A novel 3D yttrium based-graphene oxide-sodium alginate hydrogel for remarkable adsorption of fluoride from water.

3D macrostructure adsorbents have attracted great attention in water treatment recently. A series of novel 3D yttrium-based graphene oxide-sodium alginate hydrogels were prepared by sol-gel process for removal of fluoride. The hydrogels displayed a 3D network porous and amorphous structure composed of 2D sheets, with the uniform dispersion of Y(III) onto the gels. The hydrogel Y-GO-SA1.0 was selected as the optimized adsorbent for the fluoride removal due to its best adsorption performance. The adsorption experiments revealed that the maximum adsorption of fluoride occurred at pH 4. The adsorption equilibrium could be achieved within 24 h at both pH 6.5 and optimal pH 4. Based on Langmuir isotherm model, the maximum adsorption capacity of fluoride was 288.96 mg/g at pH 4.0, much higher than many other reported adsorbents. The adsorption was retarded obviously by the presence of phosphate anions. The regenerated hydrogels maintained high adsorption level for fluoride, which could be easily recycled in operation. Furthermore, the column study exhibited that the hydrogel could be used as column packing for effective removal of fluoride via continuous filtration. The column adsorption data was well described by the Thomas model, with the value of q0 much lower than that for batch adsorption experiment under the same initial F- concentration. Finally, the uptake of F- was associated with the release of -OH groups bonded to Y(III) on the gels. These results imply that the present 3D hydrogels can be potentially applied for the treatment of fluoride-containing water.