Abstract: A coating solution for producing a biofunctional surface coating and/or depth coating of a filter medium may include a solvent, an anti-pathogenic substance, an ion exchanger, and a polymeric cross-linking agent. The ion exchanger may be hygroscopic and may include functional cation exchanger groups with sulphonic acid groups.

Abstract: The present disclosure describes a filter device, e.g., a filter cartridge, for cleaning coolant water for an internal combustion engine. The filter device includes a filter housing defining a housing interior space through which coolant water can flow. An untreated water inlet and a clean water outlet are arranged in the filter housing. A water-permeable separating device divides the housing interior space into a first filtration zone and into a second filtration zone. A first packing material containing activated charcoal for removing dirt particles from the coolant water is present in the first filtration zone, and a second packing material containing hydronium cations and hydroxide anions for demineralizing the coolant water is present in the second filtration zone.

Abstract: A coating solution for producing a biofunctional surface coating and/or depth coating of a filter medium may include a solvent, an anti-pathogenic substance, an ion exchanger, and a polymeric cross-linking agent. The ion exchanger may be hygroscopic and may include functional cation exchanger groups with sulphonic acid groups.