Efficient Fluoride Removal In Drinking Water By Ammonium Bosted Nanocomposite Containing Lanthanum Oxide Nanoparticles

Here, we succeeded in fabricating a new nanocomposite by anchoring nano-La₂O₃ onto D201 modified with the positive ammonium groups（N+） for fluoride removal in drinking water. The nanocomposite（denoted as D201-La₂O₃） were well characterized by scanning electron microscope（SEM）, energy spectrum analysis（EDS）,transmission electron microscopy（TEM）, X-ray diffraction（XRD） and surface area analyzer（BET）. Results reveal that the embedded nano-La₂O₃ exhibits crystalline pattern with size of about 20-30 nm. The fluoride removal onto D201-La₂O₃ is a pH dependent process with the optimal sorption pH range between 3.0 and 7.0. As compared the host matrix D201, the resultant composites can achieve efficient fluoride removal in presence of the common competing ions SO₄ （2-）, Cl^- and NO₃^- at high contents, indicating its preferential selectivity. Additionally, the resultant D201-La₂O₃ can attach a rapid sorption equilibrium within 180 min, which is temperature relating endothermic process with the maximum sorption capacity of 122.2 mg/g. Fixed bed column test suggests that satisfactory fluoride removal can be reached for application with available treated volume of approximately 1180 BV and the effluent can be reduced to below 1mg/L, which meet the Drinking Water Standard（GB5719-2006）.XPS spectrum analysis and SEM-EDS were further conducted to elucidate the potential mechanism and the role of modified ammonium groups. XPS investigation indicates that the embedded nano-La₂O₃ will grant the dominated roles on selective fluoride sequestration rather than the modified N+ group. Furthermore, two refereed composites were prepared, i.e. the hosts were modified with neutral CH2 Cl and negative SO3-H groups. Evidently, the unique N+ groups can greatly improve directional fluoride accessibility and then, achieve efficient nano- La₂O₃ utilization within 90 min. Relatively,the can only bring about trace nano- La₂O₃ usages in outer-thin region even at 24 h. Our work set animportantbenchmark and guideline for efficient nanocomposite fabrication,through charged functional groups induced nanoparticles utilization improving. The resultant composite D201-La₂O₃ exhibits better application prospect.