Correction for ‘Oxygen vacancy enhanced catalytic activity in a Pt nanoparticle decorated GO–CexOy catalyst for the efficient synthesis of pyran based derivatives’ by Pratap S. Nayak et al., New J. Chem., 2023, 47, 13004–13015, https://doi.org/10.1039/D3NJ00605K.
A modified amine chain segment was synthesized through a reaction between polyethylene glycol (PEG) and bisphenol A epoxy resin. Subsequently, organically modified montmorillonite (OMMT) was prepared via ammonium salt formation under acidic conditions. Using phase inversion technology, an epoxy resin/organic montmorillonite composite emulsion was successfully fabricated, employing a minimal amount of an epoxy emulsifier with OMMT as a co-emulsifier. Thermal curing of this emulsion yielded the final OMMT/epoxy resin composites. Structural characterization was performed using Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) to confirm the chemical composition of the synthesized amine. X-ray diffraction (XRD) analysis verified the successful intercalation and exfoliation of montmorillonite during organic modification. The emulsion system was further evaluated through dynamic light scattering (DLS) and zeta potential measurements, which demonstrated that OMMT incorporation significantly enhanced emulsion stability by optimizing particle size distribution and increasing surface charge density. Thermal analysis revealed notable improvements in the thermomechanical properties of the composites, confirming the reinforcing effect of OMMT within the epoxy matrix.
Information regarding adsorption–desorption of pollutants on degradable microplastics in marine environments is limited. Biodegradable microplastics including polylactic acid (PLA), polyhydroxyalkanoate (PHA), and polybutylene adipate (PBAT) as well as non-biodegradable microplastic controls including polypropylene (PP) and polyethylene (PE), were selected to investigate the adsorption and desorption behaviors of phenanthrene on biodegradable microplastics in seawater. The results showed that PP (5.3%) and PE (5.5%) had relatively high adsorption and desorption capacity for phenanthrene, while PBAT had similar phenanthrene adsorption but lower desorption capacity (desorption rate 3.8%). PLA had the lowest adsorption capacity (118 μg g−1), while PHA had the lowest desorption rate (3.1%) for phenanthrene. Adsorption of phenanthrene by PLA was sensitive to the salinity, while that of PBAT, PP and PE was not affected by the salinity. The high adsorption and weak desorption of phenanthrene on PBAT were mainly affected by π–π interactions and the low crystallinity of PBAT, while those on PLA and PHA were mainly affected by hydrophilicity. The replacement of non-degradable plastics by degradable plastics could modify the adsorption–desorption behaviors of phenanthrene in marine environments. These findings provide new insights into the environmental friendliness of degradable plastics in marine environments.
Correction for ‘Synthesis of alumina-based cross-linked chitosan–HPMC biocomposite film: an efficient and user-friendly adsorbent for multipurpose water purification’ by Bapun Barik et al., New J. Chem., 2020, 44, 322–337, https://doi.org/10.1039/C9NJ03945G.
Previous studies have indicated that the antioxidant (AO) and pro-oxidant (PO) activities of antioxidants can depend on pH/concentration. To see if antioxidants carrying multiple hindered phenolic units are also affected by pH/concentration, we synthesized tetrameric antioxidants with varying solubilities: lysine-based hydrophilic antioxidants and lysine methyl ester-based hydrophobic antioxidants, each carrying four hindered phenolic units (ortho-methoxy containing syringaldehyde or vanillin). The AO activities of the synthesized antioxidants were measured using AAPH-derived radicals and pBR322 plasmid DNA. Hydrophilic sodium ascorbate and hydrophobic quercetin were used as comparison standards. Based on the study, all tetrameric antioxidants and the standards in PBS showed enhanced AO activities as concentrations increased within the tested range. In the study of pH effects on AO activities using pH 4, pH 7, and pH 9 buffers, the AO activities of all hydrophilic and hydrophobic antioxidants increased with increasing pH (pH 9 > pH 7 > pH 4), indicating that their AO activities are pH-dependent. In the PO assay employing Cu(II) ions and pBR322, sodium ascorbate and quercetin in PBS displayed strong PO effects, which intensified as their concentrations increased. In the buffers at pH 4, 7, and 9, sodium ascorbate and quercetin showed PO effects in the order of pH 9 > pH 7 > pH 4. At the same pH level, both sodium ascorbate and quercetin produced significantly stronger PO effects at high concentrations compared to low concentrations, suggesting that PO effects are concentration-dependent as well as pH-dependent. Our results with sodium ascorbate and quercetin show that both AO and PO activities increase with higher pH levels and concentrations. This indicates that a strong antioxidant can also function as a potent pro-oxidant. However, the tetrameric antioxidants synthesized with hindered phenolic building blocks did not exhibit any significant PO effects, regardless of pH levels and/or concentrations, even though they displayed strong AO activities. This suggests that sterically hindered phenolic units are beneficial in developing potent antioxidants without causing PO effects. Notably, none of our tetrameric antioxidants showed any concentration- or pH-dependent activity crossover between AO and PO effects.
Sodium carbonate (Na2CO3) roasting–leaching residues from spent hydrodesulfurization (HDS) catalysts remain hazardous and are often neglected in existing research. This study introduces an optimized two-stage sulfuric acid (H2SO4) leaching strategy, combined with nitric acid (HNO3) as an oxidant, to efficiently extract valuable metals and isolate insoluble α-Al2O3 (accounting for about 20% of the total Al recovered). The acidic leachate from the first stage was directly reused in a second leaching step, maximizing acid reuse and resource efficiency. Under optimized conditions, Mo leaching reached 97.5% and Co leaching reached 96.6%, while approximately 80% of Al was selectively recovered as potassium alum (KAl(SO4)2·12H2O). This approach not only addresses the treatment of Na2CO3 roasting–leaching residues but also transforms hazardous waste into valuable resources, advancing environmental sustainability.
