Multifunctional PMMA@Fe₃O₄@DR Magnetic Materials for Efficient Adsorption of Dyes

Fabrication of Monodisperse Magnetic Polystyrene Mesoporous Composite Microspheres for High-Efficiency Selective Adsorption and Rapid Separation of Cationic Dyes in Textile Industry Wastewater

Sustainable development has become an inevitable trend in the world's green chemical industry for a generation or more. In this study, a monodisperse magnetic polystyrene mesoporous composite microsphere (MPPS) composed of Fe3O4 nanoparticles loaded on polystyrene mesoporous microspheres is introduced. These microspheres serve as effective adsorbents for the swift removal of cationic dyes. The fabrication of the wastewater adsorbent, with its simple operation and economic practicality, involved a combination of dispersion polymerization, a sulfonation reaction, two-step swelling polymerization, and in situ alkaline oxidation technology. Notably, the adsorption capacity within 3 min reaches 184.0 mg/g, with an impressive adsorption efficiency of 92%. This is primarily attributed to the high specific surface area (Smax) of the MPPS providing more reaction sites for π-π interaction. Simultaneously, the attractive force between negatively charged sulfonic acid groups and cationic dyes is enhanced through surface modification of the MPPS. Furthermore, the MPPS, boasting a maximum saturation magnetization of 38.19 emu/g, ensures rapid separation from the solution for recycling within 3 s. Even after 5 cycles, the adsorption efficiency remains over 90%. The rapid separation of dyes is facilitated by the magnetic attraction of Fe3O4 nanoparticles from the MPPS under the application of a magnetic field. These composite mesoporous materials exhibit outstanding performance in both efficient selective adsorption and recyclability, presenting a novel green adsorbent with promising prospects for sustainable development. This innovation is poised to excel in fields such as sewage treatment, separation, and purification.

Wastewater Treatment by Polymeric Microspheres: A Review

This review addresses polymer microspheres used as adsorbent for wastewater treatment. The removal of various pollutants (including dyes, heavy metal ions, and organic pollutants) is a prominent issue, as they can cause severe health problems. Porous microspheres can provide large specific area and active sites for adsorption or photo degradation. Enhancement in performance is achieved by various modifications, such as the introduction of nanoparticles, magnetic particles, and ZIF-8. Some microspheres were synthesized from synthetic polymers such as vinylic polymer and polydopamine (PDA) through a facile fabrication process. Natural polymers (such as cellulose, alginate, and chitosan) that are biodegradable and eco-friendly are also used. The adsorbents used in industrial application require high adsorption capacity, thermal stability, and recyclability. Batch adsorption experiments were conducted to investigate the optimal conditions, influence of related factors, and adsorption capacities. Insights regarding the adsorption mechanisms were given from the kinetic model, isotherm model, and various characterization methods. The recyclability is investigated through regeneration ratio, or their maintenance of their capability through repeated adsorption-desorption cycles. The high potential of polymer microsphere for the removal of pollutants from wastewater is shown through the high adsorption capacities, environmentally friendliness, and high stability.

Novel Fe3O4-poly(methacryloxyethyltrimethyl ammonium chloride) adsorbent for the ultrafast and efficient removal of anionic dyes

The removal of anionic dyes from wastewater has attracted global concern. In this work, a novel Fe₃O₄-poly(methacryloxyethyltrimethyl ammonium chloride) (Fe₃O₄-pDMC) adsorbent for the efficient removal of anionic dyes from wastewater was successfully synthesized by grafting methacryloxyethyltrimethyl ammonium chloride (DMC) on the surfaces of Fe₃O₄. Various characterization analyses confirmed that the obtained Fe₃O₄-pDMC possessed numerous functional groups on its surfaces and retained good magnetic separation properties. Fe₃O₄-pDMC showed ultrafast removal for acid orange 7 (AO7, 58.6%, 1 min) and direct blue 15 (DB15, 98.1%, 1 min), and the maximum adsorption capacity was high (266.8 and 336.5 mg g^-1 for AO7 and DB15, respectively). In addition, the adsorption process was in accordance with pseudo-second-order kinetics and the Langmuir isotherm. The mechanism underlying the adsorption of Fe₃O₄-pDMC on anionic dyes was mainly dependent on electrostatic interaction. This study illustrated that Fe₃O₄-pDMC has great potential applications as an environmentally friendly, desirable adsorbent for the efficient removal of anionic dyes from wastewater.

