Preparation of O‐carboxymethyl‐N‐trimethyl chitosan chloride and flocculation of the wastewater in sugar refinery

A novel water soluble amphiphilic O‐ carboxymethyl‐N‐trimethyl Chitosan chloride (CMTMC) was synthesized. The structure of this material was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy and X‐ray diffraction (XRD) techniques. The results showed that CMTMC had been successfully prepared. To determine the flocculation performance of the synthesized amphiphilic polymer, a comparison was made among Chitosan (CS), N‐trimethyl chitosan chloride (TMC), O‐carboxymethyl chitosan (CMC), and CMTMC on the turbidity and COD removal efficiency of 1% (v/v) wastewater in sugar refinery suspensions at pH 5.0, 7.0 and 9.0 at a dosage range of 0–8 mg/L. The results showed that the water soluble amphiphilic polymer CMTMC, which contains longer polymer anion and polymer cation, had the best performance not only in turbidity removal but also in COD removal on sugar refinery wastewater. The using of CMTMC as a flocculant to treat wastewater in sugar refinery was actually more effective than CS, CMC, and TMC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on the flocculating properties of quaternized carboxymethyl chitosan

Summary Quaternized carboxymethyl chitosan (QCMC) was prepared through the grafting reaction of carboxymethyl chitosan (CMC) with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CTA) as a quaternizing agent in 2-propanol medium under basic condition. The synthetic conditions for QCMC were as follows: 40.0% of NaOH aqueous solution as catalyst; reaction temperature, 60.0 °C and reaction time, 10.0 h; NaOH/CMC, 0.50; CTA/CMC, 1.50 (mass ratio). The characterization by FT-IR and ¹H NMR demonstrated that QCMC was a typical amphoteric chitosan derivative in which the carboxymethyl group and the quaternary ammonium group were both introduced into the chitosan molecular chain. QCMC was applied to flocculate a simulated wastewater containing 40.15 mg/L Cd(II) or 15.62 mg/L Cr(VI) respectively. The results indicated that the appropriate pH value for removal of Cd(II) and Cr(VI) were ca 8.5 and 5.0, and the appropriate corresponding mass concentrations of QCMC was 140 mg/L and 120.0 mg/L, respectively. Under these conditions, the removal ratio of Cd(II) and Cr(VI) may reach 99.7% and 94.4%, respectively.     

Cadmium adsorption on modified chitosan‐coated bentonite: batch experimental studies

BACKGROUND: Several researchers have investigated the use of chitosan as an adsorbent for removal of heavy metals from aqueous streams. Chitosan flake or powder swells and crumbles making it unsuitable for use in an adsorption column. Chitosan also has a tendency to agglomerate or form a gel in aqueous media. The adsorption capacity can be enhanced by spreading chitosan on physical supports that can increase the accessibility of the metal binding sites. Although several attempts have been made to enhance the adsorption capacity of chitosan, using various chemicals, the sorption capacity for metal ions decreased after cross‐linking of chitosan. RESULTS: Bentonite was coated with chitosan (Chi) and its derivative, 3,4‐dimethoxy‐benzaldehyde (Chi/DMB). The product was then used as adsorbent for the removal of Cd²⁺ from aqueous solutions. The presence of imine groups resulting from chemical modification was confirmed using IR, DRS and SEM. The adsorption followed the Langmuir isotherm and could be described by pseudo‐second order kinetics. CONCLUSION: Chi/DMB coated on bentonite increased the accessibility of metal binding sites. The Chi/DMB/bentonite showed no significant pH dependence in the pH range 2–9, but bentonite coated with chitosan revealed very intensive pH dependence, which had a considerable effect on cadmium removal. As expected adsorption of Cd²⁺ by Chi/bentonite and Chi/DMB/bentonite is dependent on contact time and adsorbent dose. In addition, an EDTA solution is suitable for desorption of cadmium ions, and the reusability of Chi/DMB/bentonite is quite good. © 2012 Society of Chemical Industry     

Preparation, characterization and antimicrobial activity of quaternized carboxymethyl chitosan and application as pulp-cap

