Zeolite Synthesis Using Sewage Sludge by Molten-Salt Method

This study was conducted to synthesize zeolitic materials using sewage sludge by molten-salt method the effective method was investigate to reduce the thermal treatment time by adding zeolite seed and excessive sodium hydroxide. To synthesis zeolitic materials, sewage sludge was used as Si and Al sources, also Na2SO4 and NaOH were added as stabilizer and mineralizer respectively. Sewage sludge was prepared by calcination at 550°C/3hr to remove organic materials. As a result of thermal treatment at 950°C for 6~24hrs, more than 18 hours was required to synthesize zeolitic materials without adding zeolite seed. On the other hand, it is observed that hydroxyl-sodalite was synthesized in 9 hours thermal treatment and Na-P1 also in 12 hours when zeolite seed was added, but no other differences were observed when excessive sodium hydroxide was added. Consequently, the overall reaction time required could be reduced by adding zeolite seed and changing thermal treatment temperature. However, addition of NaOH does not show significant effect on the reduction of zeolite synthesis time.