D. R. Wicakso, A. Mirwan, E. Agustin, N. F. Nopembriani, I. Firdaus, and M. Fadillah, “Potential of silica from water treatment sludge modified with chitosan for Pb(II) and color adsorption in sasirangan waste solution”, CST, vol. 7, no. 2, pp. 188-193, Dec. 2022.