Fluoride ions sorption using functionalized magnetic metal oxides nanocomposites: a review

Fluoride is an anionic pollutant found superfluous in surface or groundwater as a result of anthropogenic actions from improper disposal of industrial effluents. In drinking water, superfluous fluoride has been revealed to trigger severe health problems in humans. Hence, developing a comprehensive wastewater decontamination process for the effective management and preservation of water contaminated with fluoride is desirable, as clean water demand is anticipated to intensify considerably over the upcoming years. In this regard, there have been increased efforts by researchers to create novel magnetic metal oxide nanocomposites which are functionalized for the remediation of wastewater owing to their biocompatibility, cost-effectiveness, relative ease to recover and reuse, non-noxiousness, and ease to separate from solutions using a magnetic field. This review makes an all-inclusive effort to assess the effects of experimental factors on the sorption of fluoride employing magnetic metal oxide nanosorbents. The removal efficiency of fluoride ions onto magnetic metal oxides nanocomposites were largely influenced by the solution pH and ions co-existing with fluoride. Overall, it was noticed from the reviewed researches that the maximum sorption capacity using various metal oxides for fluoride sorption was in the order of aluminium oxides >cerium oxides > iron oxides > magnesium oxides> titanium oxides, and most sorption of fluoride ions was inhibited by the existence of phosphate trailed by sulphate. The mechanism of fluoride sorption onto various sorbents was due to ion exchange, electrostatic attraction, and complexation mechanism.

Efficient remediation of chlorpyrifos pesticide from contaminated water by superparamagnetic adsorbent based on Arabic gum-grafted-polyamidoxime

A novel organic/inorganic biosorbent hydrogel nanocomposite based on Arabic Gum-grafted-polyamidoxime and CuFe₂O₄ magnetic nanoparticles (AG-g-PAO/CuFe₂O₄) was prepared in three steps. The prepared hydrogel nanocomposite was well characterized using Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), CHN, zeta potential, and Brunauer-Emmett-Teller (BET) analyses. The adsorption efficiency of the AG-g-PAO/CuFe₂O₄ for removing an organophosphorus pesticide (OPP) (chlorpyrifos) from aqueous solutions was studied. Effect of different experimental conditions such as the pH of the solution, adsorbent dosage, contact time, initial concentration on adsorption efficiency was evaluated. The experimental adsorption data described well by the Langmuir isotherm model and the maximum adsorption capacity (Q_max) of the prepared biosorbent for chlorpyrifos was found 769.23 mg/g. The adsorption kinetic data were well fitted by the pseudo-second-order model. It was suggested that the chlorpyrifos was adsorbed onto AG-g-PAO/CuFe₂O₄ hydrogel biosorbent mainly through electrostatic interaction and hydrogen bonding. The result of adsorption-desorption experiments revealed that the AG-g-PAO/CuFe₂O₄ can be excellently regenerated and reused after three sequential runs without a considerable decline in its adsorption performance.

High-efficiency adsorption of phenanthrene by Fe3O4-SiO2-dimethoxydiphenylsilane nanocomposite: Experimental and theoretical study

Phenanthrene (PHE), as one of representative polycyclic aromatic hydrocarbons (PAHs) can cause serious adverse effects on human health, developing effective adsorbents to alleviate PHE contamination is in urgent demand. A novel Fe₃O₄-SiO₂-Dimethoxydiphenylsilane (Fe₃O₄-SiO₂-2DMDPS) nanocomposite was fabricated from encapsulation and grafting process. Magnetic Fe₃O₄ nanoparticles were served as preliminary matrix material, SiO₂ was used to link the magnetic oxide and provide hydroxyl groups for proceeding the silane coupling reaction subsequently, and the aromatic rings in DMDPS could provide active sites for PHE adsorption via π-π interaction. SEM-EDS, TEM, BET, VSM, XRD, FTIR, Raman, Zeta potential, and XPS techniques were used to characterize magnetic nanocomposite. The prepared Fe₃O₄-SiO₂-2DMDPS exhibited an excellent adsorption performance towards PHE, it could maintain 75.97% adsorption capacity after four regeneration cycles. Homogeneous adsorption acted crucial role in the whole adsorption process and film diffusion was the rate-controlling procedure. Theoretical calculations put forward the most favorable bonding modes between Fe₃O₄-SiO₂-2DMDPS and PHE molecules, confirmed the π-π interaction was valid and it usually existed in the form of parallel-displaced. This work might aid us to develop effective modification strategy for Fe₃O₄ nanoparticles and expand its application in the PAHs removing field.

