I don't think once a week will give you much noticeable benefit. If you want your biceps to be stronger perform heavy curls at least twice a week.
Pick a weight that allows you to complete something like 3x3, 6x1(rest-pause) or 5x2 without burning out.
This is an emphasis on biceps maximal strength only i.e. you will be able to curl more weight. Volume must be small and the more often you train the less volume you use.