Flocculation characteristics of kaolin

The effect of metal cations on the flocculation behaviour of kaolin was investigated.The effects of pH, concentration of cations (Mg²⁺ and Al³⁺), and the presence of these cations in causticised cassava starch on the settling rate and percent reduction in sediment density were studied. Results show that the presence of high concentrations of divalent (Mg²⁺) and trivalent (Al³⁺) ions, and the presence of these cations in causticised cassava starch significantly contributed to the existence of low settling rates at high supernatant clarity often observed in some clay slurry treatment systems by flocculation and sedimentation method. It was also established that for efficient flocculation, the systems must be within the alkaline pH range (pH>10). The study further revealed that in some flocculation systems, fast settling corresponds to high sediment volume whereas in others, the opposite applies. It is therefore concluded that this phenomenon should be taken into consideration for proper design and operation of such treatment facilities.     

淀粉-聚丙烯酰胺接枝共聚物的工艺优化与性能研究

通过玉米淀粉接枝聚丙烯酰胺(PAM)制成了新型复合絮凝剂S-g-PAM,进行了影响接枝共聚物合成的单因素实验和正交实验,以对高岭土悬浊液的絮凝性能为评价指标。结果表明,最佳合成条件为,m(玉米淀粉)∶m(PAM)=3∶0.001(质量比),NaOH∶NaOCl=2∶3(体积比),反应时间40 min,反应温度30℃,对高岭土溶液(110NTU)最佳去浊度效果为97%,投加量为30 mg/L。S-g-PAM使用的pH值范围为8~10,最佳温度范围20~40℃,与其它絮凝剂相比,其絮凝效果较好。     

Synthesis of a starch–acrylic acid–chitosan copolymer as flocculant for dye removal

Flocculants prepared with modified natural polymers have recently attracted extensive attention in the field of water treatment. In this work, acrylic acid was successfully grafted onto the backbones of starch and chitosan by free radical polymerization. The synthesis parameters of initiator concentration, reaction temperature, and neutralization degree of acrylic acid were optimized as 0.4 wt %, 50 °C, and 70%, respectively, according to the flocculation performance. The ternary copolymer starch–acrylic acid–chitosan (SAAC) could completely remove Acid Blue 113 from 100 mg/L of simulated wastewater (color removal efficiency 99.7%) at the flocculant dosage of 100 mg/L. The SAAC also had effective flocculation capability in a wide range of flocculant dosages and pH values of wastewater. The ternary copolymer based on two natural polymers has enormous potential as flocculant with its advantages of low price, ecofriendliness, and high performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47437.     

Coagulation–flocculation of colloidal suspensions of kaolinite,bentonite, and alumina by chitosan sulfate

This article reports on the removal of colloidal suspensions of kaolinite, bentonite, and alumina using chitosan sulfate (ChS). ChS was synthesized by partial introduction of sulfate groups in the chitosan (Ch) structure. The polyampholyte (chitosan sulfate) shows variable charge depending on the pH of the solution. ChS was characterized by FTIR, ¹³C‐NMR, elemental analysis, and potentiometric titrations. The ChS coagulation–flocculation capacity for kaolinite, bentonite, and alumina aqueous suspensions was systematically studied. The coagulation–flocculation process was carried out at various pH values and ChS concentrations. The pH range in which the largest ChS removal capacity was observed depended on particle type (4.5–5.5 for kaolinite, 4.5–7.0 for bentonite, and 7.0–8.0 for alumina). The removal of colloidal particles is explained by charge neutralization due to electrostatic interactions between ChS and particles and particle entrapping when the polyelectrolyte precipitates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

自制交联阳离子淀粉絮凝剂处理含油废水

以自制的马铃薯交联阳离子淀粉为絮凝剂,对某炼油厂的含油废水进行絮凝实验,以COD去除率和油去除率为指标,得到絮凝剂最佳投加量,在此基础上考察了pH和水温的影响.实验结果表明:絮凝剂的最佳投加量为4 650 mg/L、pH为1.5～4、温度为50℃时,该絮凝剂对含油量和COD的去除效果较好.     

