Study on coagulation property of metal-polysilicate coagulants in low turbidity water treatment

In order to remove the low turbidity present in surface water, a novel metal-polysilicate coagulant was used to treat the raw water taken from Tanjiang River in Guangdong Province. This study on the effects of Al/Fe molar ratio on the performance of a complex compound formed by polysilicic acid, aluminium and ferric salt (PAFS) showed that PAFS with Al/Fe ratio of 10:3 seemed to have the best coagulation performance in removing turbidity and color. Experimental results showed that under the conditions of polymerization time of 15 d, sedimentation time of 12 min, and pH of 6?8, PAFS with Al/Fe molar ratio of 10:3 had the best coagulation efficiency and lowest residual Al concentration. The turbid- ity decreased from 23.8 NTU to 3.23 NTU and the residual Al concentration was only 0.165 mg/L in the product water. It could be speculated that colloidal impurities and particulate Al were removed by adsorption bridging and electrical neu- tralization of long chain inorganic polymer coagulants.

Molecular Structures and Mechanical Properties of Microbe Rapid Coagulation Natural Rubber

In this work,molecular structures,dynamic mechanical properties and glass transition temperatures of microbe coagulated natural rubber（NR） samples were analyzed by using pyrolysis gas chromatography-mass spectrometry（py-GC/MS）,rubber process analyzer（RPA） and dynamic mechanical thermal analysis（DMA）.And the cross-linked network structures and mechanical properties of the corresponding NR vulcanizates were further determined by using nuclear magnetic resonance（NMR） crosslink density spectrometer（XLDS-15） and universal testing machines.The results show that NR raw rubber produced by rapidly coagulated with microorganism exhibits a simple molecular structure composition and good dynamic mechanical properties,and the corresponding NR vulcanizates possess the aggregation structure of high cross-linked density,a high glass transition temperature of-61.5 ℃ and high mechanical properties（tensile strength reaches 25.2 MPa）,as compared with that coagulated with acetic acid.

Natural Rubber-Grafted-Poly （Methyl Methacrylate）： Influence of Coagulating Agents on Properties and Appearances

Graft copolymers of MMA （methyl methacrylate） with NRL （natural rubber latex） referred to as NR-g-PMMA have been prepared using CHP （cumene hydroperoxide）/TEPA （tetraetbylenepentamine） redox initiator. 1H NMR （proton nuclear magnetic resonance） and FTIR （Fourier transform infrared） analysis have confirmed the occurrence of graft copolymerisations of MMA onto NR that containing 30% and 50% of MMA monomer. The influence of coagulating agents such as formic acid, sulfuric acid and boiling water on the coagulation of NR-g-PMMA latices were investigated. These types of coagulating agent formed compact coagulum and the effect of NR-g-PMMA compounds on cure characteristics, physical properties and appearances were reported.

超疏水表面在抗/促凝血领域的研究进展

近年来,随着超疏水材料在冷凝传热、油水分离、除冰防雾、表面防腐、管道减阻等方面应用的研究逐步趋于成熟,其在生物医疗领域的应用前景也备受学者关注,由于医疗设备与血液接触时产生的凝血血栓及大量出血引发的失血性休克问题会对患者生命安全造成极大威胁。为了能够有效解决血栓出现及大量失血问题,国内外诸多学者展开了大量研究,超疏水材料由于其特殊的表面润湿性及较低的表面自由能可显著降低材料表面的血小板粘附量,其与亲水材料的组合可在止血的前提下减少出血量并降低伤口二次撕裂出血的可能,同时,研究表明超疏水材料还具有良好的抗菌性,故针对超疏水材料的研究成为了该领域的热点与方向。基于此,首先介绍了超疏水材料基本理论,主要包括Young润湿模型、Wenzel润湿模型以及Cassie-Baxter润湿模型,其次详细阐述了其在抗/促凝血过程中的作用机理,然后以部分研究为代表着重讨论了目前超疏水材料在血液接触应用领域的研究现状,指明超疏水材料在该领域的应用中主要存在的问题,最后对其未来的发展前景进行了展望。

