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A new adsorbent, Fe 3 O 4 sulfonated magnetic nanoparticle (Fe 3 O 4 -SO 3 H MNP), was developed for heavy metal ions removal from water, which could be effectively separated from the solution owing to the superparamagnetic property. The nanoparticles can be used to remove heavy metal ions due to the additional active site, “sulfo-group”, introduced by the AMPS branches grafted onto the iron oxide. The as-synthesized materials were characterized by SEM, TEM, FT-IR and BET. The FTIR, XPS and Zeta potential were used to describe the adsorption mechanism. The Fe 3 O 4 -SO 3 H MNPs showed rapid removal for Pb 2+ and Cd 2+ with maximum of adsorption capacity of 108. 93 and 80.9 mg/g at 25 °C, respectively. The adsorption isotherms for Pb 2+ and Cd 2+ fitted better with Langmuir than Freundlich models, indicated that the processes of the removal of Pb 2+ and Cd 2+ could follow a kind of similar adsorption manner. The adsorption kinetic was consistent with pseudo-second-order model. Furthermore, the reuse experiments results showed the adsorbent might have potential in treating heavy metal ions pollution in water. [ABSTRACT FROM AUTHOR]

A biocompatible and novelly-defined adsorption membrane for rapid removal of fluoride was prepared. Both adsorption and membrane techniques were used in this research. Al(OH) 3 nanoparticles modified hydroxyapatite (Al-HAP) nanowires were developed and made into Al-HAP membrane. The adsorption data of Al-HAP adsorbent could be well described by Freundlich isotherm model while the adsorption kinetic followed pseudo-second-order model. The maximum of adsorption capacity was 93.84 mg/g when the fluoride concentration was 200 mg/L. The adsorption mechanism was anion exchanges and electrostatic interactions. The contribution rates of HAP nanowires and Al(OH) 3 nanoparticles in fluoride removal were 36.70% and 63.30%, respectively. The fixed-bed column test demonstrate that the Al-HAP was biocompatible and in a good stability during the process of water treatment. The fluoride removal abilities of Al-HAP membrane with 0.3 mm thickness could reach 1568 L/m 2 when fluoride concentrations were 5 mg/L. This study indicated that the Al-HAP membrane could be developed into a very viable technology for highly effective removal of fluoride from drinking water. [ABSTRACT FROM AUTHOR]

A novelly-defined adsorption membrane for rapid removal of fluoride from drinking water was prepared. Both zirconium metal-organic frameworks (Zr-MOFs) adsorbent and membrane with large specific surface area of 740.28 m 2 /g were used for fluoride removal for the first time. For adsorption technique, fluoride adsorption on Zr-MOFs was studied on a batch mode. The adsorption data could be well described by Langmuir isotherm model while the adsorption kinetic followed pseudo-second-order model. The maximum of adsorption capacity was 102.40 mg/g at pH 7.0 when the initial fluoride concentration was 200 mg/L. The FT-IR and XPS analyses of Zr-MOFs revealed that both surface hydroxyl groups and Zr(IV) active sites played important roles in fluoride adsorption process. The as-prepared Zr-MOFs adsorbent was suitable for practical treatment of drinking water and regeneration by sodium hydroxide solution (3 wt%). For membrane experiments, Zr-MOFs membrane supported on Alumina substrate could remove fluoride efficiently through dynamic filtration. The fluoride removal capability of Zr-MOFs membrane depended on flow rate and initial concentration of fluoride. The fluoride removal abilities of Zr-MOFs membrane with 20 μm thickness could reach 5510, 5173, and 4664 L/m 2 when fluoride concentrations were 5, 8 and 10 mg/L, respectively. This study indicated that Zr-MOFs membrane could be developed into a very viable technology for highly effective removal of fluoride from drinking water. [ABSTRACT FROM AUTHOR]

