Controlled Fabrication of K2Ti8O17 Nanowires for Highly Efficient and Ultrafast Adsorption towards Methylene Blue.

Abstract

Advanced adsorbents need high adsorption rate and superior adsorption capability to clean up the organic methylene blue (MB) from wastewater. We prepared K2Ti8O17 nanowires grown along [0 1 0] direction with a one-step hydrothermal method. The K2Ti8O17 nanowires with tens of nanometers in diameter and tens of micrometers in length were achieved with smooth surfaces and twisted wire-like morphology. The K2Ti8O17 nanowires exhibit high uptake capacity of ∼208.8 mg•g-1 in the MB removal under equilibrium pH = 7. The adsorption equilibriums of MB onto K2Ti8O17 adsorbent is achieved with 97% removal rate MB within only ~21 min, which is the shortest adsorption time among the recent reported inorganic adsorbents towards MB. The adsorption process has a good agreement with the well-known pseudo-second-order kinetic model (k2 = 0.2) and the Langmuir isotherm model. The FTIR measurements suggest that the adsorption can be assigned to the hydrogen bonding and electrostatic attraction between MB and K2Ti8O17. This ultrafast removal ability owns to the larger (0 2 0) interplanar spacing and zigzag surface structure of the nanowires, which provide abundant active adsorption sites. Thermodynamic parameters reflect the spontaneous, exothermic and feasible uptake of MB. Besides, K2Ti8O17 nanowires enjoy high adsorptive ability for chromium (VI) ions and photocatalytic removal towards NO. This work highlights the great significance of K2Ti8O17 nanowires as a low cast promising material used for adsorptive elimanation of organic contaminations in fast water purification on a large scale.