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 Cd2+ from water, CdS nanoparticle-Tetrahymena thermophila hybrid system (CdS-T. thermophila) for dye pollution remediation under light irradiation was developed. The conditions of Cd2+ 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 Cd2+ by T. thermophila was 94% at low Cd2+ concentration of 1 mg L-1. The adsorption capacity of T. thermophila to Cd2+ reached 43 mg g-1 at Cd2+ concentration of 80 mg L-1. Using 0.1 g L-1 constructed CdS-T. thermophila, the decolorization rate of 50 mg L-1 Congo red solution reached 95% in 60 min under light irradiation. This study provides a new insight to effective removing Cd2+ from water by T. thermophila to construct the CdS-T. thermophila and using it to remediate dye pollution in the environment.