Sepiolite/calcium interactions in desiccant clay production

Abstract The aim of the present study is to determine the applicability of three different sepiolite samples received from the Eski s ehir region of Turkey in the production of desiccant clay. Japanese (JIS-Z-0701) and British (BS 3482-6) standards dictate that effective sepiolite should uptake humidity of at least 8% of its weight at 20% RH. This value must be 20% at 50% RH and 30% at 90% RH. Therefore, the HAC of sepiolites was modified by subjecting them to heat treatment at 200 °C and different relative humidity (RH) values of 20 to 90% as a function of time. The data obtained was interpreted on the basis of adsorption isotherms. The results indicate that raw sepiolites at 50% RH do not conform to the desiccant standards. Therefore, sepiolite/CaCl 2 mixture at the different CaCl 2 additions was evaluated for its potential as a humidity adsorbent. However, it is shown that sepiolite mixed with 5% CaCl 2 at 50% RH or above exceeds the required specifications for a commercial desiccant.