荷电超滤膜的研究：Ⅰ.氯甲基化聚砜超滤膜的研究

膜材料本身的性质是决定膜性能的主要因素，对于荷电超滤膜，荷电性和荷电程度对膜性能有较大的影响，本文研究了含氯量对氯甲基化聚砜超滤膜性能的影响，就有关制膜条件对膜的物理性能和电性能的影响也进行了研究。     

丙烯腈—醋酸乙烯二元共聚物超滤膜的制备及其性能表征

本文研究了丙烯腈-醋酸乙烯二元共聚物[P(AN-VAc)]超滤膜及其性能。研究了共聚物材料、铸膜液成份和成膜工艺条件对膜性能的影响,并对膜的物化稳定性和耐菌性能等进行了表征。实验表明,P(AN-VAc)是一种性能良好的膜材料,其对添加剂的适应性尤佳。本文还通过对红外光谱及电子显微镜扫描对膜的结构进行了初步探讨。     

吸附-微滤法对印染废水脱色的研究

采用氢氧化镁吸附与陶瓷膜微滤相结合进行活性染料废水脱色处理 .对预处理条件、微滤操作条件以及膜的化学清洗进行了研究 .结果表明 ,采用氢氧化镁吸附预处理的陶瓷膜微滤技术 ,对含活性染料的印染废水 ,具有脱色率高、操作简单的优点 .在合适的条件下 ,脱色率可达 98%以上 ,1 0 μm膜的通量在1 5 0L·m- 2 ·h- 1左右 ;采用 0 5mol·l- 1稀硝酸在一定条件下清洗 30min可使膜得到有效再生 .     

聚醚砜超滤膜的研制

以聚醚砜为原料，二甲基乙酰胺为溶剂，研究了铸膜液组成和若干因素对膜性能的影响。选择适当的膜液组成和制备条件，可制得截留分子量分别为２０００，６０００，１００００的超滤膜，用该膜对α－干扰素进行分离。截留率均可达到９９％以上。     

改性聚偏氟乙烯中空纤维超滤膜处理乳化液废水

应用改性聚偏氟乙烯中空纤维超滤膜处理乳化液废水(COD浓度100~300 g/L、含油量30~100 g/L),考察了在不同压力、温度及流速条件下,膜处理能力的变化,并研究了清洗方法对膜性能的恢复效果。结果表明,在组合预处理条件下,乳化液废水的COD去除率可达95%以上,油去除率可达99%以上,采用金属清洗剂可使膜的透过量恢复率达97%以上。该项研究为膜处理技术用于乳化液废水处理奠定了基础。     

根表铁膜对水稻吸收污灌土壤中的锌的影响

采用土-石英砂联合培养的盆栽试验,研究两个不同基因型的水稻根表铁膜的形成情况及其对水稻吸收污灌土中的锌的影响.结果表明,两基因型水稻在不同水分条件下根表铁膜的形成情况不同淹水条件下形成的铁膜数量最多,高于湿润和干-湿交替,后二者之间差异不明显.不同基因型水稻(金优22与90-68-2)根表铁膜的形成趋势一致,只是数量稍有差异;不同基因型秸秆及籽粒中锌的含量存在差异,不同铁处理的根表铁膜数量、地上部锌含量均不同.     

金属浓度,半透膜孔径,水温及配位体对半透膜囊吸收铜的影响

在实验室条件下，研究了影响树脂－半透膜囊吸收铜的主要因素，重点探讨了水相铜含量，半透膜孔径，温度以及天然河水中的有机配位体对吸收的影响。结果表明，半透膜囊吸收量与水相游离铜浓度，水温及半透膜孔径的非整数次幂成正比，其中包括ＥＤＴＡ，河水富里酸，以及河水中的各种天然有机物在内的配位体均与铜生成不能被半透膜囊吸收的络合物，研究结果进一步证实了半透膜囊对水环境中游离态微量金属进行长期监测的可行性。     

