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• FeS nanoparticles were effectively decorated onto the surface of GO. • The aggregation of nanoscale FeS decreased with enhanced reactivity. • The nanocomposites GO/FeS displayed an enhanced Cr(VI) sorption capacity. • Both surface sorption and reduction contributed to Cr(VI) removal by GO/FeS. In this paper, a novel graphene oxide (GO) decorated nanoscale FeS composite (GO/FeS) combining both advantages of GO and FeS was synthesized and tested for the highly efficient scavenging of Cr(VI) from aqueous solutions. The as- synthesized materials were characterized by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectra and X-ray photoelectron spectroscopy (XPS) in detail. The results indicated that FeS nanoparticles were effectively decorated onto the surface of GO through −OH, C O, C O, and O=C–O functional groups, resulting in larger specific surface area and higher reactivity The nanocomposites displayed an enhanced Cr(VI) scavenging capacity, and the acidic conditions favored the Cr(VI) scavenging by GO/FeS. The kinetics of Cr(VI) scavenging on GO/FeS nanoparticles was in accordance with the pseudo-second order kinetic model, suggesting that chemical interaction is mainly responsible for Cr(VI) scavenging on GO/FeS. Furthermore, the Langmuir model fit the best, and q max , i.e. the maximum scavenging capacity of Cr(VI) obtained from the Langmuir model reached 138.5 mg/g, Surface sorption and reduction were the dominant scavenging mechanisms for Cr(VI) by GO/FeS. The present study demonstrated the promise of GO/FeS as an effective scavenger for the remediation of Cr(VI) in groundwater environment. [ABSTRACT FROM AUTHOR]

A novel nanocomposite, i.e., molybdenum disulfide nanosheets embellished nanoiron (MoS 2 /NZVI), was synthesized by a modified NaBH 4 reduction procedure, and used for the effective capture of Cr(VI) in water. The characteristic analysis implied that MoS 2 could hinder the aggregation of NZVI. The batch experiments showed that Cr(VI) capture by NZVI/MoS 2 (91.7%) was obviously higher than that of either bare NZVI (62.6%) or MoS 2 (27.05%). The kinetics of Cr(VI) capture can be well described by the pseudo-second-order model. The effects of pH and natural organic matters were also evaluated. Solution pH was found to be significant to Cr(VI) capture, acidic environment (pH 5.0 and 6.0) was more suitable for Cr(VI) capture. However, natural organic matters demonstrated negative effects on Cr(VI) capture. The capture capacity of NZVI/MoS 2 nanocomposite decreased from 126.42 mg/g to 118.48 and 121.07 mg/g when humic acid and fumic acid were present in the solution. X-ray photoelectron spectroscopy analysis of the mechanism indicated that adsorption, reduction, and precipitation were involved in the capture process. The results suggested that the NZVI/MoS 2 nanocomposite may be a potential candidate for the capture of Cr(VI) from wastewater. [ABSTRACT FROM AUTHOR]

• Novel composite material of g-C 3 N 4 decorated FeS was designed and prepared. • The adsorption capacity for U(VI) was 917.1 mg/g at pH = 6.0. • The adsorption isotherm for U(VI) was described by the Freundlich model. In this study, a novel graphitic carbon nitride decorated nanoscale FeS composite (g-C 3 N 4 /FeS) was prepared and performed for the removal of U(VI) in aqueous system. Results revealed that g-C 3 N 4 /FeS had excellent adsorbability, which can reach 917.1 mg/g at 303 K. In addition, the effects of pH, adsorbent dose, contact time and initial U(VI) concentration were investigated by batch experiments. Experimental results indicated the removal of U(VI) on g-C 3 N 4 /FeS was strongly dependent on pH, and the adsorption capacity reached the maximum at pH = 6.0. Kinetics studies under different conditions indicated the removal of U(VI) on g-C 3 N 4 /FeS fitted the pseudo-second-order model well. Furthermore, the adsorption isotherms of U(VI) on g-C 3 N 4 /FeS fitted with Freundlich models well. These results demonstrated that g-C 3 N 4 /FeS could be the promising alternative material for environmental remediation. [ABSTRACT FROM AUTHOR]