| Adsorption and ion exchange methods were used to study the separation and removal of low-concentration dimethylamine from wastewater of synthetic leather production, respectively. Using the static and dynamic experimental methods, activated carbon fiber and macroporous resin were selected as adsorbents in the adsorption method, and adsorption-desorption processes were studied. The exchange and regeneration behavior of macroporous weak acid cation exchange resin were studied in the ion exchange method. The process conditions were optimized, and equilibrium, kinetic and thermodynamic process of separation were studied.In the adsorption separation of dimethylamineine with activated carbon fiber, activated carbon fibers (ACFs) were modified by gas phase oxidation. Under the optimal static adsorption condition, the adsorption efficiency to dimethylamine aqueous solution of 256 mg·L-1 was 85%. The adsorption rate was high. Langmuir model and Freundlich model can simulate well the adsorption of dimethylamine on ACF. The dynamic adsorption curve was determined. Saturated ACFs were regenerated by 5% HC1 solution and the regeneration efficiency reached nearly 100%.Macroporous resin LS-40 was used to study the adsorption process of dimethylamine. Adsorption conditions were optimized with temperature, pH value and flow rate at 60℃, 11 and 30-40 mL·min-1, respectively. When the amount of 5% H2SO4 was as twice as that of the theoretical dosage, optimal desorption conditions were obtained with the desorption rate of 95%. In the experimental range, Langmuir isotherm equation can well describe the adsorption behavior of dimethylamine on LS-40. The exchange of kinetic processes obeyed the second-order kinetic model. The control procedure of velocity was liquid film diffusion.By optimization of different types ion exchange resins, the cation exchange resin D113 was selected and used to separate low-concentration dimethylamine of wastewater. The optimal work parameters of static and dynamic exchange were obtained, respectively. Under the optimal conditions, the removal rate reached 91.5%. Under conditions with the concentration of regenerant, regenerative ratio and flow rate at 5% H2SO4, 2.5and 10 mL·min-1, the regeneration rate at room temperature was above 90%. After regeneration, the exchange capacity of ion exchange resin had basically no change. The Langmuir model can simulate well the exchange process of dimethylamine on ion exchange resin. Moving boundary model and the particle diffusion equation can describe well the exchange process of dimethylamine on the exchange resin D113. Thermodynamic studies showed that in the exchange process, enthalpy changeΔH>0, free energy changeΔG<0 and entropy changeΔS>0 which showed the exchange process was spontaneous and endothermic.
|
PDF Full Text Request