Application of spinel ferrite nanoparticles in water and wastewater treatment: A review

Ponceau 4R elimination from fruit juice: An integrated optimization strategy utilizing artificial neural networks, least squares, and chitosan-nickel ferrite Nano Sorbent

The goal of present work is to examine the efficiency of aminated-chitosan/NiFe2O4 nanoparticles (AmCs/NiFe2O4 NPs) produced for removing Ponceau 4R (P4R) from fruit juice through an adsorption process. The resulting nanoparticles were characterized using various techniques. The modeling of results was done using least squares (LS) and Radial basis function-artificial neural network (RBF-ANN). The optimum removal of P4R (91.43 %) was obtained at the following optimum conditions: pH 4.47, adsorbent dosage 0.047 g/L, contact time approximately 57.78 min, and initial concentration P4R 26.89 mg/L. The highest adsorption capacity (qm) was found to be 208.33 mg g-1. The P4R adsorption mostly followed the Freundlich and pseudo-second-order isotherm kinetic models. Both LS-based models and RBF-ANN provided good predictions for independent variables. The dye elimination efficacy for juice samples were approximately 90.34 %. Therefore, based on the obtained results, it can be claimed that the prepared AmCs/NiFe2O4 NPs can be used to remove P4R.

Insight in sulfadiazine degradation by peroxymonosulfate activated by polydopamine-derived nitrogen-doped carbon supported CoFe2O4: Co leaching inhibition and degradation enhancement

Heterogeneous catalyst-mediated sulfate radical-based advanced oxidation processes (SR-AOPs) showed excellent performance during antibiotics degradation. Spinel was a promising catalyst for SR-AOPs, but the secondary contamination due to metal ions leaching needed to be addressed. And the destruction of catalyst structure could lead to the reduction of catalytic activity and the difficulty of recovery. Thus, a novel nitrogen-doped carbon (NC)-supported CoFe2O4 (CoFe2O4@NC) was synthesized as the activator of PMS for sulfadiazine (SDZ) degradation under low Co leaching conditions. The consequences indicated that the CoFe2O4@NC/PMS system exhibited higher PMS decomposition efficiency and reaction stoichiometry efficiency than the bare CoFe2O4/PMS systems (CoFe2O4-180 and CoFe2O4-800), which in turn demonstrated a better SDZ removal performance. Under the condition of CoFe2O4@NC dosage 0.1 g/L, PMS concentration 0.5 mM, solution pH 6.8 and temperature 25°C, SDZ (20 mg/L) was almost completely degraded within 60 min. XPS analysis showed that the NC not only protected and stabilized CoFe2O4, but also provided additional active sites for PMS activation. During SDZ degradation, SO4•-, HO•, •O2- and 1O2 were involved in the reaction, among which SO4• and HO• made the main contribution. Meanwhile, CoFe2O4@NC could be recovered by magnetic separation, and showed great stability (Co leaching 0.852 mg/L) and reusability. In the fifth cycle experiment, 85.02 % SDZ degradation was obtained. Based on the detected intermediates (12 intermediates were identified) and DFT calculations, possible degradation pathways for SDZ in CoFe2O4@NC/PMS were proposed. The condensed dual descriptor indicated that the N7, N11, and C15 atoms on SDZ molecule were the main sites of electrophilic attack, which was consistent with the detected intermediates. The degradation of SDZ involved hydroxylation of NH2, cleavage of S-N and extrusion of SO2. This study explored the improvements made in NC support material to catalytic performance and resistance to dissolution of spinel, providing new insights for subsequent researches.

Cuprospinel decorated biopolymer functionalized CNFs based electrocatalytic platform integrated with grid search optimized neural network for detection of vital amino acid in beverages

An electrocatalytic platform based on a novel nanocomposite integrated with a grid search-optimized neural network (GSNN) was proposed for intelligent sensing of tryptophan. The cuprospinel-decorated chitosan-functionalized carbon nanofibers (CuFe2O4/Chit-CNFs) fabricated on a disposable electrode revealed exceptional electrocatalytic activity with a low detection limit (2 nM) and good sensitivity (79.18 μAμM-1 cm-2) over a broad linear range (0.05-152.55 μM). Cyclic voltammetry and differential pulse voltammetry were employed, and the sensing mechanism of tryptophan entails its electrocatalytic oxidation, where the synergistic impact of CuFe2O4 and Chit-CNFs boosts electrochemical response owing to their high surface area and conductivity. GSNN-based intelligent sensing returned a root mean square error (RMSE) of 2.76 and a mean absolute error (MAE) of 1.12. Moreover, the sensor's performance was tested on samples from apple juice, tomato juice, pineapple juice, and milk for assessing practicality, demonstrating recovery between 96.93 and 101.06 % and maximum relative standard deviation of 2.63 %. The proposed sensor showcased excellent selectivity, repeatability, reproducibility, and stability.

Hazardous effects of nickel ferrite nanoparticles and nickel chloride in early life stages of the freshwater snail Biomphalaria glabrata (Say, 1818)

Nickel ferrite nanoparticles (NiF NPs) have growing applications in biomedical and nanomedicine fields. However, knowledge concerning their ecotoxicity during the early developmental stages of invertebrates, such as gastropods, remains scarce. Thus, the current study aimed to evaluate whether NiF NPs and nickel chloride (NiCl2) induce toxic effects on embryos and newly hatched snails of freshwater species Biomphalaria glabrata (Say, 1818). NiF NPs were synthesized and characterized by multiple techniques, and their ecotoxicity was assessed by Biomphalaria embryotoxicity test (BET) during 144 h of exposure and an acute toxicity test (96 h) using newly hatched snails. NiF NPs induced mortality, developmental delay, reduced hatching rate, and promoted morphological changes in B. glabrata. Also, NiF NPs induced higher toxicity in embryos than in newly hatched B. glabrata. Overall, results showed that the early developmental stages of gastropods are a target group for nanoparticle toxicity in freshwater ecosystems.

Recent developments in the bio-mediated synthesis of CoFe2O4 nanoparticles using plant extracts for environmental and biomedical applications

Conventional methods for the synthesis of nanoparticles often involve toxic chemicals, exacerbating environmental issues in the context of climate change and water scarcity. Green synthesis using plant extracts offers a sustainable and viable alternative for CoFe2O4 nanoparticle production, but understanding the mechanisms and applications of this method is challenging. Here, we review the synthesis and applications of CoFe2O4 nanoparticles using plant extracts with emphasis on biomedical activity and water treatment. Plant extract-mediated CoFe2O4 nanoparticles exhibit high surface area, small particle size, unique morphology, sufficient band gap energy, and high saturation magnetization. These nanoparticles demonstrate strong antimicrobial and anticancer activities, highlighting their potential in biomedical treatments. Green CoFe2O4 are effective in removing organic dyes, heavy metals, and pharmaceuticals from water, promoting cleaner water resources. Challenges such as scalability and reproducibility still remain, but ongoing research aims to optimize synthesis protocols and explore new applications. This work underscores the importance of sustainable nanotechnology in addressing environmental challenges.

