Abstract
Dead leaves of seagrass Posidonia oceanica were activated by using one mol L−1 acetic acid and used as an eco-adsorbent for the removal of methylene blue (MB) and Pb2+ from aqueous solutions. The seagrass was characterized by chemical and physical measurements that confirmed the acid-activation of seagrass. The favourable conditions for MB and Pb2+ adsorption onto the activated seagrass (SGa) were determined to be a pH range of 2–12 and ≥6, an adsorbent dosage of 3.0 and 0.5 g L−1, respectively, and a shaking time of 30 min, which are suitable for a wide range of wastewaters. The equilibrium data were analysed using the Langmuir, Freundlich and Dubinin-Raduskavich-Kaganer (DRK) adsorption isotherm models. The Freundlich and DRK models best describe the adsorption processes of MB and Pb2+, on SGa with capacities of 2681.9 and 631.13 mg g−1, respectively. The adsorption isotherm fitting and thermodynamic studies suggest that the adsorption mechanism of MB may combine electrostatic and physical multilayer adsorption processes, in which MB may be present as monomers as well as dimers and trimers which were confirmed from UV spectroscopy whereas Pb2+ is chemically adsorbed onto SGa. The pseudo-2nd-order kinetic model was utilized to investigate the kinetics of adsorption processes. The removal process was successfully applied for MB-spiked brackish waste water from Manzala Lake, Egypt, with removal efficiencies of 91.5–99.9%.
Highlights
The discharge of toxic effluents containing heavy metals and dyes from a wide range of industries into water streams is of increasing concern due to the adverse effects of these effluents[1]
The optimum conditions for Methylene blue (MB) and Pb2+ adsorption onto SGa are a pH ranges of 2–12 and ≥6, and a dosage of ≥3 and 0.5 g L−1, respectively, at shaking time of ≥30 min, which are suitable for a wide range of wastewaters
The seagrass dead leaves were effectively activated via a simple and rapid acetic acid treatment which led to a release of the acidic OH groups in addition to partial hydrolysis of the ester groups
Summary
The discharge of toxic effluents containing heavy metals and dyes from a wide range of industries into water streams is of increasing concern due to the adverse effects of these effluents[1]. Different techniques are used to remove heavy metal and dye pollutants from wastewater, such as precipitation, solvent extraction, membrane filtration, biodegradation and advanced oxidation[4,5]. These techniques lack the advantages of being fast, economical and/or eco-friendly. The ball-shaped dead leaves of this seagrass form large wastes along the Mediterranean coast, thereby imposing an environmental threat[25,29] These dead leaves are a natural cation-imprinted lignocellulosic framework that is adopted to highly saline environments[29]. The current study presents a simple and new acid-activation procedure for the recycling of SG eco-waste as an green adsorbent for cationic pollutants from brackish water
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
