Plasma-surface modification on bentonite clay to improve the performance of adsorption of methylene blue

• Cold plasma treatment was applied for the surface modification of bentonite.
• The maximum adsorption capacity of MB was 303 mg/g.
• SEM, FT-IR and XRD measurements indicated the change in functional groups.
• The modified bentonite exhibited potential application for removal of MB.

The present study consists of the cold plasma treatment was applied for the surface modification of bentonite to improve the removal of methylene blue (MB) from aqueous solution. To achieve the aim, the conditions for adsorption, including cold plasma application time, plasma gas effect, and pH were investigated with respect to the adsorption capacity of MB. The changes of the surface property before and after cold plasma treatment were discussed. Cold plasma treated bentonite is characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), BET surface area, and X-ray diffraction (XRD). Equilibrium adsorption data were analyzed by Freundlich and Langmuir equations. Langmuir isotherm exhibited the best fit with the experimental data. Adsorption kinetics were fitted with pseudo-first-order, and pseudo-second order. Cold plasma treated bentonite was exhibited largest adsorption capacity (303 mg/g) at 30 °C.