Synthesis and Characterization of Magnetically Retrievable Fe3O4/Polyvinylpyrrolidone/Polystyrene Nanocomposite Catalyst for Efficient Catalytic Oxidation Degradation of Dyes Pollutants

A facile one-pot γ-radiation formation of gum arabic-stabilized cobalt ferrite nanoparticles as an efficient magnetically retrievable heterogeneous catalyst

Currently, there is a demand for an effective solution to address toxic pollutants in aqueous environments. Consequently, creating a cost-efficient and effective catalytic system with the added benefits of easy recovery from the medium and the ability to be reused is essential. In this study, gamma (γ) radiolysis as a simple and environmentally friendly process under ambient settings was used to successfully manufacture a nanocatalyst of cobalt ferrite nanoparticles (CoFe2O4 NPs) modified gum arabic (GA) as a nontoxic, biocompatible, and inexpensive biopolymer. The prepared GA-CoFe2O4 NPs were evaluated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX) mapping, and vibrating sample magnetometer analysis. XRD analysis illustrates the formation of CoFe2O4 NPs through the appearance of the characteristic peaks. TEM analysis shows the spherical shape of CoFe2O4 NPs with an average particle size diameter ranging from 20 to 30 nm. FTIR analysis of GA-CoFe2O4 NPs confirmed both the functionalization of GA with the CoFe2O4 NPs and the appearance of the specific signal of CoFe2O4 NPs. The atomic ratio obtained from EDX analysis matches the stoichiometric ratio of cobalt ferrite. The GA-CoFe2O4 NPs exhibit an excellent magnetic response of saturation magnetization of 47.619 emu g-1. The prepared CoFe2O4NPs were then evaluated as a catalyst for the catalytic reduction of p-NP, MO dye, and a mixture of these pollutants. The results showed that CoFe2O4 NPs have high catalytic efficiency in the reduction of mono or mixed compounds. Furthermore, recycling of the CoFe2O4 NPs catalyst was also confirmed and it could be magnetically recovered and reused for at least six times with a good catalytic efficiency.

Amine functionalized magnetic resorcinol formaldehyde as a green and reusable nanocatalyst for the Knoevenagel condensation

Herein, a novel amine-functionalized magnetic resorcinol-formaldehyde with a core-shell structure (Fe3O4@RF/Pr-NH2) is prepared through the chemical immobilization of (3-aminopropyl)trimethoxysilane over Fe3O4@RF composite. Characterization through FT-IR, EDX, PXRD, and TGA confirmed successful surface modification while preserving the crystalline structure of Fe3O4. The VSM analysis demonstrated excellent superparamagnetic properties, and SEM and TEM images revealed spherical particles for the designed nanocatalyst. The Fe3O4@RF/Pr-NH2 nanocomposite was employed as a robust nanocatalyst to promote the Knoevenagel condensation of benzaldehydes with ethyl cyanoacetate and malononitrile, resulting in the formation of substituted olefins. Various aromatic aldehydes were used as substrates in the presence of 0.01 g of Fe3O4@RF/Pr-NH2, achieving high to excellent yields (87-97%) within short reaction times (10-50 min) in EtOH at 60 °C. The high performance of Fe3O4@RF/Pr-NH2 is attributed to the hydrophobic nature of RF shell, which facilitates the accumulation of organic precursors around the catalytic active sites and enhances product yields. The designed magnetic catalyst could retain its high efficiency for at least ten runs. The metal-free, low-cost, and environmentally friendly attributes of the Fe3O4@RF/Pr-NH2 catalyst make it a promising alternative to traditional metal-based catalysts.

