* Are attracted to negatively charged surfaces

* Tend to accumulate at the interface between a positively charged surface and a liquid

* Can form a positively charged layer at the interface, which can repel other positively charged ions and attract negatively charged ions

* Can increase the surface tension of a liquid

* Can be used to modify the surface properties of materials, such as by making them more hydrophilic or more hydrophobic

Negatively charged ions (anions)

* Are attracted to positively charged surfaces

* Tend to accumulate at the interface between a negatively charged surface and a liquid

* Can form a negatively charged layer at the interface, which can repel other negatively charged ions and attract positively charged ions

* Can decrease the surface tension of a liquid

* Can be used to modify the surface properties of materials, such as by making them more hydrophilic or more hydrophobic

The behavior of charged ions at interfaces is important in a wide variety of applications, including:

* Colloidal stability

* Emulsion stability

* Surfactant behavior

* Detergent action

* Protein adsorption

* Cell membrane structure and function

* Ion transport through membranes

* Electrochemistry

* Corrosion

* Mineral processing

* Water treatment

* Oil recovery

* Food processing

* Pharmaceutical formulation

* Personal care products