Homogeneous synthesis and characterization of polyacrylamide‐grafted cationic cellulose flocculants

In this work, cationic cellulose (CC) with different degrees of substitution (DS) was successfully synthesized by the reaction between cellulose and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride (CHPTAC) in a 7 wt % NaOH and 12 wt % urea aqueous solution. The structure of the CC was characterized by using elemental analysis, ¹H‐NMR, and FTIR. The DS values of CC ranged between 0.18 and 0.50, which could be obtained by adjusting the reaction temperature, reaction time, and molar ratio of CHPTAC to anhydroglucose unit of cellulose. The cationic cellulose–graft–polyacrylamide flocculant (CC‐g‐PAM) based on CC and polyacrylamide (PAM) was also synthesized in a homogeneous aqueous solution. The flocculation characteristics of CC and CC‐g‐PAM were evaluated in a kaolin suspension. The results showed that CC‐g‐PAM was an effective flocculant for the kaolin suspension under acidic or neutral conditions, and the flocculation efficiency was over 90%, while the CC showed better flocculation performance under alkaline conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43106.     

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     

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。     

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.     

Synthesis,characterization, and flocculation properties of poly(acrylamide‐methacryloxyethyltrimethyl ammonium chloride‐methacryloxypropyltrimethoxy silane)

A novel hydrophobically modified and cationic flocculant poly(acrylamide‐methacryloxyethyltrimethyl ammonium chloride‐methacryloxypropyltrimethoxy silane) (P(AM‐DMC‐MAPMS)) was synthesized by inverse emulsion polymerization. The molecular structure of hydrophobically cationic polyacrylamide (HCPAM) was characterized by FTIR and ¹H‐NMR. The effects of DMC and MAPMS feed ratio on intrinsic viscosity and solubility were measured. The effects of hydrophobically cationic flocculants on reactive brilliant red X‐3B solution and kaolin suspension were studied. It was found that the introduction of MAPMS could increase the intrinsic viscosities of P(AM‐DMC‐MAPMS) and enhance the flocculation properties to anionic dye solution and kaolin suspension, but reduced their water‐solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

玉米淀粉改性阳离子絮凝剂的制备

以玉米淀粉为原料,经糊化后,加入阳离子化试剂,合成了阳离子性改性淀粉絮凝剂SF.以生活污水为处理体系,探讨了SF的絮凝性能.在30 mg/L时,SF对高浊度207 NTU高岭土悬浮液达到最好的处理效果,出水浊度在10 NTU以下.对生活污水中COD有一定的去除效果.SF作PAC的助凝剂处理湖水,比单独投加PAC絮凝剂有更好的处理效果,浊度去除率都在90%以上     

Dispersion—flocculation studies on a Goethite-clay system

Dispersion–flocculation studies on a Goethite–clay system using flocculants were carried out as a function of flocculant concentrations, pH of slurry, time of agitation and dispersant dosage. Also, the effects of pH and polymer concentrations on the adsorption behaviour of the system were investigated. Results show that well flocculated goethite was preferentially obtained from 4% goethite/kaolinite clay suspensions, with 50 ppm causticised starch in the slurry at pH values of 3–11·5 and with 50 ppm polyacrylamide at pH values of 3–8. Good flocs were also obtained on flocculation of the goethite suspension with 50 ppm polyacrylamide at pH values of 5–7, while the kaolinite suspension did not respond to the same dosage of causticised starch in the same pH range. Results further reveal that for the goethite/kaolinite suspension, the best results was obtained with 50 ppm polyacrylamide at pH values of 7–10. Based on the data generated in the study, it was concluded that causticised starch is a better flocculant than polyacrylamide for goethite suspensions although polyacrylamide is an excellent flocculant for kaolinite suspensions.     

阳离子淀粉染料吸附材料的制备及表征

以玉米淀粉为原料,以3-氯-2-羟丙基三甲基氯化铵（CHPTMAC）为阳离子醚化剂,以NaOH为催化剂,制备了天然高分子多糖基染料吸附剂阳离子淀粉（CS）,用于对活性染料的吸附。对醚化反应机理进行了系统研究,并考察了反应条件对CS取代度（DS）及反应效率（RE）的影响。采用RAM、XRD、SEM对产物进行表征。吸附实验表明,当DS为0.12,染料溶液pH为8时,CS对活性红195、活性金黄K-2RA的吸附量分别为21.0和20.4 mg·g^-1,去除率可达84.1%和81.6%,好于无机吸附材料活性炭。还进行了CS染料吸附材料的再生实验,4次再生后仍有较高的吸附量,表明CS染料吸附材料具有较强的可再生性能,可循环使用。该天然基染料吸附剂CS有望成为无机吸附剂及合成树脂吸附剂的理想替代品,用于工业染料废水的处理中。     

Chemical modification of cashew gum with acrylamide using an ultrasound‐assisted method

