Method for producing magnetic perovskite oxide nanomaterials used to adsorb arsenic from contaminated domestic water and materials obtained by this method

For the purpose of fabricating a nanocomposite with high capacity for arsenic adsorption, which can be directly used for efficient arsenic adsorption and produces uniform, nano-sized products at low cost, the patent "Method to produce magnetic perovskite oxide nanomaterials LaMn0.7Fe0,3O3 used to adsorb arsenic from contaminated domestic water and materials obtained by this method" has been granted by the Intellectual Property Office of Vietnam, Patent No. 1-0028457, for Dr. Vu The Ninh and associates of the Institute of Materials Science, on May 25, 2021.

The patent Method to produce magnetic perovskite oxide nanomaterials with the formula LaMn0.7Fe0,3O3 is applied to adsorb arsenic in solution and in contaminated domestic water. The production method of perov-skite perov-oxide nanomaterials LaMn0.7Fe0,3O3 is carried out by applying a process that uses the precursors of the respective metal nitrate salts and polyvinyl-alcohol to form the intermediate compound, and then decompose the intermediate to obtain the product. LaMn0.7Fe0,3O3 perovskite oxide nanomaterial is magnetic, so it can be used directly to effectively remove arsenic pollution in domestic water, and the post-adsorbed material can be separated from the solution by magnetic force.

Currently, domestic water is extracted mainly from groundwater and a little from surface water through water treatment plants. Water supply for the treatment plant, for groundwater, people must select drill sites from good quality aquifers with no or very little arsenic; With surface water taken from rivers and lakes, it is difficult to avoid the influence of toxic residues and trace elements. On the other hand, due to limited funding, the current investment in clean water supply systems and works is enough to meet the clean water needs of urban and densely populated areas. In most rural areas, including those contaminated with arsenic, people are having to collect drinking water from drilled wells.

In Vietnam, from the abundant resources that have provided cheap and readily available materials containing La, Fe, and Mn components, the authors have made a perovskite oxide nanomaterial LaMn1- xFexO3 which is not only magnetic but also has a higher arsenic adsorption capacity than other types of adsorbents being applied today. From there, this material can be used directly to treat arsenic pollution with outstanding efficiency.

The patent provides a method to fabricate a perovskite oxide nanomaterial LaMn1-xFexO3 from the precursors of the corresponding metal nitrate salts and PVA with clearly defined steps for a stable quality product. Production method uses simple equipment and methods, from which it is easy to invest in building production lines. On the other hand, with raw materials from available resources in Vietnam such as: La - a by-product of rare earth separation technology, Mn and Fe - being obtained from mines or sludge sources from water plants, the production cost of LaMn1-xFexO3 perovskite oxide products will be really reasonable.

Furthermore, the perovskite nano-adsorbent LaMn1-xFexO3 is magnetic. Magnetic adsorbent materials allow direct contact of magnetic nanoparticles with pollutants such as metal ions, organic and biological substances from domestic water and wastewater. After adsorption, the magnetic force is used to separate the magnetic adsorbent material for further treatment, so no secondary pollutants are generated. Therefore, the technique based on the magnetic separation principle will be faster, simpler and cost-effective compared to other competing technologies such as chemical precipitation, agent digestion and membrane filtration.

Exploiting this advantage of the material, the authors have demonstrated that this material can be used directly to remove arsenic from solution without using a carrier and recover the material after adsorption by magnetic force. This results in very high material efficiency and unlimited application of arsenic removal in contaminated water environments. The saturated adsorbent material can be easily regenerated for reuse or landfill (because of the small volume of the material but the high adsorption capacity) to avoid the emission of a secondary source of pollution, which is hardly provided by a majority of current materials. From here, it is possible to collect arsenic (possibly heavy metals and other toxic residues) that are released into the environment from various water sources, helping improve the living environment for sustainable development and protect the environment and community health.

SEM image of perovskite complex oxide LaMn0.7Fe0,3O3 and material parameters

Translated by Phuong Huyen
Link to Vietnamese version

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