Applied Surface Science Advances最新文献

This study deals with the development of a granulated Fe-pillared clay (Fe-PC) using carboxymethylcellulose (CMC) as a binder to present it as an innovative adsorbent for the individual and competitive adsorption of tetracycline (Tc) and tizanidine (Tz) from water. An optimum pH value of 7 was determined for both individual and multi-component adsorption. The optimal dosage of granulated Fe-PC was determined to be 1.5 g/L for Tz and 3 g/L for Tc, resulting in constant removal rates of 80 % for Tc and 90 % for Tz. Tizanidine showed a higher affinity for powdered or granulated Fe-PC compared to tetracycline, due to its smaller molecular size and increased amine functional groups. Consequently, Tz showed improved kinetic rates (initial pseudo-second order sorption rates of 170.79 and 25.62 mg/g.h for Tz and Tc, respectively) and equilibrium capacities (maximum monolayer adsorption capacity of granulated Fe-PC at room temperature over Tc and Tz, 54.89 mg/g and 66.40 mg/g). Granulation affected the kinetic rate for both adsorbates, albeit with a more pronounced effect for Tc. The adsorption of Tz was less sensitive to temperature changes, indicating a lower enthalpy change of adsorption (14.24 and 77.91 kJ/mol for Tz and Tc, respectively). HCl for Tc and NaCl for Tz were identified as optimal desorption eluents, confirming the involvement of cation exchange in Tz adsorption. Surface functional group analysis confirmed the proposed complexation mechanisms. Tz consistently showed a higher affinity for granular Fe-PC than Tc, especially at lower adsorbent dosages. This article provides a comprehensive insight into the characterization of the prepared adsorbents and their cyclic adsorption-desorption performance for Tc and Tz.

TiO₂ is a low-cost and biocompatible material with high oxidizing ability. However, their photocatalytic activity is limited to UV light irradiation. In this research, for the first time, a novel TiO₂/CeFeO₃ heterojunction was synthesized by the green synthesis method using an aqueous fraction of Artemisia vulgaris leaf extracts. TiO₂/CeFeO₃ shows enhanced photocatalytic performance under visible light irradiation. The vibrational, structural, optical, and compositional properties of TiO₂/CeFeO₃ were characterized. The as-prepared TiO₂/CeFeO₃ has spherical-shaped particles and shows a significantly diminished bandgap energy (3.25 eV to 2.75 eV). The photocatalytic performance of TiO₂/CeFeO₃ was investigated to degrade malachite green (MG) with an efficiency of up to 93.53% under its optimum dose. TiO₂/CeFeO₃ shows stable photocatalytic performance until the fourth cycle. The kinetics of the photodegradation of MG followed the pseudo-first-order reaction with a rate constant (k_app) of 2.14×10⁻² min⁻¹. The enhanced photocatalytic activity of TiO₂/CeFeO₃ was attributable to the creation of heterojunction, which suppresses the recombination rate of photogenerated electron-hole validated by the photoluminescence analysis. This work presents an eco-friendly approach to synthesizing novel heterojunction material with enhanced photocatalytic dye degradation.

The selective ortho–alkylation of 1–naphthol with methanol is carried out over various commercially available acid solid catalysts under relatively mild reaction conditions (<300 ºC), in batch, and anhydrous zeolite HY shows the best catalytic activity. Removal of the strongly adsorbed water in the zeolite is key for the alkylation reaction. Mechanistic studies based on isotopically labelled experiments reveal the transformation of O–methylated 1–naphthol into the desired ortho–C–methylation product after intramolecular rearrangement of the methyl group. These results open the way to design a new synthesis of ortho–methyl 1–naphthol and, consequently, of vitamin K3, based on a commercially available, inexpensive and non–toxic solid catalyst such as HY zeolite.

