Efficient adsorption of congo red dye from aqueous solution using green synthesized coinage nanoparticles coated activated carbon beads

In this paper, the removal of congo red (CR) dye by adsorption on coinage nanoparticles [silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs)] coated activated carbon (AC) has been discussed. The effect of various process parameters has been investigated by following the adsorption technique. Equilibrium adsorption data of CR were carried out at room temperature. The equilibrium time is independent of the initial CR concentration and the percentage removal of CR increased with increase in contact time. The adsorption data were analyzed by using adsorption isotherm studies. The characteristic parameters for isotherm and related correlation coefficients were determined from graphs of their linear equations. Kinetic studies showed that the adsorption of CR followed pseudo-first-order kinetics. AgNPs- and AuNPs-coated AC is found to be suitable adsorbent for the adsorption of CR. CR was effectively removed 88.0 ± 0.8 % from aqueous solution using AuNPs beads as the adsorption process. Desorption studies were made to elucidate recovery of the adsorbate and adsorbent for the economic competitiveness of the removal system. The PVP-supported AgNPs and AuNPs-coated AC were successfully recycled for ten successive adsorption–desorption cycles indicating its high reusability.