凝固浴牵伸对微纳层叠带状PAN原丝性能的影响

采用新型微纳层叠挤出技术制备了层叠带状聚丙烯腈(PAN)碳纤维原丝,利用扫描电子显微镜、X射线衍射仪、万能材料试验机和差示扫描量热仪对原丝的性能进行表征,研究了不同凝固浴牵伸倍数对微纳层叠带状PAN原丝截面形态、结晶性能、力学性能以及热行为的影响。研究结果表明,随着凝固浴牵伸倍数的提高,层叠带状PAN原丝的厚度显著减小,线密度显著降低;层叠带状PAN原丝的结晶度和拉伸强度随着牵伸倍数的提高呈现先增加后减小的趋势,凝固浴牵伸倍数为5.5倍时,获得的层叠带状PAN原丝的性能较好。当凝固浴牵伸倍数从5.5倍增加至6.5倍时,原丝的拉伸强度由26.08 MPa降低至23.36 MPa。实验结果表明,凝固浴牵伸倍数为5.5倍下制备的层叠带状PAN原丝具有较好的综合性能,其结晶度为39.1%,拉伸强度和拉伸模量分别为26.08及661 MPa。

电解法制备高铁酸钾及对Sb(Ⅲ)去除效能的研究

实验采用电解法制备高铁酸钾固体,采用XRD、SEM及分光光度法进行表征和纯度分析,证明了纯度可达90%以上。采用K2FeO4对水体中Sb(Ⅲ)进行降解去除,实验表明,在溶液pH=5,Sb(Ⅲ)初始浓度为2?mg/L时,投加K2FeO4为50?mg/L为最优投加量。通过K2FeO4及分解产物在不同pH值下对Sb(Ⅲ)、Sb(Ⅴ)去除实验,发现K2FeO4主要通过分解产物即絮凝、吸附作用对Sb(Ⅲ)去除,去除率在90%以上,且受pH值影响小。通过K2FeO4除Sb(Ⅲ)沉淀物的XPS、FTIR表征分析,证明了Sb(Ⅲ)可以有效的被K2FeO4去除。

植物叶蛋白提取工艺及蛋白肽制备技术研究进展

随着社会发展水平的提升,食物来源日益多元化,人们对优质蛋白质食物消费量不断增加,促使植物蛋白资源的开发和提取技术兴起。植物蛋白有动物蛋白无可比拟的优势,通过对叶蛋白深加工制备的蛋白肽,可以进一步提升植物蛋白的营养价值。因此,植物叶蛋白的提取及精深加工备受人们关注,植物叶蛋白的提取方法更是多种多样,最佳提取工艺参数也有深究。本文在前人研究的基础上对不同的叶蛋白经典提取方法及精深加工生产蛋白肽的方法进行整理综述,从主要的叶蛋白提取环节着手,回顾了各提取方法的原理知识、操作注意事项并进行优缺点评价,以期为后续植物叶蛋白提取研究及蛋白肽的制备提供理论依据及指导意见。

不同掺量硼酸对磷酸镁水泥性能的影响

通过实验对不同硼酸掺量下的磷酸镁水泥性能及水化产物晶体形态进行测试分析,探讨硼酸掺加量对磷酸镁水泥的影响。实验结果表明,加入硼酸后,磷酸镁水泥流动度提升不明显;凝结时间提升明显,但凝结时间不会随硼酸掺量的增加而持续增加,硼酸掺量4%为最佳掺量;早期抗折强度与抗压强度下降显著,后期强度变化较小。掺加硼酸会抑制水泥中钾鸟粪石结晶成型;随着硼酸掺量的增加,钾鸟粪石含量减少且由不均匀棱柱型向尖锐锥型转化。

