A novel Sargassum siliquastrum-stabilized MnS nanospheres for malachite green adsorption from aqueous solutions

In this study, the marine alga Sargassum siliquastrum was used for the first time as a stabilizer for the preparation of manganese sulfide nanoparticles (MnS NPs). After characterization, the resulting MnS NPs were literature-first applied for adsorption of malachite green (MG) cationic dye. Characterizations indicated the formation of a spherical, monodispersed, mesoporous mixture of γ-MnS (56%) and α-MnS (46%) with a small crystallite size of 19 nm and a high surface area of 156.7 m2/g. After stepwise optimization of various parameters affecting the adsorption process, MG was 99.7% removed within 60 min from neutral solution by 0.2 g/L of MnS NPs at 298 K. The data of MG adsorption are best fitted by Langmuir isotherm (R2 ≥ 0.99) with a maximum adsorption capacity of 432.2 mg/g at 328 K. Pseudo-second order (R2 = 0.99) is the most appropriate to describe adsorption kinetics. In addition, thermodynamic results revealed that the adsorption is endothermic and spontaneous. Stability and interference studies showed that MnS NPs are highly stable and more selective for MG removal than other dyes. Upon these results, MnS NPs can be applied for the effective removal of MG from various water samples.