Simple synthesis and characterization of Cs0.3WO3.15/Cs3PW12O40 composite for fast adsorption of cationic dyes from water

In this study, cesium-based polyoxometalate compounds (Cs0.3WO3.15/Cs3PW12O40) were successfully synthesized by a simple thermal decomposition method. The effect of phosphoric acid within reaction solution on the phase-change from hexagonal cesium tungstate (Cs0.3WO3.15) to Keggin-type polyoxometalate (Cs3PW12O40) and a novel Cs0.3WO3.15/Cs3PW12O40 composite formation were investigated. The products were characterized by XRD, FTIR, FESEM, EDS, DRS, and nitrogen adsorption-desorption isotherms. The powder samples were applied as adsorbent to remove the dye molecules from water. Results indicated that the Cs0.3WO3.15/Cs3PW12O40 composite exhibits higher adsorption capability toward cationic dyes compared with pure Cs0.3WO3.15 and Cs3PW12O40. The calculated surface area of pure composite was similar to 32.079 m(2)/g, which is larger than that of pure cesium tungstate (similar to 17.267 m(2)/g). The kinetics and isotherms for RhB adsorption on Cs0.30WO3.15/Cs0.30WO3.15 composite were also studied in details.