Magnetic Recoverability Research Articles

Tuning the optical, electrical, structural and photocatalytic activities of mixed metal ferrite by hydrothermal synthesis and polypyrrole reinforcement

This work describes the synthesis, characterization, and photocatalytic evaluation of a polypyrrole-reinforced zinc-nickel mixed metal ferrite (PPy@ Zn0.5Ni0.5Fe2O4) nanohybrid. A facile hydrothermal process is employed to synthesize the nanostructured zinc-nickel mixed metal ferrite (ZNF), and in situ oxidative polymerization is utilized to create the PPy nanohybrid. In this nanohybrid, PPy plays multiple roles: preventing charge recombination, reducing photocorrosion, mitigating particle aggregation in ZNF, and enhancing charge transfer and visible light absorption. The combined electron-capturing ability, intrinsic conductivity, and extensive π-conjugation of PPy, along with the magnetic nature of ZNF, render the PPy@ZNF catalyst highly efficient. The results of photoluminescence, impedance, and UV/Vis analysis confirm that PPy plays a critical role in enhancing photocatalytic performance by facilitating charge transfer and extending visible-light absorption. In practical environmental applications, the PPy@ZNF nanohybrid demonstrated superior photocatalytic activity compared to ZNF alone, degrading 98.5 % of malachite green dye under W-lamp light within 80 min, with a rate constant of 0.031 min−1. Scavenger and cyclic experiments identified the active species involved in dye degradation and assessed the reusability of the nanohybrid. Extensive testing revealed the optimal conditions for photocatalytic efficiency; the considered variables included light intensity, catalyst dose, dye concentration, temperature, irradiation time, and pH. These findings suggest that the PPy-reinforced ZNF nanohybrid offers cost-effectiveness, magnetic recoverability, structural stability, and high efficacy as a visible light-driven catalyst, making it a promising candidate for diverse environmental remediation applications.

Magnetic Silver Nanoparticles Stabilized by Superhydrophilic Polymer Brushes with Exceptional Kinetics and Catalysis.

Stimuli-responsive catalysts with exceptional kinetics and complete recoverability for efficient recyclability are essential in, for example, converting pollutants and hazardous organic compounds into less harmful chemicals. Here, we used a novel approach to stabilize silver nanoparticles (NPs) through magneto/hydro-responsive anionic polymer brushes that consist of poly (acrylic acid) (PAA) moieties at the amine functional groups of chitosan. Two types of responsive catalyst systems with variable silver loading (wt.%) of high and low (PAAgCHI/Fe3O4/Ag (H, L)) were prepared. The catalytic activity was evaluated by monitoring the reduction of organic dye compounds, 4-nitrophenol and methyl orange in the presence of NaBH4. The high dispersity and hydrophilic nature of the catalyst provided exceptional kinetics for dye reduction that surpassed previously reported nanocatalysts for organic dye reduction. Dynamic light scattering (DLS) measurements were carried out to study the colloidal stability of the nanocatalysts. The hybrid materials not only showed enhanced colloidal stability due to electrostatic repulsion among adjacent polymer brushes but also offered more rapid kinetics when compared with as-prepared Ag nanoparticles (AgNPs), which results from super-hydrophilicity and easy accumulation/diffusion of dye species within polymer brushes. Such remarkable kinetics, biodegradability, biocompatibility, low cost and facile magnetic recoverability of the Ag nanocatalysts reported here contribute to their ranking among the top catalyst systems reported in the literature. It was observed that the apparent catalytic rate constant for the reduction of methyl orange dye was enhanced, PAAgCHI/Fe3O4/Ag (H) ca. 35-fold and PAAgCHI/Fe3O4/Ag (L) ca. 23-fold, when compared against the as prepared AgNPs. Finally, the regeneration and recyclability of the nanocatalyst systems were studied over 15 consecutive cycles. It was demonstrated that the nanomaterials display excellent recyclability without a notable loss in catalytic activity.

Surface Adsorption and Photoinduced Degradation: A Study of Spinel Ferrite Nanomaterials for Removal of a Model Organic Pollutant from Water.

