A Review of the Use of Chitosan for the Removal of Particulate and Dissolved Contaminants

Abstract

Chitosan has unique properties among biopolymers, especially due to the presence of primary amino groups. Chitosan has been used for the chelation of metal ions in near‐neutral solution, the complexation of anions in acidic solution (cationic properties due to amine protonation), the coagulation of negatively charged contaminants under acidic conditions, and for precipitative flocculation at pH above the pKa of chitosan. The coagulation and flocculation properties can be used to treat particulate suspensions (organic or inorganic) and also to treat dissolved organic materials (including dyes and humic acid). This paper will give an overview of the principal results obtained in the treatment of various suspensions and solutions: (a) bentonite suspensions; (b) organic suspensions; (c) anionic dye solutions; and (d) humic acid solutions. Stoichiometry and charge restabilization were determined for the coagulation of humic acid, kaolin, and organic dyes with chitosan, indicating charge neutralization as the dominant mechanism for removal. Charge patch destabilization and bridging mechanisms were inferred in other cases, based on the effects of the apparent molecular weight of the chitosan preparations and effectiveness of sub‐stoichiometric doses of chitosan. For dye solutions, results showed that color can be removed either by sorption onto solid‐state chitosan or by coagulation‐flocculation using dissolved‐state chitosan; the reactivity of amine groups was significantly increased when dissolved chitosan was used. For humic materials, chitosan can be used as a primary coagulant or as a flocculant after coagulation with alum or other inexpensive coagulants. The influence of the degree of deacetylation and the molecular weight of chitosan on its performance as coagulant/flocculant is illustrated by several examples.     

The Potential for Use of Gold in Automotive Pollution Control Technologies: A Short Review

Recent studies relevant to the future use of gold catalysts in the automotive industry are summarized. Gold catalysts have been examined for their potential in low temperature activity to combat cold-start emission problems and removal of NO _x from lean-burn gasoline and diesel engines. The justification for developing gold catalyst technologies is based both on their promising technical performance and the relatively stable price and greater availability of gold compared with the platinum group metals (PGMs). Use of gold catalysts under mild conditions could also produce lower proportions of CO in the hydrogen streams used for automotive fuel cells and they could be used for the selective oxidation of carbon monoxide in these hydrogen streams in order to increase the efficiency of these fuel cells. Technical barriers are indicated which still remain to be overcome before application of gold catalysts is successful in the automotive sphere.     

功能高分子在新型给药系统中的应用

功能高分子材料具有独特的物理和化学性能,近年来在各类给药系统中有着广泛的应用。该文对功能高分子在新型给药系统中的应用及研究进展进行了评述;结合具体药物剂型,针对不同给药系统的特点和实际需要以及功能高分子的相关特性,讨论了功能高分子材料在药物控缓释中的独特作用和在不同给药系统中的应用前景。     

竹红菌素金属配合物与人血清白蛋白相互作用的光谱研究(英文)

利用多种光谱方法研究了Mg~(2+)-HA,Y~(3+)-HA,La~(3+)-HA等竹红菌甲素金属离子配合物(M-HA)与人血清白蛋白(HSA)之间的相互作用.结果表明在pH 7.4和5.0条件下M-HA能够与HSA形成1:1的复合物,其结合常数均大于2×10~4L/mol.电子自旋共振和荧光猝灭实验表明HSA和M-HA在激发态条件下具有光诱导电子转移作用.     

Experience in the Use of Basicity Indicators to Estimate the Redox Potential of the Glass Melt in Continuous Production (A Review)

A comparative analysis of criteria of basicity (acidity) of silicate glass is performed. Examples of evaluation of the oxidizing potential of melts using the concept of acid-base relationships are analyzed with respect to the conditions of large-scale continuous sheet glass production.     

