Study On Intercalation Of Mg/Al Layered Double Hydroxides And Its Application In The Treatment Of Dyeing Wastewater

In this thesis, by using anionic exchangealility and host-guest interaction of LDHs, Dodecyl sulfonate(DSO), dodecyl sulfate(DS) and dodecyl benzenesulfonate(DBS) anions were intercalated into layered double hydroxides(LDHs) through nitrate hydrotalcites (MgAl-NO3-LDHs) via anion exchange, co-precipitation and calcine-recovering methods. The structures, physicochemical properties and thermal performance of these intercalated materials had been investigated profoundly by XRD, FT-IR and TG-DTA. The contact angles were mensurated. Adsorption of Dispersive Blue S-3BG using LDHs was studied together with their mechanism and regeneration of performance.The performance of intercalated materials showed that crystallinity and composition would be effected by different reactive temperature, pH value and aging process. FT-IR indicated that: besides electrostatic interaction and Van der Waals force, hydrogen bonds force which was formed of S=O···H-O-M also existed between layers and surfactant anions.Compared with MgAl-NO3-LDHs, the spacing of intercalated materials singnificantly increased by calculating. The spacing among diffraction peaks existed in multiples of relations.This showed that surfactant anions were intercalated into LDHs; different intercalated methods should be used to prepare different intercalated materials.Thermolysis process included removal of interlayer water, detachment of hydroxy group as well as burning of organic phase with the release of energy. Thermal stability depended on the performance of the anions.The experimental results showed that the decolorization rate could be up to 97% when pH value was 7, the adsorption time was 80 min, the temperature was 25℃and the dosage was 1000mg/L. The adsorption of S-3BG on MgAl-NO3-LDHs was conformed to the Frendlich isotherm equation; the adsorption of S-3BG on DBS-LDHs was conformed to the Langmuir isotherm equation. The adsorption capacity of intercalated materials was DBS-LDHs﹥DSO-LDHs﹥DS-LDHs.Compared with MgAl-NO3-LDHs, the contact angles of intercalated materials had been changed significantly, as well as their hydyophilic and hydrophobic properties. In addition to the distribution of adsorption foremed by hydrophobic interaction between intercalated material and S-3BG, the adsorption process of intercalated materials also existedπ-πinteraction between benzene ring of S-3BG and benzene on the DBS, which could enter S-3BG into layers gap well, then could enhance the adsorption capacity.Thermal regeneration for re-use of MgAl-NO3-LDHs/DBS-LDHs after Reactive or Weak dyes adsorption was feasible only within the two or third cycles. Henceforth, the adsorption capacities of the regenerated materials decreased with increasing of the cycles.