Anionized

Anionized is a descriptive term used to indicate that a substance has been modified to carry a net negative charge or to contain negatively charged functional groups. It is applied across chemistry, materials science, and environmental engineering, but is not a tightly standardized term; in many contexts it is synonymous with anionic functionalization or deprotonation.

Mechanisms: Anionization can occur when acidic sites such as carboxyl (–COOH) or sulfonic (–SO3H) groups lose protons, forming carboxylate (–COO−) or sulfonate (–SO3−) groups. It can also arise from covalent grafting of anionic moieties (for example sulfate, phosphate) onto a substrate, or by adsorption of anions onto a surface with positive charge. The resulting negative surface charge is commonly characterized by zeta potential and is often pH-dependent.

Applications: Anionized materials are used to control electrostatic interactions in suspensions, to enhance adsorption or removal of anions and certain cations, and to modify interfacial properties in membranes, coatings, and catalysts. In polymers, anionization can improve solubility, dispersion, or fouling resistance and influence interactions with proteins or dyes.

Limitations: The extent and stability of anionization depend on chemical stability, pH, ionic strength, and competing species; charges may desist under changing conditions.

Notes: The term is descriptive; specific terminology often references the actual functional groups or the chemical state (for example, carboxylate, sulfonate, or deprotonated surfaces).