并流条件下聚丙烯中空纤维微孔膜的过滤特性

采用死端过滤（并流）对两种聚丙烯中空纤维微孔膜的低浊度水过滤性能进行了实验研究,并采用滤饼理论对聚丙烯微孔膜的过滤特性进行了描述．当被处理体系的阻力由膜阻力控制时,由于滤饼阻力的增加使得渗透通量快速衰减;当过程阻力由膜阻力和滤饼阻力共同主导时,渗透通量衰减变缓．在过程初期滤饼阻力与渗透总量成线性关系,但后期有偏离这种线性关系并有快速增大的趋势．分析结果表明,在相同渗透量下滤饼阻力的增加不仅与滤液本身性质有关,而且与微孔膜材料的本征性质有关,滤饼理论可以很好地解释聚丙烯微孔膜处理低浊度水溶液时的过滤性能．     

操作条件对中药四妙勇安汤超滤的影响

研究了超滤压力、温度和ｐＨ值对膜透过性的影响．结果表明,ｐＨ值对膜透过性影响很大,且碱溶液较之酸溶液使膜通量衰减更快;压力增大,膜通量衰减幅度减小;温度为３０℃时,比２０℃时的膜通量衰减程度减小,但３０、３５、４０℃时的膜通量无明显差异;在改变压力、温度下对四妙勇安汤进行了超滤,测定了氯原酸的回收率,无明显差异．     

硅藻土错流动态膜工艺处理淮河原水的运行特性

采用硅藻土错流动态膜过程直接处理淮河原水,考察商品硅藻土在不同投加量、不同附加剂配合条件下动态膜的成膜效果、出水浊度和膜通量变化.研究结果表明,采用商品硅藻土和聚合氯化铝附加剂动态膜成膜较好;继续在动态膜过滤过程中不断加入0.25 mg/L聚合氯化铝,出水浊度可以稳定在0.25 NTU或以下.错流可以适当延缓硅藻土动态膜通量衰减.     

操作条件对中药四妙通安汤超滤的影响

研究了超滤压力、温度和Ｐ至膜透过性的影响,结果表明,ＰＨ值对膜透过性影响很大,且碱溶液较之酸溶液使膜通量衰减更快;压力增大,膜通量衰减幅度减小;温度为３０℃时,比２０℃时的膜通量衰减程度减小,但３０、３５、４０℃时的膜通量无明显差异;在改变上地四妙通安汤进行了超滤、测定了氯原酸的回收率,无明显差异。     

对乳清的超滤渗透液进行纳滤脱盐的试验研究

采取超滤膜对乳清进行预处理,研究了不同操作条件下NF270纳滤膜的通量衰减规律以及对乳清中盐和乳糖的分离效果.结果表明:压力由0.4 MPa增加到0.6 MPa时,纳滤膜稳定通量增大,膜通量衰减加重.纳滤膜的盐截留率先下降后上升,乳糖透过率略有增加,增加压力有利于乳糖和盐之间的分离;当压力为0.6 MPa,转速为418.6r/min,在蛋白质的等电点pH值为4.8时,纳滤膜通量小且膜污染最为严重,此时盐截留率最低;pH值为3时所对应的膜通量与料液呈中性时相比,乳清通量增加,且通量衰减幅度小,此时盐截留率为30％,乳糖透过率达80％,因此酸性条件有利于提高通量及乳糖和盐之间的分离效果;提高膜表面的湍动程度时,膜通量增加且膜污染减弱,相应的纳滤膜的盐截留率较小,而对乳糖的透过率影响不明显.     

头孢菌素C钠溶液膜分离工艺的研究

以头孢菌素C钠盐的水溶液为对象设计实验,考察了板式膜的膜通量和溶质透过率的衰减现象,以及钠离子对膜的影响.研究结果表明,衰减的主要原因是膜表面吸附钠离子以及在膜表面形成浓差极化层;原液浓度影响膜通量是间接的;此外在宏观表现如原液浓度高、膜的处理量大、处理时间长和钠离子含量高都将加剧膜通量和溶质透过率的衰减.在实际应用中需考虑这些因素.     

超滤膜净化水库水试验研究

用中空纤维超滤膜处理哈尔滨附近B水库水,以替代混凝、沉淀、砂滤的传统自来水生产方法,研究生产饮用水的新工艺.研究了原水温度、浊度、操作压力和混凝剂的加入量对膜通量的影响.研究发现超滤膜通量与膜进水浊度的对数成反比,跨膜压力增大、适当加入混凝剂,膜通量增加.超滤出水和传统工艺的出水进行了比较,超滤膜出水浊度小于0.2 NTU,明显好于传统工艺的出水浊度.对超滤处理后的出水水质进行了全分析,超滤对铁、铝、锰、色度、好氧量、总有机碳等均有较好的处理效果,完全满足饮用水水质的标准.     