丙烯酰胺接枝淀粉在选矿废水絮凝处理中的应用

以淀粉为原料,丙烯酰胺为单体,在硝酸铈铵的引发下合成丙烯酰胺接枝淀粉絮凝剂,采用红外光谱对其进行结构表征,并通过重量法测得其接枝率和接枝效率。将絮凝剂用于某铜矿选矿废水处理,以上清层高度、固体悬浮物浓度、除浊率、CODCr去除率、除铜率为指标,研究絮凝剂用量、pH值和温度对絮凝性能的影响。结果表明,当絮凝剂投加量为6 mg/L、体系pH值为7~9、温度为25℃时,能够迅速获得较大的上清液高度,10 min后测得SS的质量浓度可达44 mg/L,浊度低至23 NTU,CODCr的质量浓度达到57 mg/L,Cu~(2+)的质量浓度达到0.61 mg/L,完全符合GB 8978—1996《污水综合排放标准》的要求。     

Effect on 2,2′-bipyridine adsorption of poly(vinyl alcohol) adsorbed on Na-kaolinite

The adsorption (pH 6) of 2,2′-bipyridine (BP) on Na⁺-kaolinite and on samples of the same clay containing 4.35 and 7.45 mg/g, respectively, of previously adsorbed poly(vinyl alcohol) (PVA) was studied. Specific adsorption of BP decreases with increasing clay particle size in the suspension as a result of particle association. Aqueous suspensions with a 1–4% concentration of kaolinite exhibit flocculation in the absence or presence of PVA, forming clusters of 43–64 units of single clay particles. The PVA adsorbed on the surface of sodium kaolinite particles causes partial dispersion of the kaolinite in the aqueous suspension; however, 7.45 mg/g of PVA adsorption or even lower (4.35 mg/g) is not able to fully impede the association of kaolinite particles.     

Electrokinetic potential of kaolinite clay in the presence of polystyrene sulfonate

The determination of the electrokinetic potential of clay is very important in many applications. Therefore, this work was aimed at studying the effect of poly(4‐ sodium styrene sulfonate) on the electrokinetic potential and the sedimentation behavior of kaolinite clays at different pH values and/or in the presence of sodium or calcium chlorides. At pH values lower than the point of zero charge (PZC) of the kaolinite clay, the zeta potential of Na‐ or Ca‐kaolinite in CaCl₂ solutions was higher than that in NaCl solutions at the same concentration. Above the PZC, the zeta potential of Na‐ or Ca‐kaolinite in NaCl solution was higher than that in CaCl₂ at the same electrolyte concentration. These results reflect the ability of calcium cations to compress the double layer of the kaolinite clay better than sodium cations. Also, below the PZC and at low concentrations of poly(4‐sodium styrene sulfonate), the zeta potential of the kaolinite clay suspensions had low value, while the sediment volumes had higher values. On the other hand, above the PZC at increasing polymer concentrations, the zeta potentials increased but the sediment volumes had lower values compared to those produced below the PZC. The data showed the zeta potential of Na‐kaolinite suspensions are higher than Ca‐kaolinite, producing lower sediment volumes of Na‐kaolinite compared to Ca‐kaolinite at the same concentrations of polymer and/or pHs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1705–1711, 2006     

Efficiency of Egyptian drilling muds in the presence of cationic polyethylene imine and anionic polyacrylamide

The flow properties of Egyptian bentonite were studied using a combination of anionic polyacrylamide (MW = 1,000,000 g mol^?1) and cationic polyethylene imine (MW = 700,000 g mol^?1). This combination gave a significant effect on the clay suspensions to be qualified in the field of drilling mud depending on the sequence their addition. It was found that, by adding 50 mg/L cationic polyethylene imine followed by 10 mg/L anionic polyacrylamide, the rheological properties were improved using 6% Egyptian bentonite suspension, especially at 20°C. But, by reversing this addition sequence, the rheological properties of bentonite suspension were declined. The zeta‐potential value of bentonite suspension in the presence of 50 mg/L polyethylene imine was ?47 mV, while at 10 mg/L polyacrylamide was ?55 mV. But, on addition of 10 mg/L polyacrylamide to bentonite suspension followed by 50 mg/L polyethylene imine induced a reduction of the zeta‐potential value to ?51 mV when compared with that of polyacrylamide alone. By reversing the addition sequence, a very high stable suspension having zeta‐potential values of ?82 mV was obtained. Potential energy profiles were constructed to investigate the relation between rheological and electrical properties. Potential energy profile at 50 mg/L polyethylene imine followed by 10 mg/L polyacrylamide to bentonite suspension produced a high repulsion potential energy between clay surfaces, i.e. the suspension stability improved. By reversing that sequence, a significant decrease in the energy barrier was observed. The most reliable clay suspension as a drilling mud could be obtained by using 6% clay suspension concentration, with 50 mg/L polyethylene imine followed by 10 mg/L polyacrylamide, at 20°C up to 24 h aging time. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1487–1495, 2007     

