壳聚糖对药液絮凝作用的研究

以壳聚糖为絮凝剂，研究了它对丹参水提液的絮凝情况。比较了絮凝剂加入量不同和分子量不同时，絮凝物的沉降速率，从而考察了它们对絮凝效果的影响以及所得产品的质量。     

壳聚糖-丙烯酰胺接枝共聚及其絮凝性能

壳聚糖-丙烯酰胺接枝共聚及其絮凝性能;壳聚糖;丙烯酰胺;接枝共聚;絮凝     

微生物絮凝剂产生菌絮凝活性研究(Ⅱ)

从福州郊区旱田地表土壤中分离得到一株絮凝剂产生菌,根据菌落形态特征,初步鉴定为链球菌.研究表明,培养基组成如下:碳源为蔗糖,氮源为牛肉膏,培养基初始pH值为5～8.5之间能取得较好的效果,添加一定浓度的Na 、Mg2 、Ca2 对培养液的絮凝活性有促进作用,而培养液中少量的Cu2 、Fe3 、Zn2 可抑制絮凝活性,该絮凝剂对高岭土悬浮液有较好的絮凝效果.结合实验现象和双电层理论初步推测了该絮凝剂的絮凝过程模型,对进一步研究微生物絮凝剂的絮凝机理有一定的参考作用.     

白砂糖酸性絮凝物的主要成分及其形成的影响因素

分析了白砂糖中酸性絮凝物的主要成分,结果表明,白砂糖中酸性絮凝物含淀粉等多糖类38.7%～47.4%(质量分数),蛋白质等含氮物质21.5%～33.7%,灰分等无机物21.56%～25.17%,蔗脂蔗腊等类脂物7.0%～11.3%。白砂糖中酸性絮凝物的形成速度受pH值和温度的影响,在pH值1.0～4.0和10.0～12.0范围内,絮凝物形成速度较快,温度在5～50℃范围内,絮凝物形成速度随着温度的升高而提高。     

微生物絮凝剂产生菌絮凝活性研究(II)

从福州郊区旱田地表土壤中分离得到一株絮凝剂产生菌,根据菌落形态特征,初步鉴定为链球菌。研究表明,培养基组成如下:碳源为蔗糖,氮源为牛肉膏,培养基初始pH值为5~8.5之间能取得较好的效果,添加一定浓度的Na+、Mg2+、Ca2+对培养液的絮凝活性有促进作用,而培养液中少量的Cu2+、Fe3+、Zn2+可抑制絮凝活性,该絮凝剂对高岭土悬浮液有较好的絮凝效果。结合实验现象和双电层理论初步推测了该絮凝剂的絮凝过程模型,对进一步研究微生物絮凝剂的絮凝机理有一定的参考作用。     

电絮凝处理脱硫废水中重金属及动力学模型

采用电絮凝法处理脱硫废水中重金属离子,研究去除过程的影响因素及动力学模型,并对电絮凝产物进行分析。考察电絮凝时间、电流密度、废水pH、曝气量对电絮凝法处理重金属离子效果的影响。结果表明,电絮凝时间40min,电流密度4mA/cm2,废水pH=7,曝气量0.4m3/h时,四种金属去除率达90%。电絮凝产物为铁的多核羟基络合物,且去除过程具有一级动力学反应特征。     

絮凝剂产生菌(DSF-1)絮凝活性研究(Ⅰ)

采用稀释划线法从土壤中分离得到一株絮凝剂产生菌DSF-1。通过高岭土悬浮液对该絮凝剂的絮凝活性做了初步研究,结果表明DSF-1产絮凝剂具有产生速度快、絮凝活性高、耐热性能良好的优点。     

阳离子聚电解质强化絮凝去除有机污染物的化学成因

强化絮凝工艺已在去除有机污染物的水处理工艺中得到较好应用,但其作用机理一直未能得到明晰的结论,而且阳离子聚电解质强化絮凝具有“高效性”和“专属性”的问题也无法回答。近年来由于分子环境科学及先进化学分析手段的应用,基于不同絮凝化学成因的强化絮凝技术研究已成为环境水化学和水污染控制技术领域的研究热点。本文综述了国际上近年提出的专属吸附絮凝、聚电解质络合絮凝和胶束吸附絮凝等强化絮凝技术化学成因的研究现状,并对今后的研究提出了展望。     

阳离子聚电解质强化絮凝去除有机污染物的化学成因

强化絮凝工艺已在去除有机污染物的水处理工艺中得到较好应用,但其作用机理一直未能得到明晰的结论,而且阳离子聚电解质强化絮凝具有“高效性“和“专属性“的问题也无法回答.近年来由于分子环境科学及先进化学分析手段的应用,基于不同絮凝化学成因的强化絮凝技术研究已成为环境水化学和水污染控制技术领域的研究热点.本文综述了国际上近年提出的专属吸附絮凝、聚电解质络合絮凝和胶束吸附絮凝等强化絮凝技术化学成因的研究现状,并对今后的研究提出了展望.     

