Development of Novel Diol-Functionalized Silica Particles toward Fast and Efficient Boron Removal

Ion-exchange adsorption may be a promising way to tackle the boron contamination in various waterbodies on condition that an effective boron-specific adsorbent with fast sorption kinetics, high efficiency and capacity, easy regeneration, and low cost is accessible. In this work, a group of novel silica-based adsorbents were synthesized for boron removal, with the objectives of assessing their adsorption behaviors and improving their boron separation performance. The adsorption efficiency was systematically evaluated and optimized under various synthesis and operating conditions, i.e., reactant ratio, chelating temperature, particle loading, contact time, and ion strength. In addition, the adsorption kinetics and isotherm were adequately demonstrated. The adsorption kinetics followed the pseudo-second order kinetic model while the adsorption isotherm was described by Langmuir, Freundlich, and Sips models. The silica adsorbent exhibited a high adsorption rate; equilibrium was reached in few minutes, due to its high hydrophilicity and nontortuous structure. A high adsorption capacity was predicted, and a heterogeneous sorption behavior was validated by the isotherm models. Finally, regeneration performance of the adsorbent in both batch experiments and liquid chromatographic (LC) column-based experiments demonstrated that the adsorption capacity was marginally sacrificed (less than 10%) after three cycles of measurements, illustrating promising reusability. These findings may open up new ways to design high-performance boron-specific adsorbents.