CuO and CeO2 assisted Fe2O3/attapulgite catalyst for heterogeneous Fenton-like oxidation of methylene blue

Customizing Cerium Oxide Particle Synthesis with Hybrid Polyion Complex Templates for Enhanced Oxidation Performance in Photo-Fenton Processes

Hybrid poly-ion complexes were synthesized through the complexation of a double hydrophilic copolymer with Ce(III) ions. These colloids act as reservoirs for cerium ions, enabling the synthesis of cerium-based Prussian blue nanoparticles with a cubic structure, a narrow size distribution around 100 nm, and good colloidal stability in water. Upon high-temperature calcination, these nanoparticles are transformed into a cerium/iron-based metal oxide catalyst (CeO2/Fe2O3). The resultant composite catalyst demonstrates superior performance in the photo-Fenton oxidation of methylene blue pollutants, achieving a conversion efficiency that rivals other metal-based oxides and cerium-based catalysts.

Recent developments in synthesis of attapulgite composite materials for refractory organic wastewater treatment: a review

Attapulgite clay, due to its unique crystalline hydrated magnesium-aluminium silicate composition and layer-chain structure, possesses exceptional adsorption and catalytic properties, which enable it or its composites to be utilized as adsorbents and catalysts for wastewater treatment. But the drawbacks of attapulgite are also very obvious, such as relatively low specific surface area (compared to traditional adsorbents such as activated carbon and activated alumina), easy aggregation, and difficulty in dispersion. In order to fully utilize and improve the performance of attapulgite, researchers have conducted extensive research on its modification, but few specialized works have comprehensively evaluated the synthesis, applications and challenges for attapulgite-based composite materials in refractory organic wastewater treatments. This paper provides a comprehensive review of controllable preparation strategies, characterization methods and mechanisms of attapulgite-based composite materials, as well as the research progress of these materials in refractory organic wastewater treatment. Based on this review, constructive recommendations, such as deep mechanism analysis from molecular level multi-functional attapulgite-based material developments, and using biodegradable materials in attapulgite-based composites, were proposed.

Enhancing Fenton-like Degradation of Organic Pollutants at Neutral pH by Multivalent Cu NCs/HAp Nanocatalysts

Heterogeneous Fenton-like catalysis is a widely used method for the degradation of organic pollutants. However, it still has some limitations such as low activity in the neutral condition, low conversion rates of metals with different valence states, and potential secondary metal pollution. In this study, a Fenton-like nanocatalyst was first created by generating ultrasmall copper nanoclusters (Cu NCs) on the surface of hydroxyapatite (HAp) through a process of doping followed by modification. This resulted in the formation of a composite nanocatalyst known as Cu NCs/HAp. With the help of hydrogen peroxide (H2O2), Cu NCs/HAp exhibits an outstanding Fenton-like catalytic performance by efficiently degrading organic dyes such as methylene blue under mild neutral conditions. The removal rate can reach over 83% within just 30 min, demonstrating ideal catalytic universality and stability. The improved Fenton-like catalytic performance of Cu NCs/HAp can be ascribed to the synergistic effect of the multivalent Cu species through two simultaneous reaction pathways. During route I, the embedded Cu NCs with a core-shell Cu0/Cu+ structure can undergo sequential oxidation to form Cu2+, which continuously activates H2O2 to generate hydroxyl radicals (•OH) and singlet oxygen (1O2). In route II, Cu2+ produced from route I and initially adsorbed on the surface of HAp can be reduced by H2O2, thus regenerating Cu+ species for route I and achieving a closed-loop reaction. This work has confirmed that Cu NCs loaded on HAp may be an alternative Fenton-like catalyst for degradation of organic pollutants and environmental remediation, opening up new avenues for potential applications of other Cu NCs in future water pollution control.

