Zeolites NaA and NaX were synthesized from initial coal gangue (milled sample) and pretreated coal gangue (calcinated and acid immersed sample) by an alkali fusion method prior to hydrothermal treatment,… Click to show full abstract
Zeolites NaA and NaX were synthesized from initial coal gangue (milled sample) and pretreated coal gangue (calcinated and acid immersed sample) by an alkali fusion method prior to hydrothermal treatment, which started by mixing NaOH with coal gangue at an optimal weight ratio of nearly 1.2:1. Results show that zeolite NaA was successfully synthesized by alkali fusion at 650 and 950 °C from initial coal gangue, while zeolite NaX was synthesized by alkali fusion at 600 °C from pretreated coal gangue. Zeolites NaX with different specific surface area, external surface area, surface area of micropore and crystallinity were synthesized when the molar ratio of SiO2/Al2O3 in raw materials ranges from 3.46 to 10.0.
               
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