Dry Water

Abstract: Dry water is a solidified, powdered form of water which has the appearance of icing sugar. It contains up to 98 % of water by weight and yet is a dry powder. Each particulate consists of a small water droplet surrounded by a network of highly hydrophobic fumed silica particles. The coating, kept together due to the cohesion between the silica particles, is strong enough to avoid coalescence of the water droplets.
Discovered in the 1960s, scientists have not been devoted any attention to dry water for almost four decades. But it was rediscovered in 2006 in order to study its structure and to exploit it for potential applications. Within the scope of this study, dry water was prepared and more various fundamental characteristics were investigated.
It showed that dry water can be easily prepared by a simple mixing process. It is characterized by good flow properties, a considerable decrease of density compared to bulk water and therefore a large air content. Microscopic droplets lead to a large water/air interface with silica particles between. When cooled to minus temperatures dry water shows significant deviations concerning the freezing point and the evaporation rate and still is flowable.
Attributed to its large water/air interface, the substance has great potential to store gases in an effective and save way in form of gas hydrates. Also the kinetics of chemical reactions can be increased by using chemical reactants instead of water. Dry acids or dry emulsions can be prepared in the same way, offering a safer way for handling and transporting hazardous liquids. But also the use as a cooling agent even at minus temperatures could be a suitable application.