天然热释电材料电气石的微结构及对水的pH值影响机理的研究

以新疆产天然电气石为原料制备了电气石微粉,利用X射线衍射仪、扫描电镜、高分辨电镜、pH酸度计研究了电气石的物相、微结构特点和电气石对水酸度及其随温度变化的影响.结果表明,电气石单个微粒为单畴的铁电体,可视为电偶极子;利用电气石微粉可以使水的酸度呈弱碱性;电气石对水酸度的影响随温度的变化进一步佐证了电气石的热释电性,并探讨了电气石对水作用的可能机理.     

高比表面积氧化铝微粉从碱性废水中除氟

以合成的活性氧化铝微粉为吸附剂,研究了碱性含氟废水中pH值、初始氟浓度、吸附时间、氧化铝添加量等对除氟率和吸附容量的影响,讨论了其吸附机理。以铝酸钠溶液为原料,经氢氧化铝、丝钠铝石、碳酸铝铵和氧化铝等物相转化,制备了比表面积为409.03 m~2·g~(-1)的介孔氧化铝微粉。当pH值为7.0～9.4时,氧化铝微粉的除氟率较高。延长吸附时间、降低氟浓度或提高微粉加入量有利于提高除氟率。Zeta电位随溶液pH值的增大而减小,等电点为9.77。当pH值为8.1时,高比表面积、静电吸引、多层吸附是碱性条件下氧化铝微粉吸附容量大(9.28 mg·g~(-1))、除氟率高(94.20%)的主要原因。同时,吸附也符合拟二级动力学模型,对氟的吸附受化学吸附控制。     

影响SnO2纳米晶体修饰的α-Al2O3微滤膜流动电势的因素

试验研究了不同电解质溶液pH值以及其离子浓度和种类对SnO2纳米晶体修饰的α-A120,微滤膜流动电势的影响规律,结果表明,对于Nacl溶液,膜流动电势随溶液浓度的增大而降低,其等电点在4．6左右;随着溶液的pH值由3增加到10,膜流动电势由正值逐渐变为负值,而对于FeSO4,CaSO4,Na2SO4,NaCl和CaCl2溶液,当溶液的浓度固定时,膜流动电势随溶液电导率的增加而降低。     

天然矿物电气石对水分子团簇的影响

以新疆产天然电气石为原料制备了电气石微粉,利用X射线衍射仪、扫描电镜、高分辨电镜、17O核磁共振研究了电气石微粉的物相结构、微结构特点和电气石的热释电性对水分子团簇结构影响,并对其作用的机理进行了探讨。结果表明,所制备的电气石微粉的结晶性完好,具有单向极性结构的热释电性材料电气石的微晶在温度涨落的环境中可视为电偶极子;电气石粉对水的17O核磁共振谱的半峰宽具有明显的影响,从HW=145.41Hz降到HW=81.11Hz,表明电气石微粉对水分子团簇结构的改善有明显的作用。     

电气石净化处理含Cr6+废水的研究

为了探讨电气石对含Cr6 废水净化处理的合适条件.利用不同的电气石粒度、用量、pH值、温度、搅动情况等条件对水中Cr6 进行吸附试验;同时对回收后的电气石的再吸附性进行试验.试验结果表明:360目的电气石用量10 g,搅拌40 min,30℃,强碱性条件下,电气石的吸附效果最好,达到国家排放标准0.5 mg/L;回收后仍可以达到原电气石的处理效果.因此,电气石具有的永久性的自发电极,其微粒自身的静电场,对Cr6 的吸附作用使Cr6 与表面羟基的离解产物OH-在电气石表面产生吸附沉淀,从而起到净化作用,且可重复利用,在环境领域具有良好的发展前景.     

真空膜结晶法结晶溶菌酶的实验研究

采用聚偏氟乙烯中空纤维微孔膜对真空膜结晶溶菌酶进行了实验研究.考察了膜下游真空度、蛋白质浓度、料液流速、添加剂、pH和离子强度对溶剂跨膜通量及溶菌酶晶体质量的影响.结果表明,真空度应控制在0.015 MPa左右;溶菌酶真空膜结晶的最佳浓度为20 mg/mL;结晶溶液的流速以288μm/s为宜;结晶溶液中加入一定添加剂如丙三醇、DMSO等,可以有效提高溶剂跨膜通量,改善晶体质量;在相同离子强度下,pH值越大膜通量越低,在不同的pH值下可以得到不同形状的晶体.     

