Synthesis and application of salt tolerance amphoteric hydrophobic associative flocculants

A series of amphoteric hydrophobic-associative flocculants with outstanding flocculation efficiency and salt tolerance, poly(acrylamide/acrylic acid/dimethyl benzyl aminoethyl acrylate chloride), are successfully prepared (named AAB series) and used to flocculate the montmorillonite suspensions. The solution properties of AAB copolymer are systematically evaluated by viscometer, rheology and steady-state fluorescence analysis. The results suggest that the space network structure forming via hydrophobic-associating interaction can increase solution viscosity and improve the bridging capacity of copolymers. Meanwhile, the apparent viscosity in salt solution increases with increase in the concentration of salt stemming from the anti-polyelectrolyte effect of polyampholyte. Further, the flocculation performances of flocculants in 1 wt% montmorillonite suspensions are evaluated by turbidity, optimal dosage and settlement rate measurement. The results elaborate that the flocculation performances of amphoteric hydrophobic-associating AAB flocculants are better than that of commercial flocculants (cationic and anionic polyacrylamide) and homemade cationic flocculant (AAB-0-5) independent of the type and concentration of salt. The novel ampholyteric hydrophobic-associative flocculants will exhibit intriguing prospective in industry water treatment, in that the anti-polyelectrolyte effect of polyampholyte and hydrophobic-associating interaction can endow excellent flocculation efficiency and salt tolerance.     

The flocculation of cane sugar muds with acrylamide–sodium acrylate copolymers

The flocculation of cane sugar muds with commercial acrylamide–sodium acrylate copolymers has been investigated through the measurement of settling rates and residual turbidities. The flocculation efficiencies of the copolymers were observed to depend on their composition, microstructure, and molecular weight, and the zeta potential of the mud particles. Adsorption of polymer at the surface of the particles was shown to occur through interaction with the acrylate groups. The experimental results are consistent with a bridging mechanism for the flocculation process, in which an observed optimum copolymer composition is associated with polymer adsorption which is sufficiently strong to resist mild shear forces yet allows the extension of polymer “loops” and “tails” into solution.     

Microelectrophoresis and electron-microscope studies with polymeric flocculants

Mechanisms for the stabilization and flocculation of colloids have been indicated by microelectrophoresis measurements and electron-microscope observations with model colloids and polymeric flocculants. Zeta-potential (ζ) changes and details of floc structure were observed with silica and polystyrene latex colloids. Bridging fibers of polyamine-type flocculants appear to extend radially from the colloidal particles and vary in thickness from 20 to 300 Å. Charge neutralization and bridging may function simultaneously. Incremental additions of cationic flocculants produce gradual reduction in the negative ζ, and maximum flocculation is observed near zero ζ. Subsequent addition of flocculant reverses the potential and finally effects redispersion of the colloid. If incipient charge reversal is produced with a relatively low molecular weight cationic polymer, large flocs may then be formed on the addition of a high molecular weight anionic flocculant. Direct addition of an anionic polymeric flocculant to a negatively charged colloid may raise the negative ζ to a surprisingly high value and may thus effect stabilization instead of flocculation of the colloid.     

不同絮凝剂对高泥氧化铜浸出液沉降的影响

为解决云南某氧化铜现场生产中酸浸矿浆含泥量高、沉降速度慢、固液分离困难的问题,对其浸出矿浆进行絮凝沉降实验研究. 实验用浸出矿浆浓度为28.73%,考察了絮凝剂种类、用量、浓度对矿浆沉降的影响. 结果表明,明矾、十二烷基丙磺酸钠、聚丙烯酰胺、明胶、改性阴离子型聚丙烯酰胺、改性阳离子型聚丙烯酰胺均不能有效改善沉降速度,而改性非离子型聚丙烯酰胺(GH-6C)可使矿浆沉降速度大大加快. 这是由于GH-6C分子链上的官能团与浸出液中的胶体粒子发生吸附架桥作用,使颗粒逐渐变大而絮凝沉降. GH-6C分子量较大,在水相中流体力学尺寸或体积也较大,絮凝网捕能力也大,可有效降低絮凝剂的使用浓度、提高絮凝效率. GH-6C浓度为0.1%、用量为0.067 g/L时,沉降指标较好.     

