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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 93.84mg/g when the fluoride concentration was 200mg/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 0.3mm thickness could reach 1568L/m 2 when fluoride concentrations were 5mg/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., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A novel graphitic carbon nitride (g-C 3 N 4 ) nanosheet adsorbent with a large surface area, remarkable hydrophilicity and high adsorption capacity, was presented for the removal of cadmium ions (Cd 2+ ) and methylene blue (MB) from aqueous solution. Adsorption measurements were conducted systematically to study the influences of the contact time, initial concentrations of Cd 2+ and MB, temperature, and pH value. The maximum adsorption capacities of g-C 3 N 4 towards Cd 2+ and MB were 94.4 and 42.1 mg g -1 , respectively, at 318.5 K when the initial concentrations of Cd 2+ and MB were 200 and 20 mg L -1 , respectively. The adsorption kinetics fit a pseudo-second-order model. The high adsorption performance of the g-C 3 N 4 adsorbent can be attributed to the multiple adsorption sites on g-C 3 N 4 , including the π-π conjugate interactions and electrostatic attractions with pollutants in water. In addition, it is significant to achieve high adsorption performance of g-C 3 N 4 nanosheets by efficiently exposing the adsorption sites by adjusting the microstructure surface properties and dispersity in solution., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Novel ultralong hydroxyapatite (HAP) nanowires were successfully prepared for fluoride removal for the first time. The fluoride adsorption on the HAP nanowires was studied on a batch mode. The results revealed that the adsorption data could be well described by the Freundlich model, and the adsorption kinetic followed the pseudo-second-order model. The maximum of adsorption capacity was 40.65 mg/g at pH 7.0 when the fluoride concentration is 200mg/L. The thermodynamic parameters suggested that the adsorption of fluoride was a spontaneous endothermic process. The FT-IR, XPS and Zeta potential analysis revealed that both anion exchange and electrostatic interactions were involved in the adsorption of fluoride. Furthermore, the HAP nanowires were made into HAP membrane through a simple process of suction filtration. Membrane filtration experiments revealed that the fluoride removal capabilities depended on the membrane thickness, flow rate and initial concentration of fluoride. The as-prepared membrane could remove fluoride efficiently through continues filtration. The filtered water amount could reach 350, 192, and 64 L/m(2) when the fluoride concentrations were 4, 5 and 8 ppm, respectively, using the HAP membrane with only 150 μm thickness. The as-synthesized ultralong HAP nanowires were thus demonstrated to be very effective and biocompatible adsorbents for fluoride removal from contaminated water., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Fenton system is one of the most popular methods to eliminate antibiotics and dyes in aquatic environment. However, the existed Fenton system is limited by various factors such as potential second pollution and narrow pH range. In this study, we report that the bottlenecks for high strength antibiotics and dyes wastewater treatment at a wide pH range can be well tackled by the nanoscale "yarn ball"-like Mo/W-containing heteropoly blue (HPB) catalyst Mg 2 Ti 6 Mo 23 O 119 SiW 12 (1). This novel catalyst displayed extremely efficient elimination for several typical organic contaminants such as malachite green (MG), tetracycline (TC) and methyl orange (MO). Compared with other materials reported in previous papers, the catalytic performance of 1 in degradation of the organic contaminants of high concentrations increased several times. More than 90% of antibiotics and dyes are degraded within 60 min. Electron spin resonance (ESR) experiments and UV–vis spectra confirmed that the catalytic mechanisms of 1 could mainly ascribe to the 1 /H 2 O 2 process and the possible photocatalytic oxidation of adsorbed H 2 O by holes (h+) in the valence band (VB) of 1 surface generated · OH for extremely efficient degradation of organic contaminants. This work widens the optimal pH values up to neutral condition and it's significant for the expansion of the heterogeneous Fenton-like catalyst family and its application in the field of water treatment. Image 1 • A HPB Fenton-like catalyst for degradation of antibiotics and dyes. • More than 90% of antibiotics and dyes are degraded within 60 min. • Widening the optimal pH values up to neutral condition. • Expanding the Fenton-like catalyst family and its application in the field of water treatment. [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]

[Display omitted] • Preassembly strategy was adopted to anchor single atoms (SAs) on carbon nitride layers. • These SAs materials exhibit enhanced activity in H 2 O 2 and PMS Fenton-like catalysis. • Intermediates investigation and computational calculation support the ecotoxicity decrease. • The gram-scaled production of SAs materials meets the requirement of industrial catalysis. Here we describe a pyrolyzing coordinated polymer (PCP) preassembly strategy with broad generality to anchor various single atoms (SAs, e.g., Cu, Fe, Co and Mn) on carbon nitride (CN) layers and demonstrate their versatilities in H 2 O 2 and PMS Fenton-like catalysis. As a demonstration of the notion, the Cu single atoms anchored on CN (denoted as SA-Cu-CN) was selected as a model material for water purification and mechanism elucidation. The Fenton-like activity of SA-Cu-CN for doxycycline (DOC) degradation can reach one to two orders of magnitude higher than that of the control materials. Reactive species involving ⋅OH and SO 4 ⋅− are suggested to be the critical oxidants for the degradation of organic pollutants. LC-MS analysis and software calculation confirmed that the contaminant was finally transformed to nontoxic byproducts. This discovery is believed to open an avenue for quickly designing versatile heterogeneous Fenton-like catalysts and promoting their wide environmental applications. [ABSTRACT FROM AUTHOR]

Here we report a defect-engineered WO 3−x @MoS 2 hollow tube that exhibits not only enhanced Fenton-like activity but also improved photoactivity in a wide range of pH as a versatile platform for water purification. Its successful performance was achieved by tuning oxygen defect and band position and investigated using tetracycline degradation and E. coli inactivation experiments as concept demonstration. The activity of WO 3−x @MoS 2 can reach one to two orders of magnitude higher than that of other materials used in this work and the ecotoxicity of intermediates was largely reduced. It exhibits an intrinsic radical character for H 2 O 2 decomposition under dark condition and an efficient photon utilization under visible light irradiation, which is clearly different from the conventional photocatalysts and Fenton reagents. The present strategy of combing the dark Fenton-like and photocatalytic activities extends the applications of the conventional photocatalysts and should be an efficient way of energy utilization. [Display omitted] • Defect-engineered WO 3−x @MoS 2 hollow tube with improved activities was prepared. • Electric field rearrangement and band alignment enhance the photon utilization. • Intrinsic radical character and high carrier separation lead to H 2 O 2 and O 2 reduction. • It exhibits versatilities for (photo-)Fenton-like catalysis in a wide range of pH. • Intermediates identification and software calculation confirm the ecotoxicity decrease. [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]