Preparation and performance of oxidative poly-silicon-ferric coagulant PSFN

A new polymer, poly-silicon-ferric with oxidization （PSFN） coagulant was produced by adding KMnO4 and stabilizer M to poly-silicon-ferric （PSF） coagulant. The micro properties of PSFN was investigated with optical microscope, transmission electron microscope（TEM）, ultraviolet/visible absorption（UVA） scanning, infrared（IR） spectrometer and oxidation-reduction potential （ORP） meter respectively, compared to that of PSE The coagulation behavior by PSFN was investigated compared to that by PSF. The results show that the micro properties of PSF have been changed greatly due to the addition of KMnO4, and there exists KMnO4 unattached in PSFN. A kind of tetrahedron structure somewhat like the connection of Si-O-Si bonds may be formed by the complexation of Mn （maybe in various valence） with PSE PSFN has lower turbidity removal than PSF at lower dose and achieves the same when the dose reaches a definite amount, while the removal of UV254 by PSFN is higher than that by PSF almost over entire dose range with the largest difference of about 17%. PSFN has more oxidization function at acidic condition than that at basic condition, and gives stronger ability of application for treating various waters than that by PSE.

酸凝奶豆腐产品开发及其品质评价

为缩短传统奶豆腐的生产时间,提升产品品质,在传统奶豆腐制作工艺基础上,改良了发酵产酸的凝乳方式,采用酸凝或乳酸菌发酵代替自然发酵凝乳,开发了酸凝或乳酸菌奶豆腐,并对其凝块中微生物多样性及其理化指标、质构特性、流变学特性、游离氨基酸含量和感官特性等进行了综合评价。结果表明,与传统奶豆腐相比,经酸凝或乳酸菌发酵生产的奶豆腐凝乳时间短,凝乳充分;产品脂肪含量和pH值较高,游离氨基酸含量丰富,并以苯丙氨酸、谷氨酸、丙氨酸含量居高,口感细腻,酸度适中。而且,酸凝奶豆腐凝块中的优势菌群更为丰富;硬度和胶着度低,更易咀嚼;受热后,融化性和流淌性好,更易拉丝。综合分析结果显示,酸凝奶豆腐的生产工艺简单,口感、风味等显著优于传统奶豆腐和乳酸菌奶豆腐,可作为新型奶豆腐在牧区进行推广应用,有利于促进牧民增收。

聚羟基脂肪酸酯(PHAs)基止血材料研究进展

在意外事故、自然灾害及军事冲突中,人体会受到严重外部创伤,出现大量的不可控出血,极易导致伤员的缺血性休克甚至死亡。因此,伤口的快速止血是提高伤者存活率的关键,快速止血一般需要借助止血材料实现。聚羟基脂肪酸酯(PHAs)是一种天然高分子化合物,具有良好的生物相容性、生物可降解性、可改性等特性,其降解产物还具有促进活体细胞增殖和分化的作用,可加速伤口愈合,是一种极具潜力的止血材料,受到生物医学研发人员的广泛关注。但在应用过程中,PHAs基材料在韧性、抗菌和凝血能力方面仍然存在缺陷。因此,若想开发基于PHAs的止血材料,必须对其韧性、抗菌能力及凝血性能进行改善。本文综述了近年来PHAs基材料在韧性、抗菌能力以及凝血性能等方面的研究进展,可为PHAs基止血材料的研究开发提供参考。PHAs基止血材料具有较高的经济价值,相关研究对严重创伤的救护和新型生物材料的应用推广具有重要意义。

小米发酵液菌种优化及作为豆腐凝固剂的应用研究

为研究不同菌种小米发酵液对豆腐凝固特性和品质的影响,采用混合菌种、泡菜菌、鼠李糖乳杆菌、酵素菌制备小米发酵液,分析不同菌种对小米发酵液组成成分的影响以及不同小米发酵液对豆腐凝固性的影响。结果表明,12 d后鼠李糖乳杆菌小米发酵液产酸量达到7 g/L;发酵第2天时,泡菜菌的pH最先下降至3.375;鼠李糖乳杆菌的可溶性固形物含量在第10天最先降至1.4%;鼠李糖乳杆菌在发酵第12天时蛋白沉淀量为35 mg/mL;鼠李糖乳杆菌在发酵第12天时沉淀率达到35%。不同菌种小米发酵液对豆腐凝固特性和品质的影响不同,泡菜菌组制得的豆腐的品质最佳;泡菜菌组制得的豆腐的含水量约为78%,持水率为64%,得率为140%;泡菜菌组制得的豆腐的蛋白质含量为15%。该研究旨在为豆腐酸性凝固剂和小米产品的开发提供理论依据。