Spinel oxide nanocrystals are attractive materials for photoinduced advanced oxidation processes that degrade organic pollutants in water due to their chemical stability and tunability, visible light absorption, and magnetic recoverability. However, a systematic understanding of the structural and chemical factors that control the reactivity of specific spinel oxide nanocrystal materials toward photoinduced degradation processes is lacking. This Perspective illustrates these knowledge gaps through an investigation into the impacts of surface chemistry and composition of spinel ferrite nanocrystals of formula MFe2O4 (M = Mg, Fe, Co, Ni, Cu, Zn) on their ability to remove a model organic pollutant (methyl orange (MO)) from water. We identify two mechanisms by which the nanocrystals remove MO from water: (i) surface adsorption and (ii) photoinduced degradation under visible light irradiation in the presence of hydrogen peroxide via the photo-Fenton reaction. Nanocrystals that do not contain any surface ligands are more effective at removing MO from water than nanocrystals that contain surface ligands, despite our observation that the ligand-less nanocrystals do not form stable colloidal dispersions in water, while ligand-coated nanocrystals are colloidally stable. For many of the spinel ferrite compositions studied here, the fraction of methyl orange removal via adsorption to the nanocrystal surface in the absence of photoexcitation is larger than the fraction removed under irradiation. Our data indicate that the composition-dependent surface charge of the nanocrystals controls the degree of surface adsorption of the charged MO molecule. Overall, these results demonstrate that careful consideration of the impacts of surface chemistry on the behavior of spinel ferrite nanocrystals is required to accurately assess and subsequently understand their activity toward the photoinduced degradation of organic molecules.

Effective removal of Cr (VI) from an aqueous solution using a carbon coated NiFe2O4 nano-adsorbent

Exploration of cubic ferrites for chromium removal is ongoing. Ferrites offer a promising avenue for chromium removal because of their unique properties, high surface area, magnetic recoverability, and potential for surface modifications to enhance adsorption capacities. Herein, the work highlights the synthesis of carbonaceous nickel ferrite (NiFe2O4/C) through an inert ambient pyrolysis process, where metal acetylacetonates are used as the sources of metal ions and carbon. The synthesized NiFe2O4/C was successfully characterized for its structure and morphology using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray analysis (EDX), Raman spectroscopy, Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. The study confirmed that, the size of nanostructure was of ∼29 nm, with a surface area of 56.925 m2/g, pore volume of 0.085 cc/g with type IV hysteresis loop. The regular spherical shape was observed through FESEM, and a carbon coating was evident and confirmed from TEM. Synthesized NiFe2O4/C was efficiently used for the Cr (VI) removal, it was found that at an equilibrium time of 60 min, nearly 85% of the chromium was removed using 0.01 g of adsorbent at native pH and efficiency was further improved by lowering the pH. The investigation further examined the isotherm and kinetics models. The material was regenerated for 5 cycles with a removal percentage of 57%.

Constructive Z-scheme interfacial charge transfer of a spinel ferrite-supported g-C3N4 heterojunction architect for photocatalytic degradation

The design and fabrication of metal ferrite-supported porous g-C3N4 (p-GCN) tandem heterojunctions constructed via the hydrothermal method. Phase identification, morphology, magnetic, thermal, and electrochemical properties were studied. The physicochemical characteristic studies confirmed the effective interaction and formation of the heterojunction architect. The fabricated materials were employed as a photocatalyst for the degradation of rhodamine B (RhB), tetracycline (TC), cartap hydrochloride (C-HCl), and complex effluent (RhB+TC+C-HCl) under sunlight irradiation. The p-GCN/AgFe2O4 (p-GCN/AFO) heterojunction demonstrates outstanding performance within 60 min of irradiation (RhB- 98.3%, TC- 98.5%, C-HCl- 99.56%, and complex effluent- 95.72%), whereas p-GCN/MgFe2O4 (p-GCN/MFO) shows slightly reduced activity (RhB- 97.14%, TC- 97.62%, C-HCl- 99.23%, and complex effluent- 91.05%). The performance improvement of nanocomposites is due to complementary sunlight absorption, sequential energy, and electron transfer properties, efficient charge separation, and excellent redox potential of its heterojunction structure. Furthermore, a thorough mechanism analysis suggests the essential role of reactive oxygen species (•OH and •O2-) and it is proposed that the nanocomposite photocatalyst follows a Z-scheme heterojunction mechanism. The high catalytic activity, the magnetic recoverability, and the excellent stability of p-GCN/AFO make it a potential candidate for the degradation of multiple organic contaminants in various industry sectors.