Porous helical carbon fibers were fabricated by the bio-inspired process, which show much higher adsorption capacity for sulfamethoxazole than that of single carbon material or carbon-based composite. It is found that the ultrahigh specific surface area, narrow pore size range and helical structure of carbon fibers are responsible for its good performance. Helical carbon fibers (HCFs) are a new kind of fascinating carbon material, and have caused much attention for their distinctive features, diversified novel properties, and applications. However, the application of HCFs still faces a series of barriers, especially in the repetitive preparation of HCFs. In this paper, we initially report the synthesis of the HCFs with ultrahigh specific surface area (3089 m2 g−1) by a bio-template process using the high purified spiral vessels (SVs) as the template. The helical structure with the ultrahigh specific surface area can efficaciously shorten the pathway for antibiotics diffusion, and the high content of nanopores (1 to 3 nm) not only guarantees the accessibility of the surface for antibiotics storage but also easily provides approachable channels for antibiotics transmission. The highest adsorption capacity for sulfamethoxazole (SMX) is 1091 mg/g at pH 6.0 ± 0.1 with a stable temperature of 20 °C when the initial SMX concentration is 80 mg/L. This study motivates a new bio-inspired design for preparing the high purified HCFs with a simple bio-template method. The results show that the porous HCFs are a new kind of ultrahigh adsorption material for the removal of SMX in aqueous solution and can be used in new technological applications. [ABSTRACT FROM AUTHOR]

• MnO 2 /GO nano-hybrids were fabricated under mild conditions. • More than 91% norfloxacin was degraded within 20 min. • The mineralization rates of norfloxacin could reach to 76%. • Possible degradation pathways were proposed. In this work, 1D MnO 2 nano-needles were prepared and grown on the graphene oxide (GO) nano-sheets successfully. The morphology and structure of materials were explored. The MnO 2 nano-needles with a length of 200–400 nm were distributed uniformly on the GO nano-sheets. As a result of GO substrate, the MnO 2 /GO nano-hybrids (MnO 2 /GO) have the much larger surface area and more surface oxygen-containing functional groups than MnO 2 nano-needles, which are beneficial for enrichment and degradation of the norfloxacin (NOR). Results showed that more than 80% NOR was degraded within 20 min at the dose of 10 mM PMS and 0.8 g/L catalysts. Moreover, the optimal pH in MnO 2 /PMS and MnO 2 /GO/PMS system were both acidic condition. Furthermore, the mechanism of PMS activation by MnO 2 /GO was investigated through radical identification using quenching experiments and EPR techniques. According to this, the HSO 5 − of PMS reacted with Mn (IV)/Mn(III) to form a redox loop, and GO played an important role in the degradation process. Finally, the transformation intermediates of NOR were identified and four probable degradation pathways were speculated. This work would provide a potential contribution towards NOR removal in the environmental remediation. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Consumption of water having excessive arsenic (As) contamination can cause adverse health effects on human beings. In this study, novel ultra-large zirconium oxide (ZrO 2) nanosheets were successfully synthesized using graphene oxide (GO) templates and their adsorption-ability was studied for arsenite (As(III)). Owing to higher values of surface area, numbers of available hydroxyl groups and strong chemisorption binding affinity towards As(III), the synthesized novel ultra-large ZrO 2 nanosheets showed high adsorption-ability for As(III) over a wide pH range. Experimental results demonstrated that the maximum adsorption-ability of the ZrO 2 nanosheets for As(III) reached to 74.9 mg/g at pH 6. BET, zeta potential, effect of initial pH, FTIR and XPS have been used to analyze the As(III) adsorption process on the ZrO 2 nanosheets. The experiments for effects of co-existing ions indicated that ZrO 2 nanosheets possessed good anti-interference ability towards co-existing ions. Furthermore, the ZrO 2 nanosheets demonstrated very fast and excellent treatment of simulated real As(III) polluted water, consequently the effluent concentration met the standard regulated by World Health Organization. This study suggested that the as-prepared ZrO 2 nanosheets could be potentially applied in practical drinking water treatment. [ABSTRACT FROM AUTHOR]

