Magnesium-zinc ferrites as magnetic adsorbents for Cr(VI) and Ni(II) ions removal: Cation distribution and antistructure modeling

Diclofenac sodium adsorption on activated carbon: experimental, modeling and bayesian statistics

The present study modeled the adsorption process of the drug diclofenac sodium on activated charcoal. For this purpose, a mass balance-based model was used considering a fixed bed column. The mass transfer rate in the solid phase was represented by a driving force model proposed in this study, and a gamma exponent with a range of 0 > γ ≤ 2 was assigned to the model. Different isotherms were adopted to represent the equilibrium at the solid/liquid interface: the Langmuir, Freundlich, Sips and Redlich-Peterson isotherms. The modeling was approached from the perspective of Bayesian statistics, and the Markov chain Monte Carlo method was used for parameter estimation. Model validation was performed with experimental data obtained under different operating conditions of initial concentration ($C_{0.

Zinc/Magnesium Ferrite Nanoparticles Functionalized with Silver for Optimized Photocatalytic Removal of Malachite Green

Water pollution is a major environmental challenge. Due to the inefficiency of conventional wastewater treatment plants in degrading many organic complex compounds, these recalcitrant pollutants end up in rivers, lakes, oceans and other bodies of water, affecting the environment and human health. Semiconductor photocatalysis is considered an efficient complement to conventional methods, and the use of various nanomaterials for this purpose has been widely explored, with a particular focus on improving their activity under visible light. This work focuses on developing magnetic and photoactive zinc/magnesium mixed ferrites (Zn0.5Mg0.5Fe2O4) by sol-gel and solvothermal synthesis methods, which are two of the most important and efficient methods used for the synthesis of ferrite nanoparticles. The nanoparticles (NPs) synthesized by the sol-gel method exhibited an average size of 14.7 nm, while those synthesized by the solvothermal method had an average size of 17.4 nm. Both types possessed a predominantly cubic structure and demonstrated superparamagnetic behavior, reaching a magnetization saturation value of 60.2 emu g-1. Due to the high recombination rate of electrons/holes, which is an intrinsic feature of ferrites, surface functionalization with silver was carried out to enhance charge separation. The results demonstrated a strong influence of adsorption and of the deposition of silver. Several optimization steps were performed during synthesis, allowing us to create efficient catalysts, as proved by the almost full removal of the dye malachite green attaining 95.0% (at a rate constant of 0.091 min-1) and 87.6% (at a rate constant of 0.017 min-1) using NPs obtained by the sol-gel and solvothermal methods, respectively. Adsorption in the dark accounted for 89.2% of the dye removal for nanoparticles prepared by sol-gel and 82.8% for the ones obtained by the solvothermal method. These results make mixed zinc/magnesium ferrites highly promising for potential industrial application in effluent photoremediation using visible light.

Influence of potassium doping on the structural, conduction mechanism, and dielectric properties of CaFe2O4

The frequency and temperature-related dielectric relaxation and electrical conduction mechanisms in potassium-doped CaFe2O4 oxide ceramic were investigated in this study throughout a temperature range of 313-673 K. The synthesis of the KCaFe2O4 compound was accomplished through a solid-state reaction route. The X-ray diffraction pattern at room temperature confirmed that the ceramic KCaFe2O4 crystallizes in the orthorhombic system with the Pbnm space group. The EDX analysis proved the absence of external elements. The surface morphology of the samples was examined using scanning electron microscopy. The conduction mechanism, validated as CBH conduction, was examined using the temperature-dependent variation of Jonscher's power law exponent. Using Nyquist plots, we have effectively constructed a relevant equivalent circuit that encompasses the influences originating from both the grains and the grain boundaries. Furthermore, in KCaFe2O4, the induced dielectric relaxation from the non-Debye to Debye type model is demonstrated by the thermal analysis of M'' (ω) and -Z'' (ω) as a function of frequency.