Reduction of toxic organic dyes in aqueous media using N-heterocyclic copper(II) complex immobilized on the beta-cyclodextrin-modified Fe3O4 nanoparticles as a magnetically recyclable catalyst

This study was undertaken to design a stable easy-recoverable nanoadsorbent (Fe3O4@CM-β-CDP@Tet-Cu(II)) hybrid with rich catalytic sites via wet-chemical method for the catalytic reduction of toxic dyes in wastewater. β-cyclodextrin (β-CD) with a hydrophilic character outside and hydrophobic inside cavity play an important role in catalytic reduction process by interacting with organic molecules and also prepared more sites for further surface modifications. Several characterization techniques including FT-IR, TGA analysis, FE-SEM/EDX, TEM, X-Ray diffraction patterns (XRD) measurements were employed to investigate the structural properties of the synthesized material. The catalytic ability of the obtained material was examined in the presence of different dyes including p-nitrophenol, Eosin Y, Rhodamine B, Congo red, and Methyl orange by UV–Vis spectroscopy as a simple and available method. Moreover, the parameters which effect on reduction process, such as dye and reducing agent (NaBH4) concentrations, mass of adsorbent and time were optimized at room temperature. The obtained data demonstrate the considerable catalytic ability of Fe3O4@CM-β-CDP@Tet-Cu (II) besides a remarkable reduction rate and high yield over a short reaction time, in particular for Methyl orange dye. Recycling experiments revealed that Fe3O4@CM-β-CDP@Tet-Cu (II) has an excellent stability wherein the catalyst was recycled five times with a slight decrease in the reduction ability without any remarkable change in morphological properties which confirm by FE-SEM analysis. The high catalytic activity, the magnetic recoverability, along with the excellent stability of Fe3O4@CM-β-CDP@Tet-Cu (II) make it a potential candidate for the reduction of multiple dyes in real wastewater samples.

Highly efficient flower-like ZnIn2S4/CoFe2O4 photocatalyst with p-n type heterojunction for enhanced hydrogen evolution under visible light irradiation

The construction of a p-n heterojunction structure is considered to be an effective method to improve the separation of electron-hole pairs in photocatalysts. A series of ZnIn2S4/CoFe2O4 (ZIS/CFO) photocatalysts with p-n heterojunctions were prepared via a method involving ultrasonication and calcination. The synthesized photocatalysts were tested and analyzed via various testing techniques, and their hydrogen evolution rates were evaluated. Compared with pure ZIS, ZIS/CFO with different mass ratios of CFO to ZIS showed improved photocatalytic hydrogen production performance, and the optimal photoactivity showed a nearly 12-fold increase, which can be attributed to the formation of p-n junctions and the formed internal electric field, accelerating the separation of electron-hole pairs and effectively improving the photocatalytic hydrogen evolution rate. The excellent stability of the ZIS/CFO composite was proven by three cycle experiments. In addition, the ZIS/CFO composite also possessed excellent magnetic properties to realize facial magnetic recoverability. This work paves the way for the design and preparation of magnetically recoverable p-n heterojunction photocatalysts.

