Abstract: Under the physiological conditions (pH2 and pH7,37℃),the Potato Dietary Fiber(PDF) made by spent starchtaken from potato was used to test its adsorption to such metal ions as Pb2+、Cu2+、Zn2+ and Ca2+. The experiment showed,under two acidity conditions the adsorbing capacity of PDF to Pb2+ was stronger than that to Cu2+ and Zn2+, while that to Ca2+was the weakest. With the increase or decrease of dosage of PDF its adsorbing capacity (qe) to metal ions would decrease or increase.This proved that it has had a good physiological activation. Therefore, much attention should be paid to its dosage when it wasused as dietary fiber. The adsorption of PDF was the synthetic effect of both chemical and physical absorption, which could beproved by its loose structure and abundant aldehyde,carboxyl groups in Infrared Spectra.That data of adsorbing metal ions byPDF were linearly fitted in physical adsorption described by Langmuirr model.

Key words: potato dietary fiber(PDF), metal ionPb~(2+)、Cu~(2+)、Zn~(2+)、Ca~(2+), mechanism of adsorption