An investigation into transition metal ion binding properties of silk fibers and particles using radioisotopes

Silk is a structural protein fiber that is stable over a wide pH range making it attractive for use in medical and environmental applications. Variation in amino acid composition has the potential for selective binding for ions under varying conditions. Here we report on the metal ion separation potential of Mulberry and Eri silk fibers and powders over a range of pH. Highly sensitive radiotracer probes, ⁶⁴Cu²⁺, ¹⁰⁹Cd²