黑液电渗析回收碱的研究

采用电渗析法回收草浆黑液中的氢氧化钠,在恒压条件下,曝气时电渗析的效率比不曝气时好,90min时,曝气和不曝气条件下疏水氟膜的R值分别为1.62×10-6mol·ml-1·cm-2和8.48×10-7mol·ml-1·cm-2.在恒流条件下,不曝气时电渗析的效果反而好,180min时,曝气和不曝气条件下疏水氟膜的R值分别为3.24×10-6mol·ml-1·cm-2和3.76×10-6mol·ml-1·cm-2.疏水氟膜的电渗析效果远好于阳离子交换膜.在恒流不曝气条件下,180min时阳离子交换膜和疏水氟膜的R值分别为4.95 ×10-7mol·ml-1·cm-2和3.76×10-6 mol·ml-1·cm-2.在各种影响因素中,电极间距较小时效果好;电流变大时,能耗迅速上升,钠离子回收率也有所下降.     

乳状液膜法萃取氨基酸的研究

本文以ＴＯＭＡＣ为载体，ＥＣＡ４３６０Ｊ为表面活性剂，内外相Ｃｌ＾－浓度梯度为推动力，研究了Ｌ－苯丙氨酸在乳状液膜体系中的传输，并对影响液膜萃取的各种因素进行了系统的阐述，确定了此体系的最佳膜相组成的实验条件，实现了Ｌ－苯丙氨酸的提取和浓缩。     

膜生物反应器处理回用生活污水的实验研究

针对当前社会对污染物减排和中水回用的需求,采用一体式膜生物反应器(SMBR)对生活污水进行处理,研究了处理效果和工艺条件.结果表明:SMBR是生活污水处理回用的简单高效的工艺方法,SMBR膜出水COD<20 mg·L-1,BOD5<1 mg·L-1,NH4 -N<1 mg·L-1,出水无悬浮物,可以达到城市杂用水回用标准.同时,SMBR对总氮、总磷具有一定的去除效果,污泥沉降性能良好,污泥指数稳定在78~115,污泥龄可达40-60 d,保证了系统内污泥质量浓度;通过控制合适的气水比25∶1~60∶1、采用间歇出水方式等工艺操作条件可以保持良好的污泥特性并可延缓膜污染,延长膜的使用寿命,提高SMBR对污水处理的效率.     

Enhanced cross-flow filtration with flat-sheet ceramic membranes by titanium-based coagulation for membrane fouling control

• Ceramic membrane filtration showed high performance for surface water treatment. • PTC pre-coagulation could enhance ceramic membrane filtration performance. • Ceramic membrane fouling was investigated by four varied mathematical models. • PTC pre-coagulation was high-effective for ceramic membrane fouling control. Application of ceramic membrane (CM) with outstanding characteristics, such as high flux and chemical-resistance, is inevitably restricted by membrane fouling. Coagulation was an economical and effective technology for membrane fouling control. This study investigated the filtration performance of ceramic membrane enhanced by the emerging titanium-based coagulant (polytitanium chloride, PTC). Particular attention was paid to the simulation of ceramic membrane fouling using four widely used mathematical models. Results show that filtration of the PTC-coagulated effluent using flat-sheet ceramic membrane achieved the removal of organic matter up to 78.0%. Permeate flux of ceramic membrane filtration reached 600 L/(m²·h), which was 10-fold higher than that observed with conventional polyaluminum chloride (PAC) case. For PTC, fouling of the ceramic membrane was attributed to the formation of cake layer, whereas for PAC, standard filtration/intermediate filtration (blocking of membrane pores) was also a key fouling mechanism. To sum up, cross-flow filtration with flat-sheet ceramic membranes could be significantly enhanced by titanium-based coagulation to produce both high-quality filtrate and high-permeation flux.     

