Functionalized magnetic particles for water treatment

Stray Magnetic Field Variations and Micromagnetic Simulations: Models for Ni0.8Fe0.2 Disks Used for Microparticle Trapping

Patterned micro-scale thin-film magnetic structures, in conjunction with weak (~few tens of Oe) applied magnetic fields, can create energy landscapes capable of trapping and transporting fluid-borne magnetic microparticles. These energy landscapes arise from magnetic field magnitude variations that arise in the vicinity of the magnetic structures. In this study, we examine means of calculating magnetic fields in the local vicinity of permalloy (Ni0.8Fe0.2) microdisks in weak (~tens of Oe) external magnetic fields. To do this, we employ micromagnetic simulations and the resulting calculations of fields. Because field calculation from micromagnetic simulations is computationally time-intensive, we discuss a method for fitting simulated results to improve calculation speed. Resulting stray fields vary dramatically based on variations in micromagnetic simulations-vortex vs. non-vortex micromagnetic results-which can each appear despite identical simulation final conditions, resulting in field strengths that differ by about a factor of two.

Removal of heavy metal ions with magnetic carbon prepared from corncob biomass

Four novel magnetic-activated carbons (MACs) were prepared, characterised, and used as adsorbents to remove heavy metal ions from wastewater samples. The MACs prepared, are advanced adsorbents for the removal of Hg(II), Cr(III), Cd(II), and Pb(II). The nature of the acid, amount, composition of the MACs, and the remotion time were evaluated in aqueous solutions. The ions removal percentages obtained, under the best conditions, were 93% for Hg(II) and higher than 99% for Pb(II), Cr(III), and Cd(II) (100 mg L-1, initial concentration in solution), with 100 mg of the MAC-3 in HNO3 3 mM. The capacity of the best adsorbent, MAC-3, for removing heavy metals ions Hg(II), Cr(III), Cd(II), and Pb(II) was studied using Langmuir and Freundlich adsorption isotherms under the best condition. The maximum adsorption capacities of Hg(II), Cr(III), Cd(II), and Pb(II) were found to be 10.72, 11.51, 11.49 and 11.49 mg g-1, the values of constants of Freundlich models were 17.98, 26.83, 9.18, and 7.18 mg g-1 respectively. For Hg(II) and Pb(II) the correlation factor (R2) was better for Freundlich model, while Cr(III) and Cd(II) showed better R2 with Langmuir model. Finally, the treatment for the elimination of heavy metal ions was carried out, with wastewater samples of industrial and domestic origin, and used for crop irrigation. The samples were collected in Irrigation District 003, Hidalgo, Mexico. The MAC-3 removes heavy metal ions from the wastewater matrix above 99%.

Nd Recovery from Wastewater with Magnetic Calcium Alginate ((1,4)-β-d-Mannuronic Acid and α-L-Guluronic Acid) Hydrogels

In this study, a magnetic adsorbent material was produced, by environmentally friendly and inexpensive precursor materials, to clean wastewater that may result from primary and secondary rare earth metal (REM) production. Then, the absorption of Nd³⁺ ions from wastewater was done and this process's kinetic and isotherm models were developed. Thus, the removal of Nd³⁺ from wastewater with magnetic materials was accomplished, and then, this precious metal was recovered by using different acid media. First, Fe sub-micron particles were successfully produced by the polyol method. To increase the stability of Fe-based particles, their surfaces were covered with an oxide layer, and the average thickness was determined as 16 nm. The synthesized Fe particles were added into the calcium alginate beads and then coated with chitosan to increase the pH stability of the gels. The chemical composition of the gels was determined by Fourier transform infrared spectroscopy, the thermal properties were determined by differential scanning calorimetry, and the magnetic properties were determined by vibrating-sample magnetometer analysis. The magnetic saturation of the hydrogels was 0.297 emu/g. After the production of magnetic calcium alginate hydrogels, Nd³⁺ ion removal from wastewater was done. Wastewater was cleaned with 94.22% efficiency. The kinetic models of the adsorption study were derived, and isotherm studies were done. Adsorption reaction fitted different kinetic models at different time intervals and the Freundlich isotherm model. The effect of pH, temperature, and solid-liquid ratio on the system was determined and the thermodynamic constants of the system were calculated. After the adsorption studies, Nd³⁺ ions were regenerated in different acid environments and achieved an 87.48% efficiency value. The removal of Nd³⁺ ions from wastewater was carried out with high efficiency, the gels obtained as a result of adsorption were regenerated with high efficiency by using acid media, and it was predicted that the gels could be reused. This study is thought to have reference results not only for the removal of REM from wastewater by magnetic adsorption materials but also for the adsorption of heavy metals from wastewater.

