甲壳素和壳聚糖在水处理中的应用

介绍了天然有机高分子化合物——甲壳素和壳聚糖的制备、化学结构和特性，阐述了其在水处理中的应用及发展前景。甲壳素和壳聚糖的来源广泛，其性能优良、无毒、无公害、可生物降解，可用作吸附剂、絮凝剂、分离膜材料、离子交换剂和杀菌剂，是一类非常有开发利用前景的新型水处理材料。     

Using Chitosan as a Coagulant in Recovery of Organic Matters from the Mash and Lauter Wastewater of Brewery

Chitosan is a natural biopolymer which can be used to replace aluminum salts and chemical polymers as a coagulant to avoid the human health problems caused by the residual of aluminum and chemical polymers in water. Chitin is a major component in shrimp and crab shells, and chitosan can be produced from chitin via a deacetylated process. Since the biodegradation of chitin is very slow, large amount of discards from the processing of crustaceans has become a major concern in seafood industry. Therefore, more works are need to find the possible applications of chitin, chitosan and their derivatives. This research used chitosan as a coagulant to recover wheat dregs in the wastewater from washing the mash and the lauter unit in a brewery, and regards this study as an example to understand the influences of the characters of the wastewater on the treatment plant of brewery. The result shows that the␣wastewater from the mash and the lauter units can have the best treatment efficiency at the coagulant dosage of 120 mg/L in the original pH 4.5. Increasing the solution pH decreased the turbidity removal efficiency. The dominant mechanisms for chitosan to remove colloids in the␣wastewater are charge bridging and neutralization, and the later becomes less significant in␣the high pH. The coagulant of chitosan removed most of the colloidal form organic matter in the wastewater, but it has only little effect on the removal of dissolving organic matter. Chitosan is a natural material, after coagulation the sludge from the mash and lauter wastewater can serve directly as an animal husbandry fodder after been dehydrated. Therefore, the loading to wastewater treatment plant and the cost of treatment could be reduced.     

Biopolymer (Chitin) from Various Marine Seashell Wastes: Isolation and Characterization

Chitin has been produced from different sea waste sources including, molluscs (mussel and oyster shell), crustacean (prawn and crab) and fish scale (pang and silver scales) using deproteinization and demineralization as chemical methods. The conditions of chemical extraction process determine the quality of chitin. The obtained results revealed that, about 1 and 10% HCl and NaOH were adequate concentrations for deproteinization and demineralization process respectively. Chitin from oyster and crab shell waste had the highest yield of 69.65 and 60.00% while prawn, mussel shell, pang and silver scales had the lowest yield of 40.89, 35.03, 35.07 and 31.11% respectively. Chitin solubility is controlled by the quantity of protonated acetyl groups within the polymeric chain of the chitin backbone, thus on the percentage of acetylated and non-acetylated d-glucos-acetamide unit. Good solubility results were obtained in mussel, oyster and crab shells respectively. The chitin molecular weight characteristics and activity are controlled by the degree of acetylation (DA) and the distribution of acetyl group extending in the polymer chain. DA is determined by acid-base titration methods and molecular weight determined by Brookfield viscometry. Both methods are found to be effective.     

Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics—Part IV: Polysaccharide Containing Natural Materials

Corn distillers’ dry grain, corncob powder, hardwood powder, and sugar beet pulp were separately anionized by oxidation with sodium hypochlorite in aqueous solution. Solid reaction products instantly precipitated upon admixing each of the above-oxidized materials with soy protein isolate. Infrared spectra and differential scanning calorimetry supported the hypothesis that soy protein isolate complexed with all of the above-oxidized polysaccharides. Reaction products with either oxidized corn distillers’ dry grain or oxidized sugar beet pulp provided hard, brittle pellets with tensile strengths as high as 9.5 MPa, suggesting that these materials could be viable as biodegradable plastics.     

Adsorption of Cationic Dye Using A newly Synthesized CaNiFe2O4/Chitosan Magnetic Nanocomposite: Kinetic and Isotherm Studies

Journal of Polymers and the Environment - Chitosan biopolymer was extracted from chitin and utilized for the synthesis of CaNiFe2O4/Chitosan as a new magnetic nanocomposite. The structural and...     

Preparation,Characterization and Properties of a Novel Electrospun Polyamide-6/ Chitosan/Graphene Oxide Composite Nanofiber

Journal of Polymers and the Environment - Chitosan (CS) is a natural biopolymer that due to its excellent properties such as biocompatibility and biodegradability is suitable for use in many...     

Alkali Treated 3D Chitosan Scaffolds with Enhanced Strength and Stability

Journal of Polymers and the Environment - 3D chitosan scaffolds treated with alkali showed enhanced mechanical properties and stability in aqueous conditions. Chitosan is a preferred polymer for...     

Chitosan Based Nanoformulation for Sustainable Agriculture with Special Reference to Abiotic Stress: A Review

Journal of Polymers and the Environment - Chitosan is a naturally occurring biological macromolecule and second most abundant polysaccharide next to cellulose, derived from deacetylation of chitin....     

