Bi-ZnFe2O4 nanoparticles exhibited the maximum MB degradation. Then, 9%Bi-ZnFe2O4 NPs were homogenized with varying amounts of S-g-C3N4 (10, 30, 50, 60, and 70 wt.%) to further enhance the photocatalytic performance of BZFG NCs. The fabricated Bi-ZnFe2O4/30%S-g-C3N4 (BZFG-30) composite outperformed ZnFe2O4, S-g-C3N4 and other BZFG NCs in terms of photocatalytic performance. The enriched photocatalytic performance of the BZFG NCs might be ascribed to a more efficient transfer and separation of photo-induced charges due to synergic effects at the Bi-ZnFe2O4/S-g-C3N4 interconnection. The proposed modification of ZnFe2O4 using Bi and S-g-C3N4 is effective, inexpensive, and environmentally safe.

Progress in the Preparation and Modification of Zinc Ferrites Used for the Photocatalytic Degradation of Organic Pollutants

Zinc ferrite is a type of photocatalytic material with high physicochemical stability, narrow band gap, high carrier separation efficiency, high porosity, and paramagnetism, which makes it easy to recover. Thus, zinc ferrite is widely used as a photocatalyst in water treatment. In this paper, the preparation principles as well as the advantages and disadvantages of typical methods used to prepare zinc ferrite including hydrothermal, co-precipitation, sol-gel, and other novel methods such as biosynthesis have been summarized. Modification methods such as elemental doping, composite formation, and morphological modification have been highlighted. Using these modification methods, the catalytic activity of zinc ferrite toward the photocatalytic degradation of organic pollutants in water has been enhanced. Biosynthesis is regarded as a promising preparation method that uses biological materials instead of chemical materials to achieve the large-scale preparation of zinc ferrite using low cost, energy efficient, and environmentally friendly processes. Meanwhile, the combination of multiple modification techniques to enhance the photocatalytic performance of zinc ferrite will be an important research trend in the future.

CuCe-Ferrite/TiO2 Nanocomposite as an Efficient Magnetically Separable Photocatalyst for Dye Pollutants Decolorization

In this work, a magnetically separated photocatalyst with great efficiency CuCe-Ferrite/TiO2 composite was prepared and characterized by X-ray diffraction (XRD), UV–Vis spectrophotometry, Fourier transformer infra-red spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). Single-phase cubic spinel was formed by calcining the prepared sample at a temperature of 550 °C, according to the results. Different concentrations of reactive red 250 (RR250) dye photodegradation was evaluated using different doses of CuCe-ferrite/ TiO2 and TiO2 NPs. Higher efficiency of RR250 photodegradation up to 100% was obtained using CuCe-ferrite/ TiO2. The photodegradation efficiency was confirmed using chemical oxygen demand (COD) test of both treated and untreated samples. The oxidation process was mostly mediated by photogenerated .O2− according to scavenger test results. The catalyst possess higher photodegradation efficiency even after regeneration for ten times.

Graphical Abstract

Green synthesis of lignin nanorods/g-C3N4 nanocomposite materials for efficient photocatalytic degradation of triclosan in environmental water

Triclosan (TCS) is a common anti-microbial ingredient in pharmaceutical and personal care products. The usage of TCS was banned by the United States Food and Drug Administration (in 2016) due to its potential health risks. However, TCS has been frequently detected in the aquatic environment. Therefore, it is vital to design low-cost and highly efficient photocatalysts to enhance TCS's photocatalytic degradation in wastewater treatment to eliminate its toxicity to environmental health. In this study, we developed a highly efficient catalyst by incorporating lignin nanorods (LNRs) into graphitic carbon nitride (GCN) nanomaterials as green LNRs/GCN-based nanocomposite photocatalysts for the effective degradation of TCS in waters. LNRs/GCN nanosheets (NSs) and LNRs/GCN-NRs based nanocomposite materials were prepared using a simple wet-impregnation method. The surface morphology and optical properties of as-synthesized materials were well-characterized using FE-SEM, XRD, XPS, and UV-DRS. The photocatalyst (LNRs/GCN-NRs) material showed maximum TCS degradation efficiency of 99.9% and a high rate constant of 0.0661 min^-1 under pH-10 with crucial reactive spices (OH and O₂^-), and excellent cycling performance (over five cycles) within 90 min of UV-light illumination. LNRs/GCN-NRs nanocomposite indicated enhanced photocatalytic performances for TCS degradation due to its strong synergistic effect between LNRs and GCN-NRs as bifunctional catalyst substrate morphology with efficient bandgap energy and accessible active sites compared to LNRs/GCN-NSs. Therefore, LNRs/GCN-NRs nanocomposite was observed to be a highly-active, low-cost, stable, eco-friendly, and efficient photocatalyst for complete degradation of TCS under UV-light irradiation.