Magnetic activated charcoal/Fe2O3 nanocomposite for the adsorptive removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) from aqueous solutions: Synthesis, characterization, optimization, kinetic and isotherm studies

Magnetic activated charcoal/Fe₂O₃ nanocomposite (AC/Fe₂O₃NC) was fabricated using Spondias dulcis leaf extract by a facile method and used for the adsorptive removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) from aqueous solutions for the first time. The nanocomposite was characterized by methods such as FE-SEM, EDS, XRD, FTIR, TGA, VSM, and BET to identify and confirm the surface morphology, elemental composition, crystalline nature, functional groups, thermal stability, magnetic behavior, and surface area respectively. Box-Behnken Design (BBD) - an optimization method, which belongs to the Response surface methodology (RSM) and a modeling tool - Artificial Neural Network (ANN) were employed to design, optimize and predict the relationship between the input parameters (pH, initial concentration of 2,4-D, time and agitation speed) versus the output parameter (adsorption efficiency of 2,4-D). Adsorption efficiency of 98.12% was obtained at optimum conditions (pH: 2.05, initial concentration: 32 ppm, contact time: 100 min, agitation speed: 130 rpm, temperature: 30 °C, and dosage: 0.2 g/L). The predictive ability of the ANN was superior (R² = 0.99) than the quadratic model, given by the RSM (R² = 0.93). The equilibrium data were best-fitted to Langmuir isotherm (R² = 0.9944) and the kinetics obeyed pseudo-second-order model (R² = 0.9993) satisfactorily. Thermodynamic studies revealed the spontaneity and exothermic nature of adsorption. The maximum adsorption capacity, q_m was found to be 255.10 mg/g, substantially larger than the reported values for 2,4-D adsorption by other magnetic nanoadsorbents. Therefore, this nanoadsorbent may be utilized as an excellent alternative for the elimination of 2,4-D from the waterbodies.

Remarkable adsorption of hydroquinone as an anion contaminant by using the magnetic supported bimetallic (NiCu-MOF@MAC) nanocomposites in aqueous solutions

The purposes of this work were to synthesize the core-shell magnetic and nonmagnetic supported bimetallic metal-organic frameworks (MOFs) on the walnut-based activated carbon by the facile preparation method to investigate the feasibility of the performance adsorption of hydroquinone in the aqueous solutions. Activated carbon as a substrate and nickel, copper, and trimesic acid were employed in the structure of the prepared MOFs. The adsorbents were characterized by XRD, FTIR, FESEM, EDX, TEM, BET, and VSM analysis. The goethite and magnetite phases were detected in the morphology of the magnetic adsorbent as confirmed by the XRD pattern. Increases in the pH value from 6 and the adsorption temperature led to a lower adsorption capacity of the samples. The maximum adsorption capacity for the well-dispersed nanoparticles of magnetic (NiCu-MOF@MAC and nonmagnetic (NiCu-MOF@AC) was calculated to be 303.03 and 454.54 mg/g by using linear Langmuir isotherm as an appropriate model, respectively. The achievements from the reusability evaluation illustrated that the magnetic bimetallic MOF nanocomposite could successfully be applied to remove hydroquinone from the wastewater on an industrial scale. The kinetic experimental data was in good agreement with the pseudo-second-order model.

Facile one pot preparation of magnetic chitosan-palygorskite nanocomposite for efficient removal of lead from water

Development of polymeric magnetic adsorbents is a promising approach to obtain efficient treatment of contaminated water. However, the synthesis of magnetic composites involving multiple components frequently involves tedious preparation steps. In the present study, a magnetic chitosan-palygorskite (MCP) nanocomposite was prepared through a straight-forward one pot synthesis approach to evaluate its lead (Pb²⁺) removal capacity from aqueous solution. The nano-architectural and physicochemical properties of the newly-developed MCP composite were described via micro- and nano-morphological analyses, and crystallinity, surface porosity and magnetic susceptibility measurements. The MCP nanocomposite was capable to remove up to 58.5 mg Pb²⁺ g^-1 of MCP from water with a good agreement of experimental data to the Langmuir isotherm model (R² = 0.98). The Pb²⁺ adsorption process on MCP was a multistep diffusion-controlled phenomenon evidenced by the well-fitting of kinetic adsorption data to the intra-particle diffusion model (R² = 0.96). Thermodynamic analysis suggested that the adsorption process at low Pb²⁺ concentration was controlled by chemisorption, whereas that at high Pb²⁺ concentration was dominated by physical adsorption. X-ray photoelectron and Fourier transform infrared spectroscopy results suggested that the Pb adsorption on MCP was governed by surface complexation and chemical reduction mechanisms. During regeneration, the MCP retained 82% Pb²⁺ adsorption capacity following four adsorption-desorption cycles with ease to recover the adsorbent using its strong magnetic property. These findings highlight the enhanced structural properties of the easily-prepared nanocomposite which holds outstanding potential to be used as an inexpensive and green adsorbent for remediating Pb²⁺ contaminated water.

DNA purification using a novel γ-Fe2O3/PEDOT hybrid nanocomposite

We report the synthesis and characterization of a new hybrid magnetic composite formed by the enveloping of magnetic iron oxide nanoparticles (γ-NP) with chains of the conductive polymer PEDOT, and its use for the efficient separation of DNA molecules from complex biological samples, allowing the high yield separation of a pure and high-quality DNA fraction. The successful formation of the γ-NP/PEDOT composite was confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, UV visible spectroscopy (UV-Vis), and magnetic hysteresis loop measurements. The nanocomposites showed an excellent capacity of DNA adsorption (Q_e ∼ 248 mg/g) in a model system consisting of salmon sperm DNA. When the γ-NP/PEDOT was used in protocols to extract the DNA from complex samples, the corresponding yield was in the range of 6.4 μg (blood) and 7.3 μg (bacteria), as evaluated quality by UV-Vis, PCR analysis, and electrophoresis assays. We also established that the captured DNA does not need to be detached from the nanocomposite for use as seeding material in PCR amplification experiments. These results and the simplicity of the protocols indicate that the γ-NP/PEDOT composite is a promising DNA absorbent, being competitive with the commercially available magnetic purification kits.