A flocculant based on cashew gum (CG) grafted with polyacrylamide (PAM) was synthesized using potassium persulfate as the chemical initiator and ultrasound energy. The intrinsic viscosity, hydrodynamic radius, and grafting efficiency of the grafted copolymers (CG‐g‐PAM) were investigated at different monomer and initiator concentrations. The CG‐g‐PAM copolymers were evaluated in kaolin suspension and river water by using jar test procedure comparatively to a commercial flocculant (Flonex‐9045). Ultrasonication resulted in reduced reaction time and high grafting efficiency. The reaction gel point was reached within 10 min and the grafting efficiency was dependent on the acrylamide concentration. The grafted copolymer CG‐g‐PAM‐15²⁸⁵ obtained with 0.285 mmol of initiator showed higher hydrodynamic radius, with flocculation efficacy of 96% comparable with the flocculant Flonex‐9045. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43634.     

亚甲基二甲胺盐酸盐淀粉醚的制备及其吸湿保湿性能研究

以淀粉为母体,羟甲基二甲胺盐酸盐(HMMAHC)为醚化剂,通过干法工艺合成出不同取代度(DS)的叔胺型阳离子淀粉——亚甲基二甲胺盐酸盐淀粉醚(SMMAHC),并考察了其吸湿、保湿性能。结果表明,该阳离子淀粉的吸湿、保湿性能均随着阳离子基团取代度的增加而增强。在相对湿度(RH)为81%的条件下,当阳离子取代度分别为0.36和0.70时,其吸湿性分别与透明质酸(HA)和丙三醇相当。而取代度为0.70的SMMAHC保湿性在相对湿度43%和15%下均与透明质酸相当,优于丙三醇。探讨了SMMAHC吸湿动力学,可应用伪二级吸附动力学模拟方程很好地描述吸湿性能,相关系数达到0.999以上。     

Fabrication of a copolymer flocculant and application for Cr(VI) removal

A copolymer flocculant (CATCS) derived from starch and chitosan was fabricated and used as eco‐friendly adsorbent for removal of Cr(VI) from aqueous solution. The CATCS flocculant was characterized by scanning electron microscope, thermogravimetic analysis, and Fourier transform infrared spectroscopy. The effects of CATCS dosage, initial Cr(VI) concentration, pH, and reaction time on removal of Cr(VI) were discussed. The results showed CATCS removed Cr(VI) effectively and the adsorption isotherm agreed well with the Freundlich isotherm and R–P isotherm models. The enthalpy change (ΔH) of the process was 16.75 kJ/mol suggesting the existence of chemisorption and the reaction was endothermic. Moreover, the negative free energy change (ΔG) indicated the adsorption process was feasible and spontaneous. The positive entropy change (ΔS) showed there was an increase of disorder in the system during the adsorption process. The adsorption kinetics results showed that the adsorption could be described by the pseudo‐second‐order kinetics mechanism. The activation energy (E_a) of the adsorption reaction was 29.16 kJ/mol. POLYM. ENG. SCI., 56:1213–1220, 2016. © 2016 Society of Plastics Engineers     

Multilayer assembly of ionic starches on old corrugated container recycled cellulosic fibers

In this study, old corrugated container recycled fibers were treated with polyelectrolyte multilayers consisting of biopolymer cationic starch with two degrees of substitution (DS) each in combination with one anionic starch. Pulp zeta potential, paper strength and the thin layer ellipsometry technique were applied to examine the influence of cationic starch DS on the formation of polyelectrolyte multilayers. The results indicated a significant interaction between the DS of cationic starch and the number of ionic starch layers formed. When low‐DS cationic starch was used, the pulp zeta potential and the paper strength increased significantly in assembling the first cationic layer. However, in depositing high‐DS cationic starch a greater zeta potential and a stronger influence on the paper strength were observed with a larger number of starch layers. This was confirmed by thin layer ellipsometry when a greater thickness of multilayers was achieved by employing high‐DS cationic starch to form a higher number of layers. © 2017 Society of Chemical Industry     

Adsorption of Hydroxypropyl Methyl Cellulose in an Aqueous System Containing Multicomponent Oxide Particles

The adsorption behavior of a hydroxypropyl methyl cellulose (HPMC) polymer in aqueous suspensions of alumina, silica, kaolin, and talc powders, two-component combinations, and one three-component combination was determined. Powders were well characterized by chemical analysis, XRD, DRIFT, SEM, particle size, surface area, and density analyses. The zeta-potential of each powder in aqueous suspension was determined over a range of pH to determine particle charging and the isoelectric point for each material. Alumina and silica powders having heavily hydroxylated surfaces were observed not to adsorb the HPMC polymer over a range of pH. The layer-type minerals talc, which was noticeably hydrophobic, and kaolin, which had differently hydrated basal planes, adsorbed the HPMC polymer but in different amounts per unit of surface area. In the two-component systems, HPMC polymer adsorption for systems of dispersed particles of like electrical charge (kaolin + silica, talc + silica or alumina, and kaolin + talc) was proportionate to the sum of the fraction x specific surface area x adsorption capacity for each particle type. In systems where particles had an opposite electrical charge (kaolin + alumina, kaolin + talc + alumina), the HPMC polymer adsorption was significantly lower than that calculated for a dispersed system. SEM analysis showed very fine, nonadsorbing alumina particles predominantly on the faces of the adsorbing kaolin particles that apparently masked polymer adsorption. Results suggested a hydrophobic mechanism for the HPMC polymer adsorption and adsorption on only one face of the kaolin particles.     

