Facile preparation of hierarchical porous 2MgO · B2O3 · 2H2O nanostructure with ultra-high adsorption performance for triphenylmethane dyes removal

Abstract

The fan-like 2MgO · B2O3 · 2H2O porous nanostructures were prepared by a solvothermal approach. FT-IR, XRD, TG-DTA, SEM, and TEM were used to characterize the obtained sample, which was constructed by nanobelts with 20 nm in width, about 5 nm in thickness and 2 μm in length. Its specific surface area was measured as 118.94 m2/g. It exhibited ultra-high removal of triphenylmethane dyes for AF, MG and BF from aqueous solution, in which the maximum adsorption capacities are much higher than those of most reported adsorbents. The higher absorption for triphenylmethane dyes can be attributed to the positive surface charge, the main existing mesopores and macropores, and larger specific surface area of the prepared 2MgO · B2O3 · 2H2O sample, which make the absorbent and anionic dye molecules existing both the stronger electrostatic attraction and hydrogen bonds of N–H· · · O and O–H· · · N. The adsorption kinetics and isotherm were found to conform to pseudo-second-order model and Langmuir model. The competitive adsorption for BF and MG and the adsorption mechanism were also investigated. The as-prepared sample is of larger adsorption capacity and good reusability, which makes it valuable in potential wastewater treatment application.