Construction of Fe3O4/SiO2/chitosan-grafted-poly(N-vinylcaprolactam) magnetic nanocomposite and their application in simultaneous extraction of Trans-resveratrol and its metabolites from rat plasma

A novel magnetic nanocomposite of chitosan-grafted-poly(N-vinylcaprolactam) (Fe₃O₄/SiO₂/CHT-g-PNVCL MNC) were synthesized. Chitosan was prepared from shrimp shells Penaeus monodon by a green deacetylation approach. N-vinylcaprolactam was first polymerized on the surface of Fe₃O₄ magnetic nanoparticles using surface-initiated atom transfer radical polymerization. Then, the Fe₃O₄ nanoparticles modified with carboxyl-terminated- poly(N-vinylcaprolactam) was grafted onto chitosan. Various techniques were used to characterize of physicochemical properties of synthesized nanomaterials. The application of Fe₃O₄/SiO₂/CHT-g-PNVCL MNC was utilized as a novel adsorbent for the simultaneous extraction of trans-resveratrol and its major phase II metabolites from rat plasma. A qualitative analysis was performed using ultra-performance liquid chromatography triple-quadrupole tandem mass spectrometry. Response surface methodology based on central composite design was used to optimize the extraction procedure including pH, amount of adsorbent, extraction time, desorption time, and volume of elution solvent. The established quantitative method succeeded in satisfying FDA requirements regarding biological analysis methods. The results of the validation of the method indicated its acceptable accuracy (-4.4 to 6.9%), linearity (r > 0.995), precision (CV < 6.3%), and stability. The lower limits of quantification of the proposed method achieved were 1.23-1.68 ngmL^-1for target analytes. The information obtained from the method validation has been used to estimate the expanded uncertainty for the determination of trans-resveratrol in rat plasma samples following orally administered trans-resveratrol. The method was applied to study the pharmacokinetics, metabolism, and bioavailability of trans-resveratrol in healthy rats following a single oral or intravenous dose.

Fenton-magnetic based therapy by dual-chemodrug-loaded magnetic hydroxyapatite against colon cancer

Fenton-based therapy is emerging as an effective and selective strategy against cancer. However, a low concentration of transition metal ions, insufficient endogenous H₂O_2, and a high level of antioxidant activity within the cancer cells have hindered the therapeutic efficacy of this strategy. To address these issues, in this study, the Fenton reagent (magnetic hydroxyapatite, mHAP) was accompanied with chemotherapy drugs (cisplatin (CDDP) and methotrexate (MTX)) and static magnetic field (SMF), in such a way to be a pH-, redox-, and magnetic-responsive nanoplatform. In vitro and in vivo experiments revealed higher toxicity of the final construct, MTX.CDDP@mHAP, toward colon cancer cells, as compared with that of free drugs. The most effective antitumor activity was observed as MTX.CDDP@mHAP-treated tumor cells were exposed to SMF (0.9 T) and no noticeable damage was observed in the normal cells and tissues. Active targeting by MTX and magnetic targeting by mHAP under magnetic field increased the tumor selectivity and enhanced the tumor site accumulation and cellular uptake of MTX.CDDP@mHAPs. The released iron ions within the cancer cells trigger the Fenton reaction while the release of chemotherapy drugs, reduction of intracellular glutathione, and application of SMF aggravated the Fenton reaction, subsequently leading to the generation of reactive oxygen species (ROS) and induction of apoptosis. Therefore, Fenton magnetic-based therapy-mediated by MTX.CDDP@mHAP could be considered as a promising strategy against colon cancer with high therapeutic efficiency and biosafety.

Hexavalent chromium removal from water: adsorption properties of in natura and magnetic nanomodified sugarcane bagasse

