Researches Of La-containing Nanosized Phosphate Materials Using As Solid La Sources In Hydroponic Culture And Using As Solid-phase Extractor

China is rich in rare earth resources, which reserves and mining yield all rank the first in the world, accounting for34%of the world’s total reserves. It has variety types and lower mining costs and also distributes widely in several provinces. Development and applications on rare earth element focus on the following aspects. Micro-Rees in steel could improve its application technology. Using as a micro fertilizer and a feed additive it can make the crops and livestock better. As an important rare earth inorganic salt, rare earth phosphate plays a significant role in the areas of optics material, catalysis and other functional materials.This paper committed to the application of La-containing nanosized phosphate materials using as solid La sources in hydroponic culture and using as solid-phase extractor in the organic acids determination.1. Studies of application of La-containing nanosized phosphate materials using as solid La sources in nutrient solution culture. Because of too much Rees entering in the environment, rare earth elements pollution constitutes a unique problem of our country. This paper proposes a method of using La-containing nanosized phosphate materials in plant hydroponic culture when studying the phytoremediation of rare earth elements. La-containing nanosized phosphate materials act as lanthanum source and phosphorus source in the nutrient solution. The root exudates of barley containing a lot of organic acids may mobilize and utilize the solid powders. We shall explore the feasibility of this approach. Three treatments are prepared, which are nHAP adsorption with La3+, nHAP doped with La3+and nanosized lanthanum phosphate respectively. The three materials are all prepared by a co-precipitation method. XRD, FTIR, TEM, the dissolution experiments and EDAX analyses indicate the materials all achieve the desired results.We have studied about the concentrations of P and La in the nutrient solutions and the barley, the biomass, the content of trace elements, antioxidant enzyme system, MDA and chlorophyll of the barley. The results indicate nanosized lanthanum phosphate could not been used in plant culture, however the other two have the possibility. Although the roots of barley secrete a lot of organic acids, nanosized lanthanum phosphate could not meet the barley’s requirements of P. Proper amounts of the other two materials could achieve it. In the basis of enough P, increasing the adsorption and doping content of La3+may achieve the desired results.2. Application of nanosized lanthanum phosphate in using as solid-phase extractor in the organic acids determination. As the high concentrations of nitrate ions, the quantitative analysis of oxalic acid in xylem saps of plants is difficult to carry out by RP-HPLC method. An improved method using nanosized LaPO4as solid-phase extractor for avoiding the interference from nitrate ions on oxalic acid is developed in this paper. The oxalic acid in xylem saps could be extracted by LaPO4and determined successfully. Oxalic acid can be adsorbed by0.05g LaPO4powers completely within120minutes at initial pH2.5. It shows a higher adsorption capacity than nHAP in our previous work and overcomes the shortcomings of nHAP which is easier to be dissolved. Then retained oxalic acid was eluted from the adsorbent with40mmol/L NaOH solutions. Recoveries for oxalic acid are between97.7%and107.3%, and the relative standard deviations (RSD) were less than3.0%. In conclusion, the proposed method is reliable and feasible as the good linearity, precision, accuracy, and selectivity for the determination of oxalic acid in the xylem saps of tomato in RP-HPLC, and also can be adapted to other plant samples.