Study of microwave-template initiated copolymerization peculiarity and evaluation on the coal floc distinctive behavior and flocculation performance

Cationic polyacrylamide (CPAM) contains a large number of acylamino and positively charged methyl ammonium chloride groups. It has the advantages of good water solubility, strong adsorption bridging ability, enhanced charge neutralization and destabilization performance, excellent flocculation effect, and wide application. Therefore, CPAM can be used in the treatment of coal washing wastewater, and the research and development of a new flocculant with high efficiency is a hot topic in this field. Template copolymer (TPADM) of methacryloyloxyethyl trimethyl ammonium chloride (DMC) and acrylamide (AM) was synthesized by microwave-template initiated polymerization with sodium polyacrylate (PAAS) as template. The microwave-template initiated polymerization is abbreviated as MW-TP. By analyzing FTIR, ¹H (¹³C) NMR and TG/DSC of TPADM, it was found that TPADM had obvious cationic fragment structure. In addition, the association constant (K_M) and the kinetics of the template reaction showed that the MW-TP was confirmed to be free radical initiated polymerization and I Zip-up (ZIP) polymerization mechanism, which demonstrated the formation of the cationic fragment structure again. This new cationic fragment structure greatly enhanced the ability of charge neutralization, electrical patching and adsorption bridging, thus improving the flocculation performance. Compared with cationic P(AM-DMC) (CPADM), Commercial cationic polypropanamide (CCPAM-1 and CCPAM-2), TPADM had better flocculation effect on coal washing wastewater. Under the optimum flocculation conditions (dosage = 16 mg/L, pH = 7.5), suspended solid (SS) concentration and turbidity of coal washing wastewater treated by TPADM reached 14.3 mg/L and 8.7 NTU, respectively. The floc formation, breakage, and regeneration analyses showed that the cationic fragment structure in TPADM could contribute to the formation of large and high density flocculation structure (d₅₀ ≥ 245 μm, D_f ≥ 2.05), and these coal flocs can regenerate rapidly after being broken. Finally, these large and compact flocs help to accelerate the flocs sedimentation and reduce the SS concentration and turbidity of coal washing wastewater, and enhance the effect of solid–liquid separation.     

Flocculation of gelatinized starch: Flocculation performance and floc characterization

The removal of single macromolecules impurity is the basis study for the promotion of flocculation technology application in the Chinese herbal medicine solution purification. We applied the flocculation process to remove gelatinized starch in solution. Three types of cationic polyacrylamide (CPAM) with different charge density were used for flocculation of gelatinized starch solution. The flocculation performance was evaluated in terms of the amylose removal ratio (AMRR), the amylopectin removal ratio (APRR), total starch removal ratio (TSRR) and supernatant turbidity (ST). The flocs were characterized by sedimentation performance, Fourier transform infrared (FTIR), scanning electron microscope (SEM) and X-ray photoelectric spectroscopy (XPS) method. The experimental results show that the flocculant CN15 has the best performance for gelatinized starch flocculation among three flocculants. According to the characterization analysis, the flocs exhibited an obvious network structure, and it is concluded that hydrogen bonding between N-H in CPAM and C-O in the starch and bridging flocculation played the essential roles in flocculation of the gelatinized starch.     

页岩压裂返排液的预处理及絮凝剂的溶液结构

页岩压裂返排液因含有多种有机添加剂,其化学需氧量较高。本文研究了新型无机复合混凝剂聚硅酸铝铁（PCM）对废水的混凝效果及与其复配使用的梳型絮凝剂（4-乙烯苄基辛基酚聚氧乙烯醚）-丙烯酰胺-（2-丙烯酰胺基-2-甲基丙磺酸钠）共聚物（PAVA）的絮凝能力,以提高页岩压裂返排液的预处理效率。结果显示,PCM在其加量0.3g/L时的浊度和COD去除率分别为96.1%和71.4%,明显高于常用的聚合氯化铝PAC的水处理性能值;PCM与5mg/L PAVA复配使用后,其用量明显降低,但处理效果更好,加量为0.2g/L时的浊度和COD去除率分别为90.0%和86.1%;PAVA的架桥絮凝能力强于常用的阴离子、阳离子高分子絮凝剂;返排液中ξ电位的绝对值越高,混凝剂的混凝效果越好。     

