Search

[Display omitted] Hazardous oxyanions in water bodies are potentially toxic to aquatic life, and the coexistence of multiple anions aggravates the toxicity. Herein, bowknot-like Zr/La bimetallic organic frameworks (Zr/La-BTC) were developed with superior hazardous oxyanion adsorption capacities, i.e., approximately 102 mg/g for arsenate and 159 mg/g for phosphate, respectively. The molar ratio of Zr to La in Zr/La-BTC plays a significant role in the structure and the adsorption efficiencies. Notably, the experiment-derived adsorption capacities of various Zr/La-BTC samples were consistent with their adsorption energies calculated by density-function theory (DFT). Further mechanism analysis revealed that coordination of Zr/La atoms with the target anion groups occurred during adsorption. The positive shift of binding energies in La 3d and Zr 3d XPS spectra and Bader charge analysis unveiled that back-donation interactions dominated the adsorption process. The reliable adsorption selectivity and reusability of 0.1Zr/La-BTC were verified with anion competition experiments and four adsorption-desorption cycles. Overall, this study provides significant insight into the design of high-performance bimetallic organic frameworks for the enhanced removal of hazardous oxyanions from water. [ABSTRACT FROM AUTHOR]

• A 3D rice-like hierarchical nanocomposite was designed by anchoring La species into LDH matrix. • La@MgAl achieved high adsorption capacities for both phosphate and fluoride. • Satisfactory selectivity and reusability of the adsorbent were proved. • Interlayer sorption and inner-sphere complexation were main mechanisms for excellent adsorption performance. • La@MgAl was effective for synchronous phosphate and fluoride remediation in real wastewater. The frequent occurrence of algae boom and skeletal fluorosis has drawn global attention to developing feasible technologies for phosphate and fluoride removal from water bodies. This study reported the synthesis of novel three-dimensional rice-like La@MgAl nanocomposites by anchoring La species into Mg-Al LDH matrix to achieve effective and synchronous phosphate and fluoride capture. Results from multiple detection methods including XRD, SEM, FTIR, and XPS revealed the introduced La cations could serve as a structural inducer to regulate the crystallinity of the La@MgAl composites and rice-like nanocomposite La@MgAl-1 was fabricated under optimal La loading amount. La@MgAl-1 possessed high adsorption capacities for both phosphate and fluoride (101.59 mg/g and 51.03 mg/g, respectively). The effective adsorption performance also sustained even after five adsorption-desorption cycles, indicating favorable reusability. The adsorption mechanism analysis revealed that the presence of unique hydrotalcite-like structure triggered memory effect to exert strong adsorption of P and F anions into the interlayered gallery. Besides, an optimum amount of La species organized on the composite wielded specific anion adsorption to phosphate and fluoride through inner-sphere complexation and ligand exchange. These encouraging results highlight the positive consequence of combining the strategic La species and LDH matrix to render a nanostructured Mg/Al/La ternary metal assembly in which various components are united in a controllable way to exert collective properties for accumulative anion adsorption properties. Besides, this study offered promising candidates for real water purification against phosphate and fluoride pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene oxide contributed to hierarchical porosity of PVDF fibers. • Appropriate fiber diameter and pore size prevented MOF from leakage. • Continuous filtration of arsenate from water was achieved. • Arsenate anions accepted electrons from MOFs during adsorption. Excessive toxic arsenic in surface water and groundwater is a prevalent worldwide problem. A novel hierarchical porous fibrous membrane (PG/MOF), incorporating Zr-based metal organic framework (MOF-808) and graphene oxide (GO), was fabricated for arsenate removal. The well-developed nanoporous fibrous skeleton allows the exposure of adsorption sites of MOF-808 for effective arsenate removal and avoids leakage. Systematic studies on adsorption isotherms, kinetics, and filtration processes determined the practical applicability of the PG/MOF. The maximum adsorption capacity obtained from the Langmuir model was over 180 mg/g. Mechanistic analysis via SEM, FTIR, and XPS revealed that coordination and π − π interaction is responsible for the superior adsorption performance. Adsorption energy and Bader charge analysis based on DFT calculations indicated that arsenate anions are spontaneously adsorbed near the benzene ring of MOF-808 on PG/MOF. This study identified a promising method for fabricating hierarchical porous MOF-based nanofibers and provides insight into the mechanisms of arsenate adsorption. [ABSTRACT FROM AUTHOR]