Increasing exposure to arsenic (As) contaminated ground water has become a global health hazard to humanity. Suitable adsorbent for As removal from water, especially for As(III) than As(V), is an urgent but still a challenging task. In this study, waste orange peel (OP) was modified with magnetic nanoparticles followed by calcination as a novel adsorbent and investigated for instantaneous oxidation and adsorption of As(III) from aqueous solutions. The batch adsorption experimental results showed that calcined magnetic orange peel composites (CMOPC) exhibited superior As(III) adsorption capacity (10.3 mg/g) as compared to similar cost effective adsorbents due to its high surface area, large pore size and greater numbers of active sites on its surface. The adsorption equilibrium data obeyed Langmuir model, and kinetic data was well described by the pseudo-second-order model. The adsorption mechanisms for As(III) might be involved ligand exchange of the hydroxyl in CMOPC to form Fe-O-As(III), and partial As(III) oxidation to As(V) followed by instantaneous adsorption on surface of CMOPC. The developed adsorbent has also demonstrated good anti-interference ability to co-existing ions, admirable regeneration ability and pronounced capacity in treating simulated real As(III) contaminated water. This study revealed that waste orange peel, after simple treatment could be used as a potential adsorbent for As(III) from aqueous solutions. [ABSTRACT FROM AUTHOR]

A new uniform-sized CeCO 3 OH nanosphere adsorbent was developed, and tested to establish its efficiency, using kinetic and thermodynamic studies, for fluoride removal. The results demonstrated that the CeCO 3 OH nanospheres exhibited much high adsorption capacities for fluoride anions due to electrostatic interactions and exchange of the carbonate and hydroxyl groups on the adsorbent surface with fluoride anions. Adsorption kinetics was fitted well by the pseudo-second-order model as compared to a pseudo-first-order rate expression, and adsorption isotherm data were well described by Langmuir model with max adsorption capacity of 45 mg/g at pH 7.0. Thermodynamic examination demonstrated that fluoride adsorption on the CeCO 3 OH nanospheres was reasonably endothermic and spontaneous. Moreover, the CeCO 3 OH nanospheres have less influence on adsorption of F − by pH and co-exiting ions, such as SO 4 2− , Cl − , HCO 3 − , CO 3 2− , NO 3 − and PO 4 3− , and the adsorption efficiency is very high at the low initial fluoride concentrations in the basis of the equilibrium adsorption capacities. This study indicated that the CeCO 3 OH nanospheres could be developed into a very viable technology for highly effective removal of fluoride from drinking water. [ABSTRACT FROM AUTHOR]