Biosorption has become a viable and ecological process in which biological materials are employed as adsorbents for the removal of potentially toxic metals, such as hexavalent chromium, from aqueous matrices. This work proposed the use of in natura (SB) and nanomodified sugarcane bagasse (SB-NP) with ferromagnetic nanoparticles (Fe₃O₄) to adsorb Cr(VI) from water. These materials were analyzed by X-ray Spectroscopy (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) to investigate their morphology and interaction with Cr(VI). It was observed the efficient impregnation of magnetite on the SB surface and the presence of functional groups such as O-H, C-H, C=O, C-O-C, C-O, and Fe-O (characteristic of magnetite). The best conditions for Cr(VI) removal in aqueous medium were determined by assessing the pH at the point of zero charge (pH_PZC = 6.1 and 5.8 for SB and SB-NP, respectively), adsorption pH and kinetics, and adsorption capacity. Batch procedures were performed using increasing concentrations of Cr(VI), 10-100 mg/L at pH 1.0, and 30 min of contact time. The adsorbent dose was 10 mg/L, and the experimental adsorption capacities (SC_exp) for SB, NP, and SB-NP were 1.49 ± 0.06 mg/g, 2.48 ± 0.57 mg/g, and 1.60 ± 0.08 mg/g, respectively. All Cr contents were determined by flame atomic absorption spectrometry (FAAS). The pseudo-2nd-order kinetic equation provided the best adjustments with r² 0.9966 and 0.9931 for SB and SB-NP, respectively. Six isotherm models (Langmuir, Freundlich, Sips, Temkin, Dubinin-Radushkevich, and Hill) were applied to the experimental data, and Freundlich, Dubinin-Radushkevich (D-R), and Temkin were the models that best described the experimental sorption process. The binding energy values (E) provided by the D-R model were 0.11 ± 0.25, 0.09 ± 0.20, and 0.08 ± 0.25 kJ/mol, for NP, SB-NP, and SB, respectively, and denote a physical interaction for the studied adsorbate-adsorbent system. The nanomodification of the biomass slightly improved the efficiency for the sorption of Cr(VI) and facilitated the removal of Cr(VI)-containing biosorbents from water medium.

Decorating graphene oxide with zeolitic imidazolate framework (ZIF-8) and pseudo-boehmite offers ultra-high adsorption capacity of diclofenac in hospital effluents

This study reports on an easy and scalable synthesis method of a novel magnetic nanocomposite (GO/ZIF-8/γ-AlOOH) based on graphene oxide (GO) nanosheets decorated with zeolitic imidazolate framework-8 (ZIF-8), pseudo-boehmite (γ-AlOOH), and iron oxide (Fe₃O₄) nanoparticles by combining solvothermal and solid-state dispersion (SSD) methods. The nanocomposite was successfully applied to remove of diclofenac sodium (DCF) - a widely used pharmaceutical - from water. Response Surface Methodology (RSM) was used to optimize the adsorption process and assess the interactions among the influencing factors on DCF removal efficiency; including contact time, adsorbent dosage, initial pH, solution temperature, and DCF concentration. Adsorption isotherm results showed a good fitting with the Langmuir isotherm model with an exceptional adsorption capacity value of 2594 mg g^-1 at 30 °C, which was highly superior to the previously reported adsorbents. In addition, kinetic and thermodynamic investigations further illustrated that the adsorption process was fast (equilibrium time = 50 min) and endothermic. The regeneration of GO/ZIF-8/γ-AlOOH nanocomposite using acetic acid solution (10% v/v) after a simple magnetic separation was confirmed in five consecutive cycles, which eliminate the usage of organic solvents. The nanocomposite has also shown a superior performance in treating a simulated hospital effluent that contained various pharmaceuticals as well as other organic, and inorganic constituents.

Adsorption-photocatalytic processes for removal of pentachlorophenol contaminant using FeNi3/SiO2/ZnO magnetic nanocomposite under simulated solar light irradiation

The adsorption followed by photocatalytic degradation process was examined for the pentachlorophenol (PCP) removal from aqueous solution. These processes were accomplished by using FeNi₃/SiO₂/ZnO magnetic nanocomposite as an adsorbent-photocatalytic agent and under the irradiation of solar light. The magnetic nanocomposite used was first synthesized and then was characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometer (VSM), and X-ray diffraction (XRD) spectroscopy. The PCP removal efficiency was tested for various factors, including pH, PCP concentration, and nanocomposite dose at different contact times. The characterization results of TEM, FE-SEM, and VSM analysis showed that the synthesized nanoparticles are amorphous and tend to agglomerate due to their high super-paramagnetic property. In addition, the EDX technique showed that the Zn and O elements had the highest weight percent in the synthesized nanocomposite, respectively. On the other hand, XRD analysis revealed that the crystalline size of the nanoparticles was about 42 nm. The kinetic of PCP degradation followed the pseudo-first-order model with R² = 0.978. According to the results of the isotherm study, the adsorption of PCP onto the nanoparticles followed the Freundlich model. The results of adsorption-photocatalytic degradation experiments showed that 100% removal of PCP was obtained at optimum conditions of pH = 3, nanocomposite dose = 0.5 g/L, contact time = 180 min, and initial PCP concentration of 10 mg/L. Through the results obtained from this study, the adsorption process followed by solar light photocatalytic degradation process using FeNi₃/SiO₂/ZnO magnetic nanocomposite is found to be an efficacious treatment method for the removal of PCP contaminant from water and wastewater.

