Adsorption Performance and Mechanisms of Methylene Blue Removal by Non-magnetic and Magnetic Particles Derived from the Vallisneria natans Waste

Vallisneria natans (V. natans) is a submerged aquatic plant, and its dried biomass waste was used to prepare magnetic particle biomass adsorbent by chemical co-precipitation via FeSO4 center dot 7H(2)O and FeCl3 center dot 6H(2)O as iron precursors. Brunauer-Emmett-Teller specific surface area, total pore volume, and average pore width were 7.434 m(2) g(-1), 0.013 cm(3) g(-1), and 6.992 nm for magnetic V. natans, correspondingly, and 3.575 m(2) g(-1), 0.004 cm(3) g(-1), and 4.476 nm for non-magnetic V. natans, respectively. The adsorption kinetics of methylene blue (MB) is a more appropriate fit for pseudo-second-order kinetic model than pseudo-first-order and intraparticle diffusion kinetic models. Isotherm results showed that the adsorption of MB onto the non-magnetic and magnetic adsorbents agrees well with Dubinin-Radushkevich isotherm model. Moreover, the thermodynamics study implied that the adsorption of MB onto both adsorbents is a spontaneous and exothermic process. The maximum adsorption capacities of MB on non-magnetic and magnetic V. natans were 657.90 and 473.93 mg g(-1) at 303 K, correspondingly.