Plasma O2 modifies the structure of synthetic zeolite-A to improve the removal of cadmium ions from aqueous solutions

Abstract

The present study addresses the removal of cadmium ions (Cd(II)) from aqueous solutions at a pH of 7.5 usingzeolite-A activated by exposure to oxygen plasma. The activation process was performed over a wide range of plasmapowers (10, 20, 30, and 40 W) and exposure times (30 to 360 s). Oxygen plasma cannot chemically modify zeolite to aconsiderable extent, but it can clean the surface, open blocked pores, and induce the formation of additional OH groupsvia exposure to humidity in ambient air. Therefore, Cd +2 ion removal is increased by approximately 10% with theplasma treatments. Infrared-attenuated total reflectance spectroscopy, X-ray diffraction, scanning electron microscopy,and energy dispersive spectroscopy were applied to analyze the changes in the surface structure and properties of thesamples.