BiPO4-coated carbon microtube electrodes: preparation and characterization of their properties and electrocatalytic degradation of methylene blue

Bismuth phosphate (BiPO₄), a very attractive candidate for organics electrodegradation, harbors tremendous potential on removing contaminants from water. Here, four carbon microtube electrodes were prepared from corncob, each coated with BiPO₄ by a different method to study the electrodegradation of methylene blue (MB). A thorough insight into the composite features of four electrodes was characterized. Better reversibility and electrocatalytic activity of the fourth electrode (BCC4) prepared by digital signal generator was presented with a current density of 5.71 mA cm^-2 at a potential of 1.6 V vs Ag/AgCl. The electrochemical impedances and actual lifetime of BCC4 were 125 Ω and 833 h, respectively. The effectiveness of each kind of BiPO₄/carbon electrode was preliminarily evaluated by analyzing the actual conversion rate of the MB concentration, which confirms MB electrodegradation by the BiPO₄/carbon electrode was mainly dominated by the hydroxyl radical oxidation. The mass transfer rate was increased by carbon microtube; thereby, electrocatalysis of BiPO₄/carbon electrode increased as revealed by an increase in the MB degradation rate. The rate constants k obtained for the degradation of MB by BiPO₄/carbon electrode at 20 ℃ was 0.0046 mM^-1 s^-1, which was 11 times than that of BiPO₄. The diffusion layer was decreased by carbon microtube, resulting in MB electrodegradation rate increased. The BiPO₄ coated on the surface of the carbon microtube electrodes strengthened their electrocatalytic performance, which shed new light on effective selection of suitable carbon electrode for degradation of organics. Therefore, BiPO₄/carbon electrode could be potentially applied in the electrodegradation of organic pollutants.

Synthesis of CuO/GO-DE Catalyst and Its Catalytic Properties and Mechanism on Ciprofloxacin Degradation

A new catalyst, copper oxide/graphene oxide-diatomaceous earth (CuO/GO-DE), was prepared by the ultrasonic impregnation method. The optimal conditions for catalyst preparation were explored, and its structure and morphology were characterized by BET, XRD, SEM, TEM, FTIR, Raman and XPS. By taking ciprofloxacin as the target pollutant, the performance and reusability of CuO/GO-DE to degrade antibiotic wastewater was evaluated, and the optimal operating conditions were obtained. The main oxidizing substances in the catalytic system under different pH conditions were analyzed, as well as the synergistic catalytic oxidation mechanism. The intermediate products of ciprofloxacin degradation were identified by LC-MS, and the possible degradation process of ciprofloxacin was proposed.

Preparation of a Heterogeneous Catalyst CuO-Fe2O3/CTS-ATP and Degradation of Methylene Blue and Ciprofloxacin

A heterogeneous particle catalyst (CuO-Fe2O3/CTS-ATP) was synthesized via injection molding and ultrasonic immersion method, which is fast and effective. The particle catalyst applied attapulgite (ATP) wrapped by chitosan (CTS) as support, which was loaded dual metal oxides CuO and Fe2O3 as active components. After a series of characterizations of catalysts, it was found that CuO and Fe2O3 were successfully and evenly loaded on the surface of the CTS-ATP support. The catalyst was used to degrade methylene blue (MB) and ciprofloxacin (CIP), and the experimental results showed that the degradation ratios of MB and CIP can reach 99.29% and 86.2%, respectively, in the optimal conditions. The degradation mechanism of as-prepared catalyst was analyzed according to its synthesis process and ∙OH production, and the double-cycle catalytic mechanism was proposed. The intermediate products of MB and CIP degradation were also identified by HPLC-MS, and the possible degradation pathways were put forward.

Recent Advances in Magnetic Nanoparticles and Nanocomposites for the Remediation of Water Resources

Water resources are of extreme importance for both human society and the environment. However, human activity has increasingly resulted in the contamination of these resources with a wide range of materials that can prevent their use. Nanomaterials provide a possible means to reduce this contamination, but their removal from water after use may be difficult. The addition of a magnetic character to nanomaterials makes their retrieval after use much easier. The following review comprises a short survey of the most recent reports in this field. It comprises five sections, an introduction into the theme, reports on single magnetic nanoparticles, magnetic nanocomposites containing two of more nanomaterials, magnetic nanocomposites containing material of a biologic origin and finally, observations about the reported research with a view to future developments. This review should provide a snapshot of developments in what is a vibrant and fast-moving area of research.