Synthesis and adsorption study of NiOnanobelts for removal of anionic dyes

NiO nanobelts with 40–90 nm in width and several tens of micrometer in length were synthesized by a hydrothermal reaction and subsequent calcination. They possessed high specific surface area of 102.4 m 2 /g and behaved as an efficient adsorbent for removal of anionic dyes including methyl blue (MB; 1,996 mg/g), methyl orange (MO) (1,291 mg/g), and Congo red (CR) (331 mg/g). The adsorption kinetics and adsorption mechanism were investigated systematically. The adsorption for MB was well represented by Langmuir isotherm model, while the adsorption kinetics was well described by the pseudo-second-order model. Fourier transform infrared studies revealed that the good adsorption capacity for anionic dyes could be largely attributed to the electrostatic attraction between SO 3 – group in dye molecule and positively charged surface of NiO. Our NiO nanobelts showed much higher adsorption capacity for MO and CR compared with other transition metal oxides and NiO nanosheets reported previously. Our product is expected to be promising material for wastewater treatment.