Preparation of Dicationic Ionic Liquid Immobilized on Fe3O4@SiO2 and Evaluation of its Catalytic Efficiency in the Oxidation of Alcohols

AbstractA novel magnetic supported dicationic ionic liquid namely Fe3O4@SiO2⋅DIL has been prepared, and characterized by various analysis methods such as FT‐IR, TEM, SEM, XRD, EDX, EDX mapping, and TGA. Afterward, catalytic activity of the Fe3O4@SiO2⋅DIL has been examined in alcohols oxidation reaction. The resulting new nanocomposite as a heterogeneous catalyst displayed remarkable activity for the oxidation of various alcohols using H2O2 under mild reaction conditions. Eventually, the as‐prepared Fe3O4@SiO2⋅DIL catalyst was also stable and reused at least five times without losing its catalytic activity and selectivity. Magnetic recoverability of the catalyst, high yields, good compliance with green chemistry protocols and economical are some advantages of the work.

Evaluation of Fe3O4-MnO2@RGO magnetic nanocomposite as an effective persulfate activator and metal adsorbent in aqueous solution.

A reduced graphene oxide (RGO) supported Fe3O4-MnO2 nanocomposite (Fe3O4-MnO2@RGO) was successfully prepared for catalytic degradation of oxytetracycline (20mg/L) by potassium persulfate (PS) and adsorption removal of mixture of Pb2+, Cu2+, and Cd2+ ions (each 0.2mM) in the synchronous scenario. The removal efficiencies of oxytetracycline, Pb2+, Cu2+, and Cd2+ ions were observed as high as 100%, 99.9%, 99.8%, and 99.8%, respectively, under the conditions of [PS]0 = 4mM, pH0 = 7.0, Fe3O4-MnO2@RGO dosage = 0.8g/L, reaction time = 90min. The ternary composite exhibited higher oxytetracycline degradation/mineralization efficiency, greater metal adsorption capacity (Cd2+ 104.1mg/g, Pb2+ 206.8mg/g, Cu2+ 70.2mg/g), and better PS utilization (62.6%) than its unary and binary counterparts including RGO, Fe3O4, Fe3O4@RGO, and Fe3O4-MnO2. More importantly, the ternary composite had good magnetic recoverability and excellent reusability. Notably, Fe, Mn, and RGO could play a synergistic role in the improvement of pollutant removal. Quenching results indicate that surface bounded SO4•- was the major contributor to oxytetracycline decomposition, and the -OH groups on the composite surface shouldered a significant role in PS activation. The results indicate that the magnetic Fe3O4-MnO2@RGO nanocomposite has a good potential for removing organic-metal co-contaminants in waterbody.

Efficient Suzuki coupling over novel magnetic nanoparticle: Fe3O4/L-(+)-tartaric acid/Pd(0).

A new eco-friendly catalytic system is devised for C-C bond formation through Suzuki coupling, using an impressive nanocatalyst (Fe3O4/L-(+)-tartaric acid/Pd-NPs). It contains immobilized palladium (0) onto magnetite nanoparticles, stabilized by tartaric acid, and is characterized by FT-IR, XRD, EDS, SEM, TEM, TGA, and VSM. The catalyst is used in an efficient synthesis of biaryls in EtOH/H2O (1:1), in the presence of K2CO3. Our Fe3O4/tartaric acid/Pd-NPs exhibit magnetic recoverability and reusability for five cycles without measurable loss of its activity.

Magnetically recoverable, non-toxic, leach resistant aluminum ferrite (AlFeO3) photocatalyst for wastewater remediation

The practical use of photocatalyst in wastewater treatment is mainly hindered due to the recoverability of the catalyst. This can be addressed by the ferrite-based compounds which enable magnetic recoverability. In this work, Aluminium Ferrite (AlFeO3), a perovskite-based magnetic photocatalyst is successfully synthesized and its photocatalytic performance is tested. For the scale-up feasibility, the material is tested in static polluted water. AlFeO3 shows effective degradation of textile dye pollutants: 99% of Rhodamine B (RhB) in 180 min and 94% of Methyl orange (MO) in 270 min at the static condition, under visible-light illumination. It also exhibits UV photoactivity which implies AlFeO3 is a potential candidate for sunlight-driven wastewater treatment. The degradation rate is increased by 1.5 times when air is bubbled during photocatalysis. The catalyst is magnetically retrieved from the treated water and reused over 5 cycles with only ∼4% efficiency loss. The environmental viability of AlFeO3 is tested for the first time using cell toxicity studies and catalyst leaching in the treated water. The results indicate that more than 90% of L929 fibroblast cells are viable even when incubated with AlFeO3 for 24 h. The negligible trace of Al and Fe presence in the treated water shows that AlFeO3 is also leach resistant. Hence, AlFeO3 is a UV–Visible-light-driven, easy-to-recover, recyclable, and eco-friendly photocatalyst that has the potential for practical use.

