Lanthanum molybdenum oxide as a new platform for highly selective adsorption and fast separation of organic dyes

Exploration of new adsorbents for quick and highly selective adsorption and efficient separation of dyes in waste water is in urgent demand due to environmental problems. Herein, a new lanthanum molybdenum oxide adsorbent, La2Mo2O9, is prepared by the calcination of a new crystalline compound [La(CH3COO)(H2O)]MoO4 (La–Mo). After the precursor (La–Mo) is calcined at 600 °C, the as-prepared La2Mo2O9 (abbr. La–Mo600) exhibits fast and highly selective adsorption for multi-sulfonic dyes. Furthermore, the dyes adsorbed on La–Mo600 can be easily eluted by a dilute alkaline solution. Thus, it can be used as a new type of adsorbent to separate dye mixtures. The La–Mo600 adsorbent possesses excellent stability in the pH range of 1–13 and can be easily re-used seven times with a negligible adsorption decline. This study suggests that the adsorbent, La2Mo2O9, may represent a promising new generation of dye adsorbents that can realize quick adsorption, high selectivity and efficient separation of organic dye mixtures.