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1.
Synthetic polymeric flocculants are used extensively for wastewater remediation, soil stabilization, and reduction in water
leakage from unlined canals. Sources of highly active, inexpensive, renewable flocculants are needed to replace synthetic
flocculants. High kaolin flocculant activity was documented for bovine blood (BB) and blood plasma with several anticoagulant
treatments. BB serum also had high flocculant activity. To address the hypothesis that some blood proteins have strong flocculating
activity, the BB proteins were separated by SEC. Then, the major proteins of the flocculant-active fractions were separated
by SDS-PAGE. Identity of the major protein components was determined by tryptic digestion and peptide analysis by MALDI TOF
MS. The sequence of selected peptides was confirmed using TOF/TOF-MS/MS fragmentation. Hemoglobin dimer (subunits α and β)
was identified as the major protein component of the active fraction in BB; its high flocculation activity was confirmed by
testing a commercial sample of hemoglobin. In the same manner, three proteins from blood plasma (fibrinogen, γ-globulin, α-2-macroglobulin)
were found to be highly active flocculants, but bovine serum albumin, α-globulin, and β-globulin were not flocculants. On
a mass basis, hemoglobin, γ-globulin, α-2-macroglobulin were as effective as anionic polyacrylamide (PAM), a widely used synthetic
flocculant. The blood proteins acted faster than PAM, and unlike PAM, the blood proteins flocculants did not require calcium
salts for their activity. 相似文献
2.
用絮凝剂二甲基二烯丙基氯化铵(DMDAAC)的均聚物和共聚物处理了模拟油田聚驱污水.考察了影响絮凝效果的因素,并进行了与无机絮凝剂的复配研究.实验结果表明:DMDAAC的均聚物和共聚物的最佳絮凝温度分别为30℃和33℃;最佳投药量范围与污水中部分水解聚丙烯酰胺浓度有关;残留聚合物含量低,阳离子度高时,絮凝效果较好;与聚合氯化铝(PAC)的复配可以实现优势互补,达到较理想的聚驱污水处理效果. 相似文献
3.
Harbor sludge (about 25% total solid) has to be dredged to keep the waterways free. Thus, annually 1.2 million m3 of dredged material has to be cleaned. For this process, three different synthetic flocculants with optimal molar masses, ionogenities, and concentrations are added in order to get a good dewatering efficiency and shear strength of the flocs. But as synthetic flocculants bring about unwanted fish toxicity and insufficient biodegradability, this study intends to check whether these flocculants can successively be substituted by cationic starches which have already been proven to be less toxic than synthetic flocculants. Five different starch derivatives with an average degree of substitution higher than 0.5 were characterized, especially in terms of the molar mass and coil size distribution, and flocculation tests, zeta potential measurements and filtrate turbidity tests were carried out in order to create optimum flocculation conditions. The flocculation and dewatering measurements clearly show that the synthetic cationic flocculant PA (0.2 kg/tTS) can be best substituted by cationic starch KS 2 (c = 0.1 kg/tTS, Mw = 1.1 e+08). For substitution of PTAC (c = 0.3 kg/tTS) by cationic starches, we observed that a maximal dewatering efficiency is reached with an approximately 3-fold dose of KS 1 (1 kg/tTS, Mw = 8.1 e+07). 相似文献
4.
The efficient and environmentally friendly method for preparation of novel flocculants using ILs with non-toxic anions are presented. Poly(ionic liquids) (PILs) were prepared by the photopolymerization of polymerizable ILs. All monomers were obtained via anion exchange reaction. Additionally, the polymers were fully characterized by 1H NMR and FTIR spectroscopy, thermal analysis and gel permeation chromatography. Furthermore, these cationic polymers containing harmless anions were used as flocculants. The efficiency was tested using the yeast suspension as a model system of negatively charged particles. The synthesized water-soluble PILs exhibited high molecular weight and significant flocculation efficiency in the wide range of concentrations. Furthermore, the results of experiments show that flocculation of yeast occurs by charge neutralization and bridging mechanism. 相似文献
5.
New hyperbranched polymers based on a carbosiloxane–carbosilane skeleton with aromatic units in the backbone have been prepared via one-pot hydrosilylation reaction using HSi(Me) 2–O–CH 2–C 6H 4–OSiMe–(CH 2) 4(C 3H 5) 2 as a novel AB 2 monomer. These polymers are easy to prepare, have narrow polydispersity values and present allyl groups on the surface which can be used as synthetic platforms for the introduction of different terminal groups like amine groups through hydrosilylation reactions, opening the door to functionalized polymers. The polymerization process was monitored using real-time 1H NMR spectroscopy and the resulting hyperbranched polymers were characterized using 1H NMR, 13C NMR, 29Si NMR and SEC/MALLS. The degree of branching in these polymers was determined by quantitative 29Si NMR spectroscopy and found to be very close to the theoretical value of 0.50 for AB 2 systems. The hydrolytic degradation of these polymers in protic solvents has been studied by 29Si NMR. 相似文献
6.
