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Newly few-layered boron nitride (BN-550) nanosheets were developed by a low-temperature synthesis method, which was used to rapidly and efficiently adsorb lead ions (Pb2+). The samples were characterized by using XRD, FT-IR, EELS, SEM, TEM, AFM and XPS, revealing that it possessed the large specific surface area (696 m2 g−1), ultrathin sheet structure (1.2 nm thickness), and abundant chemical bonds as multiple adsorption sites. The adsorption properties showed that higher adsorption capacity (845 mg g−1) for lead ions and less equilibrium time (15 min) than many adsorbents reported at present. The adsorption kinetics and isotherms of BN-550 belonged to the pseudo-second-order model and Langmuir model, respectively. The easy recyclability and stability of BN-550 were verified by the experiments regeneration and pH. Interference experiments indicated that the adsorbents were strong affinity for Pb2+ under the interference of other heavy metal ions such as Ni2+, Cu2+, and Cd2+ ions (their adsorbing capacity individually are 201, 402, and 312 mg g−1). The XPS and FT-IR analysis revealed that the excellent adsorption performances for Pb2+ attributed to the chemical binding reactions with the numerous surface functional groups, such as the strong B-O-Pb interactions and -NH2···Pb complex. The threshold value of Pb2+ removal on BN-550 nanosheets was 1080 mL g−1 when Pb2+ concentration was 50 mg L−1 in adsorption column. The unique characteristics render ultrathin nanosheets highly promising as an ideal candidate for the removal of lead ions. [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]

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]

• UiO-66-NH 2 can effectively remove norfloxacin in water. • UiO-66-NH 2 can remove norfloxacin well in the neutral pH range. • The NH 2 and Zr O bonds play important role for norfloxacin removal. • Various adsorption mechanisms for norfloxacin removal are explored. Antibiotics abuse has been a significant threat to the environment and human health. In this study, we successfully synthesized highly stable amino-functionalized Zr-based metal–organic frameworks (UiO-66-NH 2) and studied the adsorption behaviors of norfloxacin (NOR) in water. The adsorption capacities of UiO-66-NH 2 reached a maximum of 222.5 mg/g for NOR, which were considerably higher than that of most reported adsorbents. Moreover, the equilibrium time (6 h) was less than that of several previously reported adsorbents. Ionic-strength-influenced experiments showed that NaCl and CaCl 2 aqueous solutions could improve the removal efficiency of NOR. The presence of humic acid could barely affect the adsorption amount. At a concentration of 10 mg/L, the highest partition coefficient of 20.9 mg/g/µM was obtained, and the removal rate of NOR was as high as 91.6%, implying that UiO-66-NH 2 offered considerable adsorption performance at a low concentration of NOR. In addition, UiO-66-NH 2 exhibited good regeneration efficiency, thus offering the possibility to remove norfloxacin from sewage. Finally, several credible adsorption mechanisms were proposed. The results will aid us to comprehend the surface interaction between organic micropollutants and UiO-66-NH 2 and prefigure the potential of UiO-66-NH 2 as a novel adsorbent for the removal of NOR. [ABSTRACT FROM AUTHOR]