Superparamagnetic Iron Oxide Decorated Indium Hydroxide Nanocomposite: Synthesis, Characterization and Its Photocatalytic Activity

A simple and scalable liquid-based method was developed to produce a nanocomposite photocatalyst which was comprised of Fe3O4 nanoparticles (4-5 nm) decorated indium hydroxide nanorods (mean width 33 nm and average aspect ratio 2-3). The nanocomposite was produced at 25 ℃ in water via a hydroxide-induced co-precipitation ensued by a cathodic reduction during which the non-magnetic Fe(OH)3 intermediate was reduced to magnetic Fe3O4 at 20 V within 1 h. The incorporation of Fe3O4 nanoparticles served to bestow magnetic recoverability to the photocatalyst and helped enhance visible light absorption simultaneously. Interestingly, the addition of Fe3+ led to the formation of In(OH)3 nanorods rather than the commonly observed nanocubes. In comparison to the In(OH)3 system having a band gap of 4.60 eV), the band gap of the Fe3O4/In(OH)3 nanocomposite produced was determined to be 2.85 eV using the Tauc’s plot method. The effective reduction in band gap is expected to allow better absorption of visible light which in turns should help boost its photocatalytic performance. The Fe3O4/In(OH)3 nanocomposite was structurally characterized using a combination of PXRD, FESEM, EDS, and TEM and its paramagnetic property was proven with a positive mass susceptibility measured to be 1.30´10−5 cm3.g−1. Under visible light, a photocatalytic degradation efficiency of 83% was recorded within 1 hr for the nanocomposite using methylene blue as a dye. The photocatalytically-active Fe3O4/In(OH)3 should have good potential in visible-light driven waste water degradation once further optimized. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Silver ferrite embellished graphene oxide heterogenous nanocomposite for efficient electrochemical detection of gallic acid

Ferrites have attracted the research community owing to their invincible properties corresponding to their magnetic recoverability, recycling efficacy, and environmentally friendly behaviour. They are gaining importance in catalysis, sensors, supercapacitors, batteries, magnetic tunnel ferrofluids, magnetic drug delivery, and information storage. By taking advantage of ferrites, in this study, we have developed a silver ferrite embellished graphene oxide (AgFe2O4/GO) nanocomposite by decorating AgFe2O4 on graphene oxide (GO) by a viable route. The crystal structure, size, morphology, and magnetic behaviour of the fabricated nanocomposites have been investigated with the assistance of fourier transform infrared (FTIR) spectroscopy, RAMAN spectroscopy, X-ray diffraction, and scanning electron microscopic (SEM) techniques. The composite has been examined for the electrocatalytic determination of gallic acid (GA) by cyclic voltammetry and differential pulse voltammetry by its modification of glassy carbon electrode. This modified glassy carbon electrode has shown excellent electrocatalytic behaviour toward the detection of GA. These results can be used as an electrochemical standard in the estimation of total polyphenol content in the foodstuffs and extended to pharmaceutical and industrial applications.

Design of a Schiff Base Complex of Copper Coated on Epoxy-Modified Core-Shell MNPs as an Environmentally Friendly and Novel Catalyst for the One-Pot Synthesis of Various Chromene-Annulated Heterocycles.