Mn-ferrite and chitosan (CTS)-coated Mn-ferrite nanomaterials were synthesized using the polyol method with ethylene glycol as a reducing and stabilizing agent. This approach provided precise control over particle size, yielding Mn-ferrite (∼10 nm) and CTS-coated Mn-ferrite (∼15 nm) nanoparticles. SEM analysis confirmed a uniform spherical morphology for Mn-ferrite, while CTS coating introduced a rough surface texture. SQUID studies revealed a saturation magnetization (Ms) of 42.18 emu g−1 at 300 K, with negligible reduction upon CTS coating. The hyperthermia efficiency was assessed by varying the AC magnetic field (300–400 A) and material concentration (1–5 mg mL−1). At 335.2 Oe and 1 mg mL−1, Mn-ferrite and CTS-coated Mn-ferrite exhibited specific loss power (SLP) values of 223.47 W g−1 and 209.05 W g−1, respectively. Cytotoxicity studies on Garra mcclellandi fish demonstrated that both materials were non-toxic, with no structural damage observed in vital organs at 25 and 50 mg L−1 dosages. The study successfully demonstrated the synthesis of biocompatible, ferromagnetic nanomaterials with superior heating capabilities. These results suggest that CTS-coated Mn-ferrite nanoparticles are promising candidates for magneto-hyperthermia treatment (MTH), offering a balance of magnetic efficiency and biocompatibility.
Dye pollution has caused great harm to the ecological environment. In this paper, N and S co-doped biochar (K-NSBC) was obtained by a calcination–alkali activation method, then Co/Al layered double hydroxide (Co/Al-LDH) was anchored on it by a co-precipitation method to activate ozone (O3) to degrade methylene blue (MB). When the O3 concentration was 3.12 mg L−1, catalyst dosage was 0.6 g L−1, the MB concentration was 25 mg L−1, and pH was 6.8, the degradation efficiency of MB reached 99.65%. The degradation efficiency still remained at 92.75% even after Co/Al-LDH@K-NSBC was recycled five times. The results of material characterization and quenching experiments show that the presence of oxygen vacancies (Ov) on the metal surface not only accelerates the exchange of oxygen and the generation of active free radicals, but also promotes the conversion of Co3+/Co2+ and the activation of O3. Pyridine N, graphite N and thiophene S provide electron-rich groups, which promote the activation of O3 to produce reactive oxygen species (ROS). Among them, 1O2 is the main ROS leading to the degradation of MB, and its intermediates ˙OH and ˙O2− also participate in the oxidation of MB. This study is expected to provide new ideas and directions for the design of highly efficient and stable ozonation activators and industrialization of non-phase catalytic ozonation degradation of dye wastewater.
The formation of substituted benzyl aryl ethers is one of the vital industrial methods to generate pharmaceutically important intermediates and value-added compounds. Herein, the etherification of furfuryl ethyl ether was effectively carried out using a pyridinium-based carboxyl-functionalized porphyrin (PCFPc) photocatalyst under 5 W LED light irradiation. This is the first metal-/base-free protocol tolerating a variety of activated/inactivated aryl halides and benzyl alcohols to afford benzyl aryl ethers in appreciable yields (53–74%) in a lab-made photo-chamber under ambient reaction conditions. The novel PCFPc photocatalyst was prepared and then characterized using 1H and 13C NMR, FT-IR, powder XRD, XPS, and BET analyses. The proton level (H0) and band gap were determined using UV-visible spectrophotometry, supported by cyclic voltammetry analysis. The benzyl aryl ethers were successfully obtained (74%) under the optimized reaction conditions of 15 mg photocatalyst with a 1 : 1 substrate ratio, under 5 W LED light illumination at ambient temperature for 18 h. C–O bond formation was supported by (1H, 13C) NMR, DEPT-135, FT-IR and HR-MS analyses. A plausible reaction mechanism was proposed with the help of prior reports. The etherification appeared to progress via the formation of an aryl radical supported by a TEMPO scavenger. The proposed technique is simple and highly effective, and it comprises an easy separation of the photocatalyst and analysis to attain the desired product.
Direct formic acid fuel cells (DFAFCs) represent a promising energy conversion technology characterized by high efficiency and environmental compatibility. Nevertheless, operational constraints persist, including insufficient catalytic activity during anodic formic acid oxidation and limited tolerance to CO intermediates. Consequently, designing advanced catalytic systems with improved CO resistance remains a crucial research focus. This work systematically explores the electrocatalytic performance of Pt nanoclusters supported on Mo and N-modified carbon matrices for the formic acid oxidation reaction. Comprehensive material characterization was achieved through X-ray diffraction analysis, electron microscopy observations, X-ray photoelectron spectroscopy measurements, and cyclic voltammetric evaluations. Electrochemical assessments were conducted in an Ar-saturated mixture of 0.1 M HClO4 and 0.5 M HCOOH under ambient conditions. Comparative analyses with Pt/C, in-house synthesized Pt/Mo–N–C, and commercial catalysts reveal that the Pt/Mo–N–C composite demonstrates significantly enhanced catalytic activity and CO tolerance. The methodology developed herein offers a generalizable approach for fabricating diverse electrocatalytic materials.
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