Graphycal Abstract: The effectiveness and prospects of using food industry waste sorbents for water purification from copper (II) ions have been studied. The use of a regenerated sorbent made of activated carbon and kieselguhr modified with sulphide and hydrosulphide ions increases the efficiency of removing copper (II) cations from water by 65.5 times It was established that topochemical reactions occur on the surface of the modified sorbent with the formation of copper (II) sulphide CuS and elemental sulfur. The possibility of topochemical transformations was established by IR-spectral and X-ray phase studies.