Synthesis of industrial solid wastes/biochar composites and their use for adsorption of phosphate: From surface properties to sorption mechanism

This paper demonstrates the synthesis of industrial solid wastes /biochars. The produced materials were characterized by means of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). The composites were investigated for the phosphate removal from the aqueous solution. The effect of pH on removal rate was studied in the range from 3 to 12. The kinetic experimental data for phosphate adsorption was confirmed to follow pseudo-second-order kinetics with R-2 > 0.99. Batch adsorption experiments revealed the suitability of the Freundlich model to describe the phosphate adsorption by FA B-F, CG B-F, while Langmuir model was suitable for B-F (where FA: fly ash, CG: coal gangue, B: biochar, and F: ferrite). The maximum adsorption capacities of the three different samples at an initial phosphate concentration of 30 mg/L were 2.39 mg/g with B-F, 3.08 mg/g with FA B-F, and 3.20 mg/g with CG B-F. The experimental results demonstrate that the industrial solid wastes/biochar is a promising alternative material for the restoration of eutrophic water.