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 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.     

淀粉接枝型高分子絮凝剂的合成

用硝酸铵作引发剂,研究了淀粉－丙烯酰胺接枝共聚物高分子絮凝剂制备的工艺条件。实验结果表明,影响接枝聚合后反应的最佳工艺条件为：硝酸胺浓度１．０＊１０＾－３ｍｏｌ／Ｌ,单体丙烯酰胺浓度１．４ｍｏｌ／Ｌ,聚合反应温度５０℃,聚合反应时间３ｈ。同时,还探讨了淀粉接枝聚合反应的机理。     

复合微生物产絮凝剂的发酵及絮凝条件优化

将从活性污泥中筛出的高效微生物絮凝菌复合培养产絮凝剂。通过单因子实验获得复合菌最适发酵条件为淀粉10 g/L,尿素0.5 g/L,KH2PO4 2 g/L,K2HPO40.5 g/L,Fe2（SO4）30.2 g/L,pH 7.0～7.2,T=28℃、160 r/min培养24 h;形成的发酵液应用于高岭土废水絮凝实验中,絮凝剂添加1%,CaCl2（5%）添加1%,慢搅15 min,静置15 min后测得的絮凝效果最佳。复合菌经发酵及絮凝条件优化后,絮凝率可达97.07%,絮凝效果与常用的PAM效果相当,且更经济。     

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...     

Preparation and Application of a Novel Functionalized Coconut Coir Pith as a Recyclable Adsorbent for Phosphate Removal

Abstract

This study was to develop a new adsorbent, Iron(III) complex of an amino-functionalized polyacrylamide-grafted coconut coir pith (CP), a lignocellulosic residue, for the removal of phosphate from water and wastewater. The kinetics of adsorption follows a pseudo-second-order model. The equilibrium sorption capacity of 96.31 mg/g was determined at 30°C from the Langmuir isotherm equation. Complete removal of 16.4 mg/L phosphate in 1 L of fertilizer industry wastewater was achieved by 1.5 g/L AM-Fe-PGCP at pH 6.0. The acid treatment (0.1 M HCl) and re-introduction of Fe³⁺ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity.     

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。     

Synthesis and characterization of graft copolymers of ethyl acrylate/acrylamide mixtures onto starch

Graft copolymerization of ethyl acrylate/acrylamide onto corn starch using potassium permanganate–citric acid initiation system was investigated. Major factors affecting the polymerization reaction were thoroughly investigated in terms of initiator concentration, monomer concentration, polymerization time, polymerization temperature, and starch/liquor, and the obtained results implied that the polymer yield which were expressed by total monomer conversion, grafting ratio, and grafting efficiency were determined by these factors. The optimum reaction conditions were as follows: starch, 30 g; potassium permanganate (based on weight of starch), 0.1%; citric acid (based on weight of starch), 0.5%; ethyl acrylate, 20%; acrylamide, 0.4 g; time, 3 h; temperature, 40°C; starch/liquor, 1:3. We concluded that the initiator of potassium permanganate–citric acid system could be used as a cheap initiator in manufacturing the starch graft copolymer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Removal of Cu2+ Ions from Aqueous Solutions by Starch-Graft-Acrylic Acid Hydrogels

Gelatinized starch was prepared by constantly stirring a mixture of starch and water at 95°C for 1 hour. Starch-graft-acrylic acid (S-g-AA) hydrogels were prepared by grafting acrylic acid (AA) [monomer/starch (w/w) 0.5–1.5] onto gelatinized starch with ceric ammonium nitrate as initiator under nitrogen atmosphere. The surface morphology of samples was studied using a scanning electron microscope (SEM). The hydrogels were evaluated for the removal of Cu²⁺ ion from aqueous solutions at different pH. The concentration of Cu²⁺ ion in aqueous solution was kept constant at 4 mmol/L. The metal ion removal capacities changed depending on treatment time, initial pH of the solution, and monomer/starch (w/w) ratio of the S-g-AA hydrogels. Cu²⁺ ion removal capacities were determined by atomic absorption spectrometer (AAS).     