Quaternized carboxymethyl chitosan (QCMC) was prepared from which carboxymethyl chitosan (CMC) was prepared from chitosan first, then N-quaternary ammonium group was introduced by the reaction of CMC with 2, 3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by FT-IR, XRD, ¹³C NMR, ¹H NMR and gel permeation chromatography. In vitro antimicrobial activities of QCMC were evaluated against Escherichia coli, which is a Gram-negative bacterium, and Staphylococcus aureus, which is a Gram-positive bacterium. In compared with carboxymethyl chitosan (CMC) and quarternary chitosan (QC) of the same degree of substitusion (DS), we found that QCMC has stronger antimicrobial activity. Then we went deep into study of the relationship between their structure and antimicrobial activity, found that the DS of CMC do little effect to their antimicrobial activity, but as the increase of their DS of quaternization or the decrease of their molecular weight, the antimicrobial activity of QCMC become stronger. QCMC was complexed with calcium hydroxide as pulp-cap. Animal experiment results indicated that QCMC can strongly induce reparative dentine formation and showed a better ability in dentin inducing compared with calcium hydroxide.     

壳聚糖复合絮凝剂处理含油废水

壳聚糖复合絮凝剂处理含油废水,正交实验结果分析表明：pH值为7,PAM量为2mg／L,壳聚糖量为2mg／L时,对废水化学耗氧量（COD）去除率可达47．33％;pH值为7.PAM量为1mg／L,壳聚糖量为8mg/L时,对废水浊度处理得到较为满意的效果,浊度去除率可达91．73％。对浊度和COD去除率的影响因素主次顺序是：pH值〉PAM投加量〉搅拌时间〉壳聚糖投加量。     

有机改性聚合硫酸铁净水剂的制备及应用研究

以钛白粉厂的副产物FeSO4.7H2O为原料,通过用氯酸钾氧化、水解、聚合制得聚合硫酸铁（PFS）,利用有机物羧甲基纤维素（CMC）作改性剂对PFS进行改性,即得有机改性聚合硫酸铁净水剂（PFCM）。利用该净水剂处理模拟污水,脱色率达到95.5%;处理制衣厂水洗废水脱色率达到91.8%,COD去除率达到80.6%,具有良好的净水效果。还比较了CMC、PFS、PAC、PFAM、PFCM的混凝效果。结果表明：PFCM的混凝效果明显优于其他的几种絮凝剂。     

壳聚糖-TiO2复合絮凝剂处理废水的研究

将壳聚糖（CHS）和改性纳米二氧化钛（TiO2）共混制成复合絮凝剂,并对艳兰溶液进行超声降解,探讨了投加量、pH值、沉降时间对脱色率和化学需氧量（COD）的影响。实验结果表明,壳聚糖-TiO2复合絮凝剂比单一壳聚糖处理艳兰废水具有更高的脱色率和COD去除率,并且具有用量少、速度快、无二次污染等特点。因此,这种复合絮凝剂在染料废水的处理方面具有良好的应用前景。     

CMC-PAC复配絮凝剂的制备及其在含醇污水中的应用

壳聚糖作为天然的高分子絮凝剂,其来源广泛、安全环保、可生物降解、环境友好。由于壳聚糖水溶性差,需要溶解于一定的稀酸才能使用,增加了操作程序和应用成本。本文将壳聚糖改性为羧甲基壳聚糖,使其具备水溶性。壳聚糖改性后得到可溶于水的羧甲基壳聚糖（CMC）,将其与聚合氯化铝（PAC）进行复配,处理长庆油田某采气厂含醇污水,通过透光率来考察CMC-PAC复配絮凝剂对污水的处理效果。实验表明,羧甲基壳聚糖与聚合氯化铝投加量比为1∶7,反应温度为70℃,反应时间为2.5h,含醇污水透光率可达98.7%。与单独投加PAC和CMC相比,含醇污水透光率分别提高13.6%和12.3%。CMC-PAC复配絮凝剂通过吸附电中和、吸附架桥、双电层压缩、网捕等作用在含醇污水中起到了良好的絮凝效果。     

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     

有机/无机复合絮凝剂处理印染废水的研究

本文利用壳聚糖和氯乙酸反应制备有机絮凝剂羧甲基壳聚糖,利用生产钛白粉的副产品七水硫酸亚铁制得的无机高分子絮凝剂聚合磷硫酸铁,将两者复配制得无机/有机复合絮凝剂。分别对酸性艳红、直接紫、还原深兰三种染料模拟印染废水进行处理,详细研究了两种絮凝剂的复配比例、pH、添加量对印染废水处理效果。色度去除率和COD去除效果最好,达...     

