Studies On Influencing Factors And Forecast Model For The Removal Of Neutral Pharmaceuticals In Water By Nanofiltration

Pharmaceuticals (PhACs) have exposed frequently in the water environment in recent years and have been received wide attention. Although the concentration of PhACs is generally in the range of ng/L～μg/L, the damage to the ecological environment and the human body can not be ignored. Studies have shown that nanofiltration as a new type of membrane treatment technology can effectively remove PhACs.This study mainly investigated the effect of operating conditions including the operating pressure, feed concentration, pH and temperature on the removal of antipyrine (ANT) and isopropylantipyrine (AMT) with NF-W. At the same time, the SKK model and CFSD model have been used to predict the rejection of AMT and ANT by NF-X and NF-W. Finally, the applicability of the model established is studied based on the SKK model for AMT with NF-W.The results indicated that the operating pressure and temperature are important factors affecting the performance of NF membrane separation. In a certain range of pressure, the rejection of AMT and ANT increased quickly with the pressure rising at first, then converged to a steady state gradually. And the flux increased with the pressure increasing. The increase of the temperature did not conducive to the removal of AMT and ANT, but the permeate flux increased quickly. The increase of the initial concentration made the rejection increase slowly, but the permeate flux was constant. The change of pH had no effect on the removal rate and flux. This phenomenon could be explained that the steric effect is the main mechanism of NF separation for the neutral drugs AMT and ANT, and electrostatic repulsion between the solute and the negative charge of membrane surface can be ignored.The linear equation between permeate flux J, and the operating pressure P can be established through experiments under different pressures. The mass transfer parameters in the SKK model (σand Ps) and CFSD model (k and In[DK/δ]) were also obtained through the best-fit method. The results indicated that σand k increased with increasing the initial concentration of AMT and ANT, while the value of Ps and ln[DK/δ] basically did not change. Through the optimal fit relationship betwee σ、k and Cu, the mathematical equations were established, respectively. Then the Ro in the SKK and CFSD model can be calculated at any initial concentration and pressure. Verifying the two models finally, the rejection of AMT and ANT by NF-X can be predicted well, while the SKK model is more suitable for NF-W removal of AMT and ANT.In order to verify the applicability of the mathematical model established, the SKK model for the removal of AMT by NF-W has been taken as an example to study. The rejection of other three neutral drugs (ANT, AMP, ACE) with NF-W were predicted through the relationship between the molecules weight of different drugs. The rejection of ANT and AMP were predicted well because that they were derived by ANT and have similar molecular structures. But for ACE, the difference of spatial structure between ACE and AMT was obvious, and the prediction was not ideal. So a new rejection prediction model for ACE with NF-W needs to be established.