Hexamethylenetetramine functionalized graphene oxide-alginate beads nanocomposite as efficient sorbent for dye from...

In this study, a novel eco-friendly sorbent, hexamethylenetetramine (HMTA) functionalized calcium alginate (AG) immobilized graphene oxide (GO) composite (AG-GO-HMTA) and hexamethylenetetramine functionalized calcium alginate composite (AG-HMTA) were prepared. Adsorption factors including pH impact, contact time, initial dye concentration, dosage, selectivity and reusability on methylene blue (MB) removal from water were investigated. The prepared sorbents were characterized using structural (e.g. XRD, FT-IR, EDAX), thermal (e.g. TGA, DTG), and morphological (e.g. SEM, BET) analysis techniques. The equilibrium adsorption data was described by the Langmuir and Freundlich isotherms, and the adsorption kinetic and thermodynamic parameters were investigated. The field studies and regeneration of the beads were investigated. AG-GO HMTA displays a well-defined porous structure and this desired morphology arising from high quality dispersion of HMTA within the AG-GO matrix. The highest adsorption capacities were observed at pH ∼ 5, meanwhile the adsorption of MB dye molecules, positively charged, onto the beads became faster due to strong electrostatic interactions. When the value of dosage is 0.01 g, the equilibrium concentration (mg/g) are maximum at 103, 110, 164, 168 mg/g for AG, AG-GO, AG-HMTA and AG-GO-HMTA, respectively. The present work shows that pseudo first order could describe the MB adsorption onto AG while it couldn't describe the MB adsorption onto the functionalized sorbents due to the hybrid materials complicity.