ADSORPTION OF MONOVALENT CATIONIC DYES ON SOME SILICATES

Adsorption of two cationic dyes, methylene blue (MB) and malachite gre en (MG), was studied on the bentonite, sepiolite and zeolite samples b y the batch equilibration technique using a spectrophotometer. In addi tion, cation exchange capacities (CEC) of samples were determined by N H4+ saturation using Kjeldhal distillation. The adsorption data was fo und to conform with the Langmuir equation within the concentration ran ge studied, and Langmuir constants were determined for each of the sam ples. It was observed that the amount of dyes adsorbed was in excess o f CEC in the case of bentonite and sepiolite. The adsorption capacitie s of the samples for both dyes have the following order: bentonite > s epiolite > zeolite.