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• N-doped magnetic carbon aerogel (N-MCA) with high adsorption performance of 431 mg g−1 towards CR was synthesized by hydrothermal method. • Compared with MCA, the maximum adsorption capacity of CR on N-MCA can be increase 8.6 times. • Coexist dyes have almost no influence on the adsorption of CR on N-MCA, indicating high selectivity to CR. • N-MCA can be reused at least four times without obvious decrease of adsorption capacity of CR. A porous N-doped magnetic carbon aerogel (N-MCA) was successfully synthesized and applied for the removal of organic dye Congo red (CR). The surface morphology and structure of N-MCA were characterized by SEM, FT-IR, XRD, BET, EDS and VSM, which displayed well-developed porous morphologies, high specific surface areas, and excellent magnetic properties. The effects of different adsorption parameters, such as pH value, initial CR concentration, contacting time and adsorption selectivity on the adsorption capacity were studied. In addition, the adsorption isotherm and kinetics were also discussed, and the results showed that the adsorption process was in accordance with the Langmuir model and pseudo-second-order model. The maximum adsorption capacity of CR on N-MCA was 431 mg g−1, which is much higher than that of MCA. The adsorption-desorption study indicated that the composite had an excellent stability and reusability. Therefore, N-MCA could be used as an efficient adsorbent for the removal of anionic dyes in wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

A simple and rapid soft‐templating coupled with one‐pot solvent thermal method is developed to synthesize S‐doped magnetic mesoporous carbon (S‐doped MMC). In this method, phenolic resin is used as a carbon precursor and Pluronic copolymer P123 is used as a template and 2,5‐dimercapto‐1,3,4‐thiadiazole is used as sulfur source. Prepared S‐doped MMC processes a high specific surface area, the Fe3O4 particles are well embedded in the mesoporous carbon walls that exhibit a strong magnetic response, and the hydrated iron nitrate loading amount of 0.808 g is the best. Batch adsorption experiments are carried out at different pH, initial concentration, temperature, and contact time on the adsorption of methyl orange (MO) by S‐doped MMC. The kinetic data of the adsorption process are better fitted with pseudo‐second‐order model than the pseudo‐first‐order model. Langmuir model is more suitable for the equilibrium data than Freundlich model. The thermodynamic parameters including ΔG0, ΔH0, and ΔS0 indicate that the adsorption is a feasible, spontaneous, and endothermic process. Finally, it is found that the coexistence of PO43−, NO3−, SO42−, Cl−, and CO32− does not influence the adsorption process. These results illustrate S‐doped MMC can be an efficient adsorbent for the removal of MO from wastewater. [ABSTRACT FROM AUTHOR]

A novel Pb(II) imprinted magnetic polymer (Pb-IIMP) was synthesized by surface imprinting technique using Pb(II) as template, polyethyleneimine functionalized magnetic Fe 3 O 4 (MNPs@PEI) as functional monomer and epoxy chloropropane (ECH) as cross-linker and applied for the remediation of Pb(II). Batch adsorption studies were performed to evaluate the influence of different sorption parameters, such as pH, initial concentration of Pb(II), contact time, adsorption selectivity and desorption. Isotherm and kinetics studies showed that the adsorption process obeyed Langmuir and pseudo-second-order models with a maximum adsorption capacity of 123.3 mg/g for Pb-IIMP and 62.2 mg/g for non-imprinted magnetic polymer (Pb-NIMP). The relative selectivity coefficients of Pb-IIMP for Pb(II)/Cd(II) and Pb(II)/Cu(II) were 1.2 and 1.4 times greater than Pb-NIMP. In addition, Pb(II) could be desorbed from Pb-IIMP by 0.5 mol/L HCl and used for five cycles without any adsorption performance loss, which revealed that the prepared Pb-IIMP had high stability and good reusability. [ABSTRACT FROM AUTHOR]

