Many potential drugs have low water solubility, hindering their transport in the body’s aqueous material distribution medium (blood). One way to improve solubility is to decrease particle size below 1 μm diameter. One method to do this is by high-pressure homogenization, using a homogenizer, which is basically a nozzle. In this process, the drug is dispersed in a solvent and forced through a narrow orifice (nozzle) at high pressure. As the liquid enters the orifice, it experiences a pressure drop so great it partially vaporizes. As it exits the constriction, the vapor bubbles collapse violently and produce local disturbances, breaking up the surrounding solid particles.

A high-pressure homogenizer is being used to decrease the size of some drug particles. The particles are suspended in water at 25°C and sent through the homogenizer at 250 mL/min. The pressure before the orifice is 34.5 MPa, and the diameter of the pipe is 0.1 m. Determine the diameter orifice (nozzle) that results in an exit pressure at the vapor pressure of water. Neglect friction.