Synthesis of MOR Zeolite/Magnetite Composite via Seed Assisted Method

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods

“…Recent studies have shown advancements in the synthesis of magnetic zeolites. Hagio et al applied seed-assisted hydrothermal synthesis, an alternative but selective technique for preparing zeolites, to synthesize magnetic FAU-type [ 29 ] and MOR-type zeolites [ 30 ] for the first time ( Figure 9 b). In principle, with hydrothermal treatment, the addition of the target zeolite crystals as the seed into precursors can induce and accelerate the crystallization of zeolites.…”

“…According to this principle, if the seed crystals are well mixed with magnetic particles, the target zeolites crystallize near the magnetic particles. Hagio et al discovered that pre-milling seed crystals and Fe 3 O 4 particles together, before adding to the precursors, allowed for good pre-attachment among them [ 30 ]. The growth of zeolite crystals occurred in the tiny gaps between the seed and Fe 3 O 4 particles.…”

“…Since then, the synthesis of magnetic adsorbents has drawn considerable attention, as indicated by the growing number of publications. Diverse effective adsorbents have been reported to incorporate magnetic particles, such as metal oxides [ 26 , 27 ], silica-based materials [ 28 , 29 , 30 , 31 , 32 ], carbon-based materials [ 33 , 34 , 35 ], graphene oxide [ 36 ], biopolymers, such as lignin [ 37 ], cellulose [ 38 ], chitosan [ 39 ], synthetic polymers [ 40 , 41 , 42 ], molecularly imprinted polymers [ 43 ], metal organic frameworks [ 44 ], and biowaste [ 45 , 46 ]. Magnetic adsorbents can be prepared using physical methods, such as mechanical agitation (stirring, vibration, milling, and ultrasonication) at room or elevated temperatures in some cases, along with the addition of adhesives.…”

“…The challenge in magnetic adsorbent synthesis is not only to improve the adsorption performance, but also to accomplish good distribution or incorporation of magnetic particles in the adsorbent morphology. Advanced synthesis routes, such as the seed-assisted method [ 29 ], pre-milling of magnetic particles with adsorbent seed crystals [ 30 ], embedding magnetic particles with a carbon source before carbonization [ 34 ], or pre-attaching magnetic particles with precursors as a dry gel before heat treatment [ 31 ], help to improve the morphology of magnetic adsorbents. Furthermore, challenges to co-synthesizing magnetic particles and adsorbents in a one-pot synthesis have recently been explored [ 26 ].…”