High-efficient, broad-spectrum and recyclable mesoporous TiO2 adsorbent for water treatment

Cooperative adsorption and degradation in situ, known as "hook and destroy" strategy, is an appealing idea to scavenge pollutants from water efficiently. However, commercial high-adsorption-capacity adsorbents are usually based on activated carbon, which is easily damaged in the pollutant degradation process, resulting in decreasing of the adsorption performance, while the adsorption capability of most inorganic adsorbents is inadequate for practical applications. To address the issues, we prepared a novel mesoporous titanium dioxide (m-TiO2) by facile one-step hydrolysis method at room temperature. The m-TiO2 exhibits both high adsorption capacity and short equilibrium time for a wide range of pollutants, such as dyes, pharmaceuticals and pesticides, due to its large surface area and abundant functional groups. The surface charge of the m-TiO2 adsorbent can be regulated by adjusting the acidity and alkalinity of preparation conditions, hence the m-TiO2 is capable of adsorbing either positively or negatively charged pollutants. The versatility for adsorption of diverse contaminants was demonstrated in the experiment of purifying lake water with multiple pollutants. More significant, the m-TiO2 can be regenerated in minutes by in-situ degrading the adsorbed molecules using common oxidants, such as hypochlorite, the active ingredient of disinfectants. The adsorption performance has little deterioration in at least five successive cycles of adsorption and degradation. Considering the excellent adsorption performance, wide applicability and high recyclability, the mesoporous TiO2 offers a sustainable approach to increasingly complex water environmental problems.