• A cost-effective periclase-based pathway was proposed for adsorbent synthesis. • Novel Mg-La bimetal oxide nanocomposite was prepared. • Optimal urea amount induced 3D needle-like nanostructure. • Superior P and F adsorption capacities were achieved. • Inner-sphere complexation dominated the adsorption mechanism. Phosphate and fluoride are primary culprits of water eutrophication and skeleton fluorosis, respectively, severely threatening the security of aquatic lives and public health. To deal with the aqueous phosphate and fluoride pollution, PC@La nanocomposites were tailor-designed based on low-cost periclase and lanthanum salt via a facile urea hydrothermal method. Results from SEM, XRD, FTIR, XPS analysis revealed the PC@La-1.0 was constructed by Mg-La bimetal carbonated hydroxides with the three-dimensional needle-like nanostructure. Highly effective adsorption capacities for both phosphate (107.34 mg/g) and fluoride (63.11 mg/g) were achieved by PC@La-1.0. The adsorption was pH-dependent, and the optimal pH values for adsorption was 4.0–6.0. Over 80% of initial adsorption capacities remained after four adsorption–desorption cycles, indicating its satisfactory reusability. Superior adsorption selectivity for phosphate and fluoride was proven when co-existing with common ions and organics in solutions and real sewage. Mechanism analysis revealed that the unique structure of Mg-La bimetal carbonate hydroxide structure of PC@La-1.0 promoted an accumulative anion adsorption performance. Mg and La cations on PC@La-1.0 formed strong inner-sphere complexation with target phosphate and fluoride while the internal carbonate and hydroxyl groups contributed to adsorption via ion exchange. This study highlights the novel low-cost method to prepare promising candidates for efficient dephosphorization and defluorination from water. [ABSTRACT FROM AUTHOR]

[Display omitted] • A functionalized carboxymethyl chitosan aerogel is explored for Cu(Ⅱ) adsorption. • The maximum capacity of PCCSA-1.0 for absorbing Cu(Ⅱ) is 175.56 mg/g. • Continuous filtration of industrial wastewater with fixed bed columns is achieved. • PCCSA-1.0 is conducive to inhibit the enrichment of Cu(Ⅱ) ions in rice. • The generated waste after adsorption is converted into a material for secondary use. Copper ions (Cu(II)) in water pose a huge threat to human health and ecosystem security. Therefore, developing eco-friendly and sustainable strategies to eliminate the toxicity risk of Cu(II) in the aqueous environment remains a great challenge. In this work, an elastic polyethyleneimine-modified carboxymethyl chitosan aerogel was developed via a freeze-drying process for the adsorption of Cu(II). The adsorption kinetic and isotherm experiments demonstrated that the adsorption process was monolayer chemisorption and the maximum adsorption capacity calculated from Langmuir model was 175.56 mg g−1. The obtained aerogels exhibited preferential selectivity for Cu(II) even when the competing cations and organics existed. Besides, about 0.93 g of aerogel realized continuous fixed-bed column filtration of industrial wastewater with an effective purification volume of 4.14 L. Mechanistic analysis via FTIR and XPS revealed that the excellent adsorption performance for Cu(II) might be attributed to the strong electrostatic force, Vander Waals' force and coordination of N/O -containing functional groups. It is worth mentioning that the adsorbed Cu(II) ions in the aerogel were converted into a reusable photocatalyst, avoiding the secondary leakage of heavy metals. This work opened a door to synthesize carboxymethyl chitosan aerogel, promising for heavy metal wastewater treatment and realizing the concept of waste utilization. [ABSTRACT FROM AUTHOR]