镁锂合金碱性条件下腐蚀的EIS分析

为了研究镁锂合金在碱性条件下的腐蚀行为,测试了镁锂合金在不同pH值0.4 mol/L NaCl溶液中的电化学阻抗谱、pH=9和pH=14条件下不同浓度的NaCl溶液中的电化学阻抗谱及在不同体系的碱性NaCl溶液中腐蚀100 h过程中的电化学阻抗谱,并对电化学阻抗谱进行了拟合、分析.结果表明:溶液的Cl-和pH值显著影响着腐蚀速率,当Cl-浓度相同时,溶液的pH值越大电化学反应电阻越小;当pH相同时Cl-浓度越高电化学反应电阻越小,并且随Cl-浓度的增加pH值对腐蚀速率的影响逐渐减弱;镁锂合金在低Cl-浓度高pH值的条件下腐蚀0~100 h的电化学阻抗谱中随腐蚀时间的增加,高频弧和低频弧均扩张,在低Cl-浓度低pH值及高Cl-浓度任意pH值条件下低频弧变化显著,先扩张后收缩,腐蚀100 h时镁锂合金在Cl-浓度较低的溶液中无论pH值如何,其腐蚀速率远远小于在Cl-浓度较高的溶液中的腐蚀速率.     

用改性沸石处理含铜废水的试验研究

通过电导法研究了改性沸石对Cu2 的吸附性能,考察了吸附时间、改性沸石的质量、溶液的pH值及溶液中其他离子对改性沸石吸附性能的影响.结果表明,当改性沸石的质量一定时,电导率连续降低,直至恒定不变.随着改性沸石投加量的增大,电导率减小,最佳投加量为2 g,最佳pH值为5,去除效率为65%.ZnSO4、NiSO4、CdCl2、CuCl2和Cu(NO3)2的存在不会影响改性沸石对Cu2 的吸附性能.     

不同pH值下KDP过饱和溶液的成核研究

研究了不同pH值下、不同温度和过饱和度的KDP溶液的成核过程,测定了不同情况下溶液的诱导期.研究表明,当KDP溶液的过饱和比S1.3时,均匀成核起主导作用;当S<1.2时,非均匀成核起主导作用.根据经典均匀成核理论,针对KDP过饱和溶液均匀成核的情况计算出了不同pH值、不同温度下的固-液界面张力等成核参数,并从上述参数的相互比较中分析得到了改变pH值后溶液稳定性变强的原因.最后通过对表面熵因子的计算,确定了KDP晶体的微观生长机制为连续生长模式.     

pH值和缓冲剂对水热电化学沉积HA/TiO_2涂层的影响

以微弧氧化后的钛合金为基体,采用水热电化学法制备了HA/TiO2涂层。利用SEM、XRD对涂层的表面形貌、物相组成进行了表征分析,通过pH微探针原位探测电极/电解液界面pH值的变化,研究了pH值和缓冲剂对水热电化学沉积HA/TiO2涂层的影响。研究结果表明,微弧氧化膜有利于水热电化学沉积HA,得到的HA晶体分布均匀、致密。当电解液pH值在2~8时,pH值升高有利于提高水热电化学沉积HA的结晶度,并促使HA沿(002)晶面生长。在水热电化学沉积HA过程中,电极表面的pH值随沉积时间的增加先升高后逐渐降低;而溶液中的pH值随沉积时间的增加逐渐降低。pH值和缓冲剂对涂层HA晶体形貌有明显影响,加入缓冲剂后得到的HA晶体端面呈六边形棒状结构,晶体表面光滑、结晶完整。     

