摘要
Non-dispersive solvent extraction （NDSE） with p-xylene as extractant was employed as a novel separation methodto recover both ρ-toluic （PT） acid and water from purified terephthalic acid （PTA） wastewater. The mass transport behavior ofPT acid from aqueous solution to ρ-xylene was investigated by experiments and numerical simulation. Experiments showed thatNDSE is feasible and effective. Residual PT acid in the raffinate can be reduced to lower than the permitted limit of wastewaterre-use （100 g/m^3） with extraction time longer than 60 s in industrial conditions. A mathematical model of PT acid mass transportwas developed to optimize the membrane module performance. The model was validated with the experimental results withrelative errors of less than 6%. Numerical analysis for mass transfer through the lumen side, the porous membrane layer, and theshell side showed that PT acid transport in the aqueous solution is the rate determining step. The effects of the membrane andoperating parameters on membrane module performance were investigated by means of computational simulations. The keyparameters suggested for industrial NDSE design are： fiber inner radius r1=200-250 μm, extraction time tc=50-60 s, aqueous/organic volumetric ratio a/o=9.0, and temperature T-318 K.
Non-dispersive solvent extraction(NDSE) with p-xylene as extractant was employed as a novel separation method to recover both p-toluic(PT) acid and water from purified terephthalic acid(PTA) wastewater. The mass transport behavior of PT acid from aqueous solution to p-xylene was investigated by experiments and numerical simulation. Experiments showed that NDSE is feasible and effective. Residual PT acid in the raffinate can be reduced to lower than the permitted limit of wastewater re-use(100 g/m3) with extraction time longer than 60 s in industrial conditions. A mathematical model of PT acid mass transport was developed to optimize the membrane module performance. The model was validated with the experimental results with relative errors of less than 6%. Numerical analysis for mass transfer through the lumen side, the porous membrane layer, and the shell side showed that PT acid transport in the aqueous solution is the rate determining step. The effects of the membrane and operating parameters on membrane module performance were investigated by means of computational simulations. The key parameters suggested for industrial NDSE design are: fiber inner radius r1=200–250 μm, extraction time te=50–60 s, aqueous/ organic volumetric ratio a/o=9.0, and temperature T=318 K.
基金
supported by the National Natural Science Foundation of China(No.20806072)