The recent advances of MnFe2O4-based nanoparticles in environmental application: A review

The manganese ferrite (MnFe2O4)-based nanoparticles showed a substantial potential to remediate the various pollutants in environmental application due to low cost, simple magnetic separation and high removal capacity. Herein, the functionalization of various MnFe2O4-based nanoparticles was briefly summarized; Then the recent advances concerning the removal of pollutants (i.e., organics, heavy metals and antibacterial activity) on different MnFe2O4-based nanoparticles were reviewed in details. The reactivity of MnFe2O4-based nanoparticles was significantly influenced by environmental factors. It is demonstrated that interaction mechanism of various pollutants on magnetic MnFe2O4-based nanoparticles included degradation, adsorption, coordination, redox and precipitation. Finally, the current problems and future perspective of MnFe2O4-based nanoparticles were proposed. The highlight of this review is to compare the removal performance of MnFe2O4-based nanoparticles with the different hybrids. This review is crucial for the application of MnFe2O4-based nanoparticles in the environmental remediation.

Effect of solvothermal synthesis parameters on the crystallite size and atomic structure of cobalt iron oxide nanoparticles

We here investigate how the synthesis method affects the crystallite size and atomic structure of cobalt iron oxide nanoparticles. By using a simple solvothermal method, we first synthesized cobalt ferrite nanoparticles of ca. 2 and 7 nm, characterized by Transmission Electron Microscopy (TEM), Small Angle X-ray scattering (SAXS), X-ray and neutron total scattering. The smallest particle size corresponds to only a few spinel unit cells. Nevertheless, Pair Distribution Function (PDF) analysis of X-ray and neutron total scattering data shows that the atomic structure, even in the smallest nanoparticles, is well described by the spinel structure, although with significant disorder and a contraction of the unit cell parameter. These effects can be explained by the surface oxidation of the small nanoparticles, which is confirmed by X-ray near edge absorption spectroscopy (XANES). Neutron total scattering data and PDF analysis reveal a higher degree of inversion in the spinel structure of the smallest nanoparticles. Neutron total scattering data also allow magnetic PDF (mPDF) analysis, which shows that the ferrimagnetic domains correspond to ca. 80% of the crystallite size in the larger particles. A similar but less well-defined magnetic ordering was observed for the smallest nanoparticles. Finally, we used a co-precipitation synthesis method at room temperature to synthesize ferrite nanoparticles similar in size to the smallest crystallites synthesized by the solvothermal method. Structural analysis with PDF demonstrates that the ferrite nanoparticles synthesized via this method exhibit a significantly more defective structure compared to those synthesized via a solvothermal method.

Recent trends in magnetic spinel ferrites and their composites as heterogeneous Fenton-like catalysts: A review

In recent years, there has been a growing interest in utilizing spinel ferrite and their nanocomposites as Fenton-like catalysts. The use of these materials offers numerous advantages, including ability to efficiently degrade pollutants and potential for long-term and repeated use facilitated by their magnetic properties that make them easily recoverable. The remarkable catalytic properties, stability, and reusability of these materials make them highly attractive for researchers. This paper encompasses a comprehensive review of various aspects related to the Fenton process and the utilization of spinel ferrite and their composites in catalytic applications. Firstly, it provides an overview of the background, principles, mechanisms, and key parameters governing the Fenton reaction, along with the role of physical field assistance in enhancing the process. Secondly, it delves into the advantages and mechanisms of H2O2 activation induced by different spinel ferrite and their composites for the removal of organic pollutants, shedding light on their efficacy in environmental remediation. Thirdly, the paper explores the application of these materials in various Fenton-like processes, including Fenon-like, photo-Fenton-like, sono-Fenton-like, and electro-Fenton-like, for the effective removal of different types of contaminants. Furthermore, it addresses important considerations such as the toxicity, recovery, and reuse of these materials. Finally, the paper presents the challenges associated with H2O2 activation by these materials, along with proposed directions for future improvements.

Shining light on environmental remediation: a type-II heterojunction MnFe2O4/rGO nanocomposites for enhanced photocatalytic degradation of organic dyes and bisphenol A

In this study, the pressing issue of persistent organic pollutants in wastewater was addressed by designing and fabricating a magnetically separable MnFe2O4/rGO heterostructure catalyst for efficient mineralization of bisphenol A (BPA) and dyes such as alizarin red S (anionic) and malachite green (cationic), which are known for their resistance to biodegradation and carcinogenic properties. Comprehensive structural and surface analyses using XRD, XPS, SEM, and TEM/HRTEM coupled with magnetic and optical property measurements revealed the formation of the MnFe2O4/rGO heterostructures. Among all, the MnFe2O4/rGO-10 catalyst with 10% wt% of rGO exhibited 100% efficiency in the mineralization of BPA and both dyes under visible light illumination within 60 min. The stability and recyclability of the catalyst, assessed through XRD and VSM studies, demonstrated its consistent performance over multiple uses. The cost-effectiveness and stability of this catalyst underscore its potential for practical application in wastewater treatment, offering a viable solution to the persistent challenge of removing stubborn organic contaminants.

Green synthesis of calcium nanoferrites using leaf extract of Brassica oleracea for photocatalysis of malachite green dye

The calcium ferrite nanoparticles were made by the sol-gel process. X-ray diffraction, a scanning electron microscope, and UV-vis spectroscopy were used to analyze the material. There is an orthorhombic phase in the space group Pnma. There were four techniques used to calculate the average crystallite size. Using ImageJ software, the particles were aggregated and their size was ascertained. Using energy-dispersive X-ray (EDX) analysis, the composition of the material was ascertained. 2.29 eV was determined to be the band gap. Vibrating test magnetometer (VSM) provided an explanation for the materials' magnetic property. A decreased band gap energy is responsible for the 90% degradation of malachite green dye at a concentration of 15 mg/L in 150 min, with a four-cycle reusability.

