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An aluminum sludge-based composite material was constructed against the problems of phosphorus pollution and the waste of aluminum sludge resources. Utilizing metal Ce doping and hydrogel microbeads with pore preparation, the adsorption performance of the original sludge was improved. Meanwhile, the macroscopic body was constructed, and on this basis, polyethyleneimine (PEI) was introduced to complete the amino functionalization further to enhance the adsorption of phosphorus by the adsorbent, and NH-CeAIS-10 microbeads were successfully prepared. In adsorption, microbeads with larger specific surface area and richer functional groups are better choice compared to original sludge. The results of SEM, BET, FT-IR, and XPS analyses indicate that the adsorption of phosphorus by the microbeads is mainly achieved through electrostatic interactions, ligand exchange, and the formation of inner-sphere complexes. According to the Langmuir model, the maximum phosphorus adsorption capacity of NH-CeAIS-10 was 29.56 mg g−1, which was four times higher compared to native aluminum sludge. This also confirms the significant enhancement of phosphorus adsorption through the modification of aluminum sludge. Besides, in dynamic adsorption column experiments, the material exhibited up to 99% removal in simulated wastewater for up to 30 days, demonstrating the great adsorption potential of NH-CeAIS-10 in engineering applications. [ABSTRACT FROM AUTHOR]

The extensive utilization of fluorine industrial products has brought abundant fluorine pollution. The fluorine removal is important. In this study, CaO, as a novel coprecipitator, was conducted to synthesize Ca‐Fe‐SO4 layered double hydroxide (CF) via co‐precipitation of FeSO4. Ca‐Fe mixed metal oxide adsorbent (CCF) was fabricated by calcinating CF for efficient fluoride adsorption. The results showed that CCF adsorbent had an excellent adsorption performance for fluoride. It was attributed to two reasons as follows: On one hand, Ca had a strong affinity for fluoride, improving the adsorption capacity of adsorbent for fluoride. On the other hand, Fe had a strong magnetism, which could promote the recovery of the adsorbed material. The adsorption capacity of CCF for fluorine was analyzed by batch adsorption experiments, the adsorption capacity was 160.66 mg/g at temperature of 298 K and pH of 7. Moreover, the adsorption process of fluorine and the actual adsorption process were in accordance with Langmuir model and the pseudo‐second‐order kinetic model, respectively. According to the analysis of pHzpc, FITR and XPS, the main adsorption mechanisms of CCF for fluoride in water were complexation and electrostatic interactions. Therefore, this study suggested that CaO can be a novel coprecipitator to prepare a new efficient fluorine adsorbent for the treatment of industrial wastewater. [ABSTRACT FROM AUTHOR]

To explore an economic Fluoride-adsorbent with high capacity and superior selectivity as well as easy regeneration, a new synthetic strategy was constructed through a hydrothermal procedure with the aid of glucose to prepare high performance adsorbent ZrO 2 -MgO@C composite (CZMC). The adsorption capacity and the selectivity toward fluorine ions were evaluated for the synthesized adsorbents. Through characterizations of XRD, BET, SEM, HRTEM, XPS, etc., the crystal structure, the morphology and the chemical composition of the adsorbents were analyzed, illustrating that CZMC has the desirable structure with high dispersion of metal oxides in the porous carbonized microspheres. The results indicate that ZrO 2 -MgO@C composite show the F-ions adsorption capacity of 184.5 mg/g, with excellent resistance toward disturbance of other anions including NO 3 −, Cl−, SO 4 2−, CO 3 2− and PO 4 3−. DFT calculations show that the adsorption process of fluorine ions occurs spontaneously and accompanied by orbital hybridization of surface atoms. Such composite adsorbent having high adsorption capacity and superior F-selectivity as well as the feature of easy regeneration would possess promising applications in the treatment of waste water containing fluorine ions. • ZrO 2 -MgO@C was investigated for fluoride treatment. • Surface reaction is explored by DFT analysis. • Electrostatic attraction, ion exchange, and surface complexation are adsorption mechanisms. • Theoretical adsorption capacity was 184.5 mg/g. • The adsorbent has good regeneration performance and practical application value. [ABSTRACT FROM AUTHOR]