两性聚电解质在黄河高浊度水中的应用

本文合成了一系列不同阴、阳离子度的强碱弱酸型的两性聚电解质[丙烯酰胺(AM)-二甲基二烯丙基氯化铵(DMDAAC)-丙烯酸(AA)共聚物]。研究了阴、阳离子单体的配比对两性聚电解质分子量的影响;以及两性聚电解质阴、阳离子度对絮凝效果的影响。并将所合成的两性聚电解质作为絮凝剂,首次应用到黄河高浊度水的处理中。填补了国内两性聚电解质高分子絮凝剂应用于上水的空白。研究结果表明:在等电点范围内的两性聚电解质对黄河高浊度水的絮凝效果明显优于传统的非离子型、阳离子型及阴离子型絮凝剂。     

聚硅酸铝铁絮凝剂研究进展

聚硅酸铝铁作为絮凝剂应用于污水处理,因其优越的絮凝能力及宽泛的使用条件,已被广泛关注.聚硅酸铝铁在污水浊度、色度以及COD的去除方面,具有非常好的应用前景.主要从聚硅酸铝铁絮凝剂制备方法、絮凝机理及絮凝处理效果进行阐述.制备的重要方式包括:复合法、共聚法、酸溶液中和法.絮凝的机理包含压缩双电层理论、吸附电中和、吸附架桥和网捕作用,在絮凝进程中多种作用协同发挥,聚硅酸铝铁具有优于其他絮凝剂的水处理能力.影响其絮凝能力的主要因素有Al/Fe/Si摩尔比、絮凝剂投加量和处理絮凝剂pH值等.最后简述了当前研究存在的困难及对聚硅酸铝铁絮凝剂今后的发展前景及方向进行了展望.     

Effect of hydrophobic group on flocculation properties and dewatering efficiency of cationic acrylamide copolymers

Three kinds of hydrophobically modified copolymers of acrylamide with 3-acrylamido-2-hydroxypropyltrialkylammonium chloride were prepared, in which alkyls were ethyl, butyl and octyl, respectively. The conformations of the hydrophobically modified copolymers were studied using TEM micrograph. The flocculation performances and the dewatering efficiencies were investigated. The results showed that the hydrophobic group could enhance the flocculation properties. The longer the hydrophobic alkyl chain was, the better the flocculation result was. Compared with poly-diallyldimethyl ammonium chloride (PDADMAC) and poly-acrylamide (PAM), the hydrophobically modified polymers showed better performances in turbidity removal and were quite more efficient in dewatering examination.     

β‐Cyclodextrin modified cationic acrylamide polymers for flocculating waste drilling fluids

In this article, the P(AM/A‐β‐CD/DMDAAC) is used as flocculant. The synthesis and characterization of the cationic polyacrylamide flocculant modified by β‐cyclodextrin have been studied in the early article. This article stresses its excellent flocculated performance and mechanism. In the flocculated process, the bridging flocculation played a dominant role. Through the flocculation experiments, it can be seen that the flocculating rate of the P(AM/A‐β‐CD/DMDAAC) on four solutions can go up to 93.4%, 89.7%, 85.1%, and 96.7%, respectively. As can be seen from experiment data, the flocculated property of P(AM/A‐β‐CD/DMDAAC) is superior to polyacrylamide and poly (dimethyl diallyl ammonium chloride). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40197.     

Esterification of hydroxylated polymers with 2-sulfobenzoic acid cyclic anhydride: A facile approach for the synthesis of near-monodisperse strong acid homopolymers and diblock copolymers

A convenient two-step route was developed to prepare a range of low polydispersity strong acid homopolymers and several examples of well-defined diblock copolymers. Atom transfer radical polymerization (ATRP) of either 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate or glycerol monomethacrylate afforded the corresponding near-monodisperse hydroxylated homopolymers, while several diblock copolymer precursors were prepared by either (1) the one-pot ATRP of 2-hydroxypropyl methacrylate and 2-(diethylamino)ethyl methacrylate using sequential monomer addition or (2) the ATRP of either 2-hydroxypropyl methacrylate or glycerol monomethacrylate using a poly(ethylene oxide)-based macro-initiator. Excess 2-sulfobenzoic acid cyclic anhydride was used to fully esterify the hydroxy groups of these homopolymers and diblock copolymers under mild conditions. The resulting zwitterionic diblock copolymers undergo micellar self-assembly on adjusting the pH of the solution, while one of the anionic poly(ethylene oxide)-based diblock copolymers formed colloidal polyelectrolyte complexes in aqueous solution when mixed with a cationic poly(ethylene oxide)-based diblock copolymer.     