Fabrication of chitosan-coated mixed spinel ferrite integrated with graphene oxide (GO) for magnetic extraction of viral RNA for potential detection of SARS-CoV-2

Genetic variants of the COVID-19 causative virus have been arising and circulating globally. In many countries, especially in developing ones with a huge population, vaccination has become one of the major challenges. SARS-CoV-2 variants' fast transmission rate has an upsurge in the COVID cases, leading to more stress on health systems. In the current COVID-19 scenario, there is the requirement of more adequate diagnostic approaches to check the COVID-19 spread. Out of many diagnostic approaches, a magnetic nanoparticle-based reverse transcription polymerase chain reaction could be nontrivial. The use of magnetic nanoparticles is to separate nucleic acid of SARS-CoV-2 from the patient samples and apply for SARS-CoV-2 detection in an easy and more effective way. Herein, the magnetic nanoparticles are synthesized using the solgel autocombustion methods and then successfully coated with biopolymer (chitosan) using ultrasonication. Chitosan-coated nanoparticles are successfully integrated into the graphene oxide sheets to introduce carboxyl groups. Crystallite size calculation, morphological and magnetic studies of synthesized magnetic nanoparticles, and multifunctional magnetic nanoparticles are done using XRD, SEM, TEM, and VSM, respectively. Besides, the potentiality of the fabricated nanocomposites in RNA extraction protocol is also discussed with schematic representation.

In situ decorated Au NPs on chitosan-encapsulated Fe3O4-NH2 NPs as magnetic nanocomposite: Investigation of its anti-colon carcinoma, anti-gastric cancer and anti-pancreatic cancer

Chitosan is a linear polysaccharide and non-toxic bioactive polymer with a wide variety of applications due to its functional properties such as ease of modification, and biodegradability. In this investigation, magnetic cores (Fe₃O₄) were synthesized using a fabrication method involving coprecipitation of Fe²⁺ and Fe³⁺. Then the magnetic nanoparticles were encapsulated by chitosan layers. In the next step, magnetite-gold composite nanoparticles were synthesized with spherical shapes and sizes ranging from 20 to 30 nm, using sodium citrate as a natural reducing agent. The morphological and physicochemical features of the material were determined using several advanced techniques like FT-IR, ICP analysis, FESEM, EDS, XRD, TEM, XPS and VSM. In the biological part of the present study, the cell viability of Fe₃O₄, HAuCl₄, and Fe₃O₄@CS/AuNPs was very low against human colorectal carcinoma cell lines i.e. Ramos.2G6.4C10, HCT-8 [HRT-18], HCT 116, and HT-29, human gastric cancer cell lines i.e. MKN45, AGS, and KATO III, and human pancreatic cancer cell lines i.e. PANC-1, AsPC-1, and MIA PaCa-2. The IC50 of Fe₃O₄@CS/AuNPs against Ramos.2G6.4C10, HCT-8 [HRT-18], HCT 116, HT-29, MKN45, AGS, KATO III, PANC-1, AsPC-1, and MIA PaCa-2 cell lines were 385, 429, 264, 286, 442, 498, 561, 513, 528, and 425 μg/mL, respectively. Thereby, the best cytotoxicity results of our Fe₃O₄@CS/AuNPs were observed in the case of the HCT 116 cell line. Seemingly, the present nanoparticles may be used for the treatment of several types of gastro-duodenal cancers especially colon, gastric, and pancreatic cancers in near future.

MOF-derived cluster-shaped magnetic nanocomposite with hierarchical pores as an efficient and regenerative adsorbent for chlortetracycline removal

The presence of large amounts of antibiotic residues can potentially threaten environmental sustainability and human health. Thus, it is imperative to develop convenient and effective technologies for eliminating antibiotics from aquatic environments, which are major contaminant reservoirs. Herein, based on Zn/Fe-MIL-88B, we designed and synthesized a magnetic nanocomposite (MC) that contains hierarchical pores and as an effective and regenerative adsorbent for the removal of chlortetracycline (CTC) from water. The characteristics of the MC and its CTC adsorption performance were investigated systematically. The synthesized MC sample pyrolyzed at 800 °C (MC-800) consisted of metallic iron and N/O-doped graphitic carbon along with cluster-like particles with a mesoporous structure. Further, the adsorption of CTC on MC-800 (maximum adsorption amount of 1158.0 mg/g) could be described using the Freundlich isotherm model and a pseudo-second-order model, indicating that the surface of MC-800 was heterogeneous. The adsorption is likely driven by weak chemical forces, including hydrogen bond formation, cation-π electron donor-acceptor (EDA), and π-π EDA interactions. Finally, MC-800 could be recovered readily through facile magnetic separation and regenerated such that its adsorption rate remained higher than 85% even after five cycles.

Concentrative isolation of uranium traces in aqueous solutions via resurfaced-magnetic carbon nanotube suspension