等离子改性PVDF超滤膜在MBR中耐污染性能研究

对聚偏氟乙烯(PVDF)中空纤维超滤膜进行丙烯酸(Acrylic Acid,AA)等离子体化学沉积改性,傅里叶衰减全反射红外光谱(FT-IR)、扫描电镜(SEM)、能谱仪(EDS)及力学性能试验分析表明,膜表面引入了羧基,成功接枝了AA聚合单体,且改性膜柔韧性得到提高,改性后膜清水通量增加了12.04%~16.12%.采用浸没式MBR反应器,在气水比为20∶1条件下对改性膜与原膜进行平行对比实验,实验表明,表面性能的改变可有效阻碍滤饼层污染物在膜表面沉积与压实.经水力及化学清洗后,改性膜通量恢复率都略高于原膜,抗滤饼层污染的能力得到提高.改性膜与原膜出水浊度为0.0~0.6NTU,COD去除率数据表明改性膜出水效果略优于原膜.     

聚砜中空纤维超滤膜的流动电位研究

通过对聚砜中空纤维超滤膜在不同电解质溶液中的膜表面流动电位的研究,考察了膜两侧压差、电解质浓度及离子价态及溶液pH对流动电位的影响,用Helmoltz-Schmoolukovski方程与Gouy-Chapmann方程计算了膜面电荷密度,测定了污染膜经不同清洗剂清洗后的流动电位和水通量.结果表明,流动电位绝对值随电解质浓度的增大而减小;同样电解质浓度下,阳离子价态越高,流动电位绝对值越小.溶液pH对流动电位影响较大,当溶液pH超过等电点时,流动电位绝对值随溶液pH的增加而增加.在一定电解质浓度范围内过滤电解质溶液时,流动电位和通量的衰减幅度不同,对含高价阳离子的电解质溶液,流动电位的衰减比通量衰减更明显.     

低温等离子体改性聚偏氟乙烯超滤膜的性能

采用丙烯酸(AA)作为改性单体,对聚偏氟乙烯(PVDF)中空纤维膜进行等离子体化学沉积改性。通过傅里叶变换衰减全反射光谱仪(ATR-FT-IR)分析发现,改性后的膜表面引入了羧基、羟基等亲水性官能团。经低温等离子体改性后的膜,清水通量提高20%~30%,膜面和膜孔的Zeta电位分别提高了694%和58.66%,在过滤分离凹凸棒悬浊液实验中,改性膜通量衰减百分比,较原膜平均降低了8.44%,仅经水力清洗后的改性膜通量恢复率,较原膜提高8%。     

小分子物质M对聚丙烯腈溶液性质和膜结构的影响

通过小分子物质M对聚丙烯腈(PAN)溶液改性,利用流变仪、紫外可见分光光谱、相变分析、扫描电镜等研究了其对PAN溶液性质、凝固过程及PAN膜结构的影响.结果表明,小分子物质的加入,改变了聚合体系的作用力,PAN溶液的复数黏度提高,低剪切作用下剪切模量提高;小分子物质的加入,提高了聚合物的亲水性,PAN溶液出现浑浊的水用...     

复杂水质环境下基于PSO-ELM的BOD快速检测

针对检测生化需氧量(BOD)的传统五日培养法(BOD5)操作复杂、时效性差的不足,以及水质中复杂环境因素干扰检测过程等问题,提出了基于微生物膜法的快速检测系统,进而以粒子群算法(PSO)优化的极限学习机(ELM)算法来实现BOD检测。检测系统以溶解氧传感器和微生物膜反应器为核心,能够在35 min内完成检测,其中微生物反应器使用功能化的螺旋玻璃管制成,但微生物膜易受水质复杂环境的影响。为此,运用PSO-ELM算法消除水质中浊度(SS)、p H值、氧化还原电位(ORP)对检测结果的干扰,与BP神经网络和ELM算法相比,运行时间分别缩短0.92 s和0.24 s,测试误差分别减小5.3%和4.0%。在实际海水水样的测试结果中,该方法与BOD5法相对误差保持在2.69%～3.86%内。     

充气膜结构零应力态求解

充气膜结构分析全过程包括9个状态和7个分析过程,零应力态是结构分析与设计的基础,将结构数值分析态和实际物理态有机联系起来。该文首次提出了一种从弹性平衡态到零应力态的逆解析数值分析方法,非线性协调矩阵广义逆法。首先,用膜线单元模拟膜面,将膜结构转化成为网格结构,由弹性平衡态预张力和材料参数,计算膜线无应力长度和伸长量;然后,基于杆系结构平衡矩阵理论和小变形假定,建立体系的协调方程,由协调矩阵M-P广义逆求解节点位移,逆向叠加求出新状态位形。根据新位形计算膜线张力向量和节点不平衡力向量,迭代求解零应力态。根据该算法,用MATLAB编制了计算程序。算例分析验证了该方法的正确性和高效性。该文对充气膜结构设计具有重要理论意义和实际指导价值。     

Model for cooling and phase transformation behaviour of transformation induced plasticity steel on runout table in hot strip mill

Abstract

A mathematical model has been developed considering non-symmetric cooling in the thickness direction of strip on a runout table (ROT). In order to solve a one-dimensional transient heat transfer equation including the heat evolved from phase transformation, a finite element method was applied, coupled with thermodynamic and kinetic analyses. The heat capacities of each phase and heat evolution owing to phase transformation were obtained from thermodynamic analysis of the Fe–C–Mn–Si system using Thermo-Calc. The phase transformation kinetics of a transformation induced plasticity (TRIP) steel were derived by using continuous cooling experiments and thermodynamic analysis. Heat transfer coefficients of strips on the ROT were, by applying an inverse method, determined from actual mill data under various cooling conditions. Using the developed model, temperature–time variations of plain carbon and TRIP steels on the ROT were calculated. The calculated results were in good agreement with the actual mill data. In addition, quantitative phase evolution during cooling could also be predicted by the model. From this analysis, the optimum cooling pattern on a ROT for the production of TRIP steel could be determined.     