菌NⅢ_2利用淀粉废水产生絮凝剂的研究

研究了微生物絮凝剂产生菌在淀粉废水中产生微生物絮凝剂的絮凝特性。对于具有较好产生絮凝剂能力的NⅢ2菌进行最佳培养基的选择和影响絮凝剂絮凝能力的研究。实验表明,淀粉废水由于碳源丰富,是一种良好的培养基。菌最佳培养条件:COD为20000 mg/L,K2HPO为0.5 g/L,KH2PO4为0.2 g/L,(NH4)2SO4为0.2 g/L,NaCl为0.1 g/L,酵母膏为0.5 g/L,培养1 d。最佳絮凝条件为在1 L含5 g高岭土水中投加20 mL微生物絮凝剂,助凝剂CaCl2为0.5 g/L,pH调至8,则絮凝率为90%以上。对实际废水的净化实验表明,该生物絮凝剂对多种废水具有良好的净化效果,尤其是对渭河河水处理效果最好,絮凝率和浊度去除率分别为85.95%和89.15%。     

微絮凝-接触过滤技术在油田废水处理中的应用

为了提高油田废水的处理效率,降低滤后水中油和悬浮物的质量浓度,文中通过系统优化改造开发了微絮凝-接触过滤工艺。筛选确定无机高分子聚合氯化铁作为本工艺的絮凝剂,最佳投药量为3 mg/L,经现场试验考察了本工艺对油田废水处理效果。结果表明,微絮凝-接触过滤工艺滤后水中油和悬浮物的平均质量浓度分别为1 mg/L和3 mg/L,去除率分别为92%和90%,远优于传统的直接过滤。说明油田废水经本工艺处理可达到油田回注水标准,无需经过二级过滤处理,因此节省了油田污水深度处理站基建和运行的投资,具有显著的经济效益。     

微生物絮凝剂处理氧化铁红颜料废水研究

研究利用微生物絮凝剂处理氧化铁红废水,优化微生物絮凝剂处理氧化铁红废水的条件。结果表明,微生物絮凝剂具有较大废水浓度适用范围,在原水浓度为3～7gm较大范围内,絮凝率均达到75％以上。最佳絮凝剂加入量为2．0mL／L、最佳静置时间为30min、不需要投加助凝剂,最佳原水pH为6．0,絮凝效果最好达到94．5％。     

Chemically Induced Graft Copolymerization of Methacrylic Acid onto Low Density Polyethylene Films Using Sodium Bisulfite

Abstract

A simple and inexpensive technique for preparation of membranes by chemically induced graft copolymerization of methacrylic acid (MAA) onto low-density polyethylene (PE) films using sodium bisulfite (SBS) initiator was developed. Several parameters affecting the grafting rate and yield, such as the concentration of aqueous monomer solutions (4–20%) and initiator (0.025–0.2 M/L), reaction temperature (50–70°C), and within reaction times ranging from 1 to 6 h were studied. The results show that grafted films with 20% up to 500% graft were obtained under the synthesis conditions mentioned. Some selective properties of the grafted films (membranes), such as swelling behavior and mechanical properties were investigated. Also, the films were characterized by infrared (IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Such prepared graft copolymers may be of great interest in some practical uses such as dialysis and ultrafiltration membranes and also for wastewater treatment from heavy and toxic metals.     

反相乳液聚合法合成淀粉接枝丙烯酰胺的工艺研究

研究以玉米淀粉为原料,反相乳液体系中淀粉与丙烯酰胺接枝共聚反应规律。考察引发剂浓度、乳化剂用量、丙烯酰胺单体与玉米淀粉质量比接枝共聚反应的影响。通过单因素实验,获得最佳工艺条件:引发剂浓度为6mmol/L,乳化剂用量5%,丙烯酰胺单体与玉米淀粉的质量比为1.5∶1。在此条件下,可制备得到单体转化率95.46%、接枝效率88.12%、特性粘度410 mL/g的接枝共聚物,该接枝物比相对分子质量500万的聚丙烯酰胺的絮凝性能更好,在用量为25 mg/L时,对高岭土水样的浊度去除率达到88.6%。     

Hydrolysis of granular starch at sub-gelatinization temperature using a mixture of amylolytic enzymes

Native granular starches (corn, cassava, mung bean, and sago) were hydrolyzed using a mixture of alpha-amylase and glucoamylase at 35 °C for 24 h. Hydrolyzed starches were analyzed for the degree of hydrolysis and for physicochemical and functional properties. Corn starch showed the highest degree of hydrolysis, as evidenced by the presence of distinct pores penetrating deep into the granules. Enzymatic erosion occurred mainly at the surface for cassava, whereas isolated porous structures were observed in hydrolyzed mung bean and sago starch. The amylose content was significantly lower in all starches except for sago starch. The powder X-ray diffraction of all starches showed no significant changes after hydrolysis, but hydrolyzed starches showed a more crystalline nature. The action of enzymes caused significant changes in some pasting properties and in the swelling/solubility of starches. Evidently, enzymes were able to hydrolyze granular starches to a variable degree at sub-gelatinization temperature, and produced a relatively high degree of conversion.     

