Preparation and Characterization of La(III)-Al(III) Co-loaded Hydrothermal Palygorskite Adsorbent for Fluoride Removal from Groundwater

In this study, a cost-effective and easily prepared adsorbent for fluoride removal was synthetized by loading activated aluminum and lanthanum onto hydrothermal palygorskite (HP) (denoted as La-Al-TAP). And the La-Al-TAP was characterized by scanning electron microscope (SEM), x-ray diffraction analysis (XRD), and x-ray photoelectron spectroscopy (XPS). As a result, the optimal condition for La-Al-TAP preparation was proposed as follows: 0.004 mol/L La(III) and 0.125 mol/L Al(OH) colloid was loaded onto the acidulated HP (AP) with volume ratio of AP/La(III)/Al(OH) = 1:6:1, and then La-Al-AP was calcined at 300 °C for 2 h. Results proved that the La-Al-HP adsorbent had a significantly larger surface (95.58 m/g) than that of raw HP (34.31 m/g). The amorphous structure provided a favorable site for fluoride adsorption, subsequently improving the adsorption capacity of HP. The results all indicated the formation of oxide La-Al-O composite at the surface of adsorbent. The adsorption of fluoride by adsorbent La-Al-TAP was well fitted to the Langmuir isotherm and the maximum adsorption capacity was up to 1.04 mg/g. It was also found that the adsorbent could be regenerated for such six times with good security performance. In conclusion, the newly prepared La-Al-TAP adsorbent in this study has potential as an excellent adsorbent for fluoride removal in groundwater remediation works.