A novel nano flocculant was prepared through the modification of sodium alginate. In the preparation partially oxidised sodium alginate reacted with triethylenetetramine (TETA) and then reacted with carbon disulfide. The structure of the flocculants was confirmed by elemental analysis, Fourier transform infrared and UV spectrophotometry. The flocculant showed nanoparticle sizes with diameters of 300–350 nm in aqueous solution, and became precipitates after flocculation with Pb2+ ions. The flocculant was employed to adsorb Pb2+ in wastewater, and the influence of flocculant concentration, flocculation temperature, pH, and time on the adsorption properties were investigated. The results showed that adsorption capacity of the flocculant for Pb2+ could reach up to 3.43 mmol g–1, and the removal rate for Pb2+ was over 97%. The adsorption processes corresponded to pseudo second order kinetics and Langmuir isotherm model. The adsorption mechanism involved electrostatic attraction, chemical chelation, netting and sweeping actions. 相似文献
7.
The kinetics of sedimentation of titanium dioxide suspension in aqueous and water-salt media is studied in the presence of high-molecular-weight flocculants — polyacrylamide and ionic (anionic and cationic) acrylamide copolymers. Data are obtained on the influence of flocculant concentration, the chemical nature of repeating units in polymer chains of acrylamide (co)polymers, and the order of the addition of active components on the sedimentation characteristics of titanium dioxide suspension. 相似文献
8.
In this study, a novel flocculation strategy for harvesting Chlorella vulgaris with combined flocculants, poly (γ-glutamic acid) (γ-PGA) and calcium oxide (CaO), has been developed. The effect of flocculant dosage, the order of flocculant addition, mixing speed, and growth stage on the harvesting efficiency was evaluated. Results showed that the flocculation using combined flocculants significantly decreases the flocculant dosage and settling time compared with control. It was also found that CaO and γ-PGA influenced microalgal flocculation by changing the zeta potential of cells and pH of microalgal suspension. The most suitable order of flocculant addition was CaO first and then γ-PGA. The optimal mixing speed was 200 rpm for 0.5 min, followed by 50 rpm for another 4.5 min for CaO and γ-PGA with the highest flocculation efficiency of 95 % and a concentration factor of 35.5. The biomass concentration and lipid yield of the culture reusing the flocculated medium were similar to those when a fresh medium was used. Overall, the proposed method requires low energy input, alleviates biomass and water contamination, and reduces utilization of water resources and is feasible for harvesting C. vulgaris for biofuel and other bio-based chemical production. 相似文献
9.
用常见无机和有机絮凝剂处理了聚驱污水,分别考察了絮凝剂单剂和复配处理后聚驱污水中残余部分水解聚丙烯酰胺(HPAM)质量浓度和透光率随絮凝剂剂量的变化.结果表明:采用无机絮凝剂处理聚驱污水时,残余HPAM质量浓度随絮凝剂剂量增加先减小后增大;采用有机絮凝剂处理聚驱污水时,残余HPAM质量浓度随絮凝剂剂量增加而线性增加.将无机絮凝剂与无机絮凝剂复配使用,则残余HPAM质量浓度与透光率成反比;将无机絮凝剂与有机絮凝剂复配使用,则残余HPAM质量浓度取决于复配体系中阳离子聚丙烯酰胺(CPAM)的添加量. 相似文献
10.
The adsorption kinetics of anionic polyacrylamide flocculant onto kaolinite clay are examined as a function of flocculant dosage and pH. Special attention has been given to the flocculation effect during the adsorption process and the resulting inhibition of further adsorption. At pH 8.5 the adsorption capacity of anionic polyacrylamide on kaolinite is low while at pH 4.5, the adsorption capacity increases. Flocculant adsorption has been shown to be related to the amount of available surface area, pH, flocculant dosage, and the resulting floc strength, which controls the rate of new surface area exposure and hence the continuation of further adsorption. At both pH 4.5 and pH 8.5, complete adsorption is achieved at low flocculant dosages and adsorption equilibrium is achieved at high flocculant dosages after 1 day. In contrast, at intermediate flocculant dosages adsorption equilibrium is not reached over a 7-day period, due to a continuously increasing surface area. 相似文献
11.