新型有机膨润土用于印染废水处理的实验研究

采用二乙烯三胺、环氧氯丙烷合成了一种阳离子型铵盐,用其与十六烷基三甲基溴化铵对钠基膨润土进行复合插层改性,制备得到一种新型有机膨润土;以模拟染料废水和实际印染废水为处理对象,使用改性膨润土进行了吸附脱色实验,吸附完成后加入聚合氯化铝混凝。实验结果表明,与单独投加聚合氯化铝相比,采用改性膨润土吸附后再混凝的方法处理废水,可显著提高脱色率和COD去除率;处理活性艳红X-3B、酸性大红GR与活性艳蓝X-BR三种模拟染料废水时,脱色率分别可达99.4%、84.8%和96.1%;以中试规模处理实际印染废水调节池原水时,COD和色度去除率分别可达51.6%和85.9%;处理实际印染废水好氧生化出水,COD可由121.3mg/L降至65.4mg/L,色度由32倍降至8倍以下。     

乙二胺接枝型絮凝剂处理有机工业废水的研究

以聚丙烯酰胺、甲醛、乙二胺为原料,按照曼尼奇反应机理合成一种新型阳离子絮凝剂——乙二胺接枝型絮凝剂,实验表明,制备接枝型絮凝剂的最佳的条件为:聚丙烯酰胺∶甲醛∶乙二胺反应物质的量比=1∶1.40∶0.67,pH=10,温度=45℃,时间=4 h。实验证实接枝型絮凝剂处理模拟有机工业废水得到良好的效果:对于含苯废水COD为450.326 mg/L,经处理后剩余COD为66.502 mg/L,去除率达到了88.44%;对于含烃废水为695.060 mg/L,处理后剩余COD为65.990 mg/L,去除率达到了90.19%,均达到了国家规定的一级工业废水排放标准(COD≤100 mg/L)。     

马铃薯淀粉废水的综合处理工艺研究

实验以H2O2/Fe2+为氧化剂,与改性膨润土处理马铃薯淀粉废水,并考察了不同浓度H2O2的加入量、FeSO4加入量、pH值、反应时间及膨润土的加入量对COD去除率和脱色率的影响。结果表明,在反应条件为10%H2O2投加量10mL/L,0.1mol/L FeSO4加入量20mL/L,改性膨润土的用量40g/L,pH=4.0,反应时间1h时,COD去除率和脱色率分别达90%和98%。     

Adsorption of aluminium from wastewater by chitin and chitosan produced from silkworm chrysalides

Chitin, extracted from silkworm chrysalides, was employed for the production of a high‐purity and porous chitosan, as observed by scanning electron microscopy. Chitin and the chitosan produced from it were also analysed using ¹³C NMR spectroscopy to show the efficiency of deacetylation. The extracted chitin was investigated as an adsorbent material for aluminium removal from textile wastewater, by the column chromatographic method. After the treatment, the residual aluminium was lower than the limitation criterion of 0.2 mg L^?1. The isotherms of adsorption on chitin and chitosan surfaces were investigated and the best fits were observed using the Freundlich isotherm. At pH 5.0, the maximum adsorption capacity was 21.3 mg of aluminium per gram of chitosan over 70 h of experiments. Copyright © 2006 Society of Chemical Industry     

生物絮凝处理油田外排废水试验研究

对生物絮凝剂去除油田外排水CODCr进行了较深入的研究。现场试验结果表明：（1）在pH值为5.5和投加量为200mg/L生物絮凝剂的条件下，可使油田废水的CODCr由297mg/L降到134mg/L，药剂费约为0.7元／m^3；（2）该生物絮凝剂在处理油田外排水方面的性能优于聚合氯化铝和聚丙烯酰胺。     

