ZnCo binary hydroxide nanostructures for the efficient removal of cationic dyes

Abstract The decontamination of organic dyes in waste water needs efficient and simple adsorbent systems. Bimetallic hydroxides would be a kind of potential adsorbents. A ZnCo binary hydroxide nanostructure has been synthesized through microwave irradiation method. The pristine pure ZnCo binary hydroxide without any additional modification shows the unique and high performance as an efficient adsorbent for the removal of cationic dyes. Microwave irradiation with the excess base aids the formation of homogeneous lamellar ZnCo binary hydroxide with divalent metals Co2+ and Zn2+ involved. The ZnCo binary hydroxide has high specific surface area (84.2 m2 g−1) and negative charged surface with high zeta potential. Organic cationic dyes can be removed from water solution with high efficiency in the wide pH range of 2–10. The saturated adsorption capacities for cationic dyes methylene blue (MB), crystal violet (CV) and malachite green (MG) reached 460, 1100 and 2200 mg g−1, respectively. The adsorption behaviors of the ZnCo binary hydroxide fit well with Langmuir isotherm and can be well described by pseudo-second-order kinetic model. The calcined ZnCo binary hydroxide with the adsorbed dyes can be reused for further removal adsorption and photocatalytic degradation of cationic dyes.