The Y₂O₃ decorated with ZnFe₂O₄ was successfully synthesized using Citrus limon (L.) Osbeck leaf extract for the first time. A modification of Y₂O₃ with ZnFe₂O₄ nanoparticles was carried out because Y₂O₃ is stable but has a wide band gap, making it less active in visible light. On the other hand, ZnFe₂O₄ has a small band gap and is cheap. The synthesized ZnFe₂O₄/Y₂O₃ nanocomposites, ZnFe₂O₄, and Y₂O₃ nanoparticles were characterized using FTIR, XRD, TEM, SEM, and DRS UV–Vis. TEM and DRS UV–Vis results show that the ZnFe₂O₄/Y₂O₃ nanocomposite particle has a size of 49,61 nm with a unique shape and an optical band gap of 2.08 eV. The photocatalytic activity of Y₂O₃, ZnFe₂O₄, and ZnFe₂O₄/Y₂O₃ was observed based on the photodegradation of malachite green (MG) dye under visible light. The results demonstrate that ZnFe₂O₄/Y₂O₃ can degrade MG with a photodegradation percentage of 95 % within 120 min, which is better than pure ZnFe₂O₄ and Y₂O₃. After the fourth cycle, the photodegradation percentage of MG by ZnFe₂O₄/Y₂O₃ remained at 88 %, demonstrating good reusability of ZnFe₂O₄/Y₂O₃ for photocatalytic degradation. These findings demonstrate that the use of ZnFe₂O₄ as a modifier may increase the photocatalytic performance of Y₂O₃.

The rapid development of superior, highly stable, alkaline-medium-compatible, and nonprecious earth-abundant bifunctional electrocatalysts has garnered significant research interest. This interest aims to replace the costliest noble metals (Pt, Ir/IrO₂, and Ru/RuO₂) in renewable and green energy technologies for overall water splitting. However, there are still important limitations, such as lower stability and higher energy consumption. In this work, we report the synthesis of Cu-Co metal-organic frameworks (MOFs) as a bifunctional electrocatalyst using a simple chemical precipitation technique. Especially, when 11.5 mM of Co is combined with Cu MOF, it exhibits excellent bifunctional activity for overall water splitting with a lower overpotential of 0.21 V (OER) and -0.71 V (HER) at a current density of 10 mA cm⁻², which exhibits nearly several times more enhancement than that of pristine Cu and Co MOFs in a 1 M KOH electrolyte solution. The Tafel slope value of 130 mV/dec and the lower charge transfer resistance, along with relatively high stability for up to 12 h at the onset potential of OER and HER, are observed for the 11.5 mM Cu-Co MOF electrocatalyst. The present results open an alternative pathway for developing a novel design of highly efficient and scalable bifunctional electrocatalysts for overall water splitting.

In this study, surface modification of basalt fibers (BFs) utilizing atmospheric pressure plasma deposition was carried out. Using this one-step deposition approach, three siloxane precursors with different structures including methyltrimethoxysilane (MTMS), hexamethyldisiloxane (HMDSO), and tetramethoxysilane (TMOS) were deposited on BFs surface, respectively. The physicochemical properties of the thin films from three different siloxane compounds are elucidated. In comparison with MTMS-coated sample, HMDSO-coated and TMOS-coated BFs surfaces feature an improved thermal insulation performance. The results demonstrate that atmospheric pressure plasma deposition is an efficient approach to modify flexible materials surface with improved thermal insulation. Moreover, it provides a reference to decide which precursor type is preferred for certain applications.

Sensitization of wide-gap metal oxides by the porphyrins has been promising to utilize the major fraction of solar light for photocatalytic reactions. In this context, rutile-SnO₂ was anchored with hemin complex and their performance was evaluated for the 4-nitro phenol (4-NP) degradation under UV/visible light. Driven by the significant interactions between -COOH and surface -OH functional groups of hemin and SnO₂ respectively, a new linkage O=CO-Sn was formed at the interface, which was vital for charge carrier transfer between them. Both X-ray diffraction studies and scanning electron microscope analysis confirmed that the surface hemin adsorption did not alter the crystal structure and the morphology of pristine SnO₂. The light absorption properties revealed a red shift in the optical response of the composite, which facilitated the photocatalytic reactions to operate under visible light. The electrochemical and photoluminescence measurements collectively attested to the enhanced charge carrier separation in the composite compared to pure SnO₂. The synergism arising from the photo-Fenton and photocatalytic reactions was derived from the cyclic reactions of Fe(II)/Fe(III) and oxidation of hydroxyl radicals by the valence band holes of SnO₂ with H₂O₂ under UV light. In contrast, the sensitization process resulted in electron transfer from the excited state of hemin to the conduction band (CB) of SnO₂ under visible light. Such distinct mechanistic pathways by the metal oxide-porphyrin composite would be promising for wastewater purification under UV–visible light region in near future.