Chemically grafting Ni(ii)–dithiocarbamate complex onto graphene oxide nanosheets for selective and ultrafast removal of toxic anionic methyl orange dye from water

Abstract

In this study, a Ni(II)–dithiocarbamate complex was chemically anchored onto amino-functionalized graphene oxide (GO) nanosheets using 3-aminopropyltriethoxysilane as an organic linker. The grafting process involved a chemical reaction between aminopropyl-functionalized GO nanosheets and carbon disulfide (CS₂). The resultant Ni(DTC)₂-GO hybrid material was comprehensively characterized using various analytical techniques, including Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), zeta potential analysis, and surface area measurement. The hybrid's adsorption performance was evaluated using different dye solutions, with a focus on its ability to efficiently remove anionic dyes from water. Notably, the material demonstrated exceptional capability in adsorbing the anionic methyl orange (MO) dye, achieving 99% removal within just six minutes and boasting an adsorption capacity of 159.13 mg g⁻¹. These results highlight its potential as a high-performance adsorbent for water purification and environmental remediation. The study also examined the effects of initial dye concentration, adsorbent dosage, and solution pH on the adsorption process. Kinetic analysis revealed that the adsorption followed a pseudo-second-order (PSO) model, while the Freundlich isotherm provided the best fit for the adsorption behavior of MO on the hybrid. Furthermore, the hybrid material exhibited rapid and selective adsorption of anionic MO dye from a binary dye mixture comprising cationic methylene blue (MB) and MO. The hybrid was easily recoverable by filtration and retained both structural stability and adsorption efficiency over at least four reuse cycles. These findings underscore its potential as an innovative material for water treatment applications and for recovering valuable organic compounds from wastewater.