Characterization and flocculation evaluation of a new organic–inorganic hybrid polymer flocculant (PAC-AM-DMC)

A novel organic–inorganic hybrid flocculant PAC-AM-DMC is synthesized using potassium persulfate as an initiator, which was used in industrial wastewater treatment. Comparing with the traditional inorganic flocculant, this new flocculant has the advantage of low dosage and high efficiency. Simultaneously, it is less toxic and more environmentally friendly than the organic flocculant. The organic–inorganic hybrid flocculant PAC-AM-DMC demonstrates better flocculation than the commercial single type flocculant (PAC, PAM), and the effect is better than simply combining the two flocculants. It has potential for commercialization. When PAC:(AM + DMC) = 2:8, the initiator is 0.2 wt%, and the flocculant obtained by reacting at 50°C for 4 h has the best effect on sewage treatment. When the pH is 7, the treatment effect of PAC-AM-DMC is best with the dosage of 10 ppm. Correspondingly, the amount of flocculant is 10 mg/L, and the turbidity of simulated sewage is 172 nephelometric turbidity unit (NTU), which is over 98% of turbidity removal efficiency. In addition, the prepared hybrid flocculant is nearly non-corrosive and posed little damage to the equipment. And the hybrid flocculant has excellent salt resistance.     

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     

高取代度阳离子淀粉处理造纸白水的研究

采用实验室研制的高取代度阳离子淀粉作为絮凝剂对造纸白水进行处理,通过实验探讨了高取代度阳离子淀粉的加入量、废水的pH值及絮凝时间对絮凝效果的影响,确定了高取代度阳离子淀粉处理造纸白水的最佳条件为:阳离子淀粉的投加量为200mg/L,不调pH值,絮凝时间为24h。     

Flocculation properties and adsorption kinetics of cationic starches in kaolin suspensions

The flocculation characteristics of cationic starches with degree of substitution (DS 0.32–0.63) have been evaluated in 1.0 wt % kaolin suspension by spectrophotometry and colloid titration. Cationic starch is found to be an effective flocculant for removal of anionic suspension particles. Changes in the electrokinetics of kaolin as a function of pH were investigated in the absence of flocculant. The results show that kaolin in water exhibits a negative surface charge at pH > 2.5. The negative hydrophilic surface sites of kaolin are responsible for the adsorption of cationic starch molecules. The experimental data of the adsorption of cationic starch (DS 0.51) follow a Langmuir isotherm with maximum adsorption capacities of 16.89 mg/g. For the adsorption of cationic starch, chemical reaction seems significant in the rate‐controlling step and the pseudosecond‐order chemical reaction kinetics provides the best correlation for the experimental data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

壳聚糖-甲基丙烯酰氧乙基三甲基氯化铵接枝共聚物的制备与絮凝性能研究

以壳聚糖和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为原料,硝酸铈铵为引发剂,Span-20为乳化剂,通过反相乳液聚合技术,合成了壳聚糖-DMC接枝共聚物。通过正交试验考察了反应条件对接枝度的影响,得出的最佳工艺条件为:反应时间5 h、引发剂浓度16 mmol/L、壳聚糖与DMC质量比1:6、油水体积比1:1。最佳条件下平均接枝度达到110 %。将得到的壳聚糖接枝共聚物用作絮凝剂处理高岭土悬浮液,结果表明其絮凝性能优于壳聚糖和聚丙烯酰胺(PAM),且在pH值6.0、投加量为2.0 mg/L时絮凝效果最佳。     

氧化-聚硅酸锌混凝法处理厌氧生化淀粉废水的研究

采用聚硅酸锌絮凝剂处理淀粉生产废水的厌氧生化出水,试验考察了废水pH值、絮凝剂投加量、搅拌速率等因素对絮凝效果的影响,以及高锰酸钾预氧化后再絮凝处理的效果.试验结果表明,在PSAZ投加量为0.5 mL/L、pH值为8.75、快速搅拌速率为285r/min、慢速搅拌速率为60r/min的最佳条件下,废水中CODCr的去除...     

