Hydrotalcite-like LZH And Its Composite Materials For Adsorption And Photocatalytic Degradation Of Dye Wastewater

Organic dye wastewater causes serious harm to both human body and our environment because of its complex component,highly toxic,stable structure,deep chroma,and carcinogenicity-mutagenicity-teratogenicity.Now,adsorption and photocatalysis technology show great advantages in solving such wastewater.Absorption materials have fast and efficient absorption performance for the organic dye wastewater,and photocatalytic reaction can degrade the organic dye wastewater into CO₂ and H₂O thoroughly.In this project,we prepared LZH,Zn-Cu-LDH absorption materials and LZH/g-C₃N₄ photocatalytic composite materials,furthermore researched on the adsorption and photocatalytic performance for dye wastewater.The main research contents and results of are as follows;1.Two-dimensional nanosheet LZH materials with high adsorption performance were prepared by hydrothermal method using ZnSO₄ and triethanolamine?TEOA?as raw materials.We could get such material with the best performance when the reaction temperature is 110?and keep for 1h,and the addition amount of TEOA is2mL through optimization of the material preparation conditions.The adsorption performance of LZH materials on Congo Red?CR?dye solution under different preparation conditions was investigated.When the addition amount was 0.75 g/L,such material showed a relatively stable adsorption effect in the range of pH from 4 to8.The isothermal adsorption equation was used to simulate the kinetics equation of LZH materials for CR.The results showed that the adsorption of CR dye solution by the sample was single-layer adsorption and there was some chemical adsorption reaction existing in the adsorption process;2.We dope Cu into LZH materials in order to prepare three kinds of Zn-Cu-LDH with different addition amount of triethanolamine through hydrothermal method.The adsorption effects on methyl orange?MO?dye solution were systematically investigated.The removal rate of Zn-Cu-LDH to high concentration MO?500 mg/L?reached 99.4%in 60 minutes and it matched the pseudo-second-level kinetic model,showing good reusability;3.Based on the low band gap width?².7 eV?of g-C₃N₄,the LZH/g-C₃N₄composite photocatalytic material was designed,and prepared using g-C₃N₄ as raw material which is attained by calcining melamine?C₃H₆N₆?method.Then we prepare LZH/g-C₃N₄ composite photocatalytic material using g-C₃N₄ as template by hydrothermal synthesis method.The material formation mechanism was analyzed through the above-mentioned characterization methods.Then we investigated the photocatalytic effect of materials on CR,studied the photocatalytic degradation ability of CR dyes by LZH/g-C₃N₄ composite photocatalyst,and analyzed its photocatalytic mechanism.The result showed that when the percentage of g-C₃N₄ was 4wt%,the photocatalytic degradation rate of LZH/g-C₃N₄ material to 100 mg/L CR could reach89.1%.We found that there was synergistic action between various active substances during the degradation process of LZH/g-C₃N₄ on CR using free radical capture experiments.