I have used the 'baby diaper crystal' type of elements that are intended to remove small amounts of water. They work well IF:
-the flow is very low, say 1/10 of the normal element rating. The material absorbs water but depends on time in contact with the water to take it out and hold it. And apparently high velocity flows either strip the water back out or prevent it from absorbing in the first place. Just putting a water element in place of a return filter is somewhat helpful but not great.
-They re not really intended as particle cleanup.
-Water and dirt retention is small amounts. Ounces of water, not gallons. for larger systems, peter's centrifuge sounds probably better.
-They don't remove 40 gallons of antifreeze, or battery acid, or engine waste oil, or any number of other materials that hav eended up in our tanks.