Rational Design of Mesoporous ZnFe2O4@g-C3N4 Heterojunctions for Environmental Remediation and Hydrogen Evolution

Mesoporous catalysts with a high specific surface area, accessible pore structures, and appropriate band edges are desirable for optimal charge transfer across the interfaces, suppress electron-hole recombination, and promote redox reactions at the active sites. The present study demonstrates the rational design of mesoporous ZnFe2O4@g-C3N4 magnetic nanocomposites (MNCs) with different pore sizes and pore volumes following a combination of facile thermal itching and thermal impregnation methods. The MNCs preserve the structural, morphological, and physical attributes of their counterparts while ensuring their effectiveness and superior catalytic capabilities. The morphological analysis confirms the successful grafting and confinement of ZnFe2O4 nanoparticles with the polymeric g-C3N4 nanosheets to form heterojunctions with numerous interfaces. The MNCs possess uniformly distributed small mesopores (pore size <4 nm), ample active sites, and a high specific surface area of 62.50 m2/g. The mesoporous ZnFe2O4@g-C3N4 notably improve hydrogen evolution rate and methylene blue dye degradation. The optimal loading weight of ZnFe2O4 is 20 %, in which the MNCs display the highest hydrogen evolution rate of 1752 μmol g-1 h-1 and photo-Fenton dye degradation rate constants of 0.147 min-1, upon solar-light illumination. Furthermore, the photocatalysts demonstrate recyclability over five consecutive cycles, confirming their stability, while easy separation using a simple magnet underscores practical utility.

Design of silver-zinc-nickel spinel-ferrite mesoporous silica as a powerful and simply separable adsorbent for some textile dye removal

Silver-zinc-nickel spinel ferrite was prepared by the co-precipitation procedure with the precise composition Ag0.1Zn0.4Ni0.5Fe2O4 for bolstering pollutant removal effectiveness while upholding magnetic properties and then coated with a mesoporous silica layer. The surface characteristics and composition of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 were confirmed using EDX, FT-IR, VSM, XRD, TEM, SEM, and BET methods. The surface modification of Ag-Zn-Ni ferrite with a silica layer improves the texture properties, where the specific surface area and average pore size of the spinel ferrite rose to 180 m2/g and 3.15 nm, respectively. The prepared spinel ferrite@mSiO2 has been utilized as an efficient adsorbent for eliminating methyl green (MG) and indigo carmine (IC) as models of cationic and anionic dyes from wastewater, respectively. Studying pH, Pzc, adsorbent dosage, dye concentration, and temperature showed that efficient removal of MG was carried out in alkaline media (pH = 12), while the acid medium (pH = 2) was effective for IC removal. Langmuir isotherm and pseudo-second-order kinetics were found to be good fits for the adsorption data. Both dyes were adsorbed in a spontaneous, endothermic process. A possible mechanism for dye removal has been proposed. The adsorbent was effectively recovered and reused.

Enhanced Cr(VI) elimination from water by goethite-impregnated activated carbon coupled with weak electric field

A weak electric field (WEF, 2 mA cm-2) was employed to promote Fe(III)/Fe(II) cycle on goethite-impregnated activated carbon (FeOOH@AC) filled in a continuous-flow column for enhanced Cr(VI) elimination from water. Surficial analysis and Cr species distribution showed that α-FeOOH of 0.2-1 μm was successfully synthesized and evenly loaded onto AC. Electron transfer from WEF to α-FeOOH was facilitated with AC as electron shuttles, thereby boosting Fe(III) reduction in the α-FeOOH. The generated Fe(II) reduced Cr(VI) and the resultant Cr(III) subsequently precipitated with OH- and Fe(III) to form Cr(OH)3 and (CrχFe1-χ)(OH)3. Therefore, the WEF-FeOOH@AC column exhibited a much lower Cr(VI) migration rate of 0.0018 cm PV-1 in comparison with 0.0037 cm PV-1 of the FeOOH@AC column, equal to 104 % higher Cr(VI) elimination capacity and 90 % longer column service life-span. Additionally, under different Cr(VI) loadings by varying either seepage velocities or influent Cr(VI) concentrations, the WEF-FeOOH@AC column maintained 1.0-1.5 folds higher Cr(VI) elimination and 0.9-1.4 folds longer longevity than those of the FeOOH@AC column owing to the interaction between FeOOH@AC and WEF. Our research demonstrated that WEF-FeOOH@AC was a potential method to promote Cr(VI) elimination from water and offer an effective strategy to facilitate Fe(III)/Fe(II) cycle in iron oxides.

Construction of a novel ternary synergistic CuFe2O4-SnO2-rGO heterojunction for efficient removal of cyanide from contaminated water

Many industrial effluents release cyanide, a well-known hazardous and bio-recalcitrant pollutant, and thus, the treatment of cyanide wastewater is a major challenge. In the current study, a CuFe2O4-SnO2-rGO nanocomposite was synthesized to remove cyanide from an aqueous system. The structural and morphological characterizations of the nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectra (EDX) analysis. The results revealed that almost 97.7% cyanide removal occurred using the nanocomposite at an initial concentration of 100 mg L-1 within 1 h. The experimental data were fitted to various adsorption models, among which the Langmuir model fitted the data very well, confirming the monolayer adsorption process. The kinetic investigation revealed that the cyanide adsorption process followed a pseudo-second-order kinetic model, indicating a chemisorption process with a high cyanide adsorption capacity of 114 mg g-1. The result of the intraparticulate diffusion model fitting revealed a decreasing slope value (K) from stage 1 to stage 2, indicating that external mass transfer is the predominating step. Moreover, the CuFe2O4-SnO2-rGO nanocomposite shows excellent reusability.

Removal of chromium(III) from contaminated waters using cobalt ferrite: how safe is remediated water to aquatic wildlife?

The release of hazardous elements by industrial effluents to aquatic ecosystems is a potential threat to the environment. Chromium (Cr) is one of the elements whose levels in several freshwater ecosystems should be reduced to promote water reuse. In recent years, magnetic materials have gained increasing interest as sorbents because of their easy removal from treated water through magnetic separation. In this study, colloidal cobalt ferrite (CoFe2O4) particles were investigated as magnetic sorbents for chromium-aqueous chemical species. The oxidative stress responses of Mytilus galloprovincialis mussels exposed to 200 μg/L of Cr, resembling remediated water, were evaluated. More than 95% of Cr was removed from contaminated solutions by CoFe2O4 aqueous suspensions at pH 6 and pH 10. The kinetics of sorption experiments were examined using pseudo-1st order, pseudo-2nd order and Elovich models to evaluate which mathematical model has a better adjustment to the experimental data. The present study revealed that the levels of Cr that remained in remediated water induced limited biochemical changes in mussels, being considered safe for aquatic systems. Overall, the use of cobalt ferrite-based sorbents may constitute a promising approach to remediate contaminated water.

