A stable and efficient La-doped MIL-53(Al)/ZnO photocatalyst for sulfamethazine degradation

Enhanced Photocatalytic Degradation by the Preparation of a Stable La-Doped FeTiO3 Photocatalyst: Experimental and DFT Study

The rapid photocarrier recombination limits the photocatalytic activity of iron titanate (FeTiO3) to be further improved. Developing novel approaches to inhibit the rapid recombination rate of the FeTiO3 photocatalysts is crucial for efficiently degrading pollutants in wastewater. Rare earth ions, with unique electron dispositions and large ion radii, could effectively inhibit photocarrier recombination. Herein, novel lanthanum (La)-doped FeTiO3 photocatalysts were designed and successfully synthesized. The photocatalytic performance of the 12 mol % La/FeTiO3 photocatalyst was superior in degrading tetracycline hydrochloride (TCH), methylene blue (MB), and brilliant blue (BB). These degradation rate constants (k) were 0.12358, 0.01357, and 0.03064 L mg-1 min-1, respectively, which were 12.83, 1.61, and 7.78 times that of pure FeTiO3. The photoelectronic tests and density functional theory (DFT) calculations revealed that the La 4f orbital forms an impurity energy level in the conduction band of FeTiO3. This level narrows the bandgap and acts as an electron acceptor, capturing photoexcited electrons and inhibiting the rapid recombination of photoexcited electron-hole pairs in FeTiO3. This work enhances the potential of FeTiO3 in the photocatalysis field and provides important insights into the efficient degradation of organic pollutants in wastewater.

Highly efficient adsorption of antibiotic ciprofloxacin hydrochloride from aqueous solution by diatomite-basic zinc chloride composites

The antibiotic ciprofloxacin (CIP) is used to treat a variety of bacterial infections, yet it poses significant health risks to aquatic environments. While adsorption is a promising technique for CIP removal, current adsorption capacities remain limited. In this study, we introduce a diatomite and basic zinc chloride composite (ZnHC-Dt) prepared using a straightforward deposition method, with the ability to achieve highly efficient ciprofloxacin removal. ZnHC-Dt is characterized using field emission scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and the Brunauer-Emmett-Teller method (BET). We also assess the zeta potential. The optimized ZnHC-Dt adsorbent, achieved at a mass ratio of 0.45 with ZnHC/(ZnHC+Dt), is adopted with a CIP adsorption capacity of 831.96 mg/g at 25 °C, broad pH adaptability (within 3.0-10.0), rapid adsorption rate (reaching equilibrium in 4 h), and stable performance under Na+ ionic strength. The CIP adsorption process follows pseudo-second-order kinetics and aligns well with the Langmuir adsorption model. The high adsorption capacity of ZnHC-Dt can be attributed to electrostatic attraction, hydrogen bonding, surface complexation, and available adsorption sites. During the desorption process, the CIP removal rate retains 65.33% effectiveness after five cycles. The results suggest that ZnHC-Dt holds significant potential for CIP removal in aqueous solutions.

Effective photodegradation of antibiotics by guest-host synergy between photosensitizer and bismuth vanadate: Underlying mechanism and toxicity assessment

The removal of antibiotics in wastewater has attracted increasing attention. Herein, a superior photosensitized photocatalytic system was developed with acetophenone (ACP) as the guest photosensitizer, bismuth vanadate (BiVO₄) as the host catalyst and poly dimethyl diallyl ammonium chloride (PDDA) as the bridging complex, and used for the removal of sulfamerazine (SMR), sulfadiazine (SDZ) and sulfamethazine (SMZ) in water under simulated visible light (λ > 420 nm). The obtained ACP-PDDA-BiVO₄ nanoplates attained a removal efficiency of 88.9%-98.2% for SMR, SDZ and SMZ after 60 min reaction and achieved kinetic rate constant approximately 10, 4.7 and 13 times of BiVO₄, PDDA-BiVO₄ and ACP-BiVO₄, respectively, for SMZ degradation. In the guest-host photocatalytic system, ACP photosensitizer was found to have a great superiority in enhancing the light absorption, promoting the surface charge separation-transfer and efficient generation of holes (h⁺) and superoxide radical (·O₂^-), greatly contributing to the photoactivity. The SMZ degradation pathways were proposed based on the identified degradation intermediates, involving three main pathways of rearrangement, desulfonation and oxidation. The toxicity of intermediates was evaluated and the results demonstrated that the overall toxicity was reduced compared with parent SMZ. This catalyst maintained 92% photocatalytic oxidation performance after five cyclic experiments and displayed a co-photodegradation ability to others antibiotics (e.g., roxithromycin, ciprofloxacin et al.) in effluent water. Therefore, this work provides a facile photosensitized strategy for developing guest-host photocatalysts, which enabling the simultaneous antibiotics removal and effectively reduce the ecological risks in wastewater.

Microwave-assisted MOF@biomass layered nanomaterials: Characterization and applications in wastewater treatment

MOF@Biomass layered hybrids were designed through in situ growth from rice husk (RH) and microwave-assisted synthesized MIL-53(Al) particles that enable the reduction of reaction times. The synthesis process included steps to pretreat RH, Al adsorption on RH, and then MIL-53(Al) in-situ growth reaction at 125 °C for 60 min and 200 W irradiation power. The resulting hybrid (MIL-53(Al)@RH) and its parent separate materials were characterized using TGA, SEM, FTIR, XRD, among others. MIL-53(Al)@RH showed high crystallinity in the hybridized MOF particles, thermal decomposition phases, and functional groups (Al-O, O-H, CO, and CC). The hybrid particles allow an easy separation during heterogeneous processing due to their 400 times larger size compared to MIL-53(Al) crystals. The properties of the layered hybrids for removal of Oxytetracycline (OTC), Diclofenac (DCL), and Glyphosate (GLY) in aqueous solutions, were tested by adsorption (ADS) and advanced oxidation processes (AOP). The high ADS capacities (162 mg g^-1 GLY, 139 mg g^-1 OTC, 93 mg g^-1 DCL) and % removal in AOP (97% GLY, 91% OTC, 80% DCL) demonstrated that MIL-53(Al) maintained its properties after hybridization.