A novel adsorbent, hydroxyl aluminum oxalate (HAO), for the high efficient removal of fluoride from aqueous solution was successfully synthesized. The adsorbent was characterized and its performance in fluoride (F − ) removal was evaluated for the first time. Kinetic data reveal that the F − adsorption is rapid in the beginning followed by a slower adsorption process; 75.9% adsorption can be achieved within 1 min and only 16% additional removal occurred in the following 239 min. The F − adsorption kinetics was well described by the pseudo second-order kinetic model. The calculated adsorption capacity of this adsorbent for F − by Langmuir model was 400 mg g −1 at pH 6.5, which is one of the highest capabilities of today’s materials. The thermodynamic parameters calculated from the temperature-dependent isotherms indicate that the adsorption reaction of F − on the HAO is a spontaneous process. The FT-IR spectra of HAO before and after adsorbing F − show adsorption mechanism should be hydroxyl and oxalate interchange with F − . [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical Fe 3 O 4 /Co 3 S 4 nanosheets were prepared via one step phase transformation. • Fe 3 O 4 /Co 3 S 4 /PMS system achieved a great degradation on 200 mg/L of RhB. • SO 4 •− was the dominated reactive oxygen species in this Fenton-like process. • The introduction of S promoted the electron cycle of Co3+/Co2+ and Fe3+/Fe2+. • Fukui function based DFT did help to precisely predict the radical reactive sites on RhB. Fenton-like catalysts have usually superior catalytic activities, however, some drawbacks of ion leaching and difficult-to-recovery limit their applications. In this work, a hierarchical porous Fe 3 O 4 /Co 3 S 4 catalyst was fabricated via a simple phase change reaction to overcome these shortcomings. The introduced iron cooperates with cobalt achieving high-efficiency activation of peroxymonosulfate (PMS) to eliminate Rhodamine B (RhB). The results showed that 0.05 g/L Fe 3 O 4 /Co 3 S 4 and 1 mM PMS could quickly remove 100% of 200 mg/L RhB within 20 min, and the removal rate of RhB remained above 82% after 5 cycles. Moreover, the as-prepared Fe 3 O 4 /Co 3 S 4 possessed a great magnetic separation capacity and good stability of low metal leaching dose. Radical quenching experiments and electron paramagnetic resonance (EPR) techniques proved that sulfate radicals (SO 4 •−) were the dominant reactive oxygen species responding for RhB degradation. X-ray photoelectron spectroscopy (XPS) pointed out that the synergism of sulfur promoted the cycling of Co3+/Co2+ and Fe3+/Fe2+, boosting the electron transfer between Fe 3 O 4 /Co 3 S 4 and PMS. Moreover, the degradation pathways of RhB were deduced by combining liquid chromatography-mass spectrometry (LC-MS) analysis and density functional theory (DFT) calculations. The toxicities of RhB and its intermediates were evaluated as well, which provided significant assistance in the exploration of their ecological risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-ISAs@CN is effective in a wide range of pH. • More than 90% SDZ have been degraded within 30 min. • Good degradation effect could be maintained after several cycles. • Possible degradation pathways have been proposed. The use of single-atom iron catalysts in heterogeneous Fenton-like reactions has demonstrated tremendous potential for antibiotic wastewater treatment. In this study, single-atom iron fixed on nitrogen-doped porous carbon materials (Fe-ISAs@CN) was synthesised using a metal organic framework (MOF) as a precursor. Fe-ISAs@CN was applied as a heterogeneous Fenton catalyst to activate H 2 O 2 for the degradation of sulfadiazine (SDZ) in an aqueous solution. The physical and chemical properties of Fe-ISAs@CN were characterised by scanning electron microscopy (SEM), transmission electron microscope (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and rotating disk electrode (RDE) measurements. The results of our degradation experiments indicated that Fe-ISAs@CN exhibited remarkable activity and stability for the degradation of SDZ over a wide pH range; even after five cycles, Fe-ISAs@CN retained a high catalytic efficiency (>80%). The 5,5-dimethyl-1-oxaporphyrin- n -oxide (DMPO)-X signal captured by electron paramagnetic resonance (EPR) spectroscopy indicated that a large amount of hydroxyl radicals (OH) was produced in the reaction system. Quench tests indicated that the OH was the main active substance in the degradation of SDZ. The degradation products of the reaction were analysed by High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), and possible degradation pathways for the SDZ degradation were proposed. [ABSTRACT FROM AUTHOR]

A novel environment friendly adsorbent, micro–nano hierarchical structured flower-like MgO/MgCO 3 (MHS-MgO/MgCO 3 ), was developed for fluoride removal from water. The adsorbent was characterized and its defluoridation properties were investigated. Adsorption kinetics fitted well the pseudo-second-order model. Kinetic data revealed that the fluoride adsorption was rapid, more than 83–90% of fluoride could be removed within 30 min, and the adsorption equilibrium was achieved in the following 4 h. The fluoride adsorption isotherm was well described by Freundlich model. The maximum adsorption capacity was about 300 mg/g at pH = 7. Moreover, this adsorbent possessed a very wide available pH range of 5–11, and the fluoride removal efficiencies even reached up to 86.2%, 83.2% and 76.5% at pH = 11 for initial fluoride concentrations of 10, 20 and 30 mg/L, respectively. The effects of co-existing anions indicated that the anions had less effect on adsorption of fluoride except phosphate. In addition, the adsorption mechanism analysis revealed that the wide available pH range toward fluoride was mainly resulted from the exchange of the carbonate and hydroxyl groups on the surface of the MHS-MgO/MgCO 3 with fluoride anions. [ABSTRACT FROM AUTHOR]