Comparison of high-concentration azo dye removal by long HRT in MSBRs' bioaugmented with GAC and sponge media

The present study assessed the performance and fouling of adding granular activated carbon (GAC) and sponge (BioCube), as two different media, to a membrane sequencing batch reactor (MSBR) system in wastewater treatment containing Acid Red 18 (AR 18). Anaerobic phase, aerobic phase, and hydraulic retention times (HRTs) of 24 h, 12 h, and 72 h were considered for 500 mg/L AR 18 removal at a sludge retention time (SRT) of 20 days by separately adding up to 35% BioCube volume and 8 g/L GAC to the reactors. Based on the kinetic study, 63 mg/L (87% removal) and 115 mg/L (77% removal) remaining dye were reported in the GAC and BioCube membrane sequencing batch reactors (GAC-MSBR and BioCube-MSBR), respectively. A gradual oxidation-reduction potential decline toward -416 mV confirmed better dye removal in GAC-MSBR than BioCube-MSBR, observing a sudden drop to -354 mV. The morphology can explain better biological treatment in GAC-MSBR in addition to the adsorption process. Soluble microbial products (SMPs) of 126.92 mg/L and 395.18 mg/L were obtained for GAC-MSBR and BioCube-MSBR, respectively. Chemical oxygen demand (COD) and SMP indicated that the GAC-MSBR water quality is better than that of the other reactor.

Recent Advancements in Cyclodextrin-Based Adsorbents for the Removal of Hazardous Pollutants from Waters

Water is an essential substance for the survival on Earth of all living organisms. However, population growth has disturbed the natural phenomenon of living, due to industrial growth to meet ever expanding demands, and, hence, an exponential increase in environmental pollution has been reported in the last few decades. Moreover, water pollution has drawn major attention for its adverse effects on human health and the ecosystem. Various techniques have been used to treat wastewater, including biofiltration, activated sludge, membrane filtration, active oxidation process and adsorption. Among the mentioned, the last method is becoming very popular. Moreover, among the sorbents, those based on cyclodextrin have gained worldwide attention due to their excellent properties. This review article overviewed recent contributions related to the synthesis of Cyclodextrin (CD)-based adsorbents to treat wastewater, and their applications, especially for the removal of heavy metals, dyes, and organic pollutants (pharmaceuticals and endocrine disruptor chemicals). Furthermore, new adsorption trends and trials related to CD-based materials are also discussed regarding their regenerative potential. Finally, this review could be an inspiration for new research and could also anticipate future directions and challenges associated with CD-based adsorbents.

Wastewater Treatment by Polymeric Microspheres: A Review

This review addresses polymer microspheres used as adsorbent for wastewater treatment. The removal of various pollutants (including dyes, heavy metal ions, and organic pollutants) is a prominent issue, as they can cause severe health problems. Porous microspheres can provide large specific area and active sites for adsorption or photo degradation. Enhancement in performance is achieved by various modifications, such as the introduction of nanoparticles, magnetic particles, and ZIF-8. Some microspheres were synthesized from synthetic polymers such as vinylic polymer and polydopamine (PDA) through a facile fabrication process. Natural polymers (such as cellulose, alginate, and chitosan) that are biodegradable and eco-friendly are also used. The adsorbents used in industrial application require high adsorption capacity, thermal stability, and recyclability. Batch adsorption experiments were conducted to investigate the optimal conditions, influence of related factors, and adsorption capacities. Insights regarding the adsorption mechanisms were given from the kinetic model, isotherm model, and various characterization methods. The recyclability is investigated through regeneration ratio, or their maintenance of their capability through repeated adsorption-desorption cycles. The high potential of polymer microsphere for the removal of pollutants from wastewater is shown through the high adsorption capacities, environmentally friendliness, and high stability.

Recent Advances of Magnetic Gold Hybrids and Nanocomposites, and Their Potential Biological Applications

Magnetic gold nanoparticles (mGNP) have become a great interest of research for nanomaterial scientists because of their significant magnetic and plasmonic properties applicable in biomedical applications. Various synthetic approaches and surface modification techniques have been used for mGNP including the most common being the coprecipitation, thermal decomposition, and microemulsion methods in addition to the Brust Schiffrin technique, which involves the reduction of metal precursors in a two-phase system (water and toluene) in the presence of alkanethiol. The hybrid magnetic–plasmonic nanoparticles based on iron core and gold shell are being considered as potential theranostic agents. In this critical review, in addition to future works, we have summarized recent developments for synthesis and surface modification of mGNP with their applications in modern biomedical science such as drug and gene delivery, bioimaging, biosensing, and neuro-regeneration, neuro-degenerative and arthritic disorders. This review includes techniques and biological applications of mGNP majorly based on research from the previous six years.