Hybrid magnetic CoFe2O4@γ-Fe2O3@CTAB nanocomposites as efficient and reusable adsorbents for Remazol Brilliant Blue R dye

The main goal of the present survey was to elaborate, characterize and evaluate the efficiency of ferrite-based nanoparticles modified with cetyltrimethylammonium bromide (CTAB) as potential magnetic nanoadsorbents to remove Remazol Brilliant Blue R (RBBR) from water. It is proposed an innovative nanomaterial architecture based on highly magnetic and chemically stable core@shell nanoparticles covered by an adsorptive surface layer of CTAB (CoFe2O4@γ-Fe2O3@CTAB). Samples of two different mean sizes (7.5 and 14.6 nm) were synthesized using a hydrothermal coprecipitation followed by surface treatment and functionalization. Batch tests were performed to evaluate the influence of contact time, temperature, pH, shaking rate, presence of interferents and mean size on the performance of the proposed nanomaterials. The kinetics of the adsorption process followed the pseudo-second-order model with an equilibrium time of 20 min. The adsorption capacity was estimated by the Langmuir isotherm model and was found to be 56.3 mg/g (smaller size) and 45.6 mg/g (larger size) at pH = 3 and a shaking rate of 400 rpm. The process was spontaneous, exothermic, and showed increased randomness. Sulphate ions negatively impacted the removal of RBBR. The best performance of the nanoadsorbent based on smaller mean sizes can be correlated to its larger surface area. Regeneration and readsorption tests showed that the nanoadsorbents retain more than 80% of their original removal capacity, therefore they can be effectively recycled and reused.

Unraveling the multifaceted mechanisms and untapped potential of activated carbon in remediation of emerging pollutants: A comprehensive review and critical appraisal of advanced techniques

The rapid global expansion of industrialization has resulted in the discharge of a diverse range of hazardous contaminants into the ecosystem, leading to extensive environmental contamination and posing a pressing ecological concern. In this context, activated carbon (AC) has emerged as a highly promising adsorbent, offering significant advantages over conventional forms. For instance, AC has demonstrated remarkable adsorption capabilities, as evidenced by the successful removal of atrazine and ibuprofen using KOH and KOH-CO2-activated char, achieving impressive adsorption rates of 90% and 95%, respectively, at an initial dosage of 10 mg L-1. Moreover, AC can effectively adsorb aromatic compounds through π-π stacking interactions. The aromatic rings in organic molecules can align and interact with the carbon atoms in AC's structure, leading to effective adsorption. In this review, by employing a systematic analysis of recent research findings (majorly from 2015 to 2023), an in-depth exploration of AC's evolution and its wide-ranging applications in adsorbing and remediating emerging pollutants, including dyes, organic contaminants, and hazardous gases and mitigating the adverse impacts of such emerging pollutants on ecosystems have been discussed. It serves as a valuable resource for researchers, professionals, and policymakers involved in environmental remediation and pollution control, facilitating the development of sustainable and effective strategies for mitigating the global impact of emerging pollutants.

Synthesis, structural, magnetic property, and Cd(II) adsorption behavior of Ca-substituted MgFe2O4 nanomaterials in aqueous solutions

In the present study, magnetic nanomaterials (Mg1-xCaxFe2O4, 0.0 ≤ x ≤ 0.8) were prepared via a simple sol-gel method. The samples were characterized using XRD, TEM, SEM, EDX, FTIR, BET, and VSM. The structural and magnetic properties of prepared nanomaterials (NMs) were investigated, and the adsorption capacity of Cd2+ from aqueous solution was evaluated via flame atomic absorption spectroscopy (AAS). The impact of several factors on Cd2+ adsorption such as contact time (1-60 min), pH (3-8), dose (0.003-0.03 g), and initial concentration of Cd2+ (5-60 mg L-1) has been assessed. The adsorption capacity of Cd2+ for the prepared NMs followed the pseudo-second order. Several isotherm models were analyzed, and the Langmuir model was found to be the best fit for NMs. Among as-prepared NMs, Mg0.8Ca0.2Fe2O4 (MCF2, cubic 97%, orthorhombic 3%, qe 100 mg g-1) and Mg0.2Ca0.8Fe2O4 (MCF8, cubic 18%, orthorhombic 83%, qe 90 mg g-1) samples exhibited the highest adsorption performance at conditions, viz., contact time 20 min, pH 7, NM dosage 3 mg, and ions at a concentration 60 mg l-1. Cd removal percentages were achieved 93 and 75 for MCF2 and MCF8, respectively. Overall, the prepared MCF2 and MCF8 NMs could be used as effective adsorbents to eliminate toxic Cd2+ from polluted aqueous solution.

Transition Metal Catalysts for Atmospheric Heavy Metal Removal: A Review of Current Innovations and Advances

Atmospheric heavy metal pollution presents a severe threat to public health and environmental stability. Transition metal catalysts have emerged as a potent solution for the selective capture and removal of these pollutants. This review provides a comprehensive summary of current advancements in the field, emphasizing the efficiency and specificity of nanostructured transition metals, including manganese, iron, cobalt, nickel, copper, and zinc. Looking forward, we delve into the prospective trajectory of catalyst development, underscoring the need for materials with enhanced stability, regenerability, and environmental compatibility. We project that advancements in computational materials science, nanotechnology, and green chemistry will be pivotal in discovering innovative catalysts that are economically and environmentally sustainable. The integration of smart technologies for real-time monitoring and adaptive control is anticipated to revolutionize heavy metal remediation, ensuring efficient and responsive pollution abatement strategies in the face of evolving industrial scenarios and regulatory landscapes.

The synergistic triad of graphene quantum dots, polymer, and ferrites for the photodegradation of dyes in aqueous solution

This work aimed to investigate photocatalytic properties of GQDs@PEG@Mg-ZnFe2O4 nanocomposite, composed of graphene quantum dots (GQDs), polyethylene glycol (PEG), and Mg-ZnFe2O4, for the degradation of methylene blue (MB) and crystal violet (CV). This nanocomposite was synthesized using facile ultrasonics-assisted methodology. XRD analysis confirmed the formation of the spinel structure of the Mg-ZnFe2O4 in the nanocomposite, whereas the presence of GQDs and PEG was confirmed by Fourier transform infrared spectroscopy. Scanning electron microscopy (SEM) revealed a reduction in agglomeration and particle size in the ternary nanocomposite. The GQDs@PEG@Mg-ZnFe2O4 nanocomposite demonstrates a remarkable degradation efficiency of 98 % for CV and MB dyes in the presence of sunlight in 120 min, indicating its potential as an efficient photocatalyst. Vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic behavior of the GQDs@PEG@Mg-ZnFe2O4 nanocomposite which enables magnetic recovery of the photocatalyst after the degradation process. Overall, this study emphasizes the utilization of an environmentally friendly approach to effectively eliminate organic pollutants from wastewater, addressing a crucial environmental concern.

