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目的:使用耐碱纳滤膜(NFM)处理甲壳素碱煮液回收有机氮,探究不同操作条件对膜通量及目标物截留率的影响,确定膜主要操作参数,并进行纳滤(NF)浓缩传质机理分析。方法:在不同跨膜压差(TMP)及温度条件下分别对等体积的同一物料进行8h的全循环,并通过截留率及膜通量来确定最佳TMP和进料温度。在最佳膜操作条件下对物料进行纳滤浓缩回收肽。基于固定电荷TMS模型和立体位阻SHP模型,通过Matlab拟合膜相关参数,离线分析纳滤浓缩中间过程传质变化。结果:在TMP30bar,进料温度40℃条件下进行纳滤浓缩,可有效回收有机氮。物料衡算结果表明蛋白总透过率仅5.92%。在该操作条件下,纳滤浓缩过程中总氮截留率呈增长趋势。结论:使用耐酸碱纳滤膜可以有效回收有机氮。使用TMS和SHP模型,通过Matlab软件拟合膜参数,纳滤浓缩过程中膜孔会发生微弱的阻塞,且有效膜层吸附层的表面电荷密度较原始膜电荷密度大。在Donnan效应作用下,总氮的截留率呈增长趋势。
OBJECTIVE: To investigate the effects of different operating conditions on the membrane flux and the rejection rate of target materials by treating the chitosan alkali cooking liquor with alkali-tolerant nanofiltration membrane (NFM). The main operating parameters of the membrane were determined and NF, Mechanism of Concentration and Mass Transfer. Methods: The same volume of the same material was completely circulated for 8h under different TMP and temperature conditions, and the best TMP and feed temperature were determined by rejection and membrane flux. Under optimal membrane operating conditions, the material was subjected to nanofiltration to recover the peptide. Based on the stationary charge TMS model and the steric SHP model, the membrane-related parameters were fitted by Matlab, and the mass transfer changes during the nanofiltration concentration process were analyzed offline. Results: Nanofiltration concentration was carried out at TMP30bar and feed temperature of 40 ℃, which could effectively recover organic nitrogen. Material balance results show that the total protein transmittance of only 5.92%. Under the operating conditions, the total nitrogen retention during nanofiltration concentration showed an increasing trend. Conclusion: The use of acid and alkali nanofiltration membrane can effectively recover organic nitrogen. Using TMS and SHP models, the membrane parameters were fitted by Matlab software, and the pores in the nanofiltration concentrate weakly blocked, and the surface charge density of the active layer adsorbed layers was larger than that of the original membrane. Under the Donnan effect, the total nitrogen retention rate is increasing.