首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 140 毫秒
1.
为研究Ca2+对SiO2-BSA混合污染物膜污染行为的影响,针对SiO2与牛血清蛋白(BSA)共存体系,在不同Ca2+浓度下,使用原子力显微镜测定各污染物与聚偏氟乙烯(PVDF)超滤膜及各污染物之间的作用力,结合膜污染实验,探讨Ca2+对SiO2-BSA混合污染物膜污染行为的影响.结果表明:随着Ca2+浓度的增大,SiO2-BSA引起的膜污染逐渐减小,主要是因为Ca2+改变了SiO2-BSA混合体系中各污染物与膜及污染物之间的相互作用力.针对污染物与膜之间的相互作用力,Ca2+的加入触发了PVDF膜与BSA及SiO2之间的水合排斥力,从而削弱BSA在膜表面的吸附累计速率,有效减缓了运行初期的膜污染速率;针对污染物之间的作用力,Ca2+浓度的增加使得SiO2-SiO2及SiO2-BSA之间作用力增大,从而导致污染物团聚形成大尺寸聚集体,在膜面形成松散多孔的污染层,进而伴随着膜污染速率以及污染幅度的减小.  相似文献   

2.
The influence of polyepoxysuccinic acid(PESA) on the solid phase products in hydrated Portland cement pastes was investigated by isothermal calorimetry, X-ray diffraction(XRD), 29Si and 27Al nuclear magnetic resonance(NMR). The results indicated that PESA bonds Ca2+ ions in pore solution to prevent portlandite formation, and also combines with Ca2+ ions on the surface of silicate minerals to prolong the control time of phase boundary reaction process, leading to the retardation of silicate mineral hydration. Meanwhile, the interlayer Ca2+ ions in Jennite-like structure bridging PESA and C-S-H gels prevent silicate tetrahedron and aluminum tetrahedron from occupying the sites of bridging silicate tetrahedron, which causes the main existence of dimer in C-S-H structure, deceases the degree of Al3+ substituting for Si4+ and promotes the transformation from 4-coordination aluminum to 6-coordination aluminum. Furthermore, the -Ca+ chelating group from reacting PESA with Ca2+ ions combines easily with SO42- ions, resulting in transformation from ettringite, AFm to TAH(Third aluminum hydrate). However, with the higher addition of PESA, it will bridge the excess PESA by Ca2+ ions to form a new chelate with ladder-shaped double chains structure, which not only reduces the amount of PESA bonding Ca2+ ions, but also decreases its solidifying capability for SO42- ions, leading to the transformation from TAH to AFm or ettringite. Meanwhile, at later hydration, the inhibition effect of PESA on cement hydration is weakened, and the transformation degree from TAH to AFm is higher than that to AFt with the addition of PESA.  相似文献   

3.
工业废水中高氯离子使其具有腐蚀性并妨碍水生动植物生长, 破坏生态环境, 在排放之前必须进行氯离子 去除, 达到排放要求。探究了单因素对氯离子去除率的影响, 并讨论了投料比、搅拌时间、静置时间以及体系初始 pH 对去除率影响及交互作用。研究表明: 搅拌速度为400 r/min, n(Al3+) : n(Ca2+) 为1 : 3.3, 搅拌时间为30 min, 静 置时间为30 min, 废水初始pH 为10 时, 去除效果最佳。应用所得最佳条件对实际水样进行二次去除实验并探讨了 相关影响因素。对实际水样二次氯离子去除实验的最佳工艺条件: 当n(Cl-):n(Al3+) : n(Ca2+) 为1 : 3.6 : 12, 初始溶 液浓度为4 g/L 时, 并且需要在二阶段投加药品前调节体系pH 值至弱碱性, 氯离子去除效率可达95%, 浓度可降到 400 mg/L 以下。通过X 射线洐射分析可知, 沉淀产物为层状结构的弗氏盐[Ca2Al(OH)6Cl·2H2O]。此方法成本低、 无污染, 对高氯废水去除有很好的应用价值。  相似文献   

4.
Manganese-doped Ba0.925Ca0.075TiO3 lead-free piezoelectric ceramics (abbreviated as BCT) with high mechanical quality factor were synthesized by conventional solid-state reaction method. The effects of excess Ba on the crystal structure, microstructure, and electrical properties of the ceramics were systematically investigated. X-ray diffraction and Raman spectra revealed that Ca2+ ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol% extra Ba2+ ions were added after sintering. The grain size of the ceramics was decreased by adding extra Ba2+ ions. The mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%. High piezoelectric coefficients ( d33 = 150–190 pC/N ) and high mechanical quality factors ( Qm = 1 000–1 200 ) were obtained in the ceramics when the excess of Ba was between 0.5 mol% and 1 mol%. These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba.  相似文献   

