Facile and green synthesis of CuS-activated carbon nanocomposite from Sargassum siliquastrum biomass for fast and efficient removal of eosin yellow dye

Abstract

Sargassum spp. comprise significant amounts of biomass which can be risky for environmental and economic activities; thus, taking the advantage of this underutilized raw material could make a significant contribution to long-term sustainability. In this study, Sargassum siliquastrum (SS) brown alga was successfully transformed into CuS nanoparticles–activated carbon (CuS NPs–AC) composite for adsorption of the hazardous dye eosin yellow (EY) from aqueous solutions. The CuS NPs–AC sorbent was characterized through FTIR, XRD, SEM-EDX, and SBET analyses. Characterization results revealed the successful formation of CuS NPs–AC nanocomposite. Results of the adsorption process indicated that EY was efficiently removed with a percentage of 99.6% at the optimum conditions; pH 7, 120 min contact time, 2 g/L CuS NPs–AC dose, and 300 mg/L initial EY concentration. Adsorption data fitted well with pseudo-second-order kinetics and Langmuir isotherm model with a monolayer adsorption capacity of 303.03 mg/g at 328 K. Thermodynamic analyses revealed that the adsorption process was spontaneous and endothermic. The adsorbent showed high selectivity towards EY and followed a three-stage intraparticle diffusion mechanism. The potent adsorption of EY by CuS NPs–AC nanocomposite was attributed to electrostatic attraction, π-π stacking, halogen bonding, and hydrogen bonding. This study developed a reliable and cost-effective adsorbent for removing EY dye from water. Graphical Abstract: [Figure not available: see fulltext.].