Hydrothermally synthesized lanthanum carbonate nanorod for adsorption of phosphorus: Material synthesis and optimization, and demonstration of excellent performance

Eutrophication has caused severe damages to water environment, due to excessive release of nutrients (phosphorus and nitrogen). Effective removal of phosphorus is of great importance in prevention of eutrophication. In this article, we report a hydrothermal synthesized lanthanum carbonate (LC) nanorod for removal of phosphate. The concentration of urea, temperature and time were first optimized so as to obtain the best LC nanorod for the removal. It was showed that the best adsorption was obtained at pH 3 and pH 5 when pH was not controlled and was controlled, respectively. The LC worked well in pH 3-8 for the phosphate removal. The experimental data were fitted well by Langmuir isotherm; the maximum adsorption capacities of 312.5 and 303.03 mg/g were found at pH 5 and 7, respectively. The adsorption equilibrium time was 5 h; the adsorption history was well described by the pseudo-second-order equation. High ionic strength of solution (up to 1-M NaNO3) and existence of competitive substances (30-100-mg/L) showed insignificant impacts on the phosphate uptake. The spent adsorbent can be regenerated and reused satisfactorily. The mechanism study revealed that the adsorption was associated with ion exchange between carbonate and phosphate ions. Our study demonstrated that the LC nanorod was a potential adsorbent for the phosphate removal.