Degradation of 17alpha-ethinylestradiol in aqueous solution by ozonation

This study investigates the ozonation of 17alpha-ethinylestradiol (EE(2)) in aqueous solution. The affecting factors on the degradation of EE(2) were studied and described in details, such as initial EE(2) concentration, initial pH value and ozone concentration. In addition, some parameters such as pH, electrical conductivity, mineralization efficiency and degradation products were monitored during the process. The mineralization efficiency of EE(2) could reach 53.9%. During the ozonation process the rapid decrease of pH and the sharp increase of electrical conductivity indicated the formation of acidic by-products, small fragments and ions which were confirmed by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC/MS) analysis. Results showed that there were intermediate products of smaller molecule with higher polarity produced during the course of EE(2) degradation. Then a possible reaction pathway for EE(2) degradation involving all intermediates detected is proposed. During the ozonation process EE(2) was first oxidized into hydroxyl-semiquinone isomers which were subsequently degraded into low molecular weight compounds such as oxalic acid, malonate, glutarate, and so on. Furthermore, these organic acids are easily oxidized by ozone into carbon dioxide (CO(2)). This work shows that ozonation process is promising for the removal of EE(2). The results can provide some useful information for the potential treatment of EE(2) by ozonation in aqueous solution.     

电气石/壳聚糖复合纤维的表征及细胞相容性

以壳聚糖为基体,电气石为分散相,采用溶液纺丝法制备电气石/壳聚糖复合纤维,利用光学显微镜、扫描电镜以及红外光谱仪对材料进行表征。电气石/壳聚糖复合纤维与人骨肉瘤细胞株（MG63）体外共培养,初步评价了材料的细胞相容性。结果显示,电气石颗粒在复合纤维中分散均匀且被壳聚糖包裹,纤维表面无裸露电气石。细胞在电气石/壳聚糖复合纤维表面黏附及生长增殖状况良好,材料对细胞无明显毒性。该材料有望成为一种良好的创伤修复敷料。     

Effect of chromium on the corrosion behaviour of powder-processed Fe-0.45wt% P alloys

The corrosion behaviour of Fe-0.45P with/without addition of chromium, prepared by powder forging route was studied in different environments. The corrosion studies in acidic (0.25M H₂SO₄ solution of pH 0.6) and neutral/marine (3.5% NaCl solution of pH 6.8) solutions were conducted using Tafel Extrapolation method. The rate of corrosion in alkaline medium (0.5M Na₂CO₃ + 1.0M NaHCO₃ solution of pH 9.4) was measured using linear polarization technique. The studies compare electrolytic Armco iron with Fe-P alloys. It was observed that, chromium improved the resistance to corrosion in acidic and marine environments. The corrosion rates were minimal in alkaline medium and low in neutral solution.     

Facile synthesis of one-dimensional self-assembly oligo(o-phenylenediamine) materials by ammonium persulfate in acidic solution

The one-dimensional (1-D) self-assembly oligo(o-phenylenediamine) (OoPD) was prepared successfully by just mixing o-phenylenediamine (oPD) and ammonium persulfate (APS) in acidic solution at room temperature. The morphology and structure of the OoPD as-prepared were characterized by SEM, FTIR, NMR and MS. Results showed that the product was identified as dimer and trimer with the phenazine-like structure. Especially the OoPD synthesized by oxidant APS in the acidic solution showed self-assembly behaviors to form definite 1-D microfibrils. Increasing the solution pH after the oxidative oligomerization can effectively improve the 1-D microstructure's rigidity. A possible formation mechanism was proposed.     

The operation characteristics and electrochemical reactions of a specific circulation-enhanced electrokinetics

For electrokinetics remediation, the acid produced at the anode due to the water electrolysis will cause the soil acidification and destroy the soil constituents. Especially, the contaminated soils in Taiwan are usually agricultural lands; it is necessary to improve the performance of EK system to maintain the soils nature after remediation. In this study, a circulation-enhanced EK system (CEEK) was designed to neutralize the pH of the working solution and soils. Experiments were conducted by the control of different electrolyte species (sodium and potassium salts) and concentrations (10(-3) to 5x10(-2)M), respectively. Experimental results show the operational characteristics include: the CEEK system can effectively stabilize the pH of processing solution at neutral range and the current can be maintained at stable status with carbonate salts; the pH buffering range of working solution in the CEEK system depends on the electrolyte species and their concentration significantly; the water content remains roughly as their original nature in the CEEK system. For consideration of electrochemical reactions, the water electrolysis is the predominating electrochemical reaction in the CEEK system, which not only influences the pH but also the conductivity of the working solution. In the application of practical engineering, there exist linear relationships between the pH, conductivity, current and the electrolyte concentration, respectively, which can serve as a means to assist engineers to select operational parameters of CEEK.     

