Highly enhanced dye adsorption of MoO nanoplates fabricated by hydrothermal-calcination approach in presence of chitosan and thiourea.

Water pollution by organic dyes poses great challenge to the environment and living organism. Hence effective removal of organic dyes by cost effective methods have received significant attention in recent years. Herein, we report the complete removal of organic dyes (rhodamine B), methylene blue) and eosin yellow) from water via effective adsorption by MoO catalyst. Hydrothermally synthesised MoO (1) and amorphous MoS (2) using ammonium molybdate without and with thiourea exhibited low dye adsorption. In contrast, crystalline micro/nanoplates of MoO (3 and 4) obtained from calcination of 1 and 2 showed highly enhanced dye adsorption. Particularly 4 showed higher dye adsorption compared to 3. UV-Visible absorption studies confirmed complete removal of organic dyes upon stirring with MoO catalyst. Dye removal studies further revealed that cationic dyes are adsorbed faster than anionic dye that could be attributed to the surface charge of MoO. Interestingly, the adsorbed dyes were not released from MoO for more than 50 days. The exhausted MoO catalyst can be recovered by annealing at 400 °C. MoO catalyst has also been used as packing materials in dropper column and demonstrated effective removal of dyes by passing through dyes separately as well as mixture.