BS－DMPT－CHP引发体系作用机制概述

本文概述了文献中关于厌氧胶引发体系的糖精－Ｎ，Ｎ－二甲，基－对－甲苯胺－异丙苯过氧化氢（ＢＳ－ＤＭＰＴ－ＣＨＰ）的作用机制．根据动力学研究结果说明厌氧胶的固化反应是氧化还原自由基聚合反应，而在氧化还原反应中的还原剂是ＢＳ－ＤＭＰＴ的电荷转移复合物，氧化剂应是厌氧胶体系中的微量氧，ＣＨＰ的氧化作用与ＢＳ－ＤＭＰＴ没有直接的联系．     

Preliminary Study on the Use of Chitosan in Nickel Coated Polyester Paper

The preparation of nickel coated PET paper has been carried out by chemical or electroless plating using a hypophosphite-based bath. Chitosans of various types and viscosity were used to surface treat chemicals. Their performances as surface treatment chemicals in electroless plating compared to 3-aminopropyltriethoxysilane (APS) were studied.The results showed that when PET paper pretreated by chitosans were plated at 65°C, pH 6.5 and 7.5, the reactions were rather sluggish compared to those by APS. Whereas at 75°C, pH 7.5, the reaction rate and the amount of nickel deposition of PET paper treated by APS, chitosan A and chitosan B were comparable, which were 52.6, 53.2 and 54.7 g/m2, respectively.Their electromagnetic interference (EMI) shielding effectiveness showed a linear relationship with the amount of nickel deposition and were closely related to their surface resistivity of nickel coated PET paper. In addition, EMI shielding effectiveness of nickel coated PET paper pretreated by APS, chitosan A and chitosan B were over 40 dB and their surface resistivity were less than 5 × 10–2 /.     

A Cautionary Note on the Use of Split-YFP/BiFC in Plant Protein-Protein Interaction Studies

Since its introduction in plants 10 years ago, the bimolecular fluorescence complementation (BiFC) method, or split-YFP (yellow fluorescent protein), has gained popularity within the plant biology field as a method to study protein-protein interactions. BiFC is based on the restoration of fluorescence after the two non-fluorescent halves of a fluorescent protein are brought together by a protein-protein interaction event. The major drawback of BiFC is that the fluorescent protein halves are prone to self-assembly independent of a protein-protein interaction event. To circumvent this problem, several modifications of the technique have been suggested, but these modifications have not lead to improvements in plant BiFC protocols. Therefore, it remains crucial to include appropriate internal controls. Our literature survey of recent BiFC studies in plants shows that most studies use inappropriate controls, and a qualitative rather than quantitative read-out of fluorescence. Therefore, we provide a cautionary note and beginner’s guideline for the setup of BiFC experiments, discussing each step of the protocol, including vector choice, plant expression systems, negative controls, and signal detection. In addition, we present our experience with BiFC with respect to self-assembly, peptide linkers, and incubation temperature. With this note, we aim to provide a guideline that will improve the quality of plant BiFC experiments.     

壳聚糖在活性染料染羊毛织物上的应用工艺探讨

本文对壳聚糖处理过的羊毛织物用活性蓝BET染色工艺进行了探讨.讨论了壳聚糖脱乙酰度、壳聚糖浓度对羊毛染色性能的影响,并比较了经壳聚糖处理与未处理羊毛染色性能的差异.结果表明,提高处理液中壳聚糖的浓度或脱乙酰度都能提高活性染料的固色率,提高织物表面色深值K/S,而且对染色样的各项牢度影响不大.     

The Effect of Immersion on the Breaking Force and Failure Locus in an Epoxy/Mild Steel System

This paper presents the effects of immersion on the adhesion behavior in a polyamide-cured epoxy system immersed in sodium chloride electrolyte adjusted to three different pH values. The strength of lap shear joints was measured before and after exposure and after redrying. The failure locus was determined on a macroscopic and microscopic level. It was found that a large adhesion loss occurred upon immersion. Most of that loss was recovered upon redrying. All of the breaking force was recovered when the immersion fluid was distilled water. The locus of failure was primarily through the bulk of the adhesive before immersion. After immersion the failure was interfacial with a thin residue of polymer remaining on the metal surface. These results are discussed with respect to earlier work on the water absorption properties of the system.     

