... in purge. Molecular sieve is often used as a polishing layer in air dryers to reach dewpoints of -120° F.The ... out "The Comprehensive Sanitation and Safety Assessment on the Attapulgite Clay, a Natural Foodstuff Processing adjuvant". Their test results are as ... arsenic, lead and mercury are not detectable in the attapulgite clay product, while total iron, sulfates, chlorides, nitrites, etc. are ...