Construction of CdS-Tetrahymena thermophila hybrid system by efficient cadmium adsorption for dye removal under light irradiation.

The water pollution caused by heavy metals and dyes emitted by industries has become a worldwide problem. These pollutants are difficult to be biodegraded. Even at low concentrations, they are toxic and at last threaten human health. Herein, while using Tetrahymena thermophila, a single-celled ciliate protozoa, to enrich and remove the heavy metal Cd from water, CdS nanoparticle-Tetrahymena thermophila hybrid system (CdS-T. thermophila) for dye pollution remediation under light irradiation was developed. The conditions of Cd enrichment and removal by T. thermophila, construction of efficient CdS-T. thermophila, and decolorization of Congo red using CdS-T. thermophila were investigated. In the presence of cysteine ethyl ester, the removal rate of Cd by T. thermophila was 94% at low Cd concentration of 1 mg L. The adsorption capacity of T. thermophila to Cd reached 43 mg g at Cd concentration of 80 mg L. Using 0.1 g L constructed CdS-T. thermophila, the decolorization rate of 50 mg L Congo red solution reached 95% in 60 min under light irradiation. This study provides a new insight to effective removing Cd from water by T. thermophila to construct the CdS-T. thermophila and using it to remediate dye pollution in the environment.