Synthesis of a Coal Fly Ash‐Based NaP Zeolite Using the Microwave‐Ultrasonic Assisted Method: Preparation, Growth Mechanism, and Kinetics

Abstract

Fly ash was used as the raw material to prepare coal fly ash‐based NaP zeolite using the microwave‐ultrasonic‐hydrothermal method. The obtained NaP zeolite has a completed crystal structure, regular surface morphology, uniform particle size (about 1.6 um), large specific surface area (48.85 m2/g) and good thermal stability. Under microwave and ultrasonic external fields, the coal fly ash‐based NaP zeolite crystals grow in an S‐shape, achieving single crystal growth and uniform crystal growth size. The activation energy of NaP zeolite crystal growth Ea is 2.08 kJ/mol, the pre‐exponential factor A is 85.63.

Determining the Role of Water Molecules in Sodalite Formation Using the Vapor Phase Crystallization Method

“…Querol et al [44] transformed fly ash into zeolite A by both hydrothermal and microwave energy with NaOH and KOH alkaline agents, and this result was confirmed by many recent papers [45,46]. Liu et al [47] documented NaP zeolite formation using the microwaveultrasonic-hydrothermal method, whereas Wang et al [48] synthesized zeolite X via microwave extraction combined with hydrothermal processes [48]. To our knowledge, the microwave process has not been applied to form zeolite from red mud, but some literature data have documented the use of this treatment to remove silica and iron oxides from the low-iron bauxite residue (Fe ~24%) [49] and to modify red mud-based adsorption material, thus improving its adsorption phosphorus capacity in solutions [50].…”