Treatment Of The Dimethylamine Wastewater By Complex Extraction And Ion-exchange

As one of the most common chemical raw materials, Dimethylamine (DMA) is widely used in the various industries. It produced large quantities of DMA wastewater during the use and production process of DMA. The DMA wastewater would not be allowed to drain because it not only po1luted environment but also led to great waste of water resources. Aimed at this case, the complex extraction and the ion exchange technology had been used to recover DMA from the DMA wastewater in this paper. It will be beneficial to the recycling of DMA.A complex extraction method was used for the treatment of DMA wastewater. The effects of sorts and concentrations of diluents, sorts of complexing agent, pH of aqueous solution and the volume ratio of oil to water on the extraction of DMA from wastewater have been systematically studied. According to pH-swing effects anti-extraction of loaded organic phase has been researched. The results showed that extraction effiency of DMA in wastewater reached 93.0 % with 10 % P204 + 90 % hexahydrobenzene (V/V), and complexing agents were regenerated with aqueous solutions of 10 % HCl (V/V), the recovery rate of DMA was achieved 93.8 % . The extraction of DMA by P204 is an exothermal reaction with ?H of ?6.50 kJ/mol. By means of double-logarithmic coordinates, the composition of extracted species was deduced, P204:DMA as 1:1. The mechanism of complexation reaction was investigated by infrared spectra of loaded organic phase,there are hydrogenbond- association and ion-association reaction.An ion-exchange method was also adoped to treat DMA wastewater. The imfluence of the flow rate, concentration, temperature, the rate of height to diameter of resin bed on the removal of DMA from wastewater have been systematically studied. Then the effects of sorts, concentration and flow rate of eluants on the elution of DMA were also investigated in this paper. It was revealed that the DMA wastewater would be treated effectively by the strong-base cationic ion-exchange resin 001×7; the equilibrium adsorption capacity of the DMA onto 001×7 would up to 103.27 mg/g, the removal rate of DMA in wastewater exceeded 99 % at DMA flow rate of 10.2 mm/min and the rate of height to diameter 3.76; then resins would be regenerated with 4 % H2SO4 at flow rate of 5.1 mm/min, the recovery rate of DMA was achieved 100 %. The adsorption equilibrium data of DMA onto 001×7 accorded with the Langmuir isotherm. The thermodynamic parameters calculated from the Van't Hoff plots were: ?G<0, ?H>0, ?S>0, which indicated that the sorption process would be spontaneous and exothermic, purely chemisorption governed; Ea of 6.418 kJ/mol indicated that the adsorption occured more easily in nature. Kinetic studies suggested that the adsorption followed a pseudo-second-order chemical reaction, and the intraparticle diffusion was the main rate-limiting. The FT-IR of the 001×7 resin before and after DMA sorption suggested that the adsorption process of DMA on the 001×7 resin was ion-association reaction.