An ecofriendly inorganic–organic hybrid and novel Schiff base complex of copper coated on epoxy-modified Fe3O4@SiO2 MNPs was successfully designed and prepared from readily available chemicals. In this method, a Schiff base complex as a linker is utilized to protect copper nanoparticles to the core–shell Fe3O4 exterior without agglomeration. The resulted Schiff base complex of copper coated on epoxy-modified Fe3O4@SiO2 MNPs was characterized and confirmed via different analyses such as FT-IR, TGA, XRD, VSM, FE-SEM, TEM, ICP, EDX, and BET. The novel catalyst was examined for the synthesis of various chromene-annulated heterocycles through the one-pot three component reaction of aromatic aldehydes, various phenols (2-hydroxynaphthalene-1,4-dione/resorcinol/β-naphthol), and malononitrile in ethanol at reflux conditions. This method includes important aspects like no usage of column chromatography, very short reaction times, simplicity of product isolation using ethanol, excellent yields, simple procedures, and magnetic recoverability of the catalyst. All in all, our method makes a novel and significant advancement in the synthesis of various chromene-annulated heterocycles.

Magnetically separable NiFe2O4/Ag3VO4/Ag2VO2PO4 direct Z‐scheme heterostructure with enhanced visible‐light photoactivity

AbstractBACKGROUNDThe occurrence of organic contaminants in surface water has drawn great concern in recent years. The construction of a heterostructure has been shown to improve photoactivity by boosting the separation of photogenerated charge carriers. In this work, magnetically separable NiFe2O4/Ag3VO4/Ag2VO2PO4 (NFO/AVO/AVPO) heterojunction photocatalysts were synthesized via a chemical etching method in ammonia solution of different concentrations, using NFO/AVPO as the source material. The magnetic NFO/AVO/AVPO not only endows magnetic recoverability using an external magnetic field, but also possesses a heterojunction, boosting the separation of photoinduced charges.RESULTSCompared with NFO, AVPO and NFO/AVPO, NFO/AVO/AVPO composites as synthesized show improved visible‐light photoactivities. At the optimum concentration (0.15 mol L−1) of ammonia solution, the NFO/AVO/AVPO shows 8.5 and 10.7 times improved photodegradation efficiency for methylene blue and imidacloprid than that of pristine NFO/AVPO, respectively. Due to the presence of magnetic NiFe2O4, the NFO/AVO/AVPO can be magnetically separated easily from the photoreaction system using a magnet. The improved photoactivity can be attributed to the formation of a direct Z‐scheme heterojunction, which boosts the separation of photoinduced electron–hole pairs.CONCLUSIONThis work not only opens up a new method to fabricate heterojunction photocatalysts, but also paves the way for designing advanced magnetically separable photocatalysts with improved photoactivity. © 2021 Society of Chemical Industry (SCI).

A magnetically retrievable copper ionic liquid nanocatalyst for cyclooxidative synthesis of 2-phenylquinazolin-4(3H)-ones.

In the present work, we report the design and fabrication of a copper-containing ionic liquid supported magnetic nanocatalyst via a convenient and straightforward synthetic approach for the formation of 2-phenylquinazolin-4(3H)-ones using o-aminobenzamide and benzaldehydes as the reaction partners. The successful formation and properties of the as-prepared catalyst have been thoroughly investigated using diverse physico-chemical techniques including FT-IR, XRD, FE-SEM, TEM, ICP, VSM, BET and TGA. Using this nanocatalytic system, a variety of 2-phenylquinazolin-4(3H)-ones are synthesized in excellent yields with operational ease and short reaction times in an environmentally preferable solvent under open air and without using any external oxidizing agent. Besides, the catalyst possessed facile magnetic recoverability and remarkable reusability for six consecutive runs without any appreciable decrease in the catalytic efficiency.

Magnetically recoverable carbon-coated iron carbide with arsenic adsorptive removal properties

Magnetic particles, generally nanostructured and magnetite-based, have been studied extensively to remove drinking water contaminants. Compositions beyond Fe3O4 could address long-standing issues of magnetic recoverability and materials integrity in drinking waters. Herein carbon-coated iron carbide (Fe3C@C) were studied for the first time for their stability, magnetic characteristics, magnetic separability, and arsenic adsorptive properties. Experimental results show that (i) Fe3C@C with a 9-nm thick graphitic shell is chemically stable in simulated drinking water; (ii) is ferromagnetic with small magnetic remanence and a magnetic saturation that is ~ 2 × greater than Fe3O4; (iii) can be separated from water magnetically under continuous-flow conditions with greater than 99% recovery; and (iv) has a surface area-normalized adsorption capacity for arsenic (6.75 µg/m2) of the same order of magnitude as that of Fe3O4 (9.62 µg/m2). Fe3C@C can be a viable alternative to Fe3O4 with further development, for the magnetic removal of arsenic and other contaminants from drinking water sources. A comparative look at the chemical stability, adsorptive prowess, and magnetic capturability of nanostructured carbon-coated iron carbide for arsenic removal from simulated drinking water.