Preparation of polyethyleneimine functionalized magnetic Fe3O4 by using a one-step solvothermal method is reported in this paper. The effect of the amount of polyethyleneimine on the properties of the prepared materials including the shape, size, and adsorption performance was investigated in detail. The magnetic adsorbent with the best adsorption capacity was prepared and used for the removal of Pb(II) in an aqueous medium. Adsorption experiments were performed to evaluate the effect of different sorption parameters, such as pH, initial concentration of Pb2+, and contact time. Langmuir and pseudo-second-order models were used for isotherm and kinetic studies, through which a maximum adsorption capacity of 143 mg g−1 could be calculated. Pb(II) could be desorbed from magnetic Fe3O4 nanoparticles modified with polyethyleneimine by 0.5 mol L−1 HCl and used for five cycles without any adsorption performance loss, indicating that the polymeric magnetic adsorbent used in this work had good reusability and great potential for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D hydrangea-like ZnFe-LDHs/FeOOH was designed and prepared to remove phosphate. • ZnFe-LDHs/FeOOH exhibited excellent performance for phosphate removal. • ZnFe-LDHs/FeOOH were created through directional aggregation and epitaxial growth. • The mechanism included interlayer anion exchange, hydrogen bonding and coordination. • ZnFe-LDHs/FeOOH remove phosphate in natural water and laundry wastewater efficiently. Phosphate in water can cause a series of problems such as overgrowth of algae and other aquatic organisms, foul-smelling, turbid water and lower dissolved oxygen concentrations, thereby posing a serious threat to human health and environment. To efficiently remove phosphate from water, three-dimensional hydrangea-like ZnFe-layered double hydroxides/FeOOH composites (3D hydrangea-like ZnFe-LDHs/FeOOH) were designed and prepared by a facile urea hydrothermal method. The maximum adsorption capacity of phosphate by 3D hydrangea-like ZnFe-LDHs/FeOOH reached about 200 mg·g−1, much higher than that of ZnFe-LDHs prepared by co-precipitation method (53 mg·g−1) and other reported adsorbents, which confirmed that 3D morphology contributed to the improvement of adsorption capacity. Time-dependent experiments were designed to explore the formation mechanism of 3D hydrangea-like structure and the results indicated directional aggregation and epitaxial growth were two main processes. Batch experiments were conducted to investigate adsorption behavior of phosphate. The adsorption kinetics and isotherms showed that the adsorption process followed the quasi-first-order kinetics and Langmuir model. Besides, 3D hydrangea-like ZnFe-LDHs/FeOOH could be regenerated effectively and recycled at least three times. 3D hydrangea-like ZnFe-LDHs/FeOOH possessed fascinating performance in phosphate removal from real river samples and laundry detergent samples, with the removal rates of 66–100 % and 80–100 %, respectively. Furthermore, 3D hydrangea-like ZnFe-LDHs showed good adsorption performance towards other anionic dyes, including Congo Red and Orange Yellow II, with the maximum adsorption capacity of 867 mg·g−1 and 225 mg·g−1, indicating its widespread applicability. The adsorption mechanism of phosphate by 3D hydrangea-like ZnFe-LDHs was furtherly investigated, mainly containing metal coordination, anion exchange between layers and electrostatic interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel cubic magnetic MgFe 2 O 4 derived from MgFe-LDHs has been fabricated. • Selecting Fe3+ as laminar ions offers hexahedron precursor and facilitates magnetic property. • Calcination decides magnetic performance of MgFe 2 O 4 while not changing its cubic structure. • MgFe 2 O 4 can be reused three times for adsorbing MO with adsorption capacity of 520 mg g−1. • Adsorption mechanism of MO by MgFe 2 O 4 includes electrostatic interaction and coordination. A novel cubic magnetic MgFe 2 O 4 derived from MgFe-layered double hydroxides (MgFe-LDHs) has been constructed by a combination of facile urea hydrothermal method and calcinations method and applied for the efficient removal of methyl orange (MO) with a maximum adsorption capacity of 535 mg g−1. The studies of formation mechanism of cubic MgFe-LDHs demonstrate the type of ferric salt and reaction time are two most important parameters influencing their cubic structures. Besides, calcinations temperature can not only decide magnetic performance of MgFe 2 O 4 , but also not change its cubic structure. Then the structural and surface properties of cubic magnetic MgFe 2 O 4 were investigated by various characterization techniques. In addition, batch adsorption experiments were carried out to investigate the effects of different parameters such as the initial concentration of MO, pH, temperature and time on the adsorption behavior of MO on MgFe 2 O 4. The kinetics, isotherm and thermodynamics of the adsorption of MO by MgFe 2 O 4 were studied in detail. Moreover, adsorption mechanism of MO by MgFe 2 O 4 was studied deeply. At last, MO could be desorbed from MgFe 2 O 4 by 0.1 M NaOH solution and reused at least three times, indicating cubic magnetic MgFe 2 O 4 is an effective and promising adsorbent for the removal of dye pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel flower-like magnetic CoFe 2 O 4 /CoFe-LDHs microspheres have been fabricated. • The existence of SO 4 2- and reaction time can influence the formation of structure of composites. • CoFe 2 O 4 /CoFe-LDHs exhibit remarkable adsorption performance of 1940 mg g−1 towards Orange II. • Adsorption mechanism includes anion exchange, hydrogen bonding, coordination and surface adsorption. Novel three-dimensional flower-like magnetic CoFe 2 O 4 /CoFe-LDHs microspheres were fabricated via a facile one-step hydrothermal method without any other operation. CoFe 2 O 4 /CoFe-LDHs microspheres could possess strong magnetic performance directly without calcination procedure. By controlling reaction time and anion type of raw materials, three-dimensional flower-like structure microspheres could be obtained. Then the structural and surface properties of the prepared CoFe 2 O 4 /CoFe-LDHs were investigated by a comprehensive set of characterization techniques closely. Besides, as-prepared composites exhibited remarkable adsorption performance towards Orange II and the maximum adsorption capacity could be high to 1940 mg·g−1, several times higher than the adsorption capacity of other adsorbents reported and amorphous CoFe 2 O 4 /CoFe-LDHs prepared in this work, proving three dimensional porous structures could contribute to higher adsorption performance. Moreover, batch experiments were conducted systematically to evaluate the effects of the initial concentration of Orange II, pH, temperature and time on the adsorption behavior of Orange II on CoFe 2 O 4 /CoFe-LDHs. The adsorption kinetics and isotherm studies indicated adsorption progress obeyed the pseudo-second-order and Langmuir model respectively. Formation mechanism and adsorption mechanism were both studied deeply. What's more, adsorbents and sample solution could be separated from each other quickly by an external magnet. These results suggested CoFe 2 O 4 /CoFe-LDHs composite was an effective and promising adsorbent for the removal of dye pollutants. [ABSTRACT FROM AUTHOR]