Carbon-layered double hydroxide nanocomposite for efficient removal of inorganic and organic based water contaminants – unravelling the adsorption mechanism

Carbon-layered double hydroxide (C-LDH) nanocomposites were synthesized by a simple homogeneous co-precipitation process using as-prepared porous carbon and Al, Mg and Ca precursor salts of the LDH. The synthesized adsorbent was used for the removal of inorganic (fluoride, arsenic, and iron) and organic (cationic dye methylene blue, MB, and anionic dye methyl orange, MO) based water contaminants separately and simultaneously from water. Microstructural analysis revealed the formation of nano-flake-like LDH particles (dia. = 10–15 nm and length = 50–100 nm) adhered onto the surface of carbon nanospheres (50–150 nm). The surface area of the products was in the range of 758–477 m2 g−1. It rendered maximum adsorption capacities of 22.37, 20.40, 80, 122.1 and 328.95 mg g−1 for As(V), F−, Fe(II)/Fe(III), MB and MO, respectively. It was used for simultaneous removal of multiple contaminants like As(V), F−, Fe(II)/Fe(III), MB and MO from water with % adsorption up to 99.99%. This study illustrates a synergetic effect of the composition (C : LDH mol ratio) and surface properties (total surface area and mesopore : micropore surface area ratio) of the adsorbent on the relative adsorption of various pollutants.