Layered double hydroxide nanosheets deposited diatomite: high performance adsorbent for removal of anionic organic dye

It would be of significance to design a green composite for highly efficient removal of contaminants. Herein, we fabricated an environmental friendly composite via in situ deposition of positively charged layered double hydroxide (LDH) nanosheets on the surface of the negatively charged diatomite for efficient removal of dye pollutants from aqueous solutions. The resulting LDH/diatomite (LDH/DIA) composites were characterized by X–ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), and N2 adsorption–desorption technique. The adsorption performances of the resulting LDH/DIA composites were evaluated for the removal of anionic tartrazine (TR), and erythrosine (ER) dyes. The adsorption test of dyes demonstrates that the present composite can rapidly reduce the concentration of dyes in aqueous solution from ppm levels to trace levels of ≤ 1 ppb. In addition, the adsorption behavior of this new adsorbent fits well with the Freundlich isotherm and the pseudo-second-order kinetic model. Adsorption isotherm studies showed that the maximum adsorption capacities of TR and ER dyes over the LDH/DIA composite were in the sequence 555.56 and 625.23 mg g-1, which was much higher than the known adsorbents. Our results suggested that the LDH/DIA have great potential applications as environmentally friendly materials for the treatment of waste water with high concentration of anionic dyes.