Efficient removal of Cr(VI) contaminant using recoverable silica from volcanic ash as natural adsorbent: Synthesis and activity in the mechanism and kinetic adsorption

Modification of silica purified from the Merapi volcanic ash with magnetic material of Fe3O4 and attachment of cetyl triamine bromide (CTA-Br) on the magnetic cored has been performed to provide recoverable and positive surfaced of natural adsorbent. The magnetic cored was prepared via co-precipitation and CTA-Br attachment was conducted by a facile strategy. Then, the modified adsorbents were characterized by SEM, TEM, XRD, and FTIR instruments and examined for removing anionic Cr(VI) from the water media. The characterization data confirmed that crystals of Fe3O4 coated by SiO2 that has been bound with CTA-Br have been successfully formed. Additionally, increasing CTA-Br loaded gives thicker lamination on Fe3O4@SiO2/CTA-Br, but the CTA-Br loaded with higher than 0.25 mmol, leads to the coating peeled out. It is also demonstrated that Fe3O4@SiO2/CTA-Br prepared with CTA-Br 0.25 mmol is ideal for Cr(VI) anionic removal, regarding to the highest adsorption and very good separation or recovery process. Moreover, the optimal dose of Fe3O4@SiO2/CTA-Br in the Cr(VI) removal was observed at 0.25 g/20 mL under condition of pH 3 for 60 min. The adsorption of Cr(VI) well fits the Langmuir isotherm model with an adsorption capacity of 3.38 mg g-1 and is in a good agreement with pseudo-second order giving kinetic constant at 0.005 g mg-1 min-1. Thus, it is clear that the natural adsorbent material with recoverable properties for more efficient and wider application of removal Cr(VI) contaminant was expected from this study.

Advancing the development of nanocomposite adsorbent through zinc-doped nickel ferrite-pinecone biochar for removal of chromium (VI) from wastewater

Leather and textile industrial effluents are the main disseminating routes for chromium contamination of water bodies, causing adverse impacts on public and environmental health. The attempt to remediate chromium through conventional wastewater treatment methods is inefficient. Therefore, this study aims to synthesize zinc-doped nickel ferrite pinecone biochar (Zn-NiF@PBC) nanocomposite for the removal of chromium from wastewater systems. The Zn-NiF@PBC nanocomposite was synthesized via the co-precipitation method. The properties of zinc-doped nickel ferrite (Zn-NiF) were effectively modified by blending with biochar at 1, 5, 10, and 15 % (w/w) which was successfully embedded with Zn-Ni ferrite nanoparticles. This was characterized and confirmed by typical adsorbent properties such as a high surface area of 104 m2/g, conducive pore volume of 0.117 cm3/g and pore size of 3.41 nm (BET), interactive multi-functional groups (FTIR), surface charge determination (pHpzc,), crystalline structure (XRD) and very rough surface morphology (SEM). The maximum chromium adsorption was found to be 95 % at the specific experimental condition of pH 3, adsorbent dose 1 g/50 mL, contact time 120 min, and initial chromium concentration 100 mg/L. The adsorption experimental data was best fitted with the Langmuir isotherm at R2 0.98 indicating the adsorption process was homogeneous and monolayer whereas the kinetics adsorption was resembling the second-order kinetic at R2 0.99. Moreover, the adsorption thermodynamics was spontaneous, endothermic, and increased the change in entropy. Finally, the regeneration of Zn-NiF@PBC was found to be effective up to five 5 cycles but gradually degrading in terms of removal efficiency after 3 cycles. In general, Zn-NiF@PBC can remediate chromium from wastewater with huge potential for scale-up and extend to other pollutants clear-up.

Spinel ferrite nanoparticles as potential materials in chlorophenol removal from wastewater

Persistent organic pollutants (POPs) including chlorophenols (CPs) are increasing in water effluents, creating serious problems for both aquatic and terrestrial lives. Several research attempts have considered the removal of CPs by functionalised nanomaterials as adsorbents and catalysts. Besides the unique crystal structure, spinel ferrite nanomaterials (SFNs) own interesting optical and magnetic properties that give them the potential to be utilised in the removal of different types of CPs. In this review, we highlighted the recent research work that focused on the application of SFNs in the removal of different CP substances based on the number of chlorine atom attached to the phenolic compound. We have also discussed the structure and properties of SFN along with their numerous characterisation tools. We demonstrated the importance of identifying the structure, surface area, porosity, optical properties, etc. in the efficiency of the SFN during the CP removal process. The reviewed research efforts applied photocatalysis, wet peroxide oxidation (WPO), persulfate activated oxidation and adsorption. The studies presented different paths of enhancing the SFN ability to remove the CPs including doping (ion substitution), oxide composite structure and polymer composite structure. Experimental parameters such as temperature, dosage of CPs and SFN structure have shown to have a major effect in the CP removal efficiency. More attention is needed to investigate the different properties of SFN that can be tailored through different techniques and expected to have major role in the removal mechanism of CPs.

