Study of the preparation of CdS on the surface of geopolymer spheres and photocatalyst performance

Geopolymer spheres (GS) made of chemosynthetic geopolymers are prepared through a suspension solidification method. Cd2+ ions can easily absorb on the surface of the GS via van der Waals forces and ion exchange interactions. A photochemical growth method is used to grow CdS crystal particles homogeneously on the GS surface. The CdS-GS exhibited good adsorption and photocatalytic degradation performance in the decolourisation of methyl orange (MO) with a degradation efficiency of approximately 92.57%. The analysis of the CdS-GS degradation kinetics of MO indicated that it is corresponding to the pseudo-second-order rate equation. The repeating degradation experimental results indicated the CdS-GS photocatalyst had relatively stable photocatalytic performance.