Green cross-linked bionanocomposite of magnetic layered double hydroxide/guar gum polymer as an efficient adsorbent of Cr(VI) from aqueous solution.

A novel bio-adsorbent based on guar gum (GG) was synthesized through the cross-linked polymerization of N,N'-methylene bis-acrylamide (MBA) onto FeO@ nickel aluminum layered double hydroxide (Ni/Al LDH) @ GG bionanocomposite (BNC) using an in situ growth method. The structural, thermal, and morphological properties of the MLG BNC were studied by different techniques. According to field emission scanning electron microscopy, and transmission electron microscopy, there is a uniform distribution of nanoparticles with a particle size of 40-50 nm in the nanocomposite. MLG BNC was used as Cr (VI) adsorbent, and the effect of pH, concentration, and contact time on adsorption capacity was determined. It was observed that the maximum Cr(VI) adsorption by MLG was 101 mg g (pH 6, 30 min). The adsorption isotherm was represented the single-layer, and homogeneous adsorption and the high value of R illustrates a good agreement with Langmuir. The adsorption kinetic was the second-order pseudo-model.