Design of hydrophobic polyurethane-magnetite iron oxide-titanium dioxide nanocomposites for oil-water separation

Efficacious oil-water separation has become a global challenge owing to regular oil spillage accidents and escalating industrial oily wastewater. In this study, we synthesized titanium dioxide and magnetite iron oxide nanoparticles to use as a precursor for the production of the nanocomposites. Hydrophobic nanocomposites were fabricated using polyurethane, hematite and magnetite iron oxide nanoparticles, and titanium dioxide nanoparticles through a sol-gel process. The formation of the obtained nanocomposites was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. In addition, the thermogravimetric and differential thermogravimetric (TGA/DTG) and BET surface area results exhibited enhanced thermal stability of the optimized nanocomposite which displayed mesoporous type materials feature with high porosity. Furthermore, the obtained outcomes demonstrated that the distribution of nanoparticles into a polymer matrix had a significant impact on enhancing superhydrophobicity and the separation efficiency against sunflower oil. Seeing the water contact angle of the nanocomposite-coated filter paper was about 157° compared to 0° for the uncoated filter paper and endowed separation efficiency of almost 90% for 5 consecutive cycles. Thereby, these nanocomposites could be an ideal candidate for self-cleaning surfaces and oil-polluted water purification.

Competitive adsorption of Alizarin Red S and Bromocresol Green from aqueous solutions using brookite TiO2 nanoparticles: experimental and molecular dynamics simulation

In this work, the effective adsorption and the subsequent photodegradation activity, of TiO₂ brookite nanoparticles, for the removal of anionic dyes, namely, Alizarin Red S (ARS) and Bromocresol Green (BCG) were studied. Batch adsorption experiments were conducted to investigate the effect of both dyes' concentration, contact time, and temperature. Photodegradation experiments for the adsorbed dyes were achieved using ultraviolet light illumination (6 W, λ = 365 nm). The single adsorption isotherms were fitted to the Sips model. The binary adsorption isotherms were fitted using the Extended-Sips model. The results of adsorption isotherms showed that the estimated maximum adsorption uptakes in the binary system were around 140 mg g^-1 and 45.5 mg g^-1 for ARS and BCG, respectively. In terms of adsorption kinetics, the uptake toward ARS was faster than BCG molecules in which the equilibrium was obtained in 7 min for ARS, while it took 180 min for BCG. Moreover, the thermodynamics results showed that the adsorption process was spontaneous for both anionic dyes. All these macroscopic competitive adsorption results indicate high selectivity toward ARS molecules in the presence of BCG molecules. Additionally, the TiO₂ nanoparticles were successfully regenerated using UV irradiation. Moreover, molecular dynamics computational modeling was performed to understand the molecules' optimum coordination, TiO₂ geometry, adsorption selectivity, and binary solution adsorption energies. The simulation energies distribution exhibits lower adsorption energies for ARS in the range from - 628 to - 1046 [Formula: see text] for both single and binary systems. In addition to that, the water adsorption energy was found to be between - 42 and - 209 [Formula: see text].

Ultrasound Study of Magnetic and Non-Magnetic Nanoparticle Agglomeration in High Viscous Media

Ultrasound attenuation spectroscopy has found wide application in the study of colloidal dispersions such as emulsions or suspensions. The main advantage of this technique is that it can be applied to relatively high concentration systems without sample preparation. In particular, the use of Epstein-Carhart-Allegra-Hawley's (ECAH) ultrasound scattering theory, along with experimental data of ultrasound velocity or attenuation, provide the method of estimation for the particle or droplet size from nanometers to millimeters. In this study, suspensions of magnetite and silica nanoparticles in high viscous media (i.e., castor oil) were characterized by ultrasound spectroscopy. Both theoretical and experimental results showed a significant difference in ultrasound attenuation coefficients between the suspensions of magnetite and silica nanoparticles. The fitting of theoretical model to experimental ultrasound spectra was used to determine the real size of objects suspended in a high viscous medium that differed from the size distributions provided by electron microscopy imaging. The ultrasound spectroscopy technique demonstrated a greater tendency of magnetic particles toward agglomeration when compared with silica particles whose sizes were obtained from the combination of experimental and theoretical ultrasonic data and were more consistent with the electron microscopy images.

Iron Oxide Nanoparticles: Physicochemical Characteristics and Historical Developments to Commercialization for Potential Technological Applications

Iron oxide nanoparticles (IONPs) have gained increasing attention in various biomedical and industrial sectors due to their physicochemical and magnetic properties. In the biomedical field, IONPs are being developed for enzyme/protein immobilization, magnetofection, cell labeling, DNA detection, and tissue engineering. However, in some established areas, such as magnetic resonance imaging (MRI), magnetic drug targeting (MDT), magnetic fluid hyperthermia (MFH), immunomagnetic separation (IMS), and magnetic particle imaging (MPI), IONPs have crossed from the research bench, received clinical approval, and have been commercialized. Additionally, in industrial sectors IONP-based fluids (ferrofluids) have been marketed in electronic and mechanical devices for some time. This review explores the historical evolution of IONPs to their current state in biomedical and industrial applications.