Biochar supported metallo-inorganic nanocomposite: A green approach for decontamination of heavy metals from water

Heavy metal contamination of water has become a global environmental burden, which has stirred up agitation worldwide. Fabrication of adsorbents utilizing either low cost, environment friendly materials or waste products can be helpful in remediating environmental pollution. The current study evolved around the synthesis of nanocomposites derived from such raw precursors like spent tea waste biochar, hydroxyapatite, and clays. In this context, two nanocomposites, namely manganese ferrite doped hydroxyapatite/kaolinite/biochar (TK-NC) and manganese ferrite doped hydroxyapatite/vermiculite/biochar (TV-NC), were synthesized followed by their employment for decontamination of heavy metals from aqueous media. TK-NC and TV-NC exhibited the crystallite sizes in the range of 2.55-5.94 nm as obtained by Debye Scherrer Equation and Williamsons-Hall equation The fabricated nanocomposites were characterized using FT-IR, SEM-EDX, and powder XRD. Batch adsorption studies were performed, and influence of different adsorption parameters (contact time, reaction temperature, solution pH, adsorbent dose, and initial adsorbate concentration) on metal adsorption was examined. Thermodynamic studies revealed that the adsorption of Cr(VI), Ni(II) and Cu(II) on TK-NC and TV-NC was endothermic (+ΔH°) and indicates disorderness (+ΔS°) at the solid-liquid interface owing to the strong affinity of metal ions with adsorbent. The heavy metal uptake selectivity followed the following decreasing order; Cr(VI) > Cu(II) > Ni(II) by both nanocomposites, with adsorption capacities falling in the range of 204.68-343.05 mg g-1. Several adsorption kinetic and isotherm models were applied to experimentally calculated data, which suggest favorable adsorption of Cr(VI), Ni(II) and Cu(II) by TK-NC and TV-NC from the system while obeying general-order kinetics and R-P adsorption model, conferring the transition in adsorption kinetics order and involvement of multiple adsorption process.

Effective removal of Ni(II) ions from its aqueous solution by utilizing Euphorbia thymifolia as an adsorbent

Since the electroplating and alloy industries continuously pollute water resources, this paper presents a novel adsorbent to adsorb nickel ions from aqueous solutions prepared in the lab. Chhotidudhi, a creeping weed that is commonly called Euphorbia thymifolia, was used as an adsorbent in its pristine and activated forms. In order to characterize the structure, morphology, and thermal properties of ground Euphorbia thymifolia (ETR) and activated Euphorbia thymifolia (ETA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA) were used. It was observed that the FTIR spectrum showed different functional groups, such as OH, CH, CO, CN, and CF, which indicated a strong bond with metals. XRD and SEM revealed that the adsorbent is amorphous with a porous structure. Additionally, different adsorbent doses, contact times, pH, concentrations, and temperatures were investigated. Approximately 2 h was required for effective adsorption with an initial concentration of 20 mg/L, pH 7, adsorption dose of 20 mg, and temperature of 303 K. At optimized conditions, the adsorption capacity for ETR and ETA was 52.4 mg/g and 109.05 mg/g, respectively, and the removal efficiency was 81.6% and 93.8%. Both Langmuir and pseudo-second-order reactions matched the experimental results perfectly.

Adsorption and separation of Cs(I) and Ba(II) from aqueous solution using zinc ferrite-humic acid nanocomposite

Reclaimable adsorbents have an essential role in removing radionuclides from waste streams. Herein, zinc ferrite-humic acid ZFO/HA nanocomposite was synthesized for effective cesium and barium adsorption. The prepared ZFO/HA nanocomposite was analyzed using analytical techniques including XRD, FTIR, EDX, and SEM. From kinetic studies, the mechanism adsorption process follows the second model. The isotherm studies clarified that the Langmuir model fit the adsorption of both ions onto the prepared sample, and the monolayer capacities are equal to 63.33 mg/g and 42.55 mg/g for Ba(II) and Cs(I), respectively. The temperature parameter was also studied, and the adsorption reaction was spontaneous and endothermic. The maximum separation between two ions was achieved at pH 5 (αCs/Ba = 3.3).