Fenton氧化深度处理焦化废水的研究

采用Fenton氧化对焦化废水进行了深度处理。结果表明：Fenton氧化反应迅速,可迅速降低焦化废水生化出水的COD;H2O2和Fe2＋的投加量对Fenton氧化具有明显的影响;pH=3时反应体系具有最佳的COD去除效果。在H2O2投加量为1.994 mL/L,FeSO4.7H2O投加量为0.543 g/L,pH=3,温度为35℃的条件下,反应出水COD低于100 mg/L,去除率可达72.7%;Fenton氧化可有效去除生化出水中的难降解有机物。实验结果表明Fenton氧化是深度处理焦化废水的有效工艺。     

Effect of coagulant‐flocculant reagents on aerobic granular biomass

BACKGROUND: Technologies based on aerobic granular biomass are presented as a new alternative application to wastewater treatment due to its advantages in comparison with the conventional activated sludge processes. However, the properties of the aerobic granules can be influenced by the presence of residual amounts of coagulant‐flocculant reagents, frequently used as pre‐treatment before the biological process. In this work the effect of these compounds on aerobic granular biomass development was tested. RESULTS: The presence of coagulant‐flocculant reagents led to a worse biomass retention capacity with a lower VSS concentration compared with a control reactor (4.5 vs. 7.9 g VSS L^?1) and with a higher SVI (70 vs. 40 mL [g TSS]^?1) and diameter (5.0 vs. 2.3 mm). These reagents also caused a decrease in the maximum oxygen consumption rate, but the removal efficiencies of organic matter (90%) and nitrogen (60%) achieved were similar to those in the control reactor. CONCLUSION: The continuous presence of residual levels of coagulant‐flocculant reagents from the pre‐treatment unit negatively affected the formation process and the physical properties of the aerobic granules; however, the removal of organic matter and nitrogen were not affected. Copyright © 2012 Society of Chemical Industry     

UV/TiO_2/Fenton光催化氧化皂素废水的特性研究

皂素废水属于高难度难降解工业废水。采用UV/TiO2与Fenton氧化法相结合的工艺对皂素废水处理进行了研究,考察了pH值、H2O2用量、温度、反应时间等因素对处理效果的影响。实验表明,常温下pH值为5.0、H2O2用量为20 mL/L、反应时间取45 min时,TiO2光催化作用下对皂素废水中COD去除率可达94%以上,满足国家排放标准的要求。     

新型高分子硅铁混凝剂深度处理腈纶废水研究

采用自制新型氧化混凝药剂——无机氧化性高分子硅铁混凝剂(PSF)对腈纶废水生化出水进行处理,并与聚合硫酸铁、聚合氯化铝的混凝效果进行对比试验;以出水COD去除率为评价指标,通过单因素试验优化确定出适宜条件。结果表明,在初始pH为9、CaO投加量为1.0 g/L、PSF和聚丙烯酰胺投加量分别为900、6 mg/L的条件下,出水COD去除率可达到30%以上。采用PSF新型混凝剂可以有效去除腈纶废水生化出水中的溶解性大的难降解有机污染物,效果明显优于其它2种混凝剂,可以作为腈纶废水深度处理的一种新型预处理药剂。     

固体废弃物预处理中药制药废水的实验研究

采用固体废弃物(铁屑和炉渣)预处理中药制药废水,并以COD去除率和脱色率为指标考察其处理效果。考察了废水pH值、试剂投加量、反应时间等对COD去除率及脱色率的影响,确定了最适工艺条件。结果表明,在弱酸性条件下内电解处理效果较好;加入适量的H2O2可明显提高对COD和色度的去除效果;内电解处理后投加适量的石灰乳对废水的COD去除和脱色均有利。废水预处理的最适工艺条件为:常温下,废水的pH为5.0~6.5,铁屑加入量为60 g/L,炉渣加入量为100 g/L,H2O2加入量为20 mL/L,反应30 min后,加入石灰乳(16 mL/L)调节pH至9。在此条件下,废水COD去除率及脱色率可分别达到73%和96%以上,而且处理成本较低。