Research On The Synthesis Of Ionic Liquids/Layered Double Hydroxides Intercalation Composites And Their Application On The Absorption Of Dyes From Aqueous Solution

At present, the pollution of printing and dyeing wastewater is an urgent problem to be solved. Because of the characteristics of large amount of water, strong alkalinity and high organic content,printing and dyeing wastewater has been amongthe most unmanageable industrial wastewater.The adsorption method is one of the most effective methods for the decoloration of the dyeing wastewater which is an important part of the printing and dyeing wastewater treating process. Layered double hydroxides(LDHs) is a kind of anionic layered materialand its interlayer has exchangeable anions. LDHs has the potential value of research and application in various fields, such as chemical engineering, medicine, material and environment. In this study, a series of hydroxyl ammonium ionic liquids/layered double hydroxides intercalation composites(ILs/LDHs) were synthesized by coprecipitation method.The characterization results of XRD, FT-IR, and TOC indicated that ethanolamine ethanoic acid ionic liquids(ILs(b)) was successfully inserted into the interlayer of LDHsand the composite had the best crystal structure.The results of SEM and BET showed that the intercalation made the spacing between layers and the specific surface area of LDHs become larger, which helped improving the adsorptive property of LDHs. Hence, ILs/LDHs(b) was chose to be investigated the adsorbabilities towards Reactive Orange 5 and Acid Red 27 in the aqueous solution comparing with the pure LDHs.In the study of the adsorption experiments of Reactive Orange 5, the adsorption mechanism, the effect of initial pH of dye solution and adsorbent dosage on the adsorption process, SEM morphology of ILs/LDHs(b) before and after adsorption and the reuse of ILs/LDHs(b) were investigated.The results indicated that the adsorption capacity of Reactive Orange 5 of ILs/LDHs(b)(qmax=300.91mg/g) was much higher than that of pure LDHs(qmax=53.83mg/g).The adsorption rate curves of the two sorbents conformed to pseudo-second order kinetic model and the adsorption isotherm conformed to Freundlich isotherm model.The negative value of ΔGo and the positive value of ΔHo indicated that the absorption process in the system was endothermic and spontaneous.Higher initial pH value of dye solution and larger usage amount of absorbent is not advantageous to the absorption process. The initial pH value of dye solution was determined to be 6.0, and the optimal dosage of the adsorbent was determined to be 0.5g/L. The electrostatic attraction was the main acting force between ILs/LDHs(b) and Reactive Orange 5. The pore structure of the ILs/LDHs(b) after absorption become fuzzy and the most of interlamination was covered by Reactive Orange 5. For ILs/LDHs(b), the desorption ratios of ternary cycle were 57.91%, 46.67%, and 37.34%, respectively. The recycle ability for the absorption of Reactive Orange 5 of ILs/LDHs(b) showed fine.In the study of the adsorption experiments of Acid Red 27, the adsorption mechanism, the effect of initial pH of dye solution and adsorbent dosage on the adsorption process and the reuse of ILs/LDHs(b) were investigated.The results indicated that the adsorption capacity of Acid Red 27 of ILs/LDHs(b) was more than 4.5 times the adsorption capacity of pure LDHs.The adsorption rate curves of the two sorbents conformed to pseudo-second order kinetic model and the adsorption isotherm conformed to Sips isotherm model.The negative value of ΔGo and the positive value of ΔHo indicated that the absorption process in the system was endothermic and spontaneous. Higher initial pH value of dye solution and larger usage amount of absorbent is not advantageous to the absorption process. The initial pH value of dye solution was determined to be 6.0, and the optimal dosage of the adsorbent was determined to be 0.5g/L. The absorption and desorption abilities for the absorption of Acid Red 27 of ILs/LDHs(b) showed fine, which indicated good recycle abilities.To sum up, the prepared ILs/LDHs(b) in this paper had efficient absorption abilities towards anionic dyes. It can be used as a potential and effective absorbent in the decoloration of the dyeing wastewater in the dyeing and finishing industries.