Application of magnesium ferrite nanomaterials for adsorptive removal of arsenic from water: Effects of Mg and Fe ratio

Magnesium ferrites (MgFe₂O₄) drew much attention in water treatment because of higher stability, magnetic properties, availability and higher safety. MgFe₂O₄ having different Fe and Mg ratios were synthesized through a simple one-step solvothermal method and applied for the removal of toxic arsenic oxyanions from water. Three different magnesium ferrites, MF_0.1, MF_0.2 and MF_0.33, were synthesized using molar Mg and Fe ratio of 10:90, 20:80 and 33:67, respectively. The Mg and Fe ratio affected the physical and magnetic properties, surface area, crystallite size, pore diameter and magnetism, of magnesium ferrites, which were evidenced by the XRD, SEM-EDS, BET and VSM. Increasing Mg content reduced the pore size, pore volume and saturation magnetization but increased surface area and pH_PZC. It was estimated that defective iron oxide, γ-Fe₂O₃ maghemite, had been formed with the magnesium ferrites, when the ratios of Mg and Fe were non-stoichiometric. The difference in characteristics of magnesium ferrites synthesized with three ratios of Mg and Fe affected arsenic adsorption capacity and the stability of adsorbed arsenic. Arsenic adsorption data followed Freundlich isotherm model and maximum As(III) and As(V) adsorption capacities were found to be 51.48, 100.53, 103.94 mg/g and 26.06, 43.44, 45.52 mg/g by MF_0.1, MF_0.2 and MF_0.33, respectively. Fast adsorption of arsenic was confirmed by kinetic data which followed the Pseudo-2nd-order kinetic model. The MF_0.33 having stoichiometric ratio of Mg and Fe showed higher adsorption capacity and stability for arsenic than the other two at neutral pH.

Synthesis of a Novel Adsorbent Based on Chitosan Magnetite Nanoparticles for the High Sorption of Cr (VI) Ions: A Study of Photocatalysis and Recovery on Tannery Effluents

This study aims to evaluate the functionalization of chitosan biopolymer with heterocyclic moieties of 2-thioxodihydropyrimidine-4,6(1H,5H)-dione used for enhancing the sorption of Cr ions from aqueous solution. A synthesized sorbent is a nanoscale particle (around 5–7 nm), which explains the fast kinetics of sorption. The sorbent is specified using elemental analysis (EA), FTIR, BET (nitrogen sorption desorption isotherms), TGA, and SEM-EDX analyses. Sorption properties are investigated using ultraviolet emission (UV) but also using visible light (L). In the sorption diagram, the high sorption uptake and fast kinetics observed using ultraviolet conditions are shown. This work is conducted by removing Cr ions from highly contaminated tannery effluents, which have a high concentration of Cr associated with other poisonous elements such as Cd(II) and Pb(II). Under the selected conditions, complete sorption is performed during the first 60 and 45 min with a capacity of 2.05 and 2.5 mmol Cr g−1 for the crosslinked chitosan (without functionalization) in L and UV, respectively. This sorption is enhanced by functionalizing to 5.7 and 6.8 mmol Cr g−1 at the L and UV, respectively, as well as improving the sorption kinetics to 35 and 30 min for both techniques, respectively. The PFORE, and (Langmuir and Sips equations) fit the kinetics and isotherms, respectively.

Zinc ferrite nanoparticles from industrial waste for Se (IV) elimination from wastewater

The presence of high concentrations of selenium ions in wastewater is considered an environmental problem. However, the mechanism of selenium ions (Se (IV)) removal by the adsorption process has not been investigated in-depth so far. Also, the recovery and conversion of the industrial waste materials into valuable materials is a vital issue. Therefore, in this study, zinc ferrite nanopowders are economically synthesized from steel-making wastes by co-precipitation method for investigating as adsorbents of selenium species. The produced nanopowders were annealed at 150, 300, 500, and 850 °C for 5 h to scrutinize the impact of annealing temperature on their crystallite size. The compositional, optical, and magnetic features of the nanopowders were defined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), UV-Vis. spectrophotometer along with vibrating sample magnetometer (VSM). Optical absorbance spectra were found characteristic due to the electronic structure of Fe³⁺ (3d⁵) considering the C_3v local symmetry of Fe³⁺ ions. The prepared nanopowders demonstrated good adsorption capacity toward selenium ions (43.67 mg/g at pH 2.5) from an aqueous medium. Adsorption data were found fitting to Freundlich isotherm model. Thus, ZnFe₂O₄ can be recommended to effectively eliminate selenium ions from aqueous solutions.