Removal of Cr6+ ions and mordant violet 40 dye from liquid media using Pterocladia capillacea red algae derived activated carbon-iron oxides

In recent years, water pollution has become one of the most dangerous problems facing the world. Pollution of water with heavy metals and different dyes has caused many harmful effects on human health, living organisms and our environment. In this study, iron oxide nanomagnetic composite from Pterocladia Capillacea red algae-derived activated carbon (PCAC-IO) was synthesized by co-precipitation method using different iron salts and different base solutions. The synthesized nanocomposite was investigated with various characterization techniques such as FTIR, BET, SEM-EDX, TEM, XRD, and VSM. The obtained PCAC-IO adsorbent was used for Cr6+ ions and Mordant Violet 40 (MV40) dye removal. The adsorption mechanism of Cr6+ ions and MV40 dye on PCAC-IO was examined using several adsorption and kinetic isotherm models. Langmuir and Freundlich models were investigated using experimental data. Pseudo-first-order (PFO), Pseudo-second-order (PSO) and intraparticle diffusion models (IPDM) were applied to identify the adsorption mechanism. It has shown that the PSO kinetic model fits better with the experimental data obtained from PCAC-IO. This result can be interpreted as the adsorption of the adsorbate on the nanocomposite as chemical adsorption. The optimum conditions for maximum Cr6+ ions removal (96.88%) with PCAC-IO adsorbent occur at room temperature, 5 g L-1 adsorbent concentration, 100 mg L-1 initial pollutant concentration, pH 1 and at the end of 180 min, while maximum MV40 dye removal (99.76%), other conditions being the same, unlikely it occurred at pH 2.06 and after 45 min. The most suitable model for Cr6+ ions removal under the conditions of 1 L-1 g adsorbent concentration and 400 mg L-1 adsorbate concentration was Langmuir (Qmax = 151.52 mg g-1), while for MV40 removal it was Freundlich (Qmax = 303.03 mg g-1). We propose the use of activated carbon-supported iron oxide prepared from bio-waste material, especially from Pterocladia Capillacea red algae, as a promising adsorbent with high efficiency in the removal of Cr6+ ions and MV40 dye from aqueous media.

Comprehensive analysis of NiFe2O4/MWCNTs nanocomposite to degrade a healthcare waste - tetracycline

Tetracycline (TC), a commonly used antibiotic for studying bacterial illnesses in living organisms, poses a significant risk to the aquatic environment. Despite various conventional methods having been attempted to remove TC antibiotics from water solutions, they have not proven effective. Consequently, the focus of the research is on the photocatalytic degradation of TC. According to the research, MWCNTs were successfully incorporated into NiFe2O4 nanoparticles, which reduced the pace at which charge carriers recombined after joining with MWCNTs. Subsequently, the catalyst's efficacy was assessed in a batch reactor by analyzing the weight percentage change of the nanocomposite, the initial concentration of TC antibiotics, the effects of pH and contact time. The identical operational parameters were employed to investigate the degradation of TC using NiFe2O4 and MWCNTs as individual pure materials. The findings indicated that the photocatalytic process using NiFe2O4/MWCNTs achieved a degradation efficiency of 95.8% for TC at a pH value of 9. This result was obtained after a reaction time of 120 minutes, the concentration of TC solution was 10 mg L-1, with a nanocomposite dose of 0.6 g L-1 of TN 04 and 120 W m-2. The pseudo-first-order approach was used to estimate the rate at which TC degrades. After four consecutive uses, it was observed that the photocatalysts maintained their original properties, with only a slight decrease of approximately 2.4% in the removal efficiency. The study demonstrated that the NiFe2O4/MWCNTs nanocomposite exhibited considerable efficiency in degrading TC. Due to its simple manufacture and useful recovery, it has the potential to function well as a catalyst for the removal and degradation of pharmaceutical organic contaminants.

Determination of bupropion by off-line coupling Fe3O4@CuO&GO nanocomposite and ion mobility spectrometry with application to biological samples

In this study, an off-line coupling of dispersive solid-phase extraction (DSPE) and ion mobility spectrometry (IMS) was introduced to extract and determine bupropion (BUP). A magnetic nanocomposite adsorbent (Fe3O4@CuO&GO) was fabricated by combining graphene oxide (GO) sheets with Fe3O4 and CuO through coprecipitation method. The synthesized adsorbent was characterized and analyzed using the analytical techniques. The effect of extraction parameters including desorption solvent (type and volume), pH, adsorbent amount, contact time, temperature, and the volume of analyte solution on the extraction efficiency was investigated and optimized. The operational parameters of IMS method were also investigated. Under the optimum conditions (DSPE-IMS), the proposed method provided a linear range 4.0-24.0 ng for BUP with a determination coefficient R2 ≥ 0.98. LOD and LOQ values were 0.7 and 2.2 ng for BUP. The repeatability of proposed method was evaluated and reported as relative standard deviation (RSD% ≤ 5.5). The developed method was applied to determine BUP in different biological samples, in which satisfactory results were obtained (93.0-98.0%).

Amine Functionalization Leads to Enhanced Performance for Nickel- and Cobalt-Ferrite-Supported Palladium Catalysts in Nitrobenzene Hydrogenation

Easy preparation, good yield and easy recovery are the key challenges in the development of industrial catalysts. To meet all these three criteria, we have prepared intelligent, magnetizable NiFe2O4- and CoFe2O4-supported palladium catalysts that can be easily and completely recovered from the reaction medium by magnetic separation. The fast and facile preparation was achieved by a solvothermal method followed by sonochemical-assisted decomposition of the palladium nanoparticles onto the surface of the magnetic nanoparticles. The metal-support interaction was enhanced by amine functionalization of the supports using monoethanolamine. The performance and stability of the non-functionalized and amine-functionalized NiFe2O4- and CoFe2O4-supported palladium catalysts were compared in the industrially important nitrobenzene hydrogenation reaction. All catalysts showed high catalytic activity during aniline synthesis; complete nitrobenzene conversion and high aniline yield (above 97 n/n%) and selectivity (above 98 n/n%) were achieved. However, during reuse tests, the activity of the non-functionalized catalysts decreased, as the palladium was leached from the surface of the support. On the other hand, in the case of their amine-functionalized counterparts, there was no decrease in activity, and a non-significant decrease in palladium content could be measured. Based on these results, it can be concluded that amine functionalization of transition metal ferrites may result in more effective catalysts due to the enhanced metal-carrier interaction between the support and the precious metal.

