The invention concerns a capture tank for capturing a captive target compound from a gaseous and/or vaporous mixture comprising at least the captive target compound and one other material, or for capturing, concentrating or crystallising a target compound from a liquid mixture or solution comprising the target compound and at least one other material, the capture tank comprising an enclosure having a top region, a bottom region and at least one side defining the enclosure, the enclosure being at least partly open in its top region in order to communicate in use of the capture tank with the gaseous and/or vaporous mixture and for permitting ingress of a gaseous and/or vaporous mixture into the enclosure; the enclosure communicating in its bottom region with a reservoir for receiving the captured captive target compound; having means associated with its at least one side and/or its bottom region for permitting egress from the enclosure of the gaseous and/or vaporous mixture in at least partially captive target compound-depleted form; and having means for sparging at least partially through the enclosure from top to bottom a liquid mixture or solution for entraining the gaseous and/or vaporous mixture in the enclosure and carrying the entrained gaseous and/or vaporous mixture towards the bottom region of the enclosure, and a process for its operation.