The effect of the hydration of the exchangeable cation on the flocculation behaviour of China clay—polyacrylamide suspensions

The flocculation of the sodium, potassium and lithium forms of a kaolinite material have been investigated and discussed in relation to the thickness of the adsorbed layer of water molecules on the clay surfaces. Two methods of assessing flocculation in concentrated suspensions were used, namely the rates of fall of the flocculated suspensions and the rates of filtration through the settled flocs. The flocculating agent was neutral polyacrylamide. Nitrogen and water vapour adsorption isotherms are reported on the various samples, together with heats of immersion in water.The extent of flocculation decreased in the order of Li clay > K clay > Na clay; the amount of adsorbed water decreased in the order Na clay > K clay > Li clay; and the heat of wetting in the order Na clay > Li clay ? K clay. The anomalous behaviour of the Li clay is associated with the strong hydration of the Li ion on the clay surface.     

改性阳离子淀粉-凹凸棒土复合絮凝剂絮凝采收小球藻

二元接枝改性阳离子淀粉(CS-DMDAAC)/凹凸棒土是一种新型复合絮凝剂,用于小球藻的絮凝采收环节,在环保、化工、材料等领域具有更广阔的应用前景.为提高小球藻的絮凝采收率,通过单因素实验考察阳离子淀粉(CS)和CS-DMDAAC对小球藻的絮凝效果,并对CS-DMDAAC与凹凸棒土进行复配,通过单因素实验探讨了pH值、CS-DMDAAC/凹凸棒土复配比、阳离子淀粉投加量及沉降时间对小球藻絮凝率的影响,在单因素实验的基础上,以正交试验法优化CS-DMDAAC/凹凸棒土对小球藻的絮凝工艺.用扫描电镜(SEM)对凹凸棒土、CS-DMDAAC/凹凸棒土和CS-DMDAAC/凹凸棒土吸附小球藻进行表征,实验结果表明最佳絮凝工艺条件为:pH=9,CS-DMDAAC/凹凸棒土复配比为1:9,阳离子淀粉投加量为0.04g,沉降时间为210min.在该条件下进行平行实验,对小球藻的絮凝率最高达到99.1%.研究结果对CS-DMDAAC的改性以及藻类的絮凝采收具有参考价值.     

Flocculation of Clay Suspensions in the Presence of Humic and Fulvic Acids

Surface waters which contain suspended clay and organic matter, differ strongly in response to flocculation from suspensions of “pure” reference clays in controlled systems. The mechanism of interference was investigated by means of a synthetic system, consisting of suspensions of reference clay with humic and fulvic acid added. These organic soil acids increase the colloidal stability of the suspension. Due to chemical reaction taking place between the organic acids and the cationic flocculant, higher flocculant doses were required in systems where interaction of clay and organic matter occurred.     

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.     

Flocculation behavior of cationic pea starch prepared by the graft copolymerization of acrylamide for wastewater treatment

To improve the flocculation efficiency of coal mine wastewater treatment, we synthesized a cationic flocculant by grafting acrylamide (AM) onto pea starch, and we performed the characterization with elemental analysis, Fourier transform infrared spectrometry, scanning electron microscopy, thermogravimetric analysis, and NMR. The effects of the synthesis conditions were also investigated, and the optimal synthesis parameters of the cationic flocculant were obtained. The mass ratio between pea starch and AM was 0.5 with a reaction temperature of 65 °C. The dosages of ceric ammonium nitrate and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride were 0.02 and 0.11 mol/L, respectively. Application experiments for wastewater treatment were carried out consequently, and the optimal dosage of cationic pea starch was 40 mg/L within the pH range 6–8. Compared with other traditional flocculation products, the cationic pea starch showed the best flocculation behavior for coal mine wastewater. Therefore, the cationic pea‐starch‐grafted AM may be applicable as a novel flocculant in wastewater treatment and has already demonstrated outstanding features. It is bound to replace other traditional flocculants in the future. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43922.