The adsorption capacity of OAC was investigated in batch mode with three representative ions with different valence from +1 to +3 (NH4 + , Ca2+ , Cr3+). The adsorption process was demonstrated by Langmuir and Freundlich isothermal model, and the maximum adsorption capacity according to Langmuir isothrermal equation was mg/g for NH4 + , mg/g for Ca2+ and mg/g for Cr3+. | Vietnam Journal of Science and Technology 55 (4C) (2017) 245-250 RESEARCH ON ION EXCHANGE CAPACITY OF OXIDIZEDACTIVATED CARBON Pham Thi Hai Thinh1, 2, *, Tran Hong Con3, Phuong Thao3, Phan Do Hung1 1 Institute of Environmental Technology, VAST, 18 Hoang Quoc Viet, Hanoi 2 Graduate University of Science and Technology, VAST, 18 Hoang Quoc Viet, Hanoi 3 VNU, University of Science,19 Le Thanh Tong stress,Hanoi * Email: phamhaithinh1979@ Received: 11 August 2017; Accepted for publication: 17 October 2017 ABSTRACT Ion exchange capacity of oxidized activated carbon (OAC) by HNO3 and surface treatment by NaOH solution was investigated. The HNO3 oxidizedfunctional groups on the activated carbon surface, such as ketone, carboxylic acid and its derivatives, to maximum oxidation state. The OAC surface played the role as cation exchanger for adsorption of inorganic compounds, especially metallic cations. The adsorption capacity of OAC was investigated in batch mode with three representative ions with different valence from +1 to +3 (NH4+, Ca2+, Cr3+). The adsorption process was demonstrated by Langmuir and Freundlich isothermal model, and the maximum adsorption capacity according to Langmuir isothrermal equation was mg/g for NH4+, mg/g for Ca2+ and mg/g for Cr3+. The results showed the OAC modified by HNO3 and surface treatment by NaOH solution improved adsorption capacity of AC for cations in solution to a higher level. Keywords: oxidized activated carbon,ion exchange. 1. INTRODUCTION Activated carbon (AC) has been recognized as one of the most popular and widely used adsorbent. It is well known that AC is produced from a variety of carbonaceous rich materials and has high efficiency for removing organic substances than metals and other inorganic pollutants [1, 2]. Efforts are ongoing to substantially improve AC potential in removing ability for inorganic contaminants from aqueous phase by using different chemicals or suitable treatment .