Factors influencing absorbent properties of saponified starch‐g‐(acrylic acid‐co‐acrylamide)

Mixtures of acrylamide (AM) and acrylic acid (AA) were grafted onto gelatinized maize starch by using ceric ammonium nitrate (CAN) as an initiator. These graft copolymers were hydrolyzed with alkali to yield hydrogels. The effects of different reaction variables, such as the concentration of the initiator and crosslinker, initial dilution of monomers, gelatinization conditions of starch, and the ratio of AM and AA in the monomer feed, on the water absorption capacities of these hydrogels have been examined. Absorption increases on gelatinizing starch at a higher temperature for a longer time as smaller granules gelatinize only under these conditions. The higher proportion of AA in the monomer feed enhances absorption due to formation of polyelectrolyte. The optimum conditions for obtaining maximum water absorbency established in the present study are granular maize starch = 2.0 g; gelatinization temperature = 95°C; gelatinization time = 60 min; AM = 1.0 g; AA = 4.0 g; CAN = 0.008 mol/L; N,N′‐methylene bisacrylamide = 1%. The product so formed was saponified with NaOH and then precipitated in excess of methanol. The dried and finely powdered product showed the maximum water absorbency of 510 g/g. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2480–2485, 2000     

PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE POLYMER MUD BASED ON MILLET STARCH

A biodegradable polymer mud was prepared using Millet starch pre-gelatinized in the absence of a solvent. The filtration and rheological properties of the mud were studied at 25°–200°C temperature range and at 0.01–0.05 g/mL concentration of starch using filter loss and viscometric methods respectively. Experimental results showed that the new mud has better filtration control behavior and thermal stability at all the temperatures than widely used mud prepared with hydroxy propyl–modified starch. The mud displayed thermal degradation at 200°C. The values of flow index were found to be less than 1.0, showing non-Newtonian and pseudoplastic flow behavior of the mud. Shear stress and yield stress increase with increase in concentration. Viscosity decreases with increasing shear rate, showing shear thinning behavior of the mud. The polymer mud obeyed Henri Darcy and API models for static filtration as well as power law and Herschel-Bulkley models for fluid rheology. The new mud is purer and more suitable for drilling operations in environmentally sensitive areas than the widely used mud.     

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.     

助凝助沉剂在矿山酸性废水处理中的试验研究

以某铜矿山酸性废水为处理对象,综合运用Zeta电位、粒度分析等方法对助凝助沉剂加速絮凝物沉淀的机理进行研究.试验结果表明,废水pH=8.0,阳离子型高分子絮凝剂PAM的投加量为1.6mg/L,助凝助沉剂用量为2.5g/L时,可以取得较好的絮凝沉淀效果,沉淀速度较快,沉淀物粒径较大.     

Preparation of a Chemical Polyblend Sizing Agent via Polymerization of Acrylic Acid with Polyvinyl Alcohol

A polyblend sizing agent was prepared by free radical polymerization of partially neutralized acrylic acid (AA) in the presence of polyvinyl alcohol, (PVOH) (Vinarol®DV of Clariant), using ammonium persulfate (AP) initiator. Polymerization was conducted under different conditions including AP concentration (0.025–0.125 mol/L), degree of neutralization (3–50%), time (0–60 min), temperature (50–80°C), AA/PVOH ratio (0.2:1.2), type of neutralizing agent (NaOH or NH₄OH), and PVOH concentration (50–150 g/L). At optimum polymerization conditions, 100 g/L PVOH, 75 g/L AA (3% neutralized using NH₄OH), 0.1 mol/L AP, at 70°C for 25 min, a polyblend was prepared with a percent total conversion of 94%. It was then neutralized with NaOH to a pH of 7. Rheological properties of 10% aqueous solution of the polyblend or PVOH at 80°C revealed that the first was of a non-Newtonian pseudoplastic flow and the latter is of a non-Newtonian thixotropic flow. Solubility time of the polyblend film was shorter than that of PVOH, either after thermal treatment (120°C/15 min)or without thermal treatment. Sized gauzy fabric samples using the polyblend were of higher tensile strength and extent of size removal than those sized with PVOH.