Novel Carbon Paper@Magnesium Silicate Composite Porous Films: Design, Fabrication, and Adsorption Behavior for Heavy Metal Ions in Aqueous Solution

It is of great and increasing interest to explore porous adsorption films to reduce heavy metal ions in aqueous solution. Here, we for the first time fabricated carbon paper@magnesium silicate (CP@MS) composite films for the high-efficiency removal of Zn 2+ and Cu 2+ by a solid-phase transformation from hydromagnesite-coated CP (CP@MCH) precursor film in a hydrothermal route and detailedly examined adsorption process for Zn 2+ and Cu 2+ as well as the adsorption mechanism. The suitable initial pH range is beyond 4.0 for the adsorption of the CP@MS to remove Zn 2+ under the investigated conditions, and the adsorption capacity is mainly up to the pore size of the porous film. The composite film exhibits excellent adsorption capacity for both of Zn 2+ and Cu 2+ with the corresponding maximum adsorption quantity of 198.0 mg g –1 for Zn 2+ and 113.5 mg g –1 for Cu 2+, which are advantageous over most of those reported in the literature. Furthermore, the adsorption behavior of the CP@MS film follows the pseudo-second-order kinetic model and the Langmuir adsorption equation for Zn 2+ with the cation-exchange mechanism. Particularly, the CP@MS film shows promising practical applications for the removal of heavy metal ions in water by an adsorption–filtration system.