The over-reliance on tetracycline antibiotics (TC) in the animal husbandry and medical field has seriously affected the safety of the ecological environment. Therefore, how to effectively treat tetracycline wastewater has always been a long-term global challenge. Here, we developed a novel polyethyleneimine (PEI)/Zn-La layered double hydroxides (LDH)/cellulose acetate (CA) beads with cellular interconnected channels to strengthen the TC removal. The results of the exploration on its adsorption properties illustrated that the adsorption process exhibited a favorable correlation with the Langmuir model and the pseudo-second-order kinetic model, namely monolayer chemisorption. Among the many candidates, the maximum adsorption capacity of TC by 10 %PEI-0.8LDH/CA beads was 316.76 mg/g. Apart from that, the effects of pH, interfering species, actual water matrix and recycling on the adsorption of TC by PEI-LDH/CA beads were also analyzed to verify their superior removal capability. The potential for industrial-scale applications was expanded through fixed-bed column experiments. The proven adsorption mechanisms mainly included electrostatic interaction, complexation, hydrogen bonding, n-π EDA effect and cation-π interaction. The self-floating high-performance PEI-LDH/CA beads exploited in this work provided fundamental support for the practical application of antibiotic-based wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • SA/PEI-0.25 aerogel showed high elastic, stability and adsorption performance. • The maximum adsorption capacities of Cr(VI) and Cd(II) were 678.67 and 464.23 mg/g. • The fixed-bed continuous filtration of Cr(VI) and Cd(II) wastewater was realized. • SA/PEI-0.25 aerogel reduced the toxicity of heavy metal ions to rice. • The adsorption mechanisms of Cr(VI) and Cd(II) were investigated. Herein, an elastic polyethyleneimine/sodium alginate aerogel was designed by a one-step freeze-drying method. The 3D honeycomb-like structure endowed it excellent compressibility and plentiful exposed adsorption sites to accelerate Cr(VI) and Cd(II) adsorption. The adsorption processes matched the pseudo-second-order and Langmuir models, and the saturated adsorption capacity for Cr(VI) and Cd(II) was 678.67 and 464.23 mg/g, respectively. The obtained aerogel still expressed superior removal performance for Cr(VI) and Cd(II) even in the coexistent of multiple interfering factors and maintained stable adsorption capacity at least after 5 cycles. Importantly, the elastic cylindrical aerogel (∼0.59 g) could achieve dynamic filtration of industrial wastewater containing Cr(VI) and Cd(II) in fix-bed column system with corresponding effective treatment volume of 4.47 and 3.25 L, respectively. The reasonable mechanisms for the adsorption behaviors of heavy metals on the as-prepared aerogel was investigated via FTIR, XPS and Density functional theory (DFT), which could be attributed to the surface electrostatic adsorption, chelation and reduction effects. Eventually, the ecological assessment verified that eco-friendly SA/PEI aerogel had a powerful auxiliary effect on the anti-fouling growth of rice. Overall, such novel biomass aerogel adsorbent possessed great application potential and theoretical guiding significance for the purification of heavy metal wastewater. [ABSTRACT FROM AUTHOR]

The extensive use of tetracycline (TC) as veterinary therapeutics and animal growth promoters has caused human health problems. Some adsorbents have been developed to remove TC, but the adsorption capacity is still unsatisfactory. Here, we synthesized octahedral cuprous oxide nanocrystals (oct-Cu 2 O NCs) by a hydrothermal method at room temperature. Surprisingly, the maximum adsorption capacity of oct-Cu 2 O NCs reached an astonishing amount of 1112.6 mg/g. Adsorption kinetics and isotherm experiments for TC removal were carried out to evaluate its potential as an adsorbent. The key factors like pH and solution ions as well as the mechanism of TC adsorption on oct-Cu 2 O NCs were also studied. The main adsorption process may be that the hydroxyl group (-OH) on the {111} facets surface of oct-Cu 2 O NCs is replaced by the amino group (-NH 2) of TC. The high adsorption capacity is generated by the abundant Cu atoms with dangling bonds on the {111} facets surface and the strong chemical coordination between the -NH 2 of TC and Cu(I). This work provides an alternative with a promising application prospect for the treatment of TC in water. Unlabelled Image • Oct-Cu 2 O NCs with {111} facets were prepared through a simple hydrothermal method. • Oct-Cu 2 O NCs possess excellent tetracycline adsorption performance. • A large number of adsorption active sites are on the {111} facets. • Strong adsorption is generated by the coordination between -NH 2 of TC and Cu(I). [ABSTRACT FROM AUTHOR]