• Ca-modified Mg-Zr MMO was investigated for fluoride treatment. • The maximum adsorption capacity of the CCMZ reached 144.05 mg/g. • Electrostatic attraction and ion exchange are adsorption mechanisms. • The agglomeration of the products was effectively avoided. Fluoride removal is an urgent problem in the field of water treatment. In this study, fluoride adsorption was performed using Ca-Modified Mg-Zr Mixed Metal Oxides (CCMZ), which was successfully prepared by a green hydrothermal process followed by high-temperature calcination. CCMZ was prepared using a lamellar MgO and ZrO 2 Mixed Metal Oxide (MMO). Then, calcium (Ca, a strong fluorophilic metal) was dispersed over the MMO, to form a 3D spongy structure. The obtained microstructural features significantly enhanced the fluoride migration and diffusion, resulting in an adsorption capacity of 144.05 mg/g. The agglomeration of the products was effectively avoided, so CCMZ showed good selectivity and reusability. Batch adsorption experiments and subsequent sample characterization showed that the fluoride adsorption mechanism of CCMZ involved electrostatic attraction and ion exchange mechanism. Therefore, this manuscript provides a rational design and a simple preparation method for a new class of fluoride adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calcination of Fe-modified MgO (CMF) was investigated for fluoride treatment. • Electrostatic attraction, ion exchange, and hydrogen bonding are adsorption mechanisms. • Fluoride was adsorbed at a low concentration (10 mg/L) with 95.2% removal rate. • Theoretical adsorption capacity was 126.79 mg/g. • DFT results explain the bonding mode of fluoride and the adsorbent. Three-dimensional porous rhombohedral Fe-modified MgO mixed metal oxide (CMF) adsorbent was successfully prepared via a one-step hydrothermal method without the use of a template and surfactant. This material can be used to remove excess fluoride from water. Because of the integration of Fe, it efficiently responds to low concentrations of fluoride in water, and the resulting adsorbent exhibits lamellar peeling and reorganization; it also captures a large amount of fluoride. The adsorption behavior of fluoride on the surface of CMF conforms to the Freundlich isothermal model and to the pseudo-second-order kinetics model. The maximum adsorption capacity of CMF for fluoride was as high as 126.79 mg/g. Electrostatic attraction, ion exchange, and bonding of fluoride and metal were the adsorption mechanism of CMF. DFT analysis showed that Fe-modified MgO with a low doping rate is more beneficial for the adsorption of fluoride, and the adsorption energy is −1.139 eV. F bonds to metal via orbital hybridization. Moreover, cycling experiments indicated that the material has good reusability and can be used for long-term absorption of fluoride. This task may contribute to the task of developing sustainable water resources, which is beneficial to human life and natural environment. [ABSTRACT FROM AUTHOR]

It is urgent to synthesize a kind of fluoride adsorbent with excellent fluorine removal performance in the field of treating fluorine-containing water. In this study, a magnetic floriform magnesium zirconium hydrotalcite-like material doped with Fe 2 O 3 and ZrO 2 was synthesized by urea hydrothermal method. Fe 2 O 3 and ZrO 2 particles and hexagonal laminae of hydrotalcite in the adsorption materials are uniformly stacked with each other. This structure allows the adsorbent to possess a large specific surface area (48.76 m2·g−1). The results of adsorption experiments indicate that the adsorption capacity of the adsorbent for fluoride can reach 113.38 mg·g−1. In addition, the adsorbent can be applied in a wide pH range (3–10) and has strong resistance to the effect of coexisting anions. After 5 cycles of adsorption, the fluorine removal performance of the adsorbent still maintained 80.93 % of the fresh adsorbent. Finally, DFT calculation of fluoride adsorption on the adsorbent was also carried out, and combined with the results of characterization and adsorption experiments, it is found that electrostatic attraction, hydrogen bond interaction, ion exchange and chemical adsorption are the main mechanisms of adsorption. Therefore, the material may be a potential fluoride adsorbent with good application prospect due to its various excellent properties. • A magnetic floriform magnesium zirconium hydrotalcite-like material doped with Fe 2 O 3 and ZrO 2 was synthesized for the first time. • The adsorption capacity can reach 113.38 mg·g-1, which is far higher than the performance of most adsorbents. • It was found that electrostatic attraction, hydrogen bond interaction, ion exchange and chemiadsorption are main mechanisms. • The material may be a potential fluoride adsorbent with good application prospect due to its various excellent properties. [ABSTRACT FROM AUTHOR]