Extraction of silica and alumina from coal fly ash for the synthesis of zeolites

• Main Authors: Kamarudin R.A., Matlob A.S., Jubri Z., Ramli Z.
• Other Authors: 23067175400
• Format: Conference paper
• Published: 2023
• Subjects: Fly ash; Microwave; Silica; Zeolites; Aluminum; Aluminum foil; Coal ash; Emission spectroscopy; Inductively coupled plasma; Irradiation; Metal recovery; Microwave devices; Optical emission spectroscopy; Silicate minerals; Silicon oxides; Sodium; Stoves; Sustainable development; X ray diffraction; Box-Behnken design; Coal fly ash; Experimental conditions; Exposure-time; Gibbsites; Inductively coupled plasma-optical emission spectroscopy; Molar ratio; NaOH concentration; Power levels; Silica zeolites; Sodium hydroxides; XRD; Microwave irradiation

This paper reports the extraction of soluble silicates and aluminates from coal fly ash using microwave irradiation from a domestic microwave oven. Fifteen experimental conditions for the extraction were obtained using Box-Behnken design through manipulation of three variables namely sodium hydroxide (NaOH) concentration, power level of microwave irradiation and exposure time; each variable has three values. The variables with their values were; NaOH concentration (2, 4 and 6 M), exposure time to microwave irradiation (1, 3.5 and 6 min) and power level of the irradiation (10, 50 and 100 Watts). Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) was used to study the amount of silicon and aluminium in the extracts. The extracted silicates and aluminates (after the molar ratio of SiO2 to Al2O 3 was adjusted to unity by adding aluminium foil) were further incubated at 95�C for 72 hours. The products isolated from the 14 experiments were characterized by their XRD images and found to be Na-A zeolites, gibbsite and sodalite octahydrate. �2009 IEEE.