Selective adsorption of Crystal Violet via hydrogen bonded water bridges by InVO4

Selective adsorption is an effective method to achieve in the recovery of CV. We report that InVO4 is highly selective adsorbent for Crystal Violet (CV) from the water, which has much larger adsorption capacity (134.25 mg/g) than that of titanium dioxide, alumina, and silica gel (6.1–33.9 mg/g) although the specific surface areas of these solids are much larger than that of InVO4. The (200) facets of InVO4 exhibited the optimal sites for the selective-chemisorption of CV. The trigonal planar CV molecules are bonded to the (200) facets at all three vertices via a cationic quaternary amine and two tertiary amines. This adsorption mechanism mainly involved the formation of hydrogen-bonded water bridges (CV-N···H-O-H···O-VO3-In) on the basis of in-situ Fourier transform infrared (In-situ-FTIR). This study not only provides a new preparation method for vanadate adsorbent, but also provides a new idea for the recovery and utilization of CV in waste liquid.