粉末活性炭-硅藻土生物强化动态膜反应器的过滤性能

将粉末活性炭-硅藻土生物强化动态膜反应器用于处理低浊地表水源.研究结果表明:本工艺具有运行通量大、有机物去除率高、动态膜的过滤阻力较小的特点,过滤过程可以用标准过滤模型来描述.通过电镜观察得到动态膜是由滤饼层、凝胶层和滤网组成,凝胶层紧贴在滤网表面,由硅藻土、活性炭颗粒和微生物代谢物组成,凝胶层的存在有利于动态膜自生时...     

Electrocoagulation of cutting oil emulsions using aluminium plate electrodes

The treatment of very concentrated oil-water emulsions by electrocoagulation (EC) was experimentally investigated as a pre-treatment step prior to a membrane process. The oil-water emulsion was prepared from a cutting mineral oil B22 currently used for drilling and machining operations. The electrocoagulation progress was followed by the measurement of COD, turbidity and pH in a batch process with recirculation of the liquid. This study is mainly focused on the effects of operating parameters such as initial pH, current density, oil concentration and recirculation rate, on the de-emulsification efficiency. Kinetic curves showed that the EC process exhibits two phases: a "reactive phase" during which the COD and the turbidity removals increase with electrolysis, and a stationary phase for which further aluminium dissolution is useless in the pollution abatement. The results showed that the treatment efficiency increases with increasing current density, but decreases with oil concentration. It appears that treatment of the considered cutting oil is completed through dissolution of around 10mgAl/g oil, with a slight positive effect of the liquid flow rate. Best results are also obtained with initial pH near 7.     

浸没式超滤膜处理地表水除污染效能试验研究

进行中试实验考察了浸没式超滤膜处理地表水的除污染效果.实验结果表明:膜出水的浊度恒低于0.10 NTU;膜出水的CODMn值为2.34~3.12 mg/L;膜出水中大于2μm的颗粒总数为11~20个/100 mL;膜出水中未检测出细菌;短周期内的气水反冲洗并排空,可以使膜运行压力在一定程度上得以恢复.     

Aqueous nitrite ion determination by selective reduction and gas phase nitric oxide chemiluminescence

An improved method of flow injection analysis for aqueous nitrite ion exploits the sensitivity and selectivity of the nitric oxide (NO) chemilluminescence detector. Trace analysis of nitrite ion in a small sample (5-160 microL) is accomplished by conversion of nitrite ion to NO by aqueous iodide in acid. The resulting NO is transported to the gas phase through a semipermeable membrane and subsequently detected by monitoring the photoemission of the reaction between NO and ozone (O3). Chemiluminescence detection is selective for measurement of NO, and, since the detection occurs in the gas-phase, neither sample coloration nor turbidity interfere. The detection limit for a 100-microL sample is 0.04 ppb of nitrite ion. The precision at the 10 ppb level is 2% relative standard deviation, and 60-180 samples can be analyzed per hour. Samples of human saliva and food extracts were analyzed; the results from a standard colorimetric measurement are compared with those from the new chemiluminescence method in order to further validate the latter method. A high degree of selectivity is obtained due to the three discriminating steps in the process: (1) the nitrite ion to NO conversion conditions are virtually specific for nitrite ion, (2) only volatile products of the conversion will be swept to the gas phase (avoiding turbidity or color in spectrophotometric methods), and (3) the NO chemiluminescence detector selectively detects the emission from the NO + O3 reaction. The method is free of interferences, offers detection limits of low parts per billion of nitrite ion, and allows the analysis of up to 180 microL-sized samples per hour, with little sample preparation and no chromatographic separation. Much smaller samples can be analyzed by this method than in previously reported batch analysis methods, which typically require 5 mL or more of sample and often need chromatographic separations as well.     

聚醚砜超滤膜处理油田采出水试验研究

采用聚醚砜中空纤维超滤膜组件处理油田采出水,探讨了超滤用于油田回注水处理和采出水回用预处理效果.结果表明:聚醚砜超滤膜产水通量较高,处理水中石油类、悬浮物及其粒径中值均达到回注水的标准,浊度、TGB和IB细菌的去除率分别达100%、99%、99%.采用碱+表面活性剂复合药剂清洗可获得最佳的通量恢复.由于采出水中较高的H2S和COD含量,超滤产水的SDI15>3.0,超出后续纳滤/反渗透膜系统的进水要求.