Recent Progress in Spinel Ferrite (MFe2O4) Chemiresistive Based Gas Sensors

Gas-sensing technology has gained significant attention in recent years due to the increasing concern for environmental safety and human health caused by reactive gases. In particular, spinel ferrite (MFe2O4), a metal oxide semiconductor with a spinel structure, has emerged as a promising material for gas-sensing applications. This review article aims to provide an overview of the latest developments in spinel-ferrite-based gas sensors. It begins by discussing the gas-sensing mechanism of spinel ferrite sensors, which involves the interaction between the target gas molecules and the surface of the sensor material. The unique properties of spinel ferrite, such as its high surface area, tunable bandgap, and excellent stability, contribute to its gas-sensing capabilities. The article then delves into recent advancements in gas sensors based on spinel ferrite, focusing on various aspects such as microstructures, element doping, and heterostructure materials. The microstructure of spinel ferrite can be tailored to enhance the gas-sensing performance by controlling factors such as the grain size, porosity, and surface area. Element doping, such as incorporating transition metal ions, can further enhance the gas-sensing properties by modifying the electronic structure and surface chemistry of the sensor material. Additionally, the integration of spinel ferrite with other semiconductors in heterostructure configurations has shown potential for improving the selectivity and overall sensing performance. Furthermore, the article suggests that the combination of spinel ferrite and semiconductors can enhance the selectivity, stability, and sensing performance of gas sensors at room or low temperatures. This is particularly important for practical applications where real-time and accurate gas detection is crucial. In conclusion, this review highlights the potential of spinel-ferrite-based gas sensors and provides insights into the latest advancements in this field. The combination of spinel ferrite with other materials and the optimization of sensor parameters offer opportunities for the development of highly efficient and reliable gas-sensing devices for early detection and warning systems.

Toxicity Mechanisms of Copper Nanoparticles and Copper Surfaces on Bacterial Cells and Viruses

Copper is a metal historically used to prevent infections. One of the most relevant challenges in modern society are infectious disease outbreaks, where copper-based technologies can play a significant role. Currently, copper nanoparticles and surfaces are the most common antimicrobial copper-based technologies. Despite the widespread use of copper on nanoparticles and surfaces, the toxicity mechanism(s) explaining their unique antimicrobial properties are not entirely known. In general, toxicity effects described in bacteria and fungi involve the rupture of membranes, accumulation of ions inside the cell, protein inactivation, and DNA damage. A few studies have associated Cu-toxicity with ROS production and genetic material degradation in viruses. Therefore, understanding the mechanisms of the toxicity of copper nanoparticles and surfaces will contribute to developing and implementing efficient antimicrobial technologies to combat old and new infectious agents that can lead to disease outbreaks such as COVID-19. This review summarizes the current knowledge regarding the microbial toxicity of copper nanoparticles and surfaces and the gaps in this knowledge. In addition, we discuss potential applications derived from discovering new elements of copper toxicity, such as using different molecules or modifications to potentiate toxicity or antimicrobial specificity.

Review on magnetic spinel ferrite (MFe2O4) nanoparticles: From synthesis to application

Magnetic spinel ferrite materials offer various applications in biomedical, water treatment, and industrial electronic devices, which has sparked a lot of attention. This review focuses on the synthesis, characterization, and applications of spinel ferrites in a variety of fields, particularly spinel ferrites with doping. Spinel ferrites nanoparticles doped with the elements have remarkable electrical and magnetic properties, allowing them to be used in a wide range of applications such as magnetic fields, microwave absorbers, and biomedicine. Furthermore, the physical properties of spinel ferrites can be modified by substituting metallic atoms, resulting in improved performance. The most recent and noteworthy applications of magnetic ferrite nanoparticles are reviewed and discussed in this review. This review goes over the synthesis, doping and applications of different types of metal ferrite nanoparticles, as well as views on how to choose the appropriate magnetic ferrites based on the intended application.

Selective Oxidation of Tetrahydrofuran to Gamma-Butyrolactone over Spinel ZnFe2O4 Nanoparticle Catalyst

The selective oxidation of tetrahydrofuran (THF) to gamma-butyrolactone (GBL) on spinel ZnFe2O4 nanoparticles (ZFNPs) was investigated. The catalyst was prepared with the coprecipitation method and characterized by FTIR, XRD, TEM, SEM, EDS, TGA, XPS, and BET surface area. The characterization techniques showed that a nonuniform spherical spinal oxide with an average particle size of 26 nm was formed. The oxidation reaction was carried out using hydrogen peroxide as an oxidizing agent under solvent-free conditions. GC-MS analysis revealed that the main product was GBL. 2-hydroxytetrahydrofuran (THF-2-OH), gamma-hydroxybutyric acid (GHBA), and gamma-hydroxybutaldehyde (GHBAl) were obtained as minor products. The effects of different reaction parameters, such as temperature, H2O2/THF mole ratio, catalyst dose, reaction time, and reusability, were evaluated. A 47.3% conversion of THF with an 88.2% selectivity of GBL was achieved by conducting the reaction at 80 °C for nine hours using a 1:1 mole ratio of H2O2/THF. A slight increase in the conversion degree was attained at higher temperatures; however, an over-oxidation process was observed as the temperature exceeded 80 °C. The catalyst remained effective and stable over four reuses.

Genetic algorithm-assisted artificial neural network modelling for remediation and recovery of Pb (II) and Cr(VI) by manganese and cobalt spinel ferrite super nanoadsorbent

MnFe₂O₄ and CoFe₂O₄ nanoparticles were hydrothermally synthesized to examine their capability in adsorption of Pb (II) and Cr (VI). The adsorbents exhibited a high rate of adsorption, reaching 90% of their adsorption capacity in less than 30 min. Furthermore, the adsorption capability of the Magnetic Nanoparticles (MNPs) was noticeably greater at initial pollutant concentrations smaller than 40 mg/L. Maximum adsorption capacity on MnFe₂O₄ and CoFe₂O₄ nanoparticles were 40 and 25.38 mg/g for Cr (VI) and 523.32 and 476.19 mg/g for Pb (II), respectively. A data-driven model of Artificial Neural Network was used for prediction of adsorption capacity at both equilibrium and non-equilibrium condition. The model parameters including the numbers of neuron (n = 7) and data portioning for training (49.5%), validation (40.5%), and testing (10%) were obtained using Genetic Algorithm. The results indicated that the model could predict the data with high accuracy (R² = 0.998). The input parameters were initial concentration, time, pH, temperature, adsorbent dosage, and other parameters that is dependent to the physico-chemical properties of ions and adsorbents' surface (ε, α₁, α₂). The mechanism involved in Cr(VI) and Pb(II) adsorption are electrostatic physisorption and a combination of ion exchange chemisorption and electrostatic physisorption, respectively. Desorption capability and adsorbent reuse capability were also examined.

