Suspension flow has an important role in various applications such as paint, material and pharmaceutical industries. Settling is considered as a resisting phenomenon in the processes dealing with suspensions. Using nanoparticles as an additive to micro-particulates has been studied in limited studies.

This work presents an experimental investigation to assess the effectiveness of nanoparticles in reduction of suspension settling. Microscopic imaging and transmission measurement were used to analyze the stability factors in a container. Transmission analysis revealed that presence of nanoparticles in the suspension, decreased the sedimentation rate. Microscopy showed that the settling rate decreased after adding nanoparticles. This is attributed to the repulsive forces between microparticles caused by the halos of nanoparticle. Highly charged nanoparticles segregate to region near negligibly charged microspheres because of their repulsive Coulombic interactions. Therefore, microparticles exhibit an effective charge in presence of nanoparticles.

Obtained results indicate that the nanoparticles with appropriate volume fraction can stabilize suspension of microparticles and can successfully minimize the settling rate. Proposed technique can be also implemented in other applications such as heat pipes and heat transfer devices.

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