Toxicity Of Reducing The Plant Toxicity Of Nano-sized Cerium Oxide And Nano-sized Lanthanum Oxide By Surface Modification

In the production,use and disposal process of nano materials and nano products,nano materials will inevitably enter our life through a variety of ways in the natural environment,but its unique physicochemical properties may bring potential impact to the ecological environment.Therefore,it is necessary to pay more attention to the negative environmental effects and ecological effects that nanomaterials may cause when they affirm that nanomaterials have brought great technological progress.Nano CeO₂ and nano La₂O₃ two typical rare earth oxide nanomaterials,because of their good catalytic activity,are often used in chemical catalysis and exhaust gas treatment.Nano CeO₂ and nano La₂O₃ have also begun to affect our ecological environment.Studies have shown that nano CeO₂ and nano La₂O₃ have certain phytotoxicity to the tested plants.In this thesis,surface modification of nano CeO₂ and nano La₂O₃ was carried out in order to reduce the toxicity of nano CeO₂ and nano La₂O₃.The characterization and toxicity experiments of nano CeO₂ and modified nano CeO₂,nano La₂O₃ and modified nano La₂O₃ were carried out respectively:?1?we successfully prepared nano CeO₂/CeO₂ modified by ATMP and EDTMP.All the materials are spherical in shape,and the size of the modified CeO₂ particles is almost unchanged.ATMP and EDTMP are found to be less important in the materials obtained by TG analysis.The root elongation of lettuce roots,Ce content and enzyme activity,TEM was found:nano CeO₂ inhibited the growth of lettuce,while the ATMP and EDTMP modified nano CeO₂ toxicity to lettuce was significantly reduced,especially at the nano CeO₂ EDTMP modified group,root elongation and the control group is almost the same,and decrease the content of Ce into cells in Ce decreased significantly,SOD decreased,indicating the modified CeO₂,the dissociation of material surface has been effectively restrained,so as to reduce toxicity.?2?through the detailed characterization of nano La₂O₃,ATMP@La₂O₃ and EDTMP@La₂O₃,it was found that La₂O₃ nanoparticles were spherical and uniform in size.After modification,ATMP@La₂O₃ and EDTMP@La₂O₃ showed no change in morphology and crystal structure when the materials were not modified by two modifications.Through the TG diagram analysis and comparison of two different modification methods,we found that the ATMP modified by nano La₂O₃ is more,and EDTMP is relatively less.Study on the measurement and detection of TEM in root elongation by found:compared with nano La₂O₃,root elongation of ATMP modified nano La₂O₃ on cucumber inhibition effect decreased significantly,while nano La₂O₃ modified with EDTMP toxicity reduced;As the nano CeO₂ showed similar results,the distribution of La in ATMP@La₂O₃ group on cucumber roots in comparison with nano La₂O₃ was significantly decreased due to the dissociation of material surface is suppressed so as to reduce the toxicity of plants.