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BACKGROUND: Simultaneous removal of arsenic and fluoride anions from water by adsorption remains a challenge for environmental remediation practice. To address this issue, four mesoporous bimetallic oxides (MBOs) were prepared via the evaporation‐induced self‐assembly (EISA) method and studied as adsorbents for the co‐uptake of arsenate (As(V)) and fluoride (F−) from synthetic wastewater. Adsorption envelope and equilibrium experiments were performed to investigate the adsorption behaviors and properties. RESULTS: These composites possessed high surface areas (e.g. 200 m2 g−1 for meso‐Ti/Al) and well‐defined mesopores, enabling high adsorption capacities for both As(V) and F−. The maximum adsorption capacities of mesoporous titanium‐lanthanum oxide (meso‐Ti/La) were as high as 81.42 mg g−1 and 44.37 mg g−1 for As(V) and F−, respectively. Surface complexation modeling indicates that As(V) removal mainly involved bidentate surface complexation with surface ≡Me‐OH, while F− was retained by formation of monodentate surface complexes. CONCLUSION: The removal mechanisms were confirmed by X‐ray photoelectron spectroscopy. These MBOs were found to be effective for simultaneous removal of arsenic and fluoride from water. This study also demonstrated that the incorporation of multi‐components and mesoporosity into one composite is an efficient strategy for design and application of high‐efficiency adsorbents for environmental remediation of aqueous contaminants. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

To assess the feasibility of recovering P from water by combining batch adsorption enrichment with struvite crystallization, we prepared four ternary layered double hydroxides (LDHs) with P-preferring elements (i.e., zirconium (Zr) or lanthanum (La)) via a facile coprecipitation method, and evaluated their performance in recovering P from water, particularly in enriching P from a low-level P solution. We find that all ternary LDHs demonstrate remarkably high P adsorption capacities, e.g., 1029.3 mg PO 4 3− g−1 for ZnAlLa, outperforming other LDHs reported so far. Microstructural analyses show that the P uptake mechanisms are attributable to anion exchange, surface complexation and electrostatic attraction. Results of recycling tests indicate that all LDHs present good enrichment for P. Besides, more than 96% of phosphorus in the P-enriched eluates can be efficiently reclaimed via struvite crystallization in a fluidized bed reactor. These findings demonstrate the feasibility of combining adsorption enrichment with struvite crystallization for P recovery. [Display omitted] • Four ternary LDHs with P-preferring elements (Zr or La) were prepared. • These ternary LDHs show high stability against either acidic or basic solution. • These LDHs exhibit superior adsorption capacities of P compared to other LDHs. • P-enriched eluates can be obtained from consecutive adsorption-desorption cycles. • P in the eluates can be efficiently recovered via struvite crystallization in an FBR. [ABSTRACT FROM AUTHOR]

In this study, a class F fly ash and palygorskite have been acid-modified and then evaluated for the adsorption of phosphate in aqueous solution via bench-scale batch experiments. XRD, XRF, SEM, and FTIR were employed to characterize the acid-modified fly ash (MFA) and palygorskite (MPal). Both MFA and MPal show enhanced phosphate adsorption after the modification treatment. The effects of pH, adsorbent dosage, and co-ions on phosphate adsorption, as well as adsorption thermodynamics and kinetics, and leaching features of spent (used) adsorbents were also investigated. The isotherms data fit well with the Langmuir model rather than the Freundlich model, giving maximum capacities (298 K) of 13.3 mg P g − 1 for MFA and 10.5 mg P g − 1 for MPal, respectively. Surface complexation modeling of P adsorption data with the nonelectrostatic generalized composite (GC) approach indicates that phosphate were directly bound to the metal centers by ligand exchange to form two monodentate complexes, ≡ SHPO 4 − and ≡ SPO 4 2 − . The GC model appears to be an easy and efficient tool to provide an insight into the mechanism of phosphate adsorption on complex adsorbents with limited model parameters. Leaching test results suggest that the spent adsorbents can be safely disposed or further reused. [ABSTRACT FROM AUTHOR]

Abstract: Mesostructured ferric oxyhydroxides (MFOs) were synthesized using both cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (SDS) as templates in the present study. For CTAB-templating route, the effect of pH and fluoride ions on the resulting MFOs has been evaluated, and the active role of fluoride ions in promotion the mesostructural ordering was verified. Besides, the effect of solvents and hydrolysis ratio on the synthetic layered MFOs was examined via SDS-templating route. X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen physisorption were employed to characterize the MFOs before two typical MFOs with surface areas of 144.7 and 88.1m2 g−1, respectively, were evaluated as potential adsorbent for As(V) removal. Both MFOs presented adsorption isotherms well fitting the Freundlich equation. The two MFOs exhibited adsorption capacities of 75.19 and 10.68mgg−1, respectively, and could be adopted as adsorbent for As(V) removal. [Copyright &y& Elsevier]

An ordered mesoporous Mg-Al layered double hydroxide (meso-LDH350) with a fairly high Brunauer-Emmett-Teller (BET) surface area (126 m 2 g −1 ) has been facilely synthesized and then evaluated for the adsorptive removal of bromate from aqueous solutions. Adsorbents were characterized by a variety of techniques (e.g., XRD, FTIR, SEM, TG-DSC, N 2 physisorption, XPS, etc.). The adsorption studies indicated that the presence of background electrolytes and competitive anions can obviously repress the uptake of bromate on LDHs. The adsorption isotherms agree well with the Langmuir model, giving a maximum adsorption capacity of 59.34 mg g −1 (pH 7.5, 10 °C) for meso-LDH350, which is much higher than other LDH-type adsorbents reported in literature. The adsorption kinetic data can be well fitted with the pseudo-second-order rate model. Based on the macroscopic and microscopic studies, bromate adsorption on meso-LDH350 was associated with two mechanisms: the reconstruction of the layered structures of meso-LDH350 and the anion-exchange between bromate and the intercalated anions. [ABSTRACT FROM AUTHOR]

• A phenomenon of field-controlling selective adsorption was discovered. • The polarized ZnO rod can work as a self-contained field controller. • Micro ZnO rods exhibit excellent piezoelectric catalytic performance. Exploring robust catalysts is the key to environmental protection. By the controllable exposure of polarization surfaces, the piezoelectric potential of ZnO was optimized, making micro ZnO rods, which have poor photocatalytic performance inherently, unexpectedly exhibit excellent piezoelectric catalytic performance. More importantly, an interesting phenomenon of field-controlling selective adsorption was discovered for the first time. This field-controlling selective adsorption made the ZnO rod work as a self-contained field controller, which can manipulate the migration of dye molecules according to the molecular polarity, enhancing the catalytic performance. Besides, this selective adsorption can help to relieve the hole-sensitive symptoms of ZnO, making ZnO more efficient and robust. Consequently, this study offers a new working prototype of selective adsorption for efficient catalysis. [ABSTRACT FROM AUTHOR]