Parameters affecting the performance of polyelectrolytes as aids to water clarification

An investigation of the flocculation of silica and alumina suspensions by a series of synthetic flocculants of a wide range of charge density both anionic and cationic in nature has been carried out. The extent of flocculation was determined by measurements of settling rate, sediment volume and supernatant clarity. The effect of the pH of the suspension on the performance of a number of selected polymers has been investigated. In the systems examined, flocculation was largely controlled by the charge carried by the suspended particles and polymer molecules. The dosage/settling rate characteristics of kaolin suspensions flocculated with non-ionic polymers of varying molecular weight are reported. The dosages of non-ionic polymers required for optimum flocculation of kaolin suspensions of varying solids content have been measured. At low particle concentrations bridging is less effective, and is probably reduced due to the adsorption of polymer molecules on to single particles.     

Study on chain deformation of polyacrylamides in solutions and its flocculation performance during the flocculation process

Effects of external conditions, solution concentration, solvent quality, added salt, and pH on the chain conformation dimension of two kinds of polyacrylamide (PAAm) flocculants, neutral‐PAAm, and cationic‐P(AAm‐DMC) (DMC, 2‐[(methacryloyloxy)ethyl] trimethylammonium chloride), in parent solutions and their flocculation performance for Kaolin suspensions have been investigated by Ubbelohde viscometer and spectrophotometer, respectively. It was found that a negative correlation existed between the flocculation performance of PAAm flocculants and their chain sizes in parent solutions. This was attributed to the expanded chain deformation of PAAm flocculants during the flocculation process from the flocculant parent solution to the Kaolin suspension and was interpreted in term of the competitive interaction among the polymeric flocculant, solvent, and Kaolin particle in the chain deformation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

有机絮凝剂对铁矿相沉降性能影响及其吸附机理

通过模拟拜耳法赤泥沉降过程研究了聚丙烯酸铵(PAAA)、阴离子聚丙烯酰胺(APAM)和氧肟酸絮凝剂(HPAM/HCPAM)对赤铁矿和针铁矿沉降性能的影响规律和絮凝后絮体的粒径分布及分形维数,并利用傅里叶变换红外光谱探讨了絮凝剂与铁矿相的吸附机理。在不同类型絮凝剂中,添加氧肟酸絮凝剂铁矿相沉降速度最快,且氧肟酸含量越高,沉降性能越好;聚丙烯酸铵和阴离子聚丙烯酰胺絮凝剂对铁矿相沉降性能影响较小;同等条件下赤铁矿沉降速度要远高于针铁矿,增加絮凝剂添加量有助于提高针铁矿沉降速度。在赤铁矿絮体中,添加PAAA絮体粒径最大,HPAM絮体分形维数最大、致密性最好;在针铁矿絮体中,添加APAM絮体粒径最大,HCPAM絮体分形维数最大、致密性最好。氧肟酸絮凝剂与铁矿相形成结构稳定、吸附能力强的五元环状螯合物,增强了赤铁矿和针铁矿的絮凝效果;PAAA通过双齿桥接配位与赤铁矿表面发生吸附,通过单齿配位与针铁矿表面发生吸附,其吸附能力弱于五元环;APAM与赤铁矿和针铁矿表面发生化学吸附,沉降性能差。     

有机絮凝剂对铁矿相沉降性能影响及其吸附机理

通过模拟拜耳法赤泥沉降过程研究了聚丙烯酸铵(PAAA)、阴离子聚丙烯酰胺(APAM)和氧肟酸絮凝剂(HPAM/HCPAM)对赤铁矿和针铁矿沉降性能的影响规律和絮凝后絮体的粒径分布及分形维数,并利用傅里叶变换红外光谱探讨了絮凝剂与铁矿相的吸附机理。在不同类型絮凝剂中,添加氧肟酸絮凝剂铁矿相沉降速度最快,且氧肟酸含量越高,沉降性能越好;聚丙烯酸铵和阴离子聚丙烯酰胺絮凝剂对铁矿相沉降性能影响较小;同等条件下赤铁矿沉降速度要远高于针铁矿,增加絮凝剂添加量有助于提高针铁矿沉降速度。在赤铁矿絮体中,添加PAAA絮体粒径最大,HPAM絮体分形维数最大、致密性最好;在针铁矿絮体中,添加APAM絮体粒径最大,HCPAM絮体分形维数最大、致密性最好。氧肟酸絮凝剂与铁矿相形成结构稳定、吸附能力强的五元环状螯合物,增强了赤铁矿和针铁矿的絮凝效果;PAAA通过双齿桥接配位与赤铁矿表面发生吸附,通过单齿配位与针铁矿表面发生吸附,其吸附能力弱于五元环;APAM与赤铁矿和针铁矿表面发生化学吸附,沉降性能差。     