Using loose nanofiltration membrane for lake water treatment: A pilot study

• A pilot study was conducted for drinking water treatment using loose NF membranes. • The membranes had very high rejection of NOM and medium rejection of Ca²⁺/Mg²⁺. • Organic fouling was dominant and contribution of inorganic fouling was substantial. • Both organic and inorganic fouling had spatial non-uniformity on membrane surface. • Applying EDTA at basic conditions was effective in removing membrane fouling. Nanofiltration (NF) using loose membranes has a high application potential for advanced treatment of drinking water by selectively removing contaminants from the water, while membrane fouling remains one of the biggest problems of the process. This paper reported a seven-month pilot study of using a loose NF membrane to treat a sand filtration effluent which had a relatively high turbidity (~0.4 NTU) and high concentrations of organic matter (up to 5 mg/L as TOC), hardness and sulfate. Results showed that the membrane demonstrated a high rejection of TOC (by>90%) and a moderately high rejection of two pesticides (54%–82%) while a moderate rejection of both calcium and magnesium (~45%) and a low rejection of total dissolved solids (~27%). The membrane elements suffered from severe membrane fouling, with the membrane permeance decreased by 70% after 85 days operation. The membrane fouling was dominated by organic fouling, while biological fouling was moderate. Inorganic fouling was mainly caused by deposition of aluminum-bearing substances. Though inorganic foulants were minor contents on membrane, their contribution to overall membrane fouling was substantial. Membrane fouling was not uniform on membrane. While contents of organic and inorganic foulants were the highest at the inlet and outlet region, respectively, the severity of membrane fouling increased from the inlet to the outlet region of membrane element with a difference higher than 30%. While alkaline cleaning was not effective in removing the membrane foulants, the use of ethylenediamine tetraacetate (EDTA) at alkaline conditions could effectively restore the membrane permeance.     

Fouling mechanisms in the early stage of an enhanced coagulation-ultrafiltration process

We investigated the fouling performances of ultrafiltration (UF) membrane for treating in-line coagulated water in an enhanced coagulation-UF hybrid process. Then we analyzed the fouling mechanisms in the early stage of UF using mathematical models and microscopy observation methods. Finally, we discussed the impact of aeration on membrane fouling in this paper. The results showed that a two-stage of trans-membrane pressure (TMP) profile during the operation of enhanced coagulation-UF membrane was observed, and the relationship between permeability and operation time fitted well with a logarithmic curve. Membrane pores blocking and cake filtration were confirmed as main membrane fouling mechanisms using the mathematical models. The two stages of membrane fouling mechanisms were further deduced, namely, the membrane pore narrowing followed by the formation of cake layer. Membrane autopsy analysis using scanning electron microscopy (SEM) images of the membrane surface sampled from different filtration cycles also confirmed the mechanisms of pores blocking and cake filtration. Moreover, according to the variations of the permeability and membrane fouling resistance, aeration was able to mitigate and control the membrane fouling to a certain extent, but the optimization of aeration conditions still needs to be studied.     

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.     

Comparison of CNT-PVA membrane and commercial polymeric membranes in treatment of emulsified oily wastewater

CNT-PVA membrane was fabricated and compared with polymeric membranes. The separation performance was evaluated by homemade and cutting fluid emulsions. The three membranes show similar oil retention rates. CNT-PVA membranes have higher permeation fluxes compared with polymeric membranes. CNT-PVA membrane shows higher fouling resistance. Membrane separation is an attractive technique for removal of emulsified oily wastewater. However, polymeric membranes which dominate the current market usually suffer from severe membrane fouling. Therefore, membranes with high fouling resistance are imperative to treat emulsified oily wastewater. In this study, carbon nanotube-polyvinyl alcohol (CNT-PVA) membrane was fabricated. And its separation performance for emulsified oily wastewater was compared with two commercial polymeric membranes (PVDF membrane and PES membrane) by filtration of two homemade emulsions and one cutting fluid emulsion. The results show that these membranes have similar oil retention efficiencies for the three emulsions. Whereas, the permeation flux of CNT-PVA membrane is 1.60 to 3.09 times of PVDF membrane and 1.41 to 11.4 times of PES membrane, respectively. Moreover, after five consecutive operation circles of filtration process and back flush, CNT-PVA membrane can recover 62.3% to 72.9% of its initial pure water flux. However, the pure water flux recovery rates are only 24.1% to 35.3% for PVDF membrane and 6.0% to 26.3% for PES membrane, respectively. Therefore, CNT-PVA membrane are more resistant to oil fouling compared with the two polymeric membranes, showing superior potential in treatment of emulsified oily wastewater.     

Surface modification of mesoporous silica nanoparticle with 4-triethoxysilylaniline to enhance seawater desalination properties of thin-film nanocomposite reverse osmosis membranes

• Mesoporous silica nanoparticle was modified with 4-triethoxysilylaniline. • AMSN-based TFN-RO membranes were prepared for seawater desalination. • Water transport capability of the AMSN was limited by polyamide. • Polyamide still plays a key role in permeability of the TFN RO membranes. Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/m²/h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.     

