<i>Ophiorrhiza mungos</i>-Mediated Silver Nanoparticles as Effective and Reusable Adsorbents for the Removal of Methylene Blue from Water
Aklima A. Akhi, Abid Hasan, N. C. Saha, Sabbir Howlader, Sabonty Bhattacharjee, Sabonty Bhattacharjee, Kamol Dey, A. K. M. Atique Ullah, Farhana Rumzum Bhuiyan, Chakraborty Ak, Umme Sarmeen Akhtar, Md. Aftab Ali Shaikh, Benu K. Dey, Samiran Bhattacharjee, Samiran Bhattacharjee, Sumon Ganguli
Abstract
High Resolution Image Download MS PowerPoint Slide Green synthesis of silver nanoparticles (AgNPs) using a plant extract has attracted significant attention in recent years. It is found as an alternative for other physicochemical approaches because of its simplicity, low cost, and eco-friendly rapid steps. In the present study, Ophiorrhiza mungos ( Om )-mediated AgNPs have been shown to be effective bioadsorbents for methylene blue (MB) dye removal (88.1 ± 1.74%) just after 1 h at room temperature in the dark from an aqueous medium for the first time. Langmuir and Freundlich isotherms fit the experimental results having the correlation coefficient constants R 2 = 0.9956 and R 2 = 0.9838, respectively. From the Langmuir fittings, the maximum adsorption capacity and adsorption intensity were found to be 80.451 mg/g and 0.041, respectively, indicating the excellent performance and spontaneity of the process. Taking both models under consideration, interestingly, our findings indicated a fairly cooperative multilayer adsorption that might have been governed by chemisorption and physisorption, whereas the adsorption kinetics followed the pseudo-second-order kinetics mechanism. The positive and low values of enthalpy (Δ H 0 = 4.91 kJ/mol) confirmed that adsorption is endothermic and physical in nature; however, the negative free energy and positive entropy value (Δ S 0 = 53.69 J/mol K) suggested that the adsorption is spontaneous. The biosynthesized adsorbent was successfully reused up to the fifth cycle. A proposed reaction mechanism for the adsorption process of MB dye onto Om -AgNPs is suggested. The present study may offer a novel finding such as an effective and sustainable approach for the removal of MB dye from water using biosynthesized Om -AgNPs as reusable adsorbents at a comparatively faster rate at a low dose for industrial applications.