Wang Junlin,Yi Yongjie,Li Mengjia,Chang Yue,Zha Fei
Graphitic carbon nitride(g-C 3 N 4 ) microspheres supported α-FeO(OH) hybrids[α-FeO(OH)/g-C 3 N 4 ] were prepared by means of a self-assembly method in deionized water. By UV-visible diffuse reflectance spectroscopy, it has been confirmed that α-FeO(OH)/g-C 3 N 4 has a wider absorption range than g-C 3 N 4 . The feature of α-FeO(OH)/g-C 3 N 4 can be attributed to the efficient separation of the electron-hole pairs with photoluminescence spectra. The degradation rate of methyl orange(MO) is up to 99% under the optimal conditions of 110 min, initial concentration of 30 mg/L, an α-FeO(OH)/g-C 3 N 4 dosage of 15 mg as well as visible light. The mechanism for this photocatalytic reaction was proposed, with hydroxyl radicals being a major active catalytic species.
Yunquan Liu,Huimei Shan,Chunya Zeng,Hongbin Zhan,Yanyue Pang
Graphene oxide and chitosan microspheres modified with α–FeO(OH) (α–FeO(OH)/GOCS) are prepared and utilized to investigate the performance and mechanism for Cr(VI) removal from aqueous solutions and the possibility of Fe secondary pollution. Batch experiments were carried out to identify the effects of pH, mass, and volume ratio (m/v), coexisting ions, time (t), temperature (T), and Cr(VI) initial concentration (C0) on Cr(VI) removal, and to evaluate adsorption kinetics, equilibrium isotherm, and thermodynamics, as well as the possibility of Fe secondary pollution. The results showed that Cr(VI) adsorption increased withC0,t, andTbut decreased with increasing pH andm/v. Coexisting ions inhibited Cr(VI) adsorption, and this inhibition increased with increasing concentration. The influence degrees of anions and cations on the Cr(VI) adsorption in descending order were SO42−> PO42−> NO3−> Cl−and Ca2+> Mg2+> Mn2+, respectively. The equilibrium adsorption capacity of Cr(VI) was the highest at 24.16 mg/g, and the removal rate was 97.69% under pH = 3,m/v= 1.0 g/L,T= 298.15 K, andC0= 25 mg/L. Cr(VI) adsorption was well fitted to a pseudo-second-order kinetic model and was spontaneous and endothermic. The best fit of Cr(VI) adsorption with the Langmuir and Sips models indicated that it was a monolayer and heterogeneous adsorption. The fitted maximum adsorption capacity was 63.19 mg/g using the Sips model under 308.15 K. Cr(VI) removal mainly included electrostatic attraction between Cr(VI) oxyanions with surface Fe–OH2+, and the adsorbed Cr(VI) was partially reduced to Cr(III) and then precipitated on the surface. In addition, there was no Fe secondary pollution during Cr(VI) adsorption.Keywords:hydroxyl iron oxide;graphene oxide;chitosan;Cr(VI) adsorption
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