Preparation of Quaternized Lignin Derived from Oil Palm Empty Fruit Bunches and its Flocculation Properties

Quaternized lignin-based flocculant (QL) was prepared by a single-step reaction of an extracted lignin (EL) derived from oil palm empty fruit bunches (OPEFB) with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) under alkaline condition. The performance of QLs was studied for various β values (molar ratios of CHPTAC to phenylpropanoid unit of lignin), flocculant dosages, pH values, kaolin concentrations, slow mixing rates and sedimentation times. The QL10 achieved the highest turbidity removal efficiency (ε_t) with increasing flocculant dosage, pH and kaolin concentration to the optimal conditions of 5?mg?L^?1, pH 7 and 1000?mg?L^?1, and required 20?min of sedimentation time at all the mixing rates tested. The flocculation kinetics agreed well with the particle collision model. The QL10 has good sludge dewatering properties compared to the alum. It also showed encouraging results in water quality analysis for sewage wastewater flocculation in comparison to that of the alum. This indicates the potential application of QL in treating water and wastewater.     

Synthesis and flocculation behavior of cationic konjac glucomannan containing quaternary ammonium substituents

A quaternary ammonium derivative of konjac glucomannan (KGM) was prepared by a dry process from KGM and 2,3‐epoxypropyl trimethylammonium chloride. We determined the optimization of the experimental conditions by studying on the effects of the water amount, alkaline catalyst amount, reaction temperature, and reaction time on the degree of substitution. In addition, the flocculation characteristics of the cationic derivative of KGM were evaluated in a 1.0% kaolin suspension with spectrophotometry via investigation of the influence of the flocculant amount, pH, salt concentration, temperature, and settling time on the flocculation. The results show that the synthesized cationic KGM could potentially be used as a high‐performance flocculating agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dewatering of coal plant tailings: Flocculation followed by filtration

A sustainable alternative to tailings dam disposal of coal refuse is mechanical dewatering of tailings, which provides fast production of dry solids and water reuse. In this study, flocculation followed by filtration of coal plant tailings, a new concept in tailings dewatering is investigated in detail. This paper focuses on the effect of preconditioning tailings with varying flocculants and dosages on filtration kinetics and the resultant moisture content of the filter cake. The results show that the cationic flocculant, MAGNAFLOC LT 425, requires a high dosage to produce a low moisture content filter cake and clear filtrate. Optimal sized flocs were produced with the anionic flocculant, MAGNAFLOC 5250, even though the particles are negatively charged. The kinetics of the filtration was dependent on the composition of process water as indicated by supporting sedimentation tests. The concentration of divalent alkali earth metals such as Ca²⁺ and Mg²⁺ allow for large floc growth by a bridging mechanism, which involves binding of the polymer and the negativity charged particle. Filtration and settling curves at this dosage were also supported by filter cake analysis using Darcy plots. It was found that the large floc size significantly increases the permeability of the filter cake. Floc size measurements and fractal dimension showed that while the large flocs were produced with anionic flocculant, the flocs produced with the cationic flocculant were small and weak. The results indicate that the optimum dosage and flocculant type for effective and efficient filtration of coal plant tailings is approximately 350 g/t of anionic flocculant at a 35% solids content and 40 kPa filtration pressure.     

Dye flocculation using polyampholytes and polyelectrolyte‐surfactant nanoparticles

In this article, we report on the dye flocculation performance of polyampholytes containing hydrophobically modified cationic, hydrophilic nonionic, and anionic monomer units, always with an excess of cationic charges. The results are compared with homopolymers and with those obtained using nonstoichiometric polyelectrolyte–surfactant complex (PSC) dispersions with adjustable surface charge density. The polyampholytes as well as the PSC can successfully remove the dye Celliton Fast Blue (Dispers blue 3). The efficiency of dye separation is mainly influenced by the charge of polymers or complexes, demonstrating that charge neutralization is one flocculation mechanism. However, PSC, which are almost neutral, are also able to remove the dye due to their size and structure. In this case, the degree of dye removal is a little bit better and the so‐called flocculation window is broader as in the case of charge neutralization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1342–1349, 2007