Study Of The Separation Mechanism Of HTCC/PES Nanofiltration Membrane

This paper selects four kinds of pharmaceutical and personal care products (PPCPs) including Carbamazepine, Ibuprofen, Sulfamethoxazole and Atenolol. Discussed the separation effect of PPCPs with charged membrane synthesized by polyethersuifone (PES) ultraflitration membrane as the support layer and 2-hydroxypropyl trimethyl ammonium chloride chitosan (HTCC) as the active layer. Two kinds of natural organic matter (NOM) were choosen for the permeation experiment to explore the impact of NOM on PPCPs rejection. We also selected 26 kinds of organics for studying the influence of molecular size, polarity and charge on the retention of organic molecues by nanofiltration. Finally steric-hindrance pore (SHP) model and Donnan steric partitioning pore (DSPM) model were established by filtration experience of aqueous solutions of sodium chloride in order to characterization and prediction the separation performance of HTCC/PES membrane.The experimental results showed that NOM used in the study displayed obviously diverse impacts on PPCPs removal and flux decline by HTCC/PES membrane. These impacts seemed to correlate with followed three points:1. The formation of the filter cake layer could alter molecular weight cut-off,2. The hydrophobicity or hydrophilic of NOM and PPCPs.3. The hydrogen bonding interaction. The effect mechanisms have important significance to improve the nanofiltration membrane performance.In this paper, the retention of a series of organic molecules by HTCC/PES nanofiltration membranes was studied. In order to correlate the retention with the size of the molecule, which is the main factor that determines the retention, ues was made of different parameters for the molecular size:molecular weight, the Stokes diameter, the equivalent molar diameter, and a diameter obtained with energy minimization calculations. For each size parameter, the correlation with retention in nanofiltration experiments was calculated. A good correlation was found for molecular weight with the rejection rate. Two other factors were found to have an influence on retention of organic molecules:the polarity of the molecule, and the charge of the molecule.This paper carries on the taken of structure of the HTCC/PES films and the pore path rp of the film is 1.04 nm, the rate of porosity of the membrane and effective membrane thickness is 4221 m-1. Aim at solving the complexity of DSPM model calculation, this essay carries on a simplification of DSPM model and deduce process in details, which bases on the assumption of positive ionic density is greatly lower than the anti-ionic in attached positive nanofiltration film. NaCl electrolyte aqucous was choosen to carry on the experiment, and DSPM model was taking to calculate the nanofiltration film effective membrane volume charge.