Biofabricated copper ferrite nanoparticles: a potential nanosorbent for the removal of Pb (II) ions from aqueous media

In the present study, we describe a facile strategy for the easy removal of the heavy metal ion, Pb (II) using biosynthesized copper ferrite (CuFe₂O₄) Nanoparticles (Nps) prepared via a cost-effective and eco-friendly method usingPimenta dioicaleaf extract. The structural characterization was performed using UV-Visible, FT-IR, XRD, XPS, TG, SEM - EDS and TEM techniques. Various characterization techniques showed that the biosynthesized CuFe₂O₄nanoparticles have spherical shape with minimum aggregation and possess a size range between 7 and 16 nm. Batch experiments were carried out to analyze the adsorption efficiency of CuFe₂O₄Nps by varying different experimental conditions such as pH, adsorbent dose and initial metal ion concentration. From the atomic absorption spectroscopy results, the optimum removal efficiency (99.69%) occurred at a contact time of 90 min in the solution having pH 6 with 0.06 g of nanoadsorbent. The experimental data were analyzed using adsorption isotherm and fitted with kinetic models. In the present study, we report the the highest removal efficiency of 99.69% for Pb (II) ions with minimum experimental parameters which is greater than other similar reported studies. The novel CuFe₂O₄nanosorbent synthesized in the present study is highly effective in eliminating toxic pollutants. They also possess outstanding recycling characteristics for the effective removal of Pb (II) ions from aqueous media.This cost-effective and ecofriendly strategy could be utilized for addressing the emerging water contamination.

Synthesis and characterization of titanium-substituted nanocrystalline Co2-Y hexaferrite: magnetically retrievable photocatalyst for treatment of methyl orange contaminated wastewater

Rapid industrial growth causes considerable environmental havoc, adversely affecting human and aqueous life. It becomes a significant concern to deal with adequate wastewater treatment strategies by converging on water scarcity. This research work explored the synthesis of titanium-substituted Y-type barium hexaferrite (Co₂-Y), having a general formula of Ba₂Co₂Fe_12-xTi_xO₂₂ (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5), using a facile nitrate-based sol-gel auto-combustion route and its suitability was investigated as a heterogeneous catalyst within the photo-Fenton-based degradation of methyl orange (MO), one of the significant pollutants generated from textile industries. Developing a thermochemically stable and magnetically separable heterogeneous catalyst for photocatalytic decomposition of nonbiodegradable organic dye from wastewater was also emphasized. The as-prepared nanocrystalline Co₂-Y powders were analyzed using XRD, FTIR, DLS, UV-visible spectroscopy, SEM, VSM, and XPS. Furthermore, the photocatalytic degradation performance of pristine and titanium substituted Ba₂Co₂Fe_11.6Ti_0.4O₂₂ ferrite, having the lowest bandgap value among all samples, was quantified and compared in terms of apparent rate constant (k_arc) value and turnover frequency values. The enriched photocatalytic performance was correlated with the existence of multi-valance states of transition metal cations and the availability of oxygen vacancy, confirmed by the surface chemistry using the XPS analysis. The modified (enhanced thermal and chemical stability) hexaferrite catalyst was magnetically separable and reusable without significant losses to its catalytic performance. This promising catalyst may be considered as a replacement for soft ferrite materials to catalyze the degradation of several other nonbiodegradable organic pollutants from wastewater in large-scale industries.

In-situ fabrication of manganese ferrite grafted polyaniline nanocomposite: A magnetically reusable visible light photocatalyst and a robust electrode material for supercapacitor

Herein, we reported the in-situ preparation of manganese ferrite (MnFe₂O₄) grafted polyaniline (Pani), a magnetic nanocomposite for the potential visible light photocatalytic material as well as electrode material for supercapacitor. The physical characterization of the prepared nanoparticle and nanocomposite was examined with various spectroscopic and microscopic analyses. The peaks observed in the X-ray diffraction study confirm the face-centered cubic phase of MnFe₂O₄ nanoparticles with a grain size of ∼17.6 nm. The surface morphology analysis revealed the uniform distribution of spherical-like MnFe₂O₄ nanoparticles on the surface of Pani. The degradation of malachite green (MG) dye under exposure to visible light was investigated using MnFe₂O₄/Pani nanocomposite as a photocatalyst. The results exposed the faster degradation of MG dye was accomplished by MnFe₂O₄/Pani nanocomposite than MnFe₂O₄ nanoparticles. The energy storage performance of the MnFe₂O₄/Pani nanocomposite was analyzed through cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy analyses. The results exposed that the MnFe₂O₄/Pani electrode achieved a capacitance of 287.1 F/g than the MnFe₂O₄ electrode (94.55 F/g). Further, the respectable capacitance of 96.92% was achieved even after 3000 repetitive cycles stability . Based on the outcomes, the MnFe₂O₄/Pani nanocomposite can be suggested as a promising material for both photocatalytic and supercapacitor applications.

Recent advances in spinel ferrite-based magnetic photocatalysts for efficient degradation of organic pollutants

Although spinel ferrite (MFe₂O₄, M = Zn, Ni, Mn, etc.) has been reported as a promising catalyst, its low photocatalytic activity under visible light greatly restricts its practical application. Spinel ferrite-based photocatalytic composites have exhibited improved efficiency for pollutant degradation, due to interface charge carrier mobility and structural modification. Meanwhile, due to its magnetism and stability, spinel ferrite composite can be easily recycled for long-term utilization, showing its high application potential. In this review, the recent advances in the construction and photocatalytic degradation of spinel ferrite composites are discussed, with an emphasis on the relationship between structural property and photocatalytic activity. In addition, to improve their photocatalytic application, the challenges, gaps and future research prospects are proposed.

Impact of Gd3+ doping on structural, electronic, magnetic, and photocatalytic properties of MnFe2O4 nanoferrites and application in dye-polluted wastewater remediation

The present work focuses on developing Gd-doped Mn spinel nanoferrites and their potential application in the photodegradation of water pollutants. The impact of Gd³⁺ ion substitution on structural, electronic, and magnetic characteristics of manganese ferrites has been studied. Nanocrystalline samples of MnGd_xFe_2-xO₄ (x = 0.0 to 0.10, in step size of 0.02) ferrites were prepared via sol-gel self-ignition route. The Rietveld, XPS, HRTEM, and SAED characterization methods confirmed the formation of phase pure ferrite nanoparticles (~ 8-22 nm) in the cubic spinel structure. The Gd³⁺ content in these nanoferrites responded to a systematic reduction in the size of nanocrystallites and an upsurge in the density of nanoferrites. The XPS study revealed fine assimilation of constituent elements in the fcc lattice and ruled out impurities in the nanoferrites. The Fe and the Gd ions were found to be in Fe³⁺ and Gd³⁺ states, respectively. While a major fraction of the Mn ions were found to be in the Mn²⁺ state, a small fraction of Mn⁴⁺ ions was observed on the surface of nanoparticles. The nanoferrites were found to exhibit a soft ferromagnetic state from 300 to 20 K limits. The highest saturation magnetization was observed for x = 0.02 (M_S = 66.6 emu/g at 20 K). The observed magnetic properties can be understood with the competing (Fe³⁺ and Mn²⁺)_A-O^2--[Fe³⁺, Mn²⁺, and Gd³⁺]_B superexchange interactions and magnetocrystalline anisotropy. Due to the small band gap energy of Gd-doped Mn ferrites than that of the pure Mn ferrite, they have demonstrated excellent photocatalytic activity for the degradation of methylene blue (MB) dye under visible light illumination. As much as 96.35% of the MB dye was found to get degraded in 70 min of light illumination over synthesized nanoparticles and the photodegradation reaction followed pseudo-first-order kinetics. The increased optical absorbance due to lower band gap, suppressed recombination rate of charge carriers, and enhanced charge mobility make them effective visible light active photocatalysts. This study revealed that the electronic, optical, and magnetic properties of MnFe₂O₄ nanoferrites could be easily tuned by varying the Gd³⁺ content and the prepared Gd-doped MnFe₂O₄ nanomaterials have boundless potential to be utilized in the future making promising active photocatalysts and degradation of harmful industrial dyes for enhanced protection in the fields of environment and health care.