一种复合絮凝剂的絮凝性能及应用研究

以淀粉为原料，通过化学改性研制出同时兼含羟基、氰基、酰胺基和季铵盐基团的两亲型高分子絮凝剂(ASF)，然后加入铝酸纳和硅酸钠，以一定的比例进行复配，制得复合型高分子絮凝剂CF-1，并综合研究了CF-l的絮凝性能。结果表明，CF-1对印染、造纸、皮革、制药等工业废水具有很强的絮凝和脱色效果，废水的色度去除率达96％以上，SS去除率达95％以上，CODCr去除率达74％以上。而且其絮凝性能明显优于阳离子聚丙烯蠢胺(CPAM)、聚合氯化铝(PAC)、硫酸铝以及硫酸亚铁等絮凝剂。     

膨润土负载壳聚糖制备吸附剂

将壳聚糖与膨润土混合制得一种吸附剂。将其用于染料溶液的脱色、陈醋的澄清、中药注射液中鞣酸的清除等,脱色率为97％,鞣酸脱除率为50％,陈醋的透光率为25．8％。通过X射线衍射图讨论了膨润土的改性机理。改性后膨润土的片状层结构未发生变化,壳聚糖仅仅吸附在膨润土的内外表面。     

The colloidal stability of raw bentonite deformed mechanically by ultrasound

The present study examined the effect of sonication time on the particle–size and the colloidal stability (i.e. point of zero charge, PZC and zeta potential, ζ) of raw bentonite (RB) from Saudi Arabia. In this study, bentonite suspensions were sonicated for various time intervals (30, 60 and 120 min). The effect of sonication time on specific surface area and the colloidal stability behavior of bentonite at various pH and in presence of different NaCl concentration were investigated. The increased in lightness and brightness of bentonite suspension was observed during sonication experiment which could be attributed to the reduction in the particles size.With increasing sonication time the specific surface area increased and consequently the zeta potential of bentonite suspension increased. Also a shifting in the PZC from pH 3 for raw bentonite to pH 2 after 120 min of sonication.The zeta potential of sonicated bentonite suspension in presence of different concentration of NaCl shows unusual trend compared to the unsonicated bentonite. In conclusion, the stability of raw bentonite suspension was significantly modified due the application of ultrasound with rending the particle-size of the bentonite.     

壳聚糖电流变体的导电特性

电流变体是由高介电颗粒分散在低介电油相中组成的悬浮液,在电场作用下,其表观粘度急剧增大甚至发生固化,这种转变过程速度快（达毫秒级）而且是可逆的［１］．由于这种独特的电场响应性,电流变体有广阔的工程应用前景．但电流变体在显示电流变效应的同时也表现出复杂...     

Effect of hydrodynamic conditions of the kinetics of Bentonite Suspension Flocculation by Cationic Polyelectrolytes and the strength of formed flocs

The influence of Zetag and SNF FO cationic polyelectrolytes on the aggregation kinetics of bentonite particles in a flow system is studied in detail as a function of the dose of added polymer, charge density of its macromolecules, the regime and intensity of system stirring, and the type of stirrer (magnetic and mechanical stirrers). It is shown that there is an optimal regime, namely, the alternation of slow and rather rapid stirring, that provides the formation of the largest and strongest flocs. The rate of aggregation and the size of formed flocs increase with the amount of added reagent irrespective of the intensity of system stirring, as well as with an increase in the charge density of polyelectrolyte, which is responsible for the affinity of macromolecules for the surface. The effect of polymer charge on the flocculation kinetics is exhibited first of all upon the slow stirring of suspension. The difference in the sizes of aggregates resulted from the flocculation of macromolecules with different charges is leveled with an increase in stirring intensity. An empirical method for comparing the efficiency of the flocculating action of polymers in suspensions prepared using different types of stirrers is proposed.     

Photostabilization of an entomopathogenic fungus using composite clay matrices

To provide photostabilization for entomopathogenic fungi by anionic dyes, composite matrices based on clay-biopolymer combinations were prepared. In the first step, the negative surface charge of various clays (montmorillonite, attapulgite, bentonite and kaolinite) was reversed to positive by adsorption to the polycationic biopolymer chitosan. The second step involved adsorption of the toxicologically safe anionic dyes fast green (FG) and naphthol yellow S (NYS) to the clay complexes. Compared with cytotoxic photoprotectants like berberine, palmatine and acriflavine, the anionic dyes have no adverse effects up to a concentration of 1 M. In assays using various clay-chitosan-dye matrices and UV irradiation from a lamp source, it was evident that both FG and NYS provided considerable photostabilization for conidia of the entomopathogenic fungus Aschersonia spp. that served as a model biocontrol agent. Apparently, because of the light-dispersing property, bentonite and attapulgite per se provided significant photoprotection. All clay matrices containing FG provided a substantial photostabilization effect.     