Acid Red 66 Dye Removal from Aqueous Solution by Fe/C-based Composites: Adsorption, Kinetics and Thermodynamic Studies

The presence of synthetic dyes in water causes serious environmental issues owing to the low water quality, toxicity to environment and human carcinogenic effects. Adsorption has emerged as simple and environmental benign processes for wastewater treatment. This work reports the use of porous Fe-based composites as adsorbents for Acid Red 66 dye removal in an aqueous solution. The porous FeC and Fe/FeC solids were prepared by hydrothermal methods using iron sulfates and sucrose as precursors. The physicochemical properties of the solids were evaluated through X-ray diffraction (XRD), Scanning electron microscopy coupled with Energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared s (FTIR), Raman and Mössbauer spectroscopies, nitrogen adsorption–desorption isotherms, Electron Paramagnetic Resonance (EPR) and magnetic saturation techniques. Results indicated that the Fe species holds magnetic properties and formed well dispersed Fe₃O₄ nanoparticles on a carbon layer in FeC nanocomposite. Adding iron to the previous solid resulted in the formation of γ-Fe₂O₃ coating on the FeC type structure as in Fe/FeC composite. The highest dye adsorption capacity was 15.5 mg·g⁻¹ for FeC nanocomposite at 25 °C with the isotherms fitting well with the Langmuir model. The removal efficiency of 98.4% was obtained with a pristine Fe sample under similar experimental conditions.

Polymer-Functionalized Magnetic Nanoparticles: Synthesis, Characterization, and Methylene Blue Adsorption

The removal of methylene blue (MB) from wastewater has attracted global concerns. In this study, polymer-functionalized magnetic nanoparticles for MB removal, Fe₃O₄@SiO₂-MPS-g-AA-AMPS (FSMAA), were successfully synthesized by grafting acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) on the surface of vinyl-modified Fe₃O₄@SiO₂. With various characterization techniques, it was confirmed that the obtained FSMAA had a core⁻shell structure, a good magnetic property, and plenty of functional groups on its surface. MB adsorption experiments showed that the adsorption capacity of FSMAA was notably enhanced as the grafted monomer concentration and solution pH were increased. The adsorption kinetic data and isothermal data were well described by the pseudo-second-order kinetic model and the Langmuir model, respectively. The maximum adsorption capacity of FSMAA was 421.9 mg g^-1 with grafted monomer concentration at 2.0 mol L^-1 and solution pH at 9, much higher than those of other adsorbents stated in previous literatures. Based on XPS analysis, surface adsorption mechanism between FSMAA and MB was electrostatic interaction, hydrogen bonding, and hydrophobic interaction. Furthermore, FSMAA was effectively regenerated by acid pickling, and the remaining adsorption capacity was more than 60% after eight adsorption⁻regeneration cycles. All the results demonstrated the self-made FSMAA was a desirable adsorbent to remove MB from wastewater.

A Feasible Strategy for Fabricating Surface Porous Network in Fe-Si Ribbons

Porous materials have always attracted extensive attention owing to their low density, tunable porosity and high surface area. Generally, porosity is introduced in amorphous materials through dealloying or electrochemical dealloying processes. In this work, an iron-based surface porous network was successfully fabricated utilizing selective electrochemical dissolution of Fe-Si alloy ribbons based on the cellular structure prepared by melt-spinning technique. After 30 s, the surface of the ribbon gradually becomes flat and grains can be observed in the first stage of electrochemistry; after an extra 10 s, the pores spread throughout the surface of the ribbon in the second stage. The average size of pores is about 310 nm and the average size of the ligament is 150 nm. The associated dissolution mechanism has been proposed based on the inhomogeneous composition of the center and edge of the cell. The entire process of electrochemical dissolution has been divided into two stages and the entire duration of synthesis does not exceed one minute. This method is extremely feasible and provides a promising strategy for preparing surface porous materials for selective electrochemical dissolution of cellular structure.

Controlled synthesis of Fe3O4@ZIF-8 nanoparticles for drug delivery

A novel one-pot synthetic method is introduced to produce Fe₃O₄@ZIF-8 NPs, which are proven to have potential applications as drug delivery models.