Chemical cleaning of fouled PVC membrane during ultrafiltration of algal-rich water

Cleaning of hollow-fibre polyvinyl chloride (PVC) membrane with di erent chemical reagents after ultrafiltration of algal-rich water was investigated. Among the tested cleaning reagents (NaOH, HCl, EDTA, and NaClO), 100 mg/L NaClO exhibited the best performance (88.4% 1.1%) in removing the irreversible fouling resistance. This might be attributed to the fact that NaClO could eliminate almost all the major foulants such as carbohydrate-like and protein-like materials on the membrane surface, as confirmed by Fourier transform infrared spectroscopy analysis. However, negligible irreversible resistance (1.5% 1.0%) was obtained when the membrane was cleaning by 500 mg/L NaOH for 1.0 hr, although the NaOH solution could also desorb a portion of the major foulants from the fouled PVC membrane. Scanning electronic microscopy and atomic force microscopy analyses demonstrated that 500 mg/L NaOH could change the structure of the residual foulants on the membrane, making them more tightly attached to the membrane surface. This phenomenon might be responsible for the negligible membrane permeability restoration after NaOH cleaning. On the other hand, the microscopic analyses reflected that NaClO could e ectively remove the foulants accumulated on the membrane surface.     

聚丙烯中空纤维膜吸收法烟气脱硫实验研究

采用质量分数为30%的甲基二乙醇胺(MDEA)水溶液为烟气SO2吸收液,聚丙烯(PP)中空纤维微孔膜组件为吸收器,研究吸收液温度、流量变化,气体停留时间,以及气液两相流程等操作条件对聚丙烯(PP)中宅纤维膜脱硫率的影响,研究表明30%MDEA水溶液在温度35℃,流量100mL/min的最佳试验条件下,经过一个膜吸收过程...     

快速高效去除微囊藻的GO/QPEI复合纳米材料

本研究合成了一种新型高效的去除铜绿微囊藻(Microcystis aeruginosa)的氧化石墨烯/季铵盐聚乙烯亚胺(GO/QPEI)纳米复合材料.GO/QPEI在pH为4~10的条件下都具有高效去除M.aeruginosa的能力,其去除能力在2 min内可达96%以上.GO/QPEI对微囊藻的吸附更符合Freundlich方程,最大吸附量为5.58×1011cells·mg-1.吸附动力学表明GO/QPEI的假二级吸附反应.GO纳米片和QPEI的协同效应是其高效去除微囊藻的主要机制.     

活性炭纤维固定化菌对微囊藻毒素MC-LR的去除研究

研究了藻蓝蛋白提取过程中微囊藻毒素MC-LR的释放分布规律,并用活性炭纤维对一株微囊藻毒素降解菌株进行了固定化,考察了不同活性炭纤维预处理方法、活性炭纤维用量、pH值、温度以及MC-LR浓度对固定化藻毒素降解菌去除MC-LR的影响.结果表明,藻蓝蛋白提取过程中MC-LR主要分布在超滤滤液中,占MC-LR总含量的81.2%.固定化藻毒素降解菌去除MC-LR的效率明显高于非固定化藻毒素降解菌.藻毒素降解菌用(1+9)盐酸预处理后的活性炭纤维固定化,其去除效果最佳.MC-LR去除的最适条件为:活性炭纤维用量为10g/L,温度为35℃,pH值为8.0.固定化藻毒素降解菌对pH值,温度具有一定的耐受性,能够在pH5~pH9、10℃~35℃范围内有效地去除MC-LR.     

Debromination of decabromodiphenyl ether by organo-montmorillonite-supported nanoscale zero-valent iron：Preparation, characterization and influence factors

An organo-montmorillonite-supported nanoscale zero-valent iron material(M-NZVI) was synthesized to degrade decabromodiphenyl ether(BDE-209). The results showed that nanoscale zero-valent iron had good dispersion on organo-montmorillonite and was present as a core-shell structure with a particle size range of nanoscale iron between 30–90 nm, characterized by XRD, SEM, TEM, XRF, ICP-AES, and XPS. The results of the degradation of BDE-209 by M-NZVI showed that the efficiency of M-NZVI in removing BDE-209 was much higher than that of NZVI. The efficiency of M-NZVI in removing BDE-209 decreased as the pH and the initial dissolved oxygen content of the reaction solution increased, but increased as the proportion of water in the reaction solution increased.     

