Lanthanum Carbonate Hydroxide Research Articles

Lanthanum carbonate hydroxide/magnetite nanoparticles functionalized porous biochar for phosphate adsorption and recovery: Advanced capacity and mechanisms study

As the increase of global industrial activities, phosphate from industrial wastes such as sewage sludge has become one of the limiting factors for water eutrophication. Herein, lanthanum carbonate hydroxide (La(CO3)OH)/magnetite (Fe3O4) nanoparticles functionalized porous biochar (La/Fe-NBC) with high phosphate adsorption properties is synthesized through molten salt pyrolysis-coprecipitation-hydrothermal multi-step regulation, and further reveal the related processes and mechanisms. La(CO3)OH functions as active sites for phosphate adsorption, Fe3O4 imparts magnetic properties to the composite substance, also porous biochar (NBC) acts as the carrier to prevent the agglomeration of La(CO3)OH and Fe3O4 nanoparticles. The adsorption process of La/Fe-NBC for phosphate fits to the Pseudo-Second Order and Langmuir model, with the theoretical maximum adsorption capacity up to 99.46 mg P/g. And La/Fe-NBC possesses excellent magnetic field (14.50 emu/g), stability, and selectivity, which enables for efficient multiple recovery and reuse. Mechanistic studies have shown that ligand exchange (inner-sphere complexation) between phosphate and carbonate/hydroxyl groups of La(CO3)OH, and electrostatic attraction play the dominant roles during adsorption process, although susceptible to the solution pH. While co-precipitation is not influenced of pH conditions but with limited contribution to phosphate adsorption. This study may facilitate to optimize the synthesis design of phosphate multi-functional composites for low-carbon and sustainable treatment of industrial phosphate-containing wastes.

Lanthanum carbonate nanofibers for phosphorus removal from water

Cross-linked poly(vinyl alcohol) nanofibers were dipped in alternating solutions of aqueous lanthanum acetate and alkali metal carbonates (for up to 10 cycles) to precipitate lanthanum carbonate. Only sodium carbonate yielded Na–La double-metal carbonates and lanthanum carbonate hydroxide as the cycles of precipitation increased. Potassium and cesium carbonates yielded lanthanite phases that removed more P than inorganics derived from Na2CO3 (212 and 157 mg P g−1 nanofiber, respectively, at pH 7 after 110 h). The lanthanum carbonate from Na2CO3 and K2CO3 showed the greatest potential for P removal when exposed to groundwater for more than 24 h. Among the phase and pH-dependent mechanisms of P removal, lanthanite transformed to lanthanum phosphate at neutral pH and phosphate ions exchanged with carbonate ions. Hydration of crystalline phases (synthesized from Na2CO3 and Cs2CO3) was accompanied by phosphate ion sorption at pH 10. Within 24 h, phosphate ion sorption was higher at pH 10 than pH 7, indicating that ion exchange between phosphate and carbonate at pH 7 occurs relatively slower than diffusion of hydrated phosphate ions at pH 10. Selective P removal of the developed lanthanum carbonate mineralized nanofibers will help develop novel water purification technology that can be used in contaminated sites.

The effect of La on the hydrotalcite derived Ni catalysts for dry reforming of methane

A series of 20Ni-Mg-Al hydrotalcite-like (HT) precursors were prepared to study the influence of lanthanum (La) on the catalytic activity of the catalysts in the dry reforming of methane (DRM). The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD) and temperature-programmed reduction (TPR). All catalysts presented ordered mesoporous structures with a large specific surface area. XRD confirmed the presence of HT structure for all of the precursors while the La promotion resulted in an additional phase of Lanthanum carbonate hydroxide. TPR study showed larger reduction degree for the catalysts but also reduction peaks that are shifted to higher temperatures. DRM reactions at 600 and 750 °C revealed that the DRM activity was increased by the addition of La, while the stability of the catalysts was reduced at 600 °C.

Preparation and Characterization of Lanthanum Carbonate Octahydrate for the Treatment of Hyperphosphatemia

We proposed a new approach to prepare lanthanum carbonate via reactions between lanthanum chloride and NaHCO3. In the reaction, small amount of NaHCO3solution was firstly added to the acidic lanthanum chloride solution to generate lanthanum carbonate nuclei and then NaHCO3is added to the lanthanum chloride at a constant speed. This approach makes both precipitation reaction and neutralization reaction take place simultaneously. Consequently, lanthanum carbonate is produced at low pH environment (pH below 4.0) so that the risk of generating lanthanum carbonate hydroxide is reduced. The product of the above reaction is validated by EDTA titration, elemental analysis, and XRD characterization. In addition, we established a FTIR spectroscopic method to identify La(OH)CO3from La2(CO3)2·8H2O. Lanthanum carbonate exhibits considerable ability to bind phosphate.

PVP-assisted assembly of lanthanum carbonate hydroxide with hierarchical architectures and their luminescence properties

In the presence of polyvinylpyrrolidone (PVP), three-dimensional (3D) hierarchical nest-like architecture of lanthanum carbonate hydroxide (LaOHCO3) with uniform size is successfully synthesized by a facile hydrothermal process using La(NO3)3 as the starting material. The result indicates that LaOHCO3 microspheres are constructed layer-by-layer from a large number of two-dimensional plates, which are composed of numerous nanorods with a length of ∼50nm. The formation mechanism is discussed on the basis of the result of a time-dependent experiment. It is demonstrated that PVP played an important role in the formation of the hierarchical structure. The room temperature photoluminescence properties of the LaOHCO3 with different morphologies and size are investigated, showing that the nest-like LaOHCO3 exhibits a relative stronger luminescence intensity at 420nm than the synthesized rod- and apple-like LaOHCO3 samples.

Preparation and characterization of lanthanum carbonate hydroxide

Two polymorphs of LaCO 3OH were prepared from either La 2(CO 3) 3 or LaBr(OH) 2 at an ambient pressure. The first one was the same as reported before by several workers who prepared it by the hydrothermal technique. The second one is a new polymorph of LaCO 3OH. The infrared spectra and thermogravimetric curves of these two polymorphs were determined and compared. Its crystal data were determined by X-ray powder diffraction: orthorhombic, a = 5.033(3)Å, b = 8.598(5) Å, c = 7.401(3) Å. All data support that the structure of this new modification is similar to that of ancylite.