Facile Synthesis of Fe(0)@Activated Carbon Material as an Active Adsorbent towards the Removal of Cr (VI) from Aqueous Media

A novel adsorbent substrate based on zero-valent iron in activated carbon (Fe(0)@AC) was introduced in this work, and was evaluated as a cheap adsorbent for the removal of Cr(VI) from aqueous solutions. The as-prepared Fe(0)@AC material was chemically prepared via NaBH4 reduction in the presence of ferric chloride as an iron source, followed by the addition of powdered activated carbon. The different physicochemical tools confirm the successful preparation of Fe(0) composite with activated carbon as a heterogeneous composite with heterogeneous morphology of the rock-shape structure, which could play a role in the metal adsorption application. Interestingly, the removal efficiency (RE) of Cr(VI) was increased from 52% to 84% due to the Fe(0)@AC adsorbent being changed from 0.2 to 0.4 g/100 mL. Following this, the increase rate was stabilized, and the RE reached 95% in the case of 0.8 g/100 mL from Fe(0)@AC adsorbent. This result could be due to the increase in the sorbent active sites with more contents from Fe(0)@AC. The adsorption model based on the Langmuir approach could successfully describe the experimental outcomes for Cr(VI) removal by Fe(0)@AC with the correlation coefficient of 0.977. To conclude, Fe(0)@AC heterogeneous material is an active adsorbent for Cr(VI) removal from aqueous solutions.

Magnetic Nanoparticles as Effective Heavy Ion Adsorbers in Natural Samples

This paper refers to research based on tests completed on the adsorption of heavy metal ions (Pb²⁺, Cu²⁺, Cd²⁺) from selected natural liquid samples such as apple, tomato, and potato juices using surface-functionalized Mn ferrite nanoparticles (Mn_0.2Fe_2.8O₄). To determine the most efficient adsorption conditions of these heavy metals, the nanoparticles' surfaces were modified with five different ligands (phthalic anhydride, succinic anhydride, acetic anhydride, 3-phosphonopropionic acid, and 16-phosphonohexadecanoic acid). To evaluate the success of the adsorption process, the resultant liquid samples were examined for the amount of residuals using the flame atomic absorption spectroscopy method. The Mn ferrite particles selected for these tests were first characterized physicochemically by the following methods: transmission electron microscopy, scanning electron microscopy, X-ray diffraction, IR spectroscopy, Mössbauer spectroscopy.

Production of polyacrylonitrile/ionic covalent organic framework hybrid nanofibers for effective removal of chromium(VI) from water

Hexavalent Cr(VI) found in industrial wastewater is a proven carcinogen which causes serious health issues in humans around the world. This study presents a novel method to enhance the Cr(VI) oxyanion removal from wastewater by polyacrylonitrile (PAN) nanofibers through incorporation of a guanidinium-based ionic covalent organic framework (BT-DG) in the nanofibers structure. Simple electrospinning technique was employed to produce PAN nanofibers and BT-DG was synthesized through condensation between benzene-1,3,5-tricarbaldehyde and N,N'-diaminoguanidine monohydrochloride. In-situ polymerization of BT-DG onto PAN nanofibers resulted in generation of hybrid PAN-BT-DG nanofibers. This modified PAN-BT-DG was characterized by obtaining its point of zero charge (PZC), differential scanning calorimeter (DSC), scanning electron microscopy (SEM) morphology and surface elements and oxidation states by X-ray photoelectron spectroscopy (XPS). PAN-BT-DG exhibited positive surface charge below pH 4, making it an outstanding adsorbent, for Cr(VI) removal. Cr(VI) adsorption onto PAN-BT-DG followed pseudo second order kinetics and adsorption data fitted well to Freundlich isotherm model. Highest Cr(VI) removal was obtained at 55 ℃ with a maximum Langmuir adsorption capacity of 173 mg/g at pH 3. Kinetic studies revealed that Cr(VI) adsorption onto PAN-BT-DG is endothermic and thermodynamically feasible. Desorption studies were conducted on PAN-BT-DG using 1 M NaOH as the stripping solvent and PAN-BT-DG exhibited excellent regeneration after five consecutive cycles.

