Fig. 2. Effect of initial solution pH on the adsorption of (a) Pb²⁺, Cu²⁺ and Zn²⁺ on modified crosslinked cellulose/sodium alginate adsorbent, reproduced with permission from ref. 40, copyright, Royal Society of Chemistry, 2018; and (b) MO dye on functionalized MWCNTs, reproduced with permission from ref. 41, copyright, Springer, 2019.