Adsorption Behavior of Acid Yellow G by Highly-Crosslinked Amphoteric Starch

A series of crosslinked amphoteric starches with different degrees of substitution (DS) synthesized by a hemi-dry process are used to adsorb Acid Yellow G. Some factors, such as pH, dose of amphoteric starches, and initial concentration of dye, adsorption time, adsorption temperature and DS of anionic groups are investigated. The results show that the adsorption capacity of amphoteric starch changes obviously with the different conditions, while it is not affected greatly by DS of anionic groups. The adsorption capacity reaches 149.6, 145.9 and 140.9 mg/g, respectively for three absorbents, whose DS of the cationic group is 0.3, and DS of the anionic group is 0.12, 0.20, 0.33, respectively when the initial concentration of Acid Yellow is 140 mg/l. the thermodynamic data show that the adsorption process is exothermic, thus low temperature benefits the adsorption process.     

阳离子辣椒絮凝剂的制备与应用

以辣椒残渣，阳离子醚化剂，环氧丙基三甲基氯化胺为原料，通过干法合成了一种季胺型阳离子絮凝剂。采用正交实验方法，确定了制备的最佳工艺条件：辣椒与阳离子醚化剂物质的量比1：3，反应温度80℃，反应时间3h。实验用高岭土溶液模拟生活废水，加入自制絮凝剂检测凝剂性能，在此条件下合成的阳离子辣椒絮凝剂的除浊率是88％。     

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     

短芽孢杆菌RL-2的絮凝性能研究

从重庆城南污水处理厂活性污泥中筛选出一株高效胞外絮凝剂产生菌RL-2,初步鉴定为短芽孢杆菌(Bacillusbrevis)。该菌株可产生多糖类絮凝剂。RL-2絮凝高岭土悬浊液的影响因素研究结果表明:CaCl2是微生物絮凝剂RL-2的良好助凝剂,当Ca2+存在时,絮凝剂的投加量为5～20mL/L,pH值在3～9范围内,该微生物絮凝剂可有效絮凝高岭土悬浊液,其絮凝率高达98.4%;同时,RL-2对多种固体悬浊液有明显的净化效果。     

淀粉接枝丙烯酰胺的合成及其絮凝性能的研究

以玉米淀粉(St)和丙烯酰胺(AM)单体为原料,采用过硫酸钾引发剂合成了淀粉接枝丙烯酰胺共聚物(St-g-AM)。用红外光谱对接枝共聚物进行了结构表征,用粘度法测定了分子量。讨论了聚合反应的各个因素对接枝共聚反应的影响,考察了接枝共聚物的絮凝性能。结果表明,以接枝效率为考察目标,其最佳的合成工艺为:引发剂的浓度为0.07 g/100 mL,淀粉与丙烯酰胺的质量比为1∶2.2,反应温度为65℃,反应时间3 h。淀粉接枝丙烯酰胺共聚物比430万分子量的聚丙烯酰胺(PAM)对高岭土水样的絮凝性能更好,当接枝共聚物的投加量为6 mg/L时,对高岭土水样的浊度去除率达到81.77%。最佳条件所合成出的淀粉接枝丙烯酰胺的分子量为75万。     

Adsorption characterization of lead(II) and cadmium(II) on crosslinked carboxymethyl starch

The adsorption of Pb(II) and Cd(II) ions with crosslinked carboxymethyl starch (CCS) was investigated as function of the solution pH, contact time, initial metal‐ion concentration, and temperature. Isotherm studies revealed that the adsorption of metal ions onto CCS better followed the Langmuir isotherm and the Dubinin–Radushkevich isotherm with adsorption maximum capacities of about 80.0 and 47.0 mg/g for Pb(II) and Cd(II) ions, respectively. The mean free energies of adsorption were found to be between 8 and 16 kJ/mol for Pb(II) and Cd(II) ions; this suggested that the adsorption of Pb(II) and Cd(II) ions onto CCS occurred with an ion‐exchange process. For two‐target heavy‐metal ion adsorption, a pseudo‐second‐order model and intraparticle diffusion seem significant in the rate‐controlling step, but the pseudo‐second‐order chemical reaction kinetics provide the best correlation for the experimental data. The enthalpy change for the process was found to be exothermic, and the ΔS^θ values were calculated to be negative for the adsorption of Pb(II) and Cd(II) ions onto CCS. Negative free enthalpy change values indicated that the adsorption process was feasible. The studies of the kinetics, isotherm, and thermodynamics indicated that the adsorption of CCS was more effective for Pb(II) ions than for Cd(II) ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011