Adsorptive removal of pollutants from water using magnesium ferrite nanoadsorbent: a promising future material for water purification

Nanoadsorbents having large specific surface area, high pore volume with tunable pore size, affordability and easy magnetic separation gained much popularity in recent time. Iron-based nanoadsorbents showed higher adsorption capacity for different pollutant removal from water among other periodic elements. Spinel ferrite nanomaterials among iron-bearing adsorbent class performed better than single iron oxide and hydroxides due to their large surface area, mesoporous pore, high pore volume and stability. This work aimed at focusing on water treatment using magnesium ferrite (MgFe₂O₄) nanomaterials. Synthesis routes, properties and pollutant adsorption were critically investigated to explore the performance of magnesium ferrite in water treatment. Structural and surface properties were greatly affected by the factors involved in different synthesis routes and iron and magnesium ratio. Complete removal of pollutants through adsorption was achieved using magnesium ferrite. Pollutant adsorption capacity of MgFe₂O₄ and its modified forms was found several folds higher than Fe₂O₃ and Fe₃O₄ nanomaterials. In addition, MgFe₂O₄ showed strong stability in water than other pure iron oxide and hydroxide. Modification with graphene oxide, activated carbon, biochar and silica was demonstrated to be beneficial for enhanced adsorption capacity. Complex formation was suggested as a dominant mechanism for pollutant adsorption. These nanomaterials could be a viable and competitive adsorbent for diverse pollutant removal from water.

Engineered magnetic oxides nanoparticles as efficient sorbents for wastewater remediation: a review

The rapid urbanization and industrialization is causing worldwide water pollution, calling for advanced cleaning methods. For instance, pollutant adsorption on magnetic oxides is efficient and very practical due to the easy separation from solutions by an magnetic field. Here we review the synthesis and performance of magnetic oxides such as iron oxides, spinel ferrites, and perovskite oxides for water remediation. We present structural, optical, and magnetic properties. Magnetic oxides are also promising photocatalysts for the degradation of organic pollutants. Antimicrobial activities and adsorption of heavy metals and radionucleides are also discussed.

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods

The remediation of water streams, polluted by various substances, is important for realizing a sustainable future. Magnetic adsorbents are promising materials for wastewater treatment. Although numerous techniques have been developed for the preparation of magnetic adsorbents, with effective adsorption performance, reviews that focus on the synthesis methods of magnetic adsorbents for wastewater treatment and their material structures have not been reported. In this review, advancements in the synthesis methods of magnetic adsorbents for the removal of substances from water streams has been comprehensively summarized and discussed. Generally, the synthesis methods are categorized into five groups, as follows: direct use of magnetic particles as adsorbents, attachment of pre-prepared adsorbents and pre-prepared magnetic particles, synthesis of magnetic particles on pre-prepared adsorbents, synthesis of adsorbents on preprepared magnetic particles, and co-synthesis of adsorbents and magnetic particles. The main improvements in the advanced methods involved making the conventional synthesis a less energy intensive, more efficient, and simpler process, while maintaining or increasing the adsorption performance. The key challenges, such as the enhancement of the adsorption performance of materials and the design of sophisticated material structures, are discussed as well.

Preparation of molecularly imprinted resin/polydopamine nanofibers mat for the highly efficient extraction and determination of sulfonamides in environmental water

With polyacrylonitrile nanofibers mat (PAN NFsM) as a template, molecularly imprinted resin/polydopamine nanofibers mat (MIR/PDA NFsM) was synthesized for the extraction of sulfonamides (SAs) in water. The specific surface area and pore volume were increased obviously due to the functionalization of MIR. The adsorption efficiencies of MIR/PDA NFsM under optimized conditions for SAs were 92.3-99.3%. Possible adsorption mechanisms of imprinting recognition and hydrogen bond interactions were also put forward. Compared with MIR particles, the MIR/PDA NFsM exhibited much superior adsorption performance. Particularly, the outstanding mass transfer efficiency of MIR/PDA NFsM was much higher than the other reported adsorbents for SAs. Finally, a new method based on the solid-phase extraction (SPE) of MIR/PDA NFsM was successfully developed for the detection of five SAs in environmental water with HPLC-MS/MS and applied to the analysis of actual samples. Under the selected conditions, the enrichment factors of MIR/PDA NFsM of SCP, SMT, SMZ, SMR, and SMX were between 23.0 and 25.0. Low detection limits (0.26-0.76 ng L^-1), broad linear range (1.0 ng L^-1 to 10.0 μg L^-1), and satisfactory recoveries (82.8-115.6%) and precisions (RSDs < 7.2%) were obtained. Moreover, the excellent reusability properties and storage stability endowed MIR/PDA NFsM with great value for practical applications.

