dialyser

A medical/chemistry verb: to dialyze — to separate substances in a solution using a semi-permeable membrane, most familiar in the context of kidney dialysis (un patient dialysé, a patient on dialysis).

• Il est dialysé trois fois par semaine. — He is dialyzed three times a week.
• L'hôpital dialyse les patients en insuffisance rénale. — The hospital dialyzes patients with kidney failure.
• On dialyse la solution pour éliminer les petites molécules. — The solution is dialyzed to remove the small molecules.

The everyday reference is almost always the adjective/past participle dialysé(e) or the noun dialyse — learners rarely need the plain active verb outside medical or lab contexts.