5.
利用NF-HF和NF-HS纳滤膜对煤化工废水二级反渗透浓水进行处理,重点考察其对Cl-与SO42-的分离效果、结垢离子的截留率以及膜抗污染性能,并采用STRO (卷式高压反渗透膜)对纳滤产水进行浓缩处理。实验结果表明,与NF-HS相比,NF-HF具有更优的Cl-/SO42-分离效果及钙、镁、硅离子截留效果和抗污染性能;NF-HF对Cl-截留率为3.38%~6.03%,对SO42-的截留率为91.18%~97.16%;对钙、镁、硅离子的最大截留率分别为90%、80%和40%;连续运行336 h,NF-HF的运行压力从初始的3.2 MPa升高至4.5 MPa,膜通量降低11%;经碱洗后恢复初始膜通量;STRO浓缩处理NF-HF透过液时表现出良好的浓缩效果和脱除COD效果,但其耐污染性能较差。NF-HF+DTRO (碟式高压反渗透)组合工艺使煤化工废水膜浓缩液进一步分离浓缩具备良好的可行性。  相似文献   

6.
通过渗滤法考察模拟酸雨对河道淤泥气泡混合土的侵蚀作用,试验过程中测定混合土试样的物理力学指标、渗滤液的pH值和Ca2+浓度值以及矿物组分受酸雨渗滤影响后的变化规律,研究考察酸雨对混合土性质的影响。试验结果表明:酸雨导致河道淤泥气泡混合土中的矿物水解并以Ca2+离子形式析出,导致混合土中性化。酸雨的酸性越强,土体中性化程度越高,在中性化过程中又有新的矿物生成,使混合土中矿物相对含量发生改变,导致混合土物理力学性质的变化;与正常雨水作用相比,经酸雨作用后的河道淤泥气泡混合土含水率和密度升高,强度降低,破坏模式向脆性化发展,并且酸雨的酸性越强,物理力学性质的变化越明显。  相似文献   

7.
The microflotation of three single minerals, mixed coal–kaolinite and mixed coal–montmorillonite were examined to study the effects of clay and calcium ions on coal flotation. The results show that the ash content of flotation concentrate increases by 3% in the presence of clay minerals, and the ash content would further increase by 3% in co-presence of clay minerals and high concentration of Ca2+. Scanning electron microscope (SEM) images and elemental spectrum analysis indicate that fine clay particles that coat on the coal surface, which is called slime coating, can affect the coal flotation. The slime coating would be induced much more easily in the presence of Ca2+.  相似文献   

8.
为揭示不同有机物形成的污染层对硫酸钙在纳滤膜面结垢行为的影响,选用牛血清蛋白(BSA)、腐殖酸(HA)、海藻酸(SA)作为典型有机污染物对聚酰胺复合纳滤膜进行污染,之后进行硫酸钙结垢实验.利用扫描电镜(SEM)观察不同污染条件下的硫酸钙形态,采用原子力显微镜(AFM)结合自制的硫酸钙探针测定不同污染条件下膜-硫酸钙及硫酸钙-硫酸钙之间的作用力.结果表明:与新膜结垢相比,有机物吸附在纳滤膜上改变了膜面性质,影响硫酸钙晶体成核机理.3种有机污染条件下硫酸钙结垢污染程度为SAHABSA.这是因为SA与Ca~(2+)的相互作用可缩短硫酸钙晶体成核时间,增大晶体尺寸,导致纳滤膜通量迅速下降;HA与Ca~(2+)络合增大了结垢层的厚度和密实度,导致纳滤膜通量衰减较大;而BSA与Ca~(2+)的结合能力较弱,加上其特殊的心形分子结构,导致该情况下硫酸钙结垢程度弱于其他两种有机物条件.  相似文献   

9.
Ca x Ba1−x TiO3 (CBT) fine particles doped with red luminescence center of Pr3+ ions (Pr: CBT) were successfully synthesized by salt assisted spray pyrolysis (SASP) process. Scanning electronic microscope (SEM) and laser scattering analysis demonstrate that salt can be removed from the surface of particles by washing with Milli-Q water and the particles can be further separated by ball-milling to get well-dispersed Pr3+ ions doped CBT fine particles. The luminescence properties, such as photoluminescence (PL) and mechanoluminescence (ML), of as-synthesized Pr: CBT particles were investigated. For Pr: CBT fine particles with different Ca molar ratios, all the samples show one emission at 612 nm, with increasing Ca molar ratio, PL intensity of Pr: CBT fine particles become stronger and stronger. When pressure was loaded on the Pr: CBT pellet, mechanoluminescence(ML) emission was measured. The results show that the ML intensity is proportional to the applied pressure.  相似文献   

10.
A new method was developed for effective enrichment of Cd2+ ions from water with a calcium alginate (CaAlg) hydrogel filtration membrane. First, the CaAlg hydrogel filtration membrane was prepared without a pore-forming agent. This membrane was used to remove Cd2+ via ion exchange with Ca2+, and the Cd2+ was preserved in the CaAlg hydrogel. Then, the CaAlg hydrogel containing Cd2+ was soaked in a sodium citrate solution, and the hydrogel was fully dissolved. The removal rate of the CaAlg filtration membrane reached almost 100% within 120 min when the Cd2+ concentration was under 1 mg/L. Factors affecting the removal rate were investigated, such as NaAlg concentration, operating pressure, operating time and the initial concentration of Cd2+. The effects of initial Cd2+ concentration, pressure and filtration time on the enrichment factor were also investigated. The results show that the enrichment factor reached 87.3 when the pressure was 0.18 MPa and the filtration time was 240 min. Different enrichment factors could be achieved by adjusting the operating pressure and filtration time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号