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium nanoparticles

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium （Pd） nanoparticles was studied for the first time. The effects of Pd loading, dye concentration and reuse repetitions of membranes were investigated. In reduction, the dye concentration decreased whereas the pH rose gradually. An optimal Pd loading was found. The catalytic membranes were able to be reused more than 3 times.     

纳米铁的合成、性质及其在环境修复领域的应用

由于纳米铁的特殊性质,它在环境修复领域中的应用日渐增加。本文主要介绍了纳米铁的合成、性质以及在环境修复领域的应用情况。文章归纳了目前常用的几种纳米铁合成的物理方法和化学方法;介绍了纳米铁微粒重要的理化性质;并总结了纳米铁用于修复含氯有机物污染、重金属污染和其他无机物污染场地的应用情况。     

曝气强度对膜生物反应器处理石化废水工艺运行特征的影响

采用膜生物反应器(Membrane Bioreactor,MBR)处理石化废水,研究曝气强度分别为1.50,3.00 m3/(m2·h)的条件下,MBR对石化废水中主要污染物的去除特征、跨膜压差(Trans Membrane Pressure,TMP)和混合液性质的变化特征。结果表明:在两种曝气强度条件下MBR对COD、NH+4-N及挥发酚等污染物的平均去除率分别为80.74%、80.23%、96.79%和97.55%、99.34%、98.84%,即在不同曝气条件下,曝气强度的变化对MBR的污染物去除性能无显著影响。但随着曝气强度由1.50 m3/(m2·h)增加到3.00 m3/(m2·h),MBR达到设定的最大跨膜压差(TMPMax=25k Pa)的运行时间由11.8 d增加到31.4 d,TMP上升速率降低。通过活性污泥颗粒粒径分析发现:增加曝气强度后,对膜污染影响显著的活性污泥颗粒粒径范围(0~2μm)所占体积比由2.10%减小到1.78%;并且混合液中溶解性微生物产物(soluble microbial product,SMP)和胞外聚合物(extracellular polymeric substance,EPS)质量浓度分别由24.07 mg/L和15.66 mg/g减小到15.14 mg/L和9.81 mg/g,从而降低了膜污染速率。     

Inhibitory effects of nisin-coated multi-walled carbon nanotube sheet on biofilm formation from Bacillus anthracis spores

Multi-walled carbon nanotube（MWCNT） sheet was fabricated from a drawable MWCNT forest and then deposited on poly（methyl methacrylate） film. The film was further coated with a natural antimicrobial peptide nisin. We studied the effects of nisin coating on the attachment of Bacillus anthracis spores, the germination of attached spores, and the subsequent biofilm formation from attached spores. It was found that the strong adsorptivity and the super hydrophobicity of MWCNTs provided an ideal platform for nisin coating. Nisin coating on MWCNT sheets decreased surface hydrophobicity, reduced spore attachment, and reduced the germination of attached spores by 3.5 fold, and further inhibited the subsequent biofilm formation by 94.6% compared to that on uncoated MWCNT sheet. Nisin also changed the morphology of vegetative cells in the formed biofilm.The results of this study demonstrated that the anti-adhesion and antimicrobial effect of nisin in combination with the physical properties of carbon nanotubes had the potential in producing effective anti-biofilm formation surfaces.     

Efficient dechlorination of chlorinated solvent pollutants under UV irradiation by using the synthesized TiO2 nano-sheets in aqueous phase

Titanium dioxide(TiO2), which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetrachloroethene(PCE), trichloroethene(TCE) and 1,1,1-trichloroethane(TCA). The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO2 system compared to UV/commercial P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene(NB) as a probe of hydroxyl radical(.OH), the degradation rate was better over UV/synthesized TiO2, suggesting the high concentration of.OH generated in UV/synthesized TiO2system. In addition,.OH concentration was confirmed by the strong peak displayed in EPR analysis over UV/synthesized TiO2system. The characterization result using XRD and TEM showed that the synthesized TiO2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 nm, side length of 50 nm and width of 33 nm and a surface 90.3 m2/g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO2. The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater.