Rapid Ammonium Removal Enabled by Sub-micron Zeolite A-Derived Beads from Natural Kaolin via Ambient-Temperature Synthesis
摘要
In this study, we synthesized sub-micron zeolite A beads from natural kaolin for rapid ammonium removal in water. Zeolite A is a widely used synthetic zeolite with well-established ion exchange applications. Acknowledging that the conventional synthesis of zeolite A requires energy-intensive hydrothermal conditions, we investigated a synthesis route that forms sub-micron zeolite for 5 days at ambient temperature, reducing energy demand and leading to faster adsorption kinetics due to the reduced particle size. The material was further refined into beads to improve material recovery and ease of use. The pseudo-second-order kinetic model indicated that the sub-micron zeolite beads exhibited a rate constant of 0.0289 g mg−1 min−1, approximately 3.5 times that of the conventional zeolite beads (0.0082 g mg−1 min−1). However, the Langmuir maximum adsorption capacity for the sub-micron beads was lower at 8.69 mg/g than for the conventional zeolite beads at 16.30 mg/g. A trade-off exists between sub-micron and conventional beads: sub-micron beads offer lower capacity but faster speed and are more cost-effective to produce.