Simplified Fabrication of Optically Transparent Composites Reinforced with Nanostructured Chitin

Optically transparent films reinforced with micro to nano scale chitin particles were successfully developed in this study. Chitin composites based on micro scale particles which are larger than the optical wavelength do not cause light scattering provided that chitin particles are composed of nano structure networks which allow monomer impregnation and polymerization. This could lead a simplified process for fabricating transparent composites. The composites reinforced by the chitin micro particles not only retained the transparency of the plastic but also helped the effectiveness of its co-efficient of thermal expansion as similar to chitin nanofibers. Furthermore, chitin nanofibers transparent films are thermally stable against temperature as high as 200 °C for a long period of time. This could lead to number of important commercial applications, and is a significant move towards the sustainable utilization of marine bio-resources.     

Perspective on the Therapeutic Applications of Algal Polysaccharides

Journal of Polymers and the Environment - Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused...     

壳聚糖吸附重金属离子的研究进展

综述了,我国近几年来壳聚糖处理含重金属离子废水的研究进展。壳聚糖及其改性产品的吸附性能主要体现在对各种金属离子的吸附上,为了有选择性地吸附某种或某些金属离子,人们通过修饰、交联、接枝等方法对壳聚糖进行了各种改性研究。     

Use of Chitosan as Coagulant to Treat Wastewater from Milk Processing Plant

Chitosan is a natural high molecular polymer made from crab, shrimp and lobster shells. When used as coagulant in water treatment, not like aluminum and synthetic polymers, chitosan has no harmful effect on human health, and the disposal of waste from seafood processing industry can also be solved. In this study the wastewater from the system of cleaning in place (CIP) containing high content of fat and protein was coagulated using chitosan, and the fat and the protein can be recycled. Chitosan is a natural material, the sludge cake from the coagulation after dehydrated could be used directly as feed supplement, therefore not only saving the spent on waste disposal but also recycling useful material. The result shows that the optimal result was reached under the condition of pH 7 with the coagulant dosage of 25 mg/l. The analysis of cost-effective shows that no extra cost to use chitosan as coagulant in the wastewater treatment, and it is an expanded application for chitosan.     

An Overview on Surface Modification of Cotton Fiber for Apparel Use

About 48 % cotton fiber is consumed as clothing materials all over the globe. It is popular for softness, versatility, absorbance and breathability. Cotton is hydrophilic in nature and therefore, it can absorb sweat from the human body and can release in the surface that makes it comfortable. But it has some inherent limitations such as wrinkle, shrinkage, low dye uptake and microbial degradation. Various approaches have been made to overcome the above limitations. Surface modification of textiles to impart antimicrobial activity, shrinkage, wrinkle resistance, decreased skin irritation, increase dye exhaustion and even enhancing fragrance is the most recent trends in textile chemistry. Various monomers, polymers and biopolymers are applied in different ways to improve different properties of cotton. Chitosan is the mostly used biopolymer in this regard for its biocompatibility, biodegradability, nontoxicity and antimicrobial activity. This paper is a short overview of the most recent development in surface modification of cotton using biopolymers such as chitosan, starch and its derivatives and some other synthetic monomers and polymers.     

Water Retention Capacity of Polysaccharides from Prickly Pear Nopals of <Emphasis Type="Italic">Opuntia Ficus Indica</Emphasis> and <Emphasis Type="Italic">Opuntia Litoralis</Emphasis>: Physical–Chemical Approach

Polysaccharides were isolated from nopals mucilage pulp and peel of Opuntia Ficus Indica (OFI) and Opuntia litoralis (OL) by aqueous extraction and purified by ultrafiltration. Studying the glycosyl residue composition, these polysaccharides were assumed to be rhamnogalacturonan I (RG-I). The macromolecular features of these compounds have been characterized by SEC/MALLS and by low shear viscosimetry. In the present work, we have undertaken a comparative study about different polysaccharides resulting from OFI and OL growing in different area. This comparison is to see the influence of the geographical area in which these two plants push on the mechanism of retention of water by the different polysaccharides extract. The polysaccharides resulting from the nopal peels of the two plants are highly methylated (>70%), thus they are much more hydrophobic especially for peels of OFI growing in the desert area than those resulting from pulps. Consequently, they probably prevent the evaporation of water in nopals by increasing their water retention capacity. Prickly pear nopals of OFI and OL contain a significant amount of water (>80%), carbohydrates (75% compared to the soluble matter), proteins (8% compared to the soluble matter) and salt (17% compared to the soluble matter). Thus, they represent an important source of water and alimentation especially in the arid and semi-arid areas.     

Synthesis and Characterization of Chitosan-Acrylic Acid Based Hydrogels and Investigation the Properties of Bilayered Design with Incorporated Alginate Beads

Journal of Polymers and the Environment - The paper presents the synthesis of hydrogels via free-radical polymerization, based on Chitosan (CS) grafted with Acrylic acid (AA), using a two-step...     

