Adsorption of Ca(II), Mg(II), Zn(II), and Cd(II) on Chitosan Membrane Blended with Rice Hull Ash Silica and Polyethylene Glycol - Mahatmanti, F. Widhi; Department of Chemistry, Faculty of Mathematics and Natural Sciences, Semarang State University, Kampus Sekaran, Gunungpati, Semarang 50227 (Universitas Gadjah Mada, 2016)