Cellulose grafted malic acid@metal sulfides as adsorbents for removal of methyl green dye from aqueous solutions

Nanocomposites based on natural biopolymers are attractive materials for preparing high adsorbents to remove different pollutants from water due to their ability, good porosity, high specific surface area, and easy separation. Herein, to explore eco-friendly cellulose biosorbents, we fabricated cellulose-based nanocomposite CL/M@Hg and CL/M@Pb using the grafting of cellulose with malic acid and metal sulfides via a one-pot procedure. The synthesis nanocomposites were characterized using FT-IR, EDS, TGA, XRD, and SEM. Characterization results predicted that the successful preparation of CL/M@Hg and CL/M@Pb. EDS/SEM results confirmed the distribution of metal sulfide nanoparticles on the as-prepared CL/M composites. In addition, methyl green (MG) adsorption using them was studied and the effect of important parameters such as initial pH solution, adsorbents dose, and contact time was investigated and discussed. At optimum conditions, the maximum adsorption capacity of MG dye using CL/M@Hg and CL/M@Pb was found to be 123.27 mg/g (R=88.05 %) and 134.75 mg/g (R=96.25 %), respectively. The adsorption kinetics were described well by the pseudo-second-order (PSO) model rather than the pseudo-first-order (PFO) model. Due to the presence of active sites on the surface of the as-prepared nanocomposites, we proposed that the adsorption mechanism included a lot of electrostatic attractions, n-π stacking, and hydrogen bonding. The as-prepared nanocomposites are recyclable for six cycles without significant loss of their adsorption capacity. Therefore, they have great potential for the remediation of organic dyes from wastewater.