水中聚乙烯微塑料风化行为对混凝过程的影响

以地表水中丰度较高的聚乙烯(PE)微塑料作为研究对象,开展吸附和混凝试验,在解析PE微塑料对水中有机物吸附能力的基础上,用氙灯对PE微塑料进行光老化以模拟微塑料在自然条件下的风化行为,深入研究PE微塑料风化行为对混凝过程的影响。结果表明:粒度为50~200目的 PE微塑料对有机物的吸附量为310~350 mg/g(以碳计),不存在显著的吸附性能差异。在混凝过程中,相较于未添加PE微塑料的情况,添加未风化的PE微塑料会降低有机物去除率,而添加风化PE微塑料则能明显提升有机物去除率。同时,混凝过程对风化PE微塑料的去除率高于未风化PE微塑料,表明PE微塑料的风化行为有利于其在混凝过程中被去除。根据混凝过程中絮体特征可知,PE微塑料的风化行为对形成絮体的尺寸影响极小,但能显著提高絮体的生长速度。

酶辅助微生物凝固对天然橡胶性能的影响

采用酶辅助微生物凝固鲜胶乳提高天然橡胶产品性能,探究了酶用量对天然橡胶理化指标、硫化特性、加工性能、力学性能、机理及生热性能的影响。结果表明,随着酶用量的提高,生胶塑性初值和门尼黏度升高,塑性保持率降低;硫化胶正硫化时间(t_(90))和焦烧时间(t_(10))变短;生胶的弹性模量(G′)高,损耗因子(t_(anδ))小;硫化胶的拉伸强度、100%定伸应力及撕裂强度均呈上升趋势,老化处理后,硫化胶的力学性能同样保持升高的趋势;同时硫化胶温升呈下降趋势;此外,氮含量和凝胶含量有降低趋势,而丙酮溶物含量有升高趋势。

干喷湿纺聚丙烯腈凝固丝的表征方法研究

以干喷湿纺聚丙烯腈(PAN)凝固丝为研究对象,通过优化试样处理方法和测试条件,建立了一套表征PAN凝固丝组成、形貌、结晶、取向及可拉伸性的方法。结果表明:采用擦拭法擦拭4次以上,PAN凝固丝的溶剂残留率保持稳定,萃取3 h以上可完全除去PAN凝固丝内的残留溶剂;在偏光显微镜和扫描电子显微镜下可分别观察PAN凝固丝的皮芯结构及截面的细微网状结构;PAN凝固丝的结晶度可直接使用X射线衍射仪分析计算,水洗温度对PAN凝固丝取向程度的测试结果影响较小;PAN凝固丝在空气中的自然拉伸比与在水浴中的最大拉伸倍数存在正相关性,自然拉伸比可作为衡量PAN凝固丝可拉伸性的参数。

Optimized coagulation pretreatment alleviates ultrafiltration membrane fouling: The role of floc properties and slow-mixing speed on mechanisms of chitosan-assisted coagulation

To alleviate ultrafiltration(UF) membrane fouling, the pre-coagulation of poly-aluminum chloride(PACl) with the aid of chitosan(CTS) was conducted for synthetic humic acid–kaolin water treatment. Pre-coagulation of three molecular weights(MW) CTSs(50–190 kDa(CTSL), 190–310 kDa(CTSM) and 310–375 kDa(CTSH)) was optimized with slow-mixing speeds of 30, 60 and 90 r/min, respectively. The removal efficiency and floc properties as well as membrane fouling were analyzed, and were compared to results obtained by conventional coagulation with PACl. Results showed that variations in floc properties could be ascribed to the coagulation mechanisms of CTS_L/CTS_M/CTS_H at different slow-mixing speeds, resulting in reduced UF membrane fouling. Specifically, at the low speed of 30 r/min, all three CTS types produced flocs with similar properties, while CTSLresulted in the lowest removal efficiency and aggravated irreversible fouling. At the appropriate speed of 60 r/min, CTSMgenerated the most compact flocs with the combined effects of bridging and path mechanisms. The compact cake layer formed could alleviate irreversible fouling,which was beneficial for prolonging the operation of the UF membrane. At the high speed of90 r/min, CTSHformed fragile flocs and aggravated irreversible membrane fouling. We considered membrane fouling to be affected by floc properties and the resultant removal efficiency, which was governed by the MW of the CTS used and the slow-mixing speed applied as well.

