On the equipment design of a spinning disk reactor for the production of novel nano silver in amorphous zeolite particles

Abstract

In recent years there is an increasing use of silver nanoparticles (AgNPs) in a wide range of products, due to enhanced antibacterial and antiviral properties. In most applications, AgNPs are used immobilized on supporting surfaces, such as a coating over a medium or embedded into polymer matrixes, sensibly reducing their active surface. To overcome this constraint, it appears to be profitable to use microporous materials as a support to AgNPs, such as zeolites. One difficulty to produce AgNPs in zeolite particles (AgNP-Z) is the impossibility to adopt standard coating procedures at nano-scale. For this reason, AgNPs were produced separately and then embedded into zeolites during the synthesis of the latter. This result was achieved by use of a spinning disk reactor (SDR) during both involved process steps. In a first step, AgNPs were produced by SDR, achieving the production of particles of modal size equal to 66 nm after proper process optimization. After this, the synthesised AgNPs suspension was then employed during the chemical zeolite synthesis over the disk surface. SEM analysis confirmed the homogeneous position of the AgNPs placed deep within the formed amorphous zeolite structure cavities to achieve chemical availability. By adopting this technique AgNP-Z globules of a mean diameter of 150 nm forming particles of about 54 μm have been successfully produced. Finally, the experimental work assisted to extent general insight to the design and operation of a SDR for particles production, and a simplified model will here be proposed and validated.