Hierarchical porous MgBO2(OH) microspheres: Hydrothermal synthesis,thermal decomposition, and application as adsorbents for Congo red removal

A facile eco-friendly hydrothermal route(180 °C, 12.0 h) has been developed for the first time to the uniform hierarchical porous MgBO(OH) microspheres without the aid of any organic additive, surfactant or template, by using the abundant MgCl·6 HO, HBOand NaOH as the raw materials. The as-obtained porous microspheres exhibit a specific surface area of 94.752 mg·g, pore volume of 0.814 cm3·g, and ca. 84.0% of which have a diameter of 2.25–3.40 μm. The thermal decomposition of the porous MgBO(OH) microspheres(650 °C,2.5 °C·min) leads to the porous MgBOmicrospheres with well-retained morphology. When utilized as the adsorbents for the removal of CR from mimic waste water, the present porous MgBO(OH) microspheres exhibit satisfactory adsorption capacity, with the maximum adsorption capacity qmof 309.1 mg·g, much higher than that derived from most of the referenced adsorbents. This opens a new window for the facile green hydrothermal synthesis of the hierarchical porous MgBO(OH) microspheres, and extends the potential application of the 3 D hierarchical porous metal borates as high-efficiency adsorbents for organic dyes removal.