Green Synthesis of Metal and Metal Oxide Nanoparticles: Principles of Green Chemistry and Raw Materials

Increased request for metal and metal oxide nanoparticles nanoparticles has led to their large-scale production using high-energy methods with various toxic solvents. This cause environmental contamination, thus eco-friendly “green” synthesis methods has become necessary. An alternative way to synthesize metal nanoparticles includes using bioresources, such as plants and plant products, bacteria, fungi, yeast, algae, etc. “Green” synthesis has low toxicity, is safe for human health and environment compared to other methods, meaning it is the best approach for obtaining metal and metal oxide nanoparticles. This review reveals 12 principles of “green” chemistry and examples of biological components suitable for “green” synthesis, as well as modern scientific research of eco-friendly synthesis methods of magnetic and metal nanoparticles. Particularly, using extracts of green tea, fruits, roots, leaves, etc., to obtain Fe3O4 NPs. The various precursors as egg white (albumen), leaf and fruit extracts, etc., can be used for the „green” synthesis of spinel magnetic NPs. “Green” nanoparticles are being widely used as antimicrobials, photocatalysts and adsorbents. “Green” magnetic nanoparticles demonstrate low toxicity and high biocompatibility, which allows for their biomedical application, especially for targeted drug delivery, contrast imaging and magnetic hyperthermia applications. The synthesis of silver, gold, platinum and palladium nanoparticles using extracts from fungi, red algae, fruits, etc., has been described.

The Influence of Li+ and K+ Added Cations and Annealing Temperature on the Magnetic and Dielectric Properties of Mg-Zn Ferrite

This paper presents the results of an investigation on the magnetic and dielectric properties of Mg_0.5Zn_0.5Fe₂O₄ spinel ferrite with a 1% weight percentage of Li⁺ and K⁺ added cations. The addition of metal ions plays an important role in increasing the porosity and favors the formation of ferrite at low temperatures. The goal of this new research is to demonstrate that by selecting the type of metallic cations for addition or choosing an optimal sintering temperature, it may be possible to improve the magnetic and electrical properties of Mg-Zn ferrite. The samples were prepared using sol-gel self-combustion techniques and annealed at 1000 °C, 1100 °C, and 1200 °C. Scanning electron microscopy revealed the shape and grain size of the samples, and the phase composition was analyzed using the X-ray diffraction technique. The magnetic information, such as remanent magnetization M_R, saturation magnetization M_S, and coercivity H_C, were extracted from the hysteresis loops of the samples. The electrical investigation was focused on the low- and high-frequency dependence of dielectric constant and dielectric losses. The results are discussed in terms of microstructural changes induced by the additions of Li⁺ and K⁺ metallic cations. Conclusions are drawn concerning the optimization of magnetic and electrical properties for the development of Mg-Zn ferrite with possible applications in the field of magnetic materials or electronics.

Magnetic nanoadsorbents for micropollutant removal in real water treatment: a review

Pure water will become a golden resource in the context of the rising pollution, climate change and the recycling economy, calling for advanced purification methods such as the use of nanostructured adsorbents. However, coming up with an ideal nanoadsorbent for micropollutant removal is a real challenge because nanoadsorbents, which demonstrate very good performances at laboratory scale, do not necessarily have suitable properties in in full-scale water purification and wastewater treatment systems. Here, magnetic nanoadsorbents appear promising because they can be easily separated from the slurry phase into a denser sludge phase by applying a magnetic field. Yet, there are only few examples of large-scale use of magnetic adsorbents for water purification and wastewater treatment. Here, we review magnetic nanoadsorbents for the removal of micropollutants, and we explain the integration of magnetic separation in the existing treatment plants. We found that the use of magnetic nanoadsorbents is an effective option in water treatment, but lacks maturity in full-scale water treatment facilities. The concentrations of magnetic nanoadsorbents in final effluents can be controlled by using magnetic separation, thus minimizing the ecotoxicicological impact. Academia and the water industry should better collaborate to integrate magnetic separation in full-scale water purification and wastewater treatment plants.