Carboxymethyl Tamarind-g-poly(acrylamide)/Silica: A High Performance Hybrid Nanocomposite for Adsorption of Methylene Blue Dye

Here, synthesis of an efficient nanocomposite based on a polyacrylamide grafted carboxymethyl tamarind (CMT-g-PAM) and a SiO₂ nanoparticle is presented. The synthesized nanocomposites are characterized using FT-IR, SEM, TEM, ¹³C NMR, elemental analysis, viscosity, rheological measurement, and molecular weight determination. Various characterizations reveal the existence of an excellent polymer matrix–nanoparticle interaction, which is at a maximum when 1.5 wt % of SiO₂ is introduced in the polymer matrix (i.e., CMT-g-PAM/SiO₂-3). Nanocomposites show tremendous methylene blue (MB) dye adsorption capacity, because of their higher hydrodynamic radius as well as hydrodynamic volume, which originates from proper polymer matrix–SiO₂ nanoparticle interaction. CMT-g-PAM/SiO₂-3 exhibited a maximum adsorption capacity (Q_max) of 43.859 mg·g^–1. The adsorption behavior of the nanocomposite shows that adsorption kinetics and isotherms are in good agreement with pseudo-second-order and Langmuir equations, respectively. Negative values of ΔG° confirmed the spontaneous nature of adsorption. Further, desorption experiments affirmed that the developed nanocomposite has excellent regenerative efficacy.