Effect of coagulation temperature on structures and properties of poly(p-phenylene benzobisoxazole) (DHPBO) fibers during dry-jet wet-spinning process

The effect of coagulation temperature on the morphology, microstructures and mechanical properties of dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO) fibers was investigated during dry-jet wet-spinning process, in which the coagulation bath concentration and drawn ratio were kept as 10 wt% of PPA in water and 1.7, respectively. The structures and mechanical properties of the as-spun DHPBO fibers were characterized by FTIR, XRD, SEM, and single fiber tensile testing. The results indicated that in PPA/H2O coagulation system, when the coagulation temperature was 25°C, highly crystallized DHPBO as-spun fibers possessing fine crystallites, circular and smooth morphology, and excellent mechanical properties could be achieved.

Coagulation behavior and floc properties of compound bioflocculant–polyaluminum chloride dual-coagulants and polymeric aluminum in low temperature surface water treatment

This study was intended to compare coagulation behavior and floc properties of two dualcoagulants polyaluminum chloride–compound bioflocculant（PAC–CBF）（PAC dose first） and compound bioflocculant–polyaluminum chloride（CBF–PAC）（CBF dose first） with those of PAC alone in low temperature drinking water treatment. Results showed that dualcoagulants could improve DOC removal efficiency from 30% up to 34%. Moreover, CBF contributed to the increase of floc size and growth rate, especially those of PAC–CBF were almost twice bigger than those of PAC. However, dual-coagulants formed looser and weaker flocs with lower breakage factors in which fractal dimension of PAC–CBF flocs was low which indicates a looser floc structure. The floc recovery ability was in the following order：PAC–CBF 〉 PAC alone 〉 CBF–PAC. The flocculation mechanism of PAC was charge neutralization and enmeshment, meanwhile the negatively charged CBF added absorption and bridging effect.

丝素湿法纺丝中凝固浴对再生丝结构影响机制

为了研究凝固剂种类对再生丝性能的影响,本文分别以十二烷基硫酸钠、去离子水和75%乙醇作为凝固浴,通过再生丝素蛋白湿法纺丝,得到三种再生丝RSF(SDS)、RSF(DI)和RSF(ET)。结果表明,RSF(SDS)具有良好的机械性能,其断裂伸长率达126%,高于20%RSF(DI)和26%RSF(ET)再生丝;傅里叶变换红外光谱分析表明,RSF(SDS)中含有较高比例的β-折叠结构;进一步通过X射线衍射和差示量热法分析显示,RSF(SDS)纤维比RSF(DI)和RSF(ET)纤维具有更多存在于无定形区的β-折叠结构;荧光探针法验证了SDS能够促进丝素蛋白更快速地形成β-折叠结构,乙醇则会诱导丝素蛋白更快速地形成结晶。本文制备了具有优异延伸性的再生丝,可为丝素蛋白湿法纺丝提供一种新思路。

高浓聚合氯化铁混凝剂的制备及其混凝效果研究

以氯化铁和无水碳酸钠为原料 ,加入稳定剂W ,采用共聚工艺合成了一系列不同碱化度 (B)、不同n(W )∶n(Fe)的聚合氯化铁 (简称PFC)混凝剂。通过烧杯实验 ,研究了PFC除浊效果 ,pH值对混凝除浊效果的影响 ;并与氯化铁、工业聚合硫酸铁 (PFS)进行了比较 ;通过电泳实验 ,测量了不同投药量下凝聚颗粒的Zeta电位 。