The concentrative isolation of metal traces from aqueous solutions is of vital importance for environmental and industrial processes. Developing reliable systems of nanoscale that can be fine-tuned to effectively isolate these metals remains an intriguing aim which can potentially beget economic benefits and mitigate major environmental concerns. Here we demonstrate a conceptual metal extraction system where magnetic multi-wall carbon nanotubes (M-MWCNTs) are surface-equipped with a molecular network of polyethylenimine (PEI) to serve as a reusable nano-ionic exchanger, referred to as "M-MWCNTs-PEI". The designed nano-ionic exchanger forms readily stable suspensions with the metal-bearing aqueous solutions eliminating the need for vigorous agitation. Besides, it can be magnetically manipulated and separated in/from the solution. To exemplify its potential for the isolation of metal traces, the M-MWCNTs-PEI was tested with the uranium trace ions in aqueous media. The M-MWCNTs-PEI featured distinct sorption capacity of ~488 mg/g at pH 6, with moderate, but stable, binding affinity toward uranium ions. As such, excellent isolation performance is demonstrated while bound uranium ions are effectively concentrated and recovered from the interfacial PEI molecular network. This was efficiently achieved by exposing the loaded M-MWCNTs-PEI to solutions of small volumes and specific chemistry. Such combined qualities of large capacity and reusability have not been observed with the previously reported ion exchange systems. Altogether, our observations here demonstrate how functional systems of nanoscale can be adapted for industrial applications while this concept can be extended to address other important resources such as rare-earth and lanthanide elements.

Metal-organic framework MIL101 (Cr)-NH2 functionalized magnetic graphene oxide for ultrasonic-assisted magnetic solid phase extraction of neonicotinoid insecticides from fruit and water samples

In this work, a magnetic nanocomposite composed of graphene oxide (GO), silica-coated cobalt ferrite (CoFe2O4@SiO2) nanoparticles and amino-functionalized metal-organic framework (MIL 101 (Cr)-NH2) was fabricated and employed for ultrasonic-assisted magnetic solid phase extraction (UA-MSPE) of neonicotinoid insecticides. Various techniques such as Fourier transform infrared (FT-IR) spectrometry, vibrating sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FE-SEM) measurements were executed to investigate features and morphology of the adsorbent. The magnetic graphene oxide functionalized MIL-101 (Cr)-NH2 (MGO/MIL) combines the advantages of magnetic GO and MIL 101(Cr)-NH2 such as excellent thermal and chemical stability, high surface area, accessible coordinative unsaturated sites, sufficient stability in aqueous solutions and rapid and easy separation from the solution. Some of the important extraction factors such as type and volume of desorption solvent, desorption time, salt concentration, adsorbent amount, pH and extraction time were investigated in detail to achieve high MSPE recovery. In optimal condition, the limits of detection (LODs) for Acetamiprid and Imidacloprid were achieved 0.022 and 0.019 ng mL-1, respectively. Good determination coefficients (R2 more than 0.9990) with satisfactory linearity in the range of 0.064-3500 ng mL-1 were found for this method. The relative standard deviations for intra- and inter-day analyses were in the range of 3.93-4.56% and 7.80-8.50%, respectively. The method was successfully used for analyzing of neonicotinoid insecticides in water and fruit samples and acceptable recoveries from 82.13% to 102.27% were obtained. The results indicated that the nanocomposite is feasible for the adsorption of trace amounts of the target analytes from the fruit and water samples.

Ag NPs on chitosan-alginate coated magnetite for synthesis of indazolo[2,1-b]phthalazines and human lung protective effects against α-Guttiferin

Biocomposite nanomaterials have been evolved as the new generation catalysts and therapeutic supplement in these days. Magnetically isolation has added new features to this category. This has encouraged us to synthesize a novel Ag NP adorned chitosan-alginate dual bio-polysaccharide (two of the more versatile polysaccharides) modified core-shell magnetic nanocomposite (Fe₃O₄/CS-Alg/Ag NPs). The material was meticulously characterized following different physicochemical techniques, such as, FT-IR, ICP-OES, FESEM, EDX, atomic mapping, TEM, VSM, XRD and XPS studies. The as synthesized material was catalytically explored in the one-pot multicomponent synthesis of biologically potent 2H-indazolo[2,1-b]phthalazine-trione derivatives involving a wide range of substrates. The reactions were ended up with excellent yields under solvent-free heating conditions. The catalyst recyclability, heterogeneity and leaching tests were performed to ensure its high stability and robustness. It could be reused as much as 10 times in succession with almost unchanged catalytic performances. In the lung protective part of the present research, the human lung toxicity was induced by α-Guttiferin. The cell viability of lung MRC-5, CCD19Lu, WI-38, and BEAS-2B cell lines was measured by trypan blue assay. Caspase-3 activity was assessed by the caspase activity colorimetric assay kit and mitochondrial membrane potential of lung cells was studied by Rhodamine123 fluorescence dye. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test was used to show DNA fragmentation and apoptosis of lung cells. Also, the Rat inflammatory cytokine assay kit was used to measure the concentrations of inflammatory cytokines. The catalyst-treated cell cutlers significantly (p ≤ 0.01) reduced the DNA fragmentation, caspase-3 activity, and inflammatory cytokines concentrations, and raised the mitochondrial membrane potential and cell viability in the high concentration of α-Guttiferin-treated lung MRC-5, CCD19Lu, WI-38, and BEAS-2B cells. The best result of lung protective properties of catalyst against α-Guttiferin was seen in the high dose of catalyst i.e., 4 μg. DPPH test revealed similar antioxidant potentials for catalyst and butylated hydroxytoluene. The catalyst inhibited half of the DPPH molecules in the concentration of 171 μg/mL. According to the above results, catalyst can be administrated as a lung protective drug for the treatment of lung diseases after approving in the clinical trial studies in humans.