Sulfate radicals-based advanced oxidation processes for the degradation of pharmaceuticals and personal care products: A review on relevant activation mechanisms, performance, and perspectives

Owing to the rapid development of modern industry, a greater number of organic pollutants are discharged into the water matrices. In recent decades, research efforts have focused on developing more effective technologies for the remediation of water containing pharmaceuticals and personal care products (PPCPs). Recently, sulfate radicals-based advanced oxidation processes (SR-AOPs) have been extensively used due to their high oxidizing potential, and effectiveness compared with other AOPs in PPCPs remediation. The present review provides a comprehensive assessment of the different methods such as heat, ultraviolet (UV) light, photo-generated electrons, ultrasound (US), electrochemical, carbon nanomaterials, homogeneous, and heterogeneous catalysts for activating peroxymonosulfate (PMS) and peroxydisulfate (PDS). In addition, possible activation mechanisms from the point of radical and non-radical pathways are discussed. Then, biodegradability enhancement and toxicity reduction are highlighted. Comparison with other AOPs and treatment of PPCPs by the integrated process are evaluated as well. Lastly, conclusions and future perspectives on this research topic are elaborated.

Impact of Ni Content on the Structure and Sonophotocatalytic Activity of Ni-Zn-Co Ferrite Nanoparticles

The structure, morphology, and sonophotocatalytic activity of Ni-Zn-Co ferrite nanoparticles, embedded in a SiO₂ matrix and produced by a modified sol-gel method, followed by thermal treatment, were investigated. The thermal analysis confirmed the formation of metal succinate precursors up to 200 °C, their decomposition to metal oxides and the formation of Ni-Zn-Co ferrites up to 500 °C. The crystalline phases, crystallite size and lattice parameter were determined based on X-ray diffraction patterns. Transmission electron microscopy revealed the shape, size, and distribution pattern of the ferrite nanoparticles. The particle sizes ranged between 34 and 40 nm. All the samples showed optical responses in the visible range. The best sonophotocatalytic activity against the rhodamine B solution under visible irradiation was obtained for Ni_0.3Zn_0.3Co_0.4Fe₂O₄@SiO₂.

Spinel ferrites materials for sulfate radical-based advanced oxidation process: A review

In the past decade, the sulfate radical-based advanced oxidation processes (SR-AOPs) have been increasingly investigated because of their excellent performance and ubiquity in the degradation of emerging contaminants. Generally, sulfate radicals can be generated by activating peroxodisulfate (PDS) or peroxymonosulfate (PMS). To date, spinel ferrites (SF) materials have been greatly favored by researchers in activating PMS/PDS for their capability and unique superiorities. This article reviewed the recent advances in various pure SF, modified SF, and SF composites for PDS/PMS activation. In addition, synthesis methods, mechanisms, and potential applications of SF-based SR-AOPs were also examined and discussed in detail. Finally, we present future research directions and challenges for the application of SF materials in SR-AOPs.

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.

Effects of Rhenium Substitution of Co and Fe in Spinel CoFe2O4 Ferrite Nanomaterials

In this work, nanoparticles of Co_1-xRe_xFe₂O₄ and CoFe_2-xRe_xO₄ (0 ≤ x ≤ 0.05) were synthesized by the sol-gel method. The Rietveld refinement analysis of XRD and Raman data revealed that all of the prepared samples were single phase with a cubic spinel-type structure. With the substitution of Re, the lattice parameters were slightly increased, and Raman spectra peak positions corresponding to the movement of the tetrahedral sublattice shifted to a higher energy position. Furthermore, Raman spectra showed the splitting of T_2g mode into branches, indicating the presence of different cations at crystallographic A- and B-sites. The SEM micrograph confirms that surface Re exchange changes the coordination environment of metals and induces Fe-site structure distortion, thereby revealing more active sites for reactions and indicating the bulk sample's porous and agglomerated morphology. The vibrating sample magnetometer (VSM) results demonstrated that the synthesized nanoparticles of all samples were ferromagnetic across the entire temperature range of 300-4 K. The estimated magnetic parameters, such as the saturation magnetization, remanent magnetization, coercivity, blocking temperature (T_B), and magnetic anisotropy, were found to reduce for the Co-site doping with the increasing doping ratio of Re, while in the Fe site, they enhanced with the increasing doping ratio. The ZFC-FC magnetization curve revealed the presence of spin-glass-like behavior due to the strong dipole-dipole interactions in these ferrite nanoparticles over the whole temperature range. Finally, the dielectric constant (ε_r') and dielectric loss (tanδ) were sharply enhanced at low frequencies, while the AC conductivity increased at high frequencies. The sharp increases at high temperatures are explained by enhancing the barrier for charge mobility at grain boundaries, suggesting that samples were highly resistive. Interestingly, these parameters (ε_r', tanδ) were found to be higher for the Fe-site doping with the increasing Re doping ratio compared with the Co site.

Covalent and Non-covalent Functionalized Nanomaterials for Environmental Restoration

Nanotechnology has emerged as an extraordinary and rapidly developing discipline of science. It has remolded the fate of the whole world by providing diverse horizons in different fields. Nanomaterials are appealing because of their incredibly small size and large surface area. Apart from the naturally occurring nanomaterials, synthetic nanomaterials are being prepared on large scales with different sizes and properties. Such nanomaterials are being utilized as an innovative and green approach in multiple fields. To expand the applications and enhance the properties of the nanomaterials, their functionalization and engineering are being performed on a massive scale. The functionalization helps to add to the existing useful properties of the nanomaterials, hence broadening the scope of their utilization. A large class of covalent and non-covalent functionalized nanomaterials (FNMs) including carbons, metal oxides, quantum dots, and composites of these materials with other organic or inorganic materials are being synthesized and used for environmental remediation applications including wastewater treatment. This review summarizes recent advances in the synthesis, reporting techniques, and applications of FNMs in adsorptive and photocatalytic removal of pollutants from wastewater. Future prospects are also examined, along with suggestions for attaining massive benefits in the areas of FNMs.