Magnesium Silicate Honeycomb Structure on Attapulgite Clay Composite by Self-Template Method for Adsorption of Methylene Blue.

A series of porous silica materials coated with honeycomb-like magnesium silicate were prepared under hydrothermal conditions, using natural one-dimensional porous attapulgite as the template and a silicon source with different Mg/Si ratios, by adjusting the amount of MgCl⋅6HO and the attapulgite precursor and regulating pH. The influence of the Mg/Si ratios was carefully investigated on morphology, pore structure, and related adsorption actions toward methylene blue. The Langmuir isotherm and pseudo-second-order kinetic models were used to explain the adsorption behavior of methylene blue. The synthesized composite with the lowest magnesium content displayed the highest removal capability of 166.67 mg/g for methylene blue, with a zeta potential of -18.18 mV, a specific surface area of 310.4 m/g, and an average pore size of 3.7 nm. The removal result was the synergetic adsorption between porous magnesium silicate grown on the surface and the rest of the silica, further indicating that the attapulgite is available as a silicon source and a rod-shaped template for magnesium silicate.