Hydration of alkali-activated ground granulated blast furnace slag

The hydration of ground granulated blast furnace slag (GGBFS) at 25 °C in controlled pH environments was investigated during 28 days of hydration. GGBFS was activated by NaOH, and it was found that the rate of reaction depends on the pH of the starting solution. The main product was identified as C-S-H, and, in the pastes with high pH, hydrotalcite was observed at later stages of hydration. The pH of the mixing solution should be higher than pH 11.5 to effectively activate the hydration of GGBFS. As deduced from very low electrical conductivity measurements, GGBFS pastes had very tortuous and disconnected pores. The effect of the pH of the aqueous solution on the composition, microstructure and properties of alkali-activated GGBFS pastes are also discussed.     

pH sensitive multiwalled carbon nanotubes

The CNTs-based sensors have received considerable attention because of their outstanding properties, such as faster response, higher sensitivity, and lower operating temperature. And we expect that CNTs-based electrochemical sensors offer substantial improvements in the performance of pH sensing device. This letter reports experimental results that demonstrate the pH sensing capability of the multiwalled carbon nanotubes (MWCNTs) film by using the thermal chemical vapor deposition (thermal CVD). It was found that electronic properties of MWCNTs can be changed by the introduction of different pH value solutions. The absorption of the hydroxide in pH buffer solution changes conductivity of the MWCNTs. We observed in situ measurement of electrical conductivity by cycling solution range from acid to base.     

pH-Controlled Delivery of Doxorubicin to Cancer Cells, Based on Small Mesoporous Carbon Nanospheres

Mesoporous carbon nanospheres (MCNs) with small diameters of ≈90 nm are developed as an efficient transmembrane delivery vehicle of an anticancer drug, doxorubicin (DOX). MCNs exhibit a high loading capacity toward DOX due to hydrophobic interactions and the supramolecular π stacking between DOX and the carbonaceous structures, on which the pH-dependent drug release are successfully achieved. Specifically, DOX can be loaded onto MCNs in basic solution and in a physiological pH range, while release occurs in acidic solution in its ionized state. By effective passive and active targeting, MCNs can be readily internalized into HeLa cells, where the carried DOX can be efficiently released in the acidic microenvironment of the tumors for further therapy. The endocytosis and cytotoxicity of DOX@MCNs toward HeLa cells are investigated by confocal microscopy and MTT assay. This smart pH-dependent drug loading and release property of DOX@MCNs makes it possible to reduce the cytotoxicity to normal tissues during circulation in the body since the normal physiological pH is ≈7.4.     

Synthesis of a quaternary amine anion exchange resin and study [of] its adsorption behaviour for chromate oxyanions

Glycidyl methacrylate/N,N'-methylene bis-acrylamide (GMA/MBA) was prepared and allowed to react with tetraethylenepentamine (TEP) to give glycidyl methacrylate amine resin (RPA) followed by treatment with glycidyl trimethylammonium chloride (GTA) to give glycidyl methacrylate resin bearing quaternary ammonium chloride moieties (RQA). Zeta potential measurements showed that RQA particles are positively charged over pH 2-10 indicating the strong basic nature of the quaternary amine sites. The effect of pH on the recovery of chromate by RPA and RQA was examined. The results indicated that RQA is an efficient sorbent for chromate from both acidic and basic media. The repeated use of RQA was tested through stripping the adsorbed chromate using a mixture of 0.05 NaOH and 2 M NaCl in the case of the uptake from acidic media and using 2 M NaCl solution in the case of alkaline solutions.