In situ immobilization of ultra-fine Ag NPs onto magnetic Ag@RF@Fe3O4 core-satellite nanocomposites for the rapid catalytic reduction of nitrophenols

Novel magnetic Ag@RF@Fe₃O₄ core-satellite (MCS) nanocomposites were prepared through in situ photoreduction upon bridging Fe(III) and Ag⁺ via hydroxyl groups in resorcinol formaldehyde (RF) resin by virtue of the coordination effect. The catalytic activity of MCS nanocomposites was evaluated based on catalytic 4-nitrophenol (4-NP) reduction with NaBH₄ as the reducing agent. It was noteworthy that the MCS-3 was beneficial to obtain a superior reaction rate constant of 2.27 min^-1 and a TOF up to 72.7 h^-1. Moreover, the MCS could be easily recovered by applying an external magnetic field and was reused for five times without significantly decrease in catalytic activity. Kinetic and thermodynamic study revealed that catalytic 4-NP reduction using MCS nanocatalysts obeyed the Langmuir-Hinshelwood mechanism and was controlled by the diffusion rate of substrates. Overall, the immobilization of ultra-fine Ag nanoparticles and the extremely negative potentials around MCS nanocomposites, which were effective for the diffusion of reactants, synergistically accelerated the catalytic reduction reactions.

Optimization, equilibrium, adsorption behavior and role of surface functional groups on graphene oxide-based nanocomposite towards diclofenac drug

Aquatic contamination of diclofenac (DCF), an emergent non-steroidal anti-inflammatory drug (NSAIDs), can result in adverse effects to many ecosystems through biomagnification. Hence, introducing effective remediation techniques to sequester the pharmaceutical wastes is highly fundamental to prevent their accumulation in the environment. Generally, adsorption has been presented as a green and efficient approach. Herein, we report the characterization and application of the novel magnetic nanocomposite (GO@CoFe₂O₄) derived from cobalt-based ferrite (CoFe₂O₄) and graphene oxide (GO) for DCF adsorption. For the optimization procedure, the response surface methodology (RSM) was adopted to investigate the impacts of DCF concentration (1.6-18.4 mg/L), DCF dosage (0.08-0.92 g/L), and solution pH (2.6-9.4) to find the optimum conditions for DCF removal, at 10.5 mg/L, 0.74 g/L, and pH 4, respectively. For the adsorption experiments, the kinetic, isotherm, thermodynamic, and intraparticle diffusion models were systematically studied. Moreover, we have elucidated the role of functional groups on the surface of GO@CoFe₂O₄ in enhancing the adsorption of DCF drug. With good removal efficiency (up to 86.1%), high maximum adsorption capacity (32.4 mg/g), GO@CoFe₂O₄ can be a potential candidate to eliminate DCF drug from water.

Enhanced adsorption performance and regeneration of magnetic Fe3O4 nanoparticles assisted extracellular polymeric substances in sulfonamide-contaminated water

It is still unclear about the superiority of the nanoscale Fe₃O₄-assisted extracellular polymeric substances (EPS) compared to traditional EPS and its application feasibility in sulfonamide-contaminated aqueous system. This study reported eco-friendly and reusable EPS/Fe₃O₄ was applied in the sulfonamide-contaminated water treatment, including sulfamethoxazole (SMX), sulfamerazine (SM1), sulfamethazine (SM2) and sulfadiazine (SDZ), respectively. EPS/Fe₃O₄ exhibited the adsorption performance of 77.93%, 74.13%, 65.62%, and 56.64% for SMX, SM1, SM2 and SDZ, respectively, increased by 7.93%, 19.02%, 13.78% and 9.93% compared to traditional EPS. The initial pH value tuned adsorption performance via varying existing species of each sulfonamides. The adsorption process could be well fitted by Freundlich and pseudo-second-order kinetics models. Moreover, the multiple evidences from SEM, FTIR, zeta potential and XRD explained the adsorption mechanisms (i.e., chemisorption, ion exchange, hydroxyl group and hydrophobicity). Desorption and recycle adsorption experiments demonstrated the well regeneration ability of EPS/Fe₃O₄ as biosorbent (67.12% adsorption performance for SMX after five adsorption-desorption cycles), suggesting EPS/Fe₃O₄ was considered as a superior choice for sulfonamide-contaminated water treatment compared to the unrecyclable EPS.

A simple and effective synthesis of magnetic γ-Fe2O3@SiO2@TiO2-Ag microspheres as a recyclable photocatalyst: dye degradation and antibacterial potential

PURPOSE AND METHODS

In this study, an effective technique for synthesizing γ-Fe₂O₃@SiO₂@TiO₂-Ag magnetically separable photocatalyst was introduced by combining co-precipitation, sol-gel, and photo-deposition methods. A series of analyses including FTIR, SEM, EDS, XRD, and VSM were applied to characterize the prepared materials and the investigations on photocatalytic activity of the prepared composites were accomplished.