The Effect of Immersion on the Breaking Force and Failure Locus in an Epoxy/Mild Steel System

This paper presents the effects of immersion on the adhesion behavior in a polyamide-cured epoxy system immersed in sodium chloride electrolyte adjusted to three different pH values. The strength of lap shear joints was measured before and after exposure and after redrying. The failure locus was determined on a macroscopic and microscopic level. It was found that a large adhesion loss occurred upon immersion. Most of that loss was recovered upon redrying. All of the breaking force was recovered when the immersion fluid was distilled water. The locus of failure was primarily through the bulk of the adhesive before immersion. After immersion the failure was interfacial with a thin residue of polymer remaining on the metal surface. These results are discussed with respect to earlier work on the water absorption properties of the system.     

煤化学研究进展综述

主要对分子煤化学及煤化学中有关煤矸石和粉煤灰两大固体废弃物的综合利用情况进行了综述,分析了煤炭直接液化技术及其在我国的应用状况,阐述了工业型煤的发展现状与方向,并展望了煤化学的发展前景。     

工业杀菌剂在我国循环水中的研究现状与展望

工业杀菌剂广泛应用于循环冷却水系统中,介绍了国内工业杀菌剂的发展、研究现状与展望,重点描述了杀菌剂在我国油田、石油化工、热电、焦化等行业循环水中的应用研究现状,并对工业杀菌剂在循环水中的发展前景进行了展望。     

苹果汁中棒曲霉素的控制与降解技术研究进展

浓缩苹果汁中棒曲霉素超标使苹果汁品质下降,这是限制我国浓缩苹果汁出口的主要原因之一。针对苹果汁中棒曲霉素的产生特点,从苹果贮藏、苹果汁生产两方面简要分析棒曲霉素含量的控制方法,并对苹果汁中棒曲霉素的降解方法从物理、化学两方面进行探讨。     

Adipose-Derived Stem Cells: A Review of Signaling Networks Governing Cell Fate and Regenerative Potential in the Context of Craniofacial and Long Bone Skeletal Repair

Improvements in medical care, nutrition and social care are resulting in a commendable change in world population demographics with an ever increasing skew towards an aging population. As the proportion of the world’s population that is considered elderly increases, so does the incidence of osteodegenerative disease and the resultant burden on healthcare. The increasing demand coupled with the limitations of contemporary approaches, have provided the impetus to develop novel tissue regeneration therapies. The use of stem cells, with their potential for self-renewal and differentiation, is one potential solution. Adipose-derived stem cells (ASCs), which are relatively easy to harvest and readily available have emerged as an ideal candidate. In this review, we explore the potential for ASCs to provide tangible therapies for craniofacial and long bone skeletal defects, outline key signaling pathways that direct these cells and describe how the developmental signaling program may provide clues on how to guide these cells in vivo. This review also provides an overview of the importance of establishing an osteogenic microniche using appropriately customized scaffolds and delineates some of the key challenges that still need to be overcome for adult stem cell skeletal regenerative therapy to become a clinical reality.     

