“…The amine group in chitosan is advantageous, because it is easily modified by a cross-linking reaction process, one of which is glutaraldehyde as an efficient crosslinking agent (Akakuru, et.al., 2017;Mulyasuryani, Haryanto, Sulistyarti, & Rumhayati, 2018;Nair, Best & Cameron, 2020). The cross-linked chitosan forms a hydrogel that can be used as a supporting membrane in the development of Pb 2+ sensors (Novitasari, et al, 2016). Meanwhile, clay is a mineral with the main content of SiO2 and Al2O3, in which the outer surface layer binds the Na + , K + and NH4 + ions (Yahaya, Jikan, Badarulzaman, & Adamu, 2017;Garcia-Valles, Alfonso, Martinez, & Roca, 2020).…”