RESULTS

Compared to bare γ-Fe₂O₃@SiO₂@TiO₂, the Ag-doped composite was more active in terms of photocatalytic characteristics. By applying γ-Fe₂O₃@SiO₂@TiO₂-Ag, the decomposition rate of the Basic blue 41 reached to about 94% after 3 h of UV irradiation; this rate was 63% for pure γ-Fe₂O₃@SiO₂@TiO₂. The results indicated that the dye degradation kinetics followed first-order kinetic model. During the five cycles of separation, it was observed that the Ag-doped composite was greatly effective and stable in terms of recycling. Moreover, the results indicated that antibacterial activity of γ-Fe₂O₃@SiO₂@TiO₂-Ag was remarkably stronger than that of pure Fe₂O₃@SiO₂@TiO₂ particles.

CONCLUSION

It was concluded that by modifying magnetic TiO₂ by silver nanoparticles, charge separation was eased by catching photo-generated electrons, resulted in an enhanced photo- and biological activity. Graphical abstract.

Carbon-based magnetic nanocomposite as catalyst for persulfate activation: a critical review

The activation of persulfate to produce active radicals has been attracting wide attention in environmental remediation fields. Among various catalysts, non-metal carbocatalysts and carbon-based composites have shown attractive prospects given that they are environmental-friendly, highly efficient, abundant, and diverse. In this paper, the use of carbon-based magnetic nanocomposites as catalysts for persulfate activation was reviewed and discussed. The preparation methods of carbon-based magnetic nanocomposites were first briefly summarized. Subsequently, the use of activated carbon, carbon nanotubes, graphene oxide, biochar, and nanodiamond-based magnetic composites to activate persulfate was discussed, respectively. A synergetic effect between carbon materials and magnetic nanoparticles facilitated the activation process because of the increased electron transfer capacity, good dispersity of magnetic nanoparticles, and good repeatability and separability. Both radical and non-radical pathways were detected in the activation processes, but the specific mechanisms were greatly influenced by the components of the catalyst and solution conditions. And fundamental studies were needed to clarify the inner mechanisms of the process. In the end, strategies for enhancing the catalytic performances of carbon-based magnetic nanocomposites were suggested. It is expected that this review will provide some inspirations for developing highly efficient and green catalyst, as well as sulfate radical-based advanced oxidation technology for the remediation water environment.

Preparation and Characterization of Agar Based Magnetic Nanocomposite for Potential Biomedical Applications

PURPOSE

The purpose of the present study was to make a biocompatible agar based composite material via incorporation of appropriate additives within the agar matrix for potential applications in drug delivery and biomedical fields.

METHODOLOGY

Agar based composites were prepared by the incorporation of magnetic iron oxide nano particles, graphite and sodium aluminum as additives in different proportions within the agar matrix by a simple thermophysico- mechanical method. The as prepared agar based composites were then characterized by different techniques i.e. FTIR, SEM, TGA, XRD and EDX analyses. The FTIR peaks confirmed the presence of each component in the agar composite. SEM images showed the uniform distribution of each component in the agar composite. TGA study showed the thermal stability range of different composite sheets. XRD pattern revealed the crystallinity and EDX analysis confirmed the elemental composition of the prepared composites. The prepared agar based composites were evaluated for antimicrobial activities against three pathogenic bacterial strains Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia and the result indicated efficient antimicrobial activities for all composites.

CONCLUSION

From the overall study, it was concluded that due to the non-toxic nature, thermal stability and excellent antibacterial properties, the prepared agar based composites can receive potential biomedical applications.

Hierarchically structured ternary heterojunctions based on Ce3+/ Ce4+ modified Fe3O4 nanoparticles anchored onto graphene oxide sheets as magnetic visible-light-active photocatalysts for decontamination of oxytetracycline

The main prerequisite of an active visible-light-driven photocatalyst is to effectively utilize the visible light to induce electron-hole (e^-/h⁺) pairs of expanded lifetime. To this end, for the first time, the ternary heterojunctions of CeO₂/Fe₃O₄ /Graphene oxide and Ce³⁺/ Fe₃O₄ /Graphene oxide (CeO₂/Fe₃O₄/GO and Fe_2.8Ce_0.2O₄/GO) were prepared via facile ultrasonic-assisted procedures and employed for destruction of oxytetracycline (OTC) under visible light irradiation. The changes in the relative crystal structure, morphology, atomic and surface functional group composition, magnetic, and optic properties of magnetite were uncovered by various techniques. The substantial degradation and mineralization of OTC via visible light/Fe_2.8Ce_0.2O₄/GO system were thoroughly discussed in terms of narrowed band gap energy, the principal function of Ce³⁺/Ce⁴⁺ and Fe²⁺/Fe³⁺ redox pairs and GO platelets, enhanced charge separation and transfer, and enlarged active surface area. Furthermore, the performance of visible light/Fe_2.8Ce_0.2O₄/GO system was evaluated for treating real wastewater and its efficiency was investigated using a number of enhancers and scavengers. Finally, the generated byproducts in the course of photodegradation were determined and the oxidation pathway, photocatalytic kinetics, and plausible mechanism were proposed. The results confirmed that the introduced Ce ions and graphene oxide sheets boost the photo-catalytic efficiency of magnetite for photodegradation of OTC.