In the conventional polyelectrolyte titration, toluidine blue (TB) has been used exclusively as an indicator. This is a very convenient method for analyses of polyelectrolytes with fairly high charge density, but it is very difficult, or impossible, to analyze samples with low charge density such as commercial cationic starches because of the unclear color change of TB at the end point. Also analyses of polyelectrolytes with ultrahigh molecular weights over 10 7 (such as common flocculants) are often accompanied by serious errors. Usually, the concentration of standard titrant is around 0.2 × 10 ?3 N. On the other hand, the standard titrant with very dilute concentration such as 1 × 10 ?4 N can be used in the polyelectrolyte titration using a fluorescent indicator because the sensitivity of fluorescence detection is extremely high. It has been elucidated that this method can be employed for accurate analyses of cationic starches, cationic and anionic flocculants, and also for determination of sulfonic and carboxyl groups contained in the same molecule by the titration at pH 2.8 and 9.5, respectively. © 1993 John Wiley & Sons, Inc. 相似文献
12.
Oil-in-water emulsions are usually formed during oil production and treatment. Before being discarded, such dispersions should be treated. In order to improve the oil–water separation process using physical processes (decantation, flotation, centrifugation, etc.) the particle size of the disperse phase should be increased. This may be achieved through flocculation, which consists in the agglomeration of various particles or drops, using, as flocculating agents, high molecular weight hydrophilic macromolecules. A few studies have been carried out on the flocculation of finely divided oil drops in brine with the aid of generally ionic polyelectrolytes. This work shows the results obtained using nonionic polymers as flocculants. Commercial samples of poly(ethylene oxide- b-propylene oxide) and poly(vinyl alcohol) were evaluated through flocculation–flotation tests as well as the drop size distribution. The performance of such additives as flocculants for oil–water dispersions is related to their structure, composition, molecular weight and hydrophilic–lipophilic balance. The composition of the produced water is also an important parameter when choosing the features of the flocculant additive. 相似文献
13.
Abstract Homopolymer of linseed oil and its four copolymers with styrene, 1-decene, isodecyl acrylate and octyl acrylate, respectively, have been synthesized in this present context. The prepared polymers are characterized by NMR and FTIR spectroscopy. The molecular weights have been measured by gel permeation chromatography. Their effectiveness as pour point depressant (PPD), viscosity index improver (VII) and their shear stability in terms of permanent shear stability index have been evaluated in lube oil. The copolymers acted as better PPDs than the homopolymer whereas the homopolymer of linseed oil excelled as VII. Further it was observed that all the prepared polymers were stable enough under severe mechanical shear. 相似文献
14.
Various non-linear highly branched polymers such as multiarm stars, block copolymer micelles and bottlebrush-like polymers have been studied in order to analyze their intramolecular structure and effects of spatial ordering resulting from their specific macromolecular architecture. These polymers constitute a class of compact macromolecules which, due to the high intramolecular density, interact strongly, excluding each other in space. Investigations of the structure and dynamics in such systems, using various experimental methods as well as computer simulations, have been performed. Small angle X-ray scattering is used to characterize the structure and mechanical spectroscopy is used for the detection of the dynamic behavior of the systems. Simulations have been performed using the cooperative motion algorithm with lattice polymers equivalent to the considered macromolecules. Results of both experiments and the simulation seem to support the concept of slow structural cooperative rearrangements controlling the flow in such systems. The effects are analogous to those related to flow in low molecular liquids but take place on another size scale. The new slow relaxation processes creates new super soft-states which are characterized by shear modulus plateau lower than 10 4 Pa. 相似文献
15.
The separation and isolation of semiconducting and metallic single‐walled carbon nanotubes (SWNTs) on a large scale remains a barrier to many commercial applications. Selective extraction of semiconducting SWNTs by wrapping and dispersion with conjugated polymers has been demonstrated to be effective, but the structural parameters of conjugated polymers that dictate selectivity are poorly understood. Here, we report nanotube dispersions with a poly(fluorene‐ co‐pyridine) copolymer and its cationic methylated derivative, and show that electron‐deficient conjugated π‐systems bias the dispersion selectivity toward metallic SWNTs. Differentiation of semiconducting and metallic SWNT populations was carried out by a combination of UV/Vis‐NIR absorption spectroscopy, Raman spectroscopy, fluorescence spectroscopy, and electrical conductivity measurements. These results provide new insight into the rational design of conjugated polymers for the selective dispersion of metallic SWNTs. 相似文献
16.