Modelling and optimization of factors influencing adsorptive performance of agrowaste-derived Nanocellulose Iron Oxide Nanobiocomposites during remediation of Arsenic contaminated groundwater

Nanocellulose Iron Oxide Nanobiocomposites (NIONs) were synthesized from rice husk and sugarcane bagasse derived nanocelluloses for adsorptive removal of arsenic and associated contaminants present in groundwater samples. These NIONSs were superparamagnetic, hence magnetically recoverable and demonstrated promising recyclability. Synthesis of NIONs was confirmed by Transmission electron microscopy (TEM), X-Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopic (XPS). FTIR and XPS data together with adsorption kinetics provide insights into probable adsorption mechanism of Arsenic by NIONs. The experimental conditions for 10 different variants were modelled using response surface methodology (RSM) based on central composite design (CCD), considering the parameters; adsorbate dosage, adsorbent dosage, pH and contact time. The results identified the best performing variants and the optimal conditions for maximal absorption (~99%). These results were validated using a three-layer feed-forward Multilayer Perceptron (MLP) based Artificial Neural Network (ANN) model. Both RSM and ANN chemometric models were in close conformity for optimized conditions of highest adsorption by specific variants. The standardized conditions were used to expand the study to field-based arsenic contaminated groundwater samples and their performance to commercial adsorbents. NIONs show promising commercial potential for water remediation applications due to their high adsorptive performance, magnetic recoverability and recyclability.

Removal of arsenic contaminants using a novel porous nanoadsorbent with superior magnetic recovery

Novel porous and magnetic iron oxide nanoparticles (PMNPs) with good magnetic properties were synthesized through a simple sol–gel method and exhibited excellent adsorption performance for aqueous arsenic contaminants as well as magnetic recoverability. Hysteresis loop analysis confirmed that the PMNPs were typical superparamagnetic material with a ultrahigh magnetic saturation (Ms) of 94.77 emu/g, which allowed their quick and complete recovery even under magnetic fields less than 0.25 T. The kinetics and isotherms results confirmed that adsorption equilibrium could achieved in 30 min and the saturated adsorption capacities for As(III) and As(V) exceeded 0.64 and 0.76 mmol/g at 30 °C. The effects of initial pH and diverse co-existing ions demonstrated that the optimal conditions for arsenic removal were closely related to the PMNPs surface charge distribution and the electron density of As(III) and As(V). In addition, after 10 adsorption–desorption cycles, PMNPs still held more than 80% of the primal arsenic adsorption capacities.

Preparation, characterization and application of nano-[Fe3O4@-SiO2@R-NHMe2][H2PO4] as a novel magnetically recoverable catalyst for the synthesis of pyrimido[4,5-b]quinolines

A novel organic-inorganic hybrid magnetic nanomaterial namely nano-[Fe3O4@-SiO2@R-NHMe2][H2PO4] (nano-[FSRN][H2PO4]) has been prepared, and characterized by FT-IR, EDS, FE-SEM, VSM, XRD and TGA analyses. Afterward, an important class of uracil-bearing heterocycles namely pyrimido[4,5-b]quinolines has been synthesized through the one-pot multi-component reaction of 6-amino-1,3-dimethyluracil with arylaldehydes and dimedone using nano-[FSRN][H2PO4] as a dual-functional catalyst under solvent-free conditions. High yields, short reaction times, magnetic recoverability of the catalyst, no need to column chromatography for purification of the products and good compliance with green chemistry protocols are some advantages of the work.