板料成形回弹研究现状及展望

分析了板料冲压成形过程中产生回弹的影响因素，总结了控制回弹问题所采用的一些方法，介绍了预测与控制回弹的前沿技术，提出了目前有待解决的问题，特别是对高强度板的回弹。     

非晶态晶化导向剂在洗涤剂用4A沸石合成中的应用

用工业原料 ,在常温下合成非晶态晶化导向剂 ,并应用于水热合成体系制备 4A沸石。考察了晶化导向剂加入量以及胶化、陈化和晶化时间等因素对成品的影响 ,得到了结晶粒度高、粒度均匀、钙离子交换度 (>310mgCaCO3/g沸石 )高的产品 ,并使总反应时间由原来的 5h～ 7h降为 80min。     

A study on the adhesion of calcium carbonate to glass. Energy balance in the deposition process

This work describes an experimental investigation on the adhesion of in situ synthesized calcite colloidal particles to rotating glass slides. The relative importance of the hydrodynamic processes involved was analyzed by measuring the amount adhered as a function of both the temperature and the rotation velocity. The adhesion was found to be temperature-dependent. At a given rotation speed of the slide, there exists a value of the temperature for which the adhesion is maximum. This value is lower, the higher the rotation speed. Comparison between experimentally determined particle fluxes (number of particles adhered per unit time and unit surface area of collector) and those calculated from Levich's theory (where laminar flow and absence of particle-collector repulsion are assumed) suggests that the hydrodynamic regime in the vicinity of the slide changes from laminar to turbulent when either the velocity or the temperature is increased above a certain critical value, corresponding to maximum adhesion. The effect of the electrolytes CaCl₂ and MgCl₂ on the adhesion was also studied in the range of concentrations between 0.7 and 70 mM. For fixed hydrodynamic conditions and temperature, the adhesion between the particle and the collector was found to be controlled by the interfacial interactions, including Lifshitz-van der Waals (LW), electrostatic double layer (EL), and acid-base (AB). The calcite-solution and glass-solution interfaces were completely characterized by using electrophoresis, contact angle, and thin-layer wicking techniques, together with van Oss et al.'s model of interfacial thermodynamics. From these data, the total energy of interaction between the particle and the substrate was computed using either the classical DLVO model (EL + LW) or the extended theory (EL + LW + AB) for different electrolyte concentrations, and reasonably good agreement was found between the experimentally observed particle attachment and the predictions of the extended DLVO theory.     

Variants in the PPARGC1A Gene may Influence the Effect of Fat Intake on Resting Metabolic Rate in Obese Women

Recent studies have shown that dietary intake and genetic variants play a decisive role in the risk of obesity. Therefore, this study was designed to examine the interaction between dietary fat and PPARGC1A polymorphisms on the level of resting metabolic rate (RMR). We enrolled 288 Iranian overweight and obese women in this cross‐sectional study. We sequenced the 648 b.p. DNA in Exon 8 of PPARGC1A gene. We analyzed the two single‐nucleotide polymorphisms, namely rs11290186 and rs2970847, in this region. All participants were assessed for RMR, dietary intake, and body composition. This study demonstrated that total cholesterol and insulin levels were positively associated with T allele carriers of rs2970847. Moreover, the A‐deletion allele carrier of the rs11290186 genotype had higher triacylglycerol and insulin concentrations. The current study revealed that, after adjustment for energy intake, the AA genotype of PPARGC1A (rs11290186) had a direct association with polyunsaturated fatty acids and linoleic acid intakes. Another important finding in our study was that there was an interaction seen between fat and saturated fatty acids intake with the PPARGC1A genotypes. Women with fat intakes of more than 30% of calorie intake per day and the A‐deletion genotype had a lower RMR and RMR/fat free mass (FFM). It seems that the PPARGC1A polymorphisms lead to the downregulation of insulin signaling and subsequently insulin resistance. In addition, the interactions between the PPARGC1A polymorphisms (rs11290186) and the level of dietary fat intake probably can have an effect on RMR and RMR/FFM in obese women.     

现代学徒制中企业师傅角色定位探究

随着我国现代学徒制的不断推进,企业师傅所发挥的作用越来越大,然而企业师傅究竟充当什么样的角色,还没有一个明确、清晰的界定。通过对我国现代学制中企业师傅角色定位中出现问题的梳理和分析,提出了企业师傅应该是专业技能的大师傅和学生职场生活的贴心人这一角色定位。