Adsorption of anionic and cationic azo dyes from wastewater using novel and effective multicomponent adsorbent

Abstract

Water pollution is rising worldwide, necessitating innovative and effective treatment solutions. This study introduces a multicomponent/multifunctional novel nanocomposite synthesized from polyethyleneimine (PEI), graphene oxide (GO), bentonite clay, and MgFeAl-layered triple hydroxide (LTH), termed as AGO/Bentonite/LTH. In this study, the synthesized AGO/Bentonite/LTH nanocomposite was utilized to remove azo dyes (methyl orange and crystal violet) from contaminated water samples. The novel AGO/Bentonite/LTH nanocomposite was benchmarked against its pristine materials and their binary combinations. The results indicated the superior adsorption performance of the AGO/Bentonite/LTH nanocomposite relative to all other adsorbents synthesized and examined herein. All the synthesized adsorbents were characterized using different techniques in order to reveal their textural properties, functional groups, morphology, thermal stability, and crystallinity before applying them to decontaminate wastewater samples contaminated with methyl orange (MO) and crystal violet (CV). The Langmuir adsorption isotherm model predicted that the maximum adsorption capacities of CV and MO onto the AGO/Bentonite/LTH nanocomposite are 1705.1 and 1171.8 mg/g, respectively. On the other hand, zeta potential, pH, and FTIR studies suggested the existence of multiple mechanisms governing the adsorption of CV and MO onto the AGO/Bentonite/LTH nanocomposite. Thermodynamic results indicated the endothermicity and exothermicity of CV and MO adsorption, respectively. Another interesting finding reported herein is the high reusability of this nanocomposite as demonstrated by the minimal reduction in the removal of these two pollutants with the repetitive use of the nanocomposite. Additionally, the nanocomposite can also be easily and cheaply regenerated via a few rinses with a diluted NaOH aqueous solution. These interesting observations suggest that the synthesized AGO/Bentonite/LTH nanocomposite is a potent material for efficient dye removal from contaminated water bodies.