Adsorption of Nickel and Chromium Ions by Amine-Functionalized Silica Aerogel Sudarat Sertsing, Thanaphat Chukeaw, Sitthiphong Pengpanich and Bawornpong Pornchuti MATEC Web Conf., 156 (2018) 03014 Published online: 14 March 2018 DOI: 10.1051/matecconf/201815603014