Cu²⁺ And Cd²⁺ Adsorption Performance And Biosafety Evaluation Of Nano Manganese Dioxide

Copper and cadmium pollution is increasingly more serious problem in China. Measurements of controlling polluted water quality has becoming the key problem of food safety and human healthy to be solved. In this research, a potential adsorbent, Nano Mn O2(n Mn O2) economically and efficiently were synthesized by KMn O4 solution and ethanol. Adsorption study and XRD, XPS, FTIR analysis were performed to research the adsorptive property and adsorption mechanism. Then the rice seedlings hydroponic toxicology experiment and earthworm experiment were performed to research the way nanoparticles translocated into plants and evaluate the Nano manganese dioxide. All these experiments were designed to support Cu2+ and Cd2+ water pollution management and provide evidence to expand what n Mn O2 can be used on controlling heavy metal ions(HMI) polluted water & soil environment. Some main conclusions are listed below:(1) Systhesis of Nano manganese dioxide(n Mn O2) The results showed that the specific surface area of n Mn O2 was 141.66 m2/g. The adsorption data were fitted to Pseudo-second-order kinetic model(R2 Cu=0.99;R2 Cd=0.98), Elovich model(R2 Cu=0.91;R2 Cd =0.93) and Langmuir adsorption model(R2 Cu=0.98, R2 Cd=0.94). The max adsorption capacity of Cu2+ and Cd2+ were 104.5 and 89.1 mg/g, respectively. Increasing the temperature could improve the adsorption capacity of n Mn O2 for the heavy metal ions. The adsorption capacity of n Mn O2 for Cu2+ and Cd2+ are higher in a high p H system. 35.8 yuan and 73.8 yuan will be spending on adsorbing Cu2+ and Cd2+ with n Mn O2. The experimental results show that n Mn O2 is efficient on adsorbing Cu2+ and Cd2+.(2) the nMnO2 significantly alleviate the toxicity of heavy metal and HMI loaded nMnO2 translocated into plants with no HMI release and make a heavy oxidative stress. With nano hydroxyapatite as reference, we researched on the toxicology of the n Mn O2 nanoparticles composite copper and cadmium in rice seedlings. TEM photo confirmed that the n Mn O2 nanoparticles in rice seedlings exist; smaller diameter nanoparticles make more damage to rice seedlings, nanometer manganese dioxide reduces the accumulation of heavy metal ions by rice seedlings, the highest content of heavy metals in mesocotyl, at the same time the n Mn O2 can promote plant root length and the total surface area. But nano particles especially n Mn O2 causes extremely strong oxidative stress reaction. Then we detected the Cd2+ or Cu2+ fluxes on the surface of root hair, the results of it indicates that the heavy metal was not translocated in an ironic form.(3) nMnO2 promoted the toxicity of HMI to eisenia fetida This experiment performed a high usage of nano particle to study the earthworm under the direct exposure of heavy metal loaded nanoparticles acute toxicity effect. The results showed that n Mn O2 can significantly reduce the accumulation of earthworm on Cd, but it could significantly stimulate eisenia fetida antioxidant enzyme system of stress reaction. This indicated that the n Mn O2 reduced the LC50 of Cd for one eisenia fetida, under the synergy of nanometer manganese dioxide, the toxicity of Cd promoted from " medium toxic level " to "high toxic level". In the treatment Cu group, earthworms did not die.