Biodegradable water-soluble polycarboxylic acid design: Biodegradability and builder performance in detergent formulation of partially dicarboxylated polyuronide containing sugar residues in the backbone

Partially dicarboxylated polyuronide having a variable amount of unreacted sugar blocks as an enzymatically cleavable segment was prepared by the controlled oxidation of pectic acid and alginic acid. It was found that partially dicarboxylated polyuronides containing uronide blocks showed better biodegradability than those having no uronide block in the polycarboxylate chain. The rate of biodegradation varies according to the degree of dicarboxylation. It was confirmed that dicarboxy polyuronides containing more than 70% unreacted uronide residues tended to biodegrade quickly. The biodegradability obtained by the BOD test and the enzymatic degradability are well correlated, suggesting that these polymers are first cleaved at the sugar blocks by carbohydrase with subsequent assimilation of the resultant oligomeric fractions. Detergency was dependent on the content of the carboxylate groups in the polymer. The polymers with high carboxylate contents showed better builder performance. The detergency of dicarboxy pectic acid was better than that of dicarboxy alginic acid when compared on the basis of an equal degree of dicarboxylation.     

Partial characterization of the exopolysaccharide from Oscillatoria trichoides Szafer and the role of released polysaccharide in sequestration of Cr6+

The structural investigation and the chromium adsorptive potential of an exopolysaccharide (EPS) released during the growth of an indigenous cyanobacterium, Oscillatoria trichoides Szafer, were investigated in a laboratory‐scale study. The results showed that, of the total EPS produced, 410.53 milligrams/gram (mg g^?1) were released polysaccharides (RPS) and 11.36 mg g^?1 were capsular polysaccharides (CPS). The sorption of hexavalent chromium (Cr⁶⁺) by the RPS achieved a maximum amount of metal removal (q_max) value of 76.92 mg g^?1 of polysaccharide dry weight. The highest coefficient of determination (0.9742) for the Langmuir adsorption model indicates best fitness of the model in explaining the sorption as a unilayer process. Equilibrium studies indicated that 30 to 40 milligrams per liter initial chromium concentration and a pH of 2 were optimal for biosorption of chromium by the RPS. Scanning electron microscopy with energy‐dispersive X‐ray spectroscopy analysis of Cr⁶⁺‐treated RPS showed the presence of 3.76% bound chromium. Compositional analysis of the EPS showed the presence of carbohydrates, proteins, pyruvic acid, and hexosamines. High‐performance liquid chromatography analysis demonstrated the presence of hexoses, as neutral sugars and glucuronic acid as an acidic sugar. The presence of carboxylic groups was also detected by infrared spectroscopy. The presence of these chemical constituents may serve as binding sites for the metal ions; therefore, the RPS of this species appears to be a promising biosorbent for Cr⁶⁺.     

Chitin biodegradation and wound healing in tree bark tissues

Chitin biodegradation and wounded bark tissue healing were demonstrated in several evergreen and deciduous trees by dressing with a sheet of chitin-containing films or sponges. Chitinase activities in the tree bark tissues around the wounds were enhanced by this treatment up to four times those of the untreated wounds. Significant seasonal changes of chitinase activities were observed with the bark and leaf tissues of deciduous trees, but few with those of evergreen trees. A sheet of chitin films implanted or dressed in the tree bark tissues was biodegraded within 4 to 24 weeks after implantation and was assimilated into the wounded bark tissues, resulting in the stimulation of the wounded bark tissue healing.     

Preparation and Characterization of PVDF/g-C3N4/Chitosan Polymeric Membrane for the Removal of Direct Blue 14 Dye

Journal of Polymers and the Environment - Polyvinylidene fluoride (PVDF)/g-C3N4/Chitosan thin film membranes were prepared by immersing of PVDF/g-C3N4 membrane in solution containing various...     

Synthesis and Characterization of Chitosan-Grafted-Poly(2-Hydroxyaniline) Microstructures for Water Decontamination

Chitosan as a biopolymer, biodegradable, safe, non-toxic and widely abundant in nature was grafted with poly(2-hydroxyaniline) (P2-HA) through aqueous chemical oxidative copolymerization using ammonium persulphate in acetic acid medium. The grafting conditions were studied by varying grafting parameters. The effect of oxidant, 2-hydroxyaniline (2-HA) and acetic acid concentrations on the rate of copolymerization was studied. The synthesized graft characterized using UV–Vis, FTIR, TGA, XRD, and scanning electron microscope and compared with chitosan and P2-HA. The grafting enhances the thermal properties of chitosan. The effect of temperature on the rate of grafting copolymerization reaction was studied. The apparent activation energy (Ea) of the copolymerization reaction found to be 21.1116 kJ/mol. Also, ΔH^* and ΔS^*, were calculated and found to 22.8630 kJ/mol and ?109.4290 J/mol K respectively. The mechanism of the grafting copolymerization reaction discussed. Chitosan, P2-HA and chitosan-graft-P2-HA used for the removal of Cr, Fe, Mn, Cu and Zn divalent ions from a contaminated water samples. The adsorption isotherm parameters are given.