Magnetic water treatment in a wastewater treatment plant: Part I - sorption and magnetic particles

The application of magnetic sorption to treat wastewaters is nowadays seen as a potential industrial method. In this work we apply magnetite particles to remediate real wastewater samples, with several contaminants competing for the same active sorption center at the same time. We also apply our studies at three different sampling points of a Wastewater Treatment Plant. In general terms, magnetite particles have shown a very good behaviour concerning the reduction of detergents and COD, while phosphates and total nitrogen, and the majority of heavy metals are high to moderately removed. The influence of the type of wastewater (i.e., sampling point) has also shown to be important especially for high concentration of contaminants.

Advanced Functional Nanostructures based on Magnetic Iron Oxide Nanomaterials for Water Remediation: A Review

The fast growth of industrialization combined with the increasing population has led to an unparalleled demand for providing water in a safe, reliable, and cost-effective way, which has become one of the biggest challenges of the twenty-first century faced by global society. The application of nanotechnology in water treatment and pollution cleanup is a promising alternative in order to overcome the current limitations. In particular, the application of magnetic iron oxide nanoparticles (MIONs) for environmental remediation has currently received remarkable attention due to its unique combination of physicochemical and magnetic properties. Given the broadening use of these functional engineered nanomaterials, there is a growing concern about the adverse effects upon exposure of products and by-products to the environment. This makes vitally relevant the development of green chemistry in the synthesis processes combined with a trustworthy risk assessment of the nanotoxicity of MIONs as the scientific knowledge of the potential hazard of nanomaterials remains limited. This work provides comprehensive coverage of the recent progress on designing and developing iron oxide-based nanomaterials through a green synthesis strategy, including the use of benign solvents and ligands. Despite the limitations of nanotoxicity and environmental risks of iron oxide-based nanoparticles for the ecosystem, this critical review presents a contribution to the emerging knowledge concerning the theoretical and experimental studies on the toxicity of MIONs. Potential improvement of applications of advanced iron oxide-based hybrid nanostructures in water treatment and pollution control is also addressed in this review.

A review of the application of adsorbents for landfill leachate treatment: Focus on magnetic adsorption

Landfill leachate is a significant environmental threat due to the complexity and variety of its pollutants. There are various physical, chemical, and biological treatment methods proposed for leachate treatment. Adsorption with conventional adsorbents such as activated carbon is a process which has been widely employed with relative success. Magnetic adsorbents are a special type of adsorbents with favorable stability, high adsorption capacities, and excellent recycling and reuse capabilities when compared to conventional sorbents. Research regarding the synthesis and use of magnetic adsorbents has been growing at a rapid pace, exhibiting >8-fold increase in publications in the decade of 2010 to 2020. In the current study, both conventional and magnetic adsorbents for landfill leachate treatment have been comprehensively reviewed and discussed. The application of magnetic adsorbents for landfill leachate treatment is relatively new, with numerous avenues of research open to study. Although the production of magnetic adsorbents is significantly more expensive than conventional adsorbents, when taking into consideration all life cycle costs, they are much more competitive than it initially appears. If environmental impacts are of concern, research should shift towards the use of greener chemicals and processes for magnetic adsorbent synthesis, because preliminary analysis of the current synthesis processes shows a much higher environmental impact compared to conventional adsorbents, in particular in terms of global warming potential and energy use.

Implication of Magnetic Nanoparticles in Cancer Detection, Screening and Treatment

During the last few decades, magnetic nanoparticles have been evaluated as promising materials in the field of cancer detection, screening, and treatment. Early diagnosis and screening of cancer may be achieved using magnetic nanoparticles either within the magnetic resonance imaging technique and/or sensing systems. These sensors are designed to selectively detect specific biomarkers, compounds that can be related to the onset or evolution of cancer, during and after the treatment of this widespread disease. Some of the particular properties of magnetic nanoparticles are extensively exploited in cancer therapy as drug delivery agents to selectively target the envisaged location by tailored in vivo manipulation using an external magnetic field. Furthermore, individualized treatment with antineoplastic drugs may be combined with magnetic resonance imaging to achieve an efficient therapy. This review summarizes the studies about the implications of magnetic nanoparticles in cancer diagnosis, treatment and drug delivery as well as prospects for future development and challenges of magnetic nanoparticles in the field of oncology.