Filtracije

Filtracije, or filtration, is a separation process in which solids are removed from liquids or gases by passing the mixture through a porous barrier known as a filter. The barrier retains particles larger than its pore size, while the fluid or gas passes through as filtrate. Filtration can be driven by gravity, pressure, or vacuum and can rely on mechanical sieving, adsorption, or diffusion.

Media and configurations vary. Depth filters, such as sand, activated carbon, or glass fiber, trap contaminants within a thick bed. Membrane filtration uses thin, dense layers or porous membranes to separate by size; pore sizes range from microfiltration to nanofiltration and beyond. Filtration can be classified as surface filtration or depth filtration, and as gravity-driven or pressure-driven.

Common laboratory methods include gravity filtration with a filter paper, and vacuum filtration using a Büchner funnel to speed separation. In industrial settings, cartridge filters, bag filters, and membrane systems are used. Membrane-based processes include microfiltration (roughly 0.1–10 μm), ultrafiltration (2–100 nm), nanofiltration (0.5–2 nm), and reverse osmosis, which remove most dissolved substances.

Applications span water purification, air filtration for clean rooms and HVAC, beverage and food processing, pharmaceutical manufacturing, and environmental engineering. Filtration also plays a role in analytical chemistry, where filtrates are analyzed separately from retained solids.

Limitations include filter fouling and clogging, which reduce flow and require cleaning or replacement, and the need to select materials compatible with the process fluids. Filtracije is a fundamental unit operation across science and industry.