Why did increasing the filtration pressure increase rate but not concentration of solutes?

Increasing the filtration pressure increases the rate of filtration, but not the concentration of solutes, due to the following reasons:

Pressure-Driven Flow: Filtration is a pressure-driven process where the applied pressure forces the fluid through a semipermeable membrane. The higher the filtration pressure, the greater the driving force, and consequently, the faster the fluid flows through the membrane. This results in an increased filtration rate.

Concentration Independence: The concentration of solutes in the filtrate remains relatively constant regardless of the filtration pressure. This is because the semipermeable membrane acts as a molecular filter, allowing water and small solutes to pass through while retaining larger solutes and particles. The concentration of solutes in the filtrate primarily depends on the characteristics of the membrane and the composition of the feed solution.

Membrane Properties: The semipermeable membrane has specific properties that determine its selectivity and efficiency in separating solutes. These properties, such as pore size, charge, and surface chemistry, play a crucial role in controlling the passage of solutes. Increasing the filtration pressure does not significantly alter the membrane's properties or its ability to retain or pass specific solutes.

Therefore, while increasing the filtration pressure can enhance the rate of filtration by overcoming flow resistance, it does not directly affect the concentration of solutes in the filtrate. The concentration of solutes is mainly governed by the membrane's characteristics and the solute composition of the feed solution.