聚芳醚酮超滤膜的研究

本文以国产聚芳醚酮为原料，研究了铸膜液组成，聚合物浓度，添加剂种类和用量等对超滤膜性能的影响，选择适宜组成的铸膜液，可以制得截留分子量为２０００，６０００，１００００的超滤膜。上述超滤膜对α－干扰素的分离浓缩效果较好，其截留率均可达到９９％以上。     

Experimental and computational assessment of 1,4-Dioxane degradation in a photo-Fenton reactive ceramic membrane filtration process

• 1,4-Dioxane was degraded via the photo-Fenton reactive membrane filtration. • Degradation efficiency and AQY were both enhanced in photocatalytic membrane. • There is a tradeoff between photocatalytic degradation and membrane permeation flux. • Degradation pathways of 1,4-Dioxane is revealed by DFT analysis. The present study evaluated a photo-Fenton reactive membrane that achieved enhanced 1,4-Dioxane removal performance. As a common organic solvent and stabilizer, 1,4-Dioxane is widely used in a variety of industrial products and poses negative environmental and health impacts. The membrane was prepared by covalently coating photocatalyst of goethite (α-FeOOH) on a ceramic porous membrane as we reported previously. The effects of UV irradiation, H₂O₂ and catalyst on the removal efficiency of 1,4-Dioxane in batch reactors were first evaluated for optimized reaction conditions, followed by a systematical investigation of 1,4-Dioxane removal in the photo-Fenton membrane filtration mode. Under optimized conditions, the 1,4-Dioxane removal rate reached up to 16% with combination of 2 mmol/L H₂O₂ and UV₃₆₅ irradiation (2000 µW/cm²) when the feed water was filtered by the photo-Fenton reactive membrane at a hydraulic retention time of 6 min. The removal efficiency and apparent quantum yield (AQY) were both enhanced in the filtration compared to the batch mode of the same photo-Fenton reaction. Moreover, the proposed degradation pathways were analyzed by density functional theory (DFT) calculations, which provided a new insight into the degradation mechanisms of 1,4-Dioxane in photo-Fenton reactions on the functionalized ceramic membrane.     

G-CNTs/PVDF mixed matrix membranes with improved antifouling properties and filtration performance

A novel nanocomposite OMWCNT-A-GO was synthesized by conjugating OMWCNT and GO. The P-OMWCNT-A-GO membrane was fabricated by non-solvent induced phase inversion. The P-OMWCNT-A-GO exhibits the best water flux, BSA rejection and flux recovery. It should be due to the enhanced membrane pore size, porosity and hydrophilicity. Although carbon nanomaterials have been widely used as effective nanofillers for fabrication of mixed matrix membranes (MMMs) with outstanding performances, the reproducibility of the fabricated MMMs is still hindered by the non-homogenous dispersion of these carbon nanofillers in membrane substrate. Herein, we report an effective way to improve the compatibility of carbon-based nanomaterials with membrane matrixes. By chemically conjugating the oxidized CNTs (o-CNTs) and GO using hexanediamine as cross-linker, a novel carbon nanohybrid material (G-CNTs) was synthesized, which inherited both the advanced properties of multi-walled carbon nanotubes (CNTs) and graphene oxide (GO). The G-CNTs incorporated polyvinylidene fluoride (PVDF) MMMs (G-CNTs/PVDF) were fabricated via a non-solvent induced phase separation (NIPS) method. The filtration and antifouling performances of G-CNTs/PVDF were evaluated using distillate water and a 1 g/L bovine serum albumin (BSA) aqueous solution under 0.10 MPa. Compared to the MMMs prepared with o-CNTs, GO, the physical mixture of o-CNTs and GO and pure PVDF membrane, the G-CNTs/PVDF membrane exhibited the highest water flux up to 220 L/m²/h and a flux recovery ratio as high as 90%, as well as the best BSA rejection rate. The excellent performances should be attributed to the increased membrane pore size, porosity and hydrophilicity of the resulted membrane. The successful synthesis of the novel nanohybrid G-CNTs provides a new type of nanofillers for MMMs fabrication.