The creation of tailor-made receptors which are able to recognize molecular targets with high affinity and selectivity has
attracted much attention in the field of chemistry, physics, and biology. Molecular imprinting has proved to be an effective
technique for generating specific recognition sites in synthetic polymers. The synthesis of molecular imprinted polymers specific
for proteins and peptides has been a focus for many scientists working in the area of molecular recognition, since the creation
of synthetic polymers that can specifically recognize biomacromolecules is a very challenging but potentially extremely rewarding
work. These polymers with specificity for biological macromolecules have considerable potential for applications in the areas
of solid phase extraction, catalysis, medicine, clinical analysis, drug delivery, environmental monitoring, and sensors. In
this review, the authors discuss the developed approaches associated with the imprinting of peptides and proteins, and provide
an overview of the significant progress achieved within this field. Finally, the possible mechanism of the molecular imprinting
and recognition has been discussed. 相似文献
17.
以川中矿区典型的压裂酸化废水为研究对象,考察了溶液pH值、无机混凝剂、有机高分子絮凝剂、以及无机混凝剂与有机高分子絮凝剂共同作用对废水Zeta电位的影响,从理论上对油田废水的絮凝特点进行了表征.实验结果证明:油田作业废水适合在酸性条件下进行絮凝处理;聚硅硫酸铁和阳离子有机高分子絮凝剂能使废水颗粒表面Zeta电位明显正移;当联合使用时,先加无机混凝剂,后加有机絮凝剂,能提高污水处理质量. 相似文献
18.
Harvesting microalgae from medium is a major challenge due to their small size and low concentrations. In an attempt to find a cost-effective and eco-friendly harvesting technique, mung bean ( Vigna radiata) protein extract (MBPE) was used for flocculation of Nannochloropsis sp. The effects of parameters such as pH, flocculant dose, algae concentration, and mixing time were used to study the flocculation efficiency (FE) of MBPE. Optimum parameters of MBPE dosage of 20 mL L ?1 and a mixing rate of 300 rpm for 6 min achieved a FE of >92% after 2 h of settling time. MBPE-aggregated microlga flocs were characterized by microscopy. Zeta potential values decreased with increasing flocculant dose, and the values obtained were ?6.93 ± 0.60, ?5.36 ± 0.64, and ?4.44 ± 0.22 for doses of 10, 20, and 30 mL L ?1, respectively. In conclusion, MBPE flocculants used in this study are safe, nontoxic, and pollution free, so they could be used for an effective, convenient, and rapid harvesting of microalgae in an eco-friendly approach. These methods are sustainable and could be applied in industrial scale for aquaculture nutrition. 相似文献
19.
制备了无机高分子复合絮凝剂聚硅酸硫酸铁(PFSS)和助凝剂壳聚糖(CTS),考察了影响合成及絮凝剂应用的因素,探讨了其组成、投加量以及pH值对城市废水絮凝效果的影响,通过对模拟废水和城市废水絮凝试验,得出最佳的合成和应用条件:n(Fe)∶n(Si)=1∶1,PFSS的碱化度为1.5,聚合硫酸铁(PFS)的pH=2,聚硅酸(PS)的活化时间为1.5 h;n(PFSS)∶n(CTS)=5∶1,投加量为(20+4) mg/L,pH值的范围为6~9,沉降时间为15 min。 复合絮凝剂(PFSS-CTS)在最佳条件下浊度、色度、COD的去除率分别达到95.04%、91.26%和83.45%。 相似文献
20.
Developing high-performance but low-cost n-type polymers remains a significant challenge in the commercialization of organic field-effect transistors (OFETs). To achieve this objective, it is essential to design the key electron-deficient units with simple structures and facile preparation processes, which can facilitate the production of low-cost n-type polymers. Herein, by sequentially introducing fluorine and cyano functionalities onto trans-1,3-butadiene, we developed a series of structurally simple but highly electron-deficient building blocks, namely 1,4-dicyano-butadiene ( CNDE ), 3-fluoro-1,4-dicyano-butadiene ( CNFDE ), and 2,3-difluoro-1,4-dicyano-butadiene ( CNDFDE ), featuring a highly coplanar backbone and deep-positioned lowest unoccupied molecular orbital (LUMO) energy levels (−3.03–4.33 eV), which render them highly attractive for developing n-type semiconducting polymers. Notably, all these electron-deficient units can be easily accessed by a two-step high-yield synthetic procedure from low-cost raw materials, thus rendering them highly promising candidates for commercial applications. Upon polymerization with diketopyrrolopyrrole ( DPP ), three copolymers were developed that demonstrated unipolar n-type transport characteristics in OFETs with the highest electron mobility of >1 cm 2 V −1 s −1. Hence, CNDE , CNFDE , and CNDFDE represent a class of novel, simple, and efficient electron-deficient units for constructing low-cost n-type polymers, thereby providing valuable insight for OFET applications. 相似文献
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