Synthesis of Modified Pectin and Its Flocculating Properties

Modified polysaccharide was synthesized by the reaction of amylopectin with a cationic monomer, (1,2-epoxyprop-3-yl)triethylammonium chloride, in alkaline solution in the presence of Fenton’s reagent. The influence of the concentrations of amylopectin, gelatin, their polymer-inorganic hybrids, and modified pectin on their flocculating properties in free (unrestricted) sedimentation of ocher suspension as a model disperse system was studied. Amylopectin exerts a stabilizing effect, whereas the modified pectin and polymer-inorganic hybrid exert a flocculating effect. The influence of the mode of introducing polymer additives on the flocculating effect and aggregation of ocher particles was analyzed.     

Wet-grinding assisted ultrasonic dispersion of pristine multi-walled carbon nanotubes (MWCNTs) in chitosan solution

Ultrasonication is often used to disperse nano-particles in aqueous solution. However, a good dispersion of nano-particles in aqueous solution is not always achieved, due to the fact that incoming ultrasonicwaves in liquid are usually reflected and damped at the gas/liquid interface. In this work, we report a so-called wet-grinding assisted ultrasonication (GU) method, in which wet-grinding of multi-walled carbon nanotubes (MWCNTs) in chitosan solution is carried out before ultrasonication. The dispersions of MWCNTs were characterized by visual comparison, UV/vis spectroscopy, and scanning electron microscopy (SEM). The results demonstrate that the dispersion quality of chitosan/MWCNT suspension prepared by wet-grinding assisted ultrasonication is much better than that by ultrasonication or wet-grinding alone. It was found that wet-grinding could improve the water wettability of MWCNTs and eliminate the barrier of air layer around MWCNTs to ultrasonicwaves. Meanwhile, the composite from the chitosan/MWCNTs suspension prepared by GU method has an obvious improvement in mechanical property compared to pure chitosan. This simple method for integrating MWCNTs and biocompatible chitosan into a homogeneous dispersion may have great potential application in biotechnology, such as preparing composite materials for medicine, bio-fiber, biosensor, antibacterial coating, and cell cultivation.     

Studying Flocculation Mechanism of Chitosan with Pyrene-fluores-cence Probe Method

A peak/ratio in pyrene-fluorescence spectrum was employed to measure the polarity of micro-environment of chitosan adsorb-ing py--rene molecules. The authors have in the first time detect-ed the pyrene-fluorescence spectrum of chitosan with different degrees of deacetylation (D. D. ), and found the relationship between the flocculaflon of bentonite colloid by chitosan and the peak/ratio values of different molecular weight (M. W. ) and D .D. of chitosan. We find that M.W. plays a key role in the flocculatlon, but D.D. has limited effect on it. From micro-en-vironmental structure of view, it can be proved that the inter-particle bridging rather than charge neutralization dominates the flocculatlon with chitosan.     

Optimization of the use of polyelectrolytes for dewatering industrial sludges of various origins

 Four different industrial slurries were flocculated with polymeric flocculating agents (port sediment, sewage sludge, sugar beet washings and an aluminum hydroxide suspension). The quantities of flocculating agent employed were optimized with the aid of a patented, portable flocculation and dewatering apparatus. Using sewage sludge as an example, it was possible to arrive at predictions for particular doses of flocculating by means of a combined method of dewatering experiments and electrokinetical measurements. The results of monoflocculation and dual flocculation made it possible to deduce that there are similarities in the flocculation and dewatering behavior of slurries with comparable parameters. Comparison of the sediment particles and the polymer coils revealed a size ratio of 60:1, with the former being the larger. This was then used to devise modifications to the patch charge model and the bridging model as a function of the molar mass of the flocculating agent. The modifications were found to agree well with the experimental findings and the structural conceptions of macromolecular substances. Received: 26 July 1996 Accepted: 29 August 1996     

The dynamics of dilute colloidal suspensions subject to time-dependent flow fields by conservative dichroism

An apparatus is described which permits simultaneous determination of the conservative linear dichroism and the average orientation angle of a dilute suspension of optically anisotropic, nonabsorbing spheroids subjected to a transient shear field. The magnitude of the dichroism reflects the degree of alignment of the particles along their average orientation angle and measurement of this property in time directly obtains the rotational motion of the particles. This experiment makes use of a photoelastic modulator in a novel optical train; the first and second harmonics of the detector signal, which are independent functions of the dichroism and orientation angle, are measured simultaneously as functions of time. Preliminary data on a dilute suspension of bentonite in 90% glycerine and 10% water subjected to an instantaneous simple shear are presented to illustrate the technique. The qualitative features of these data are adequately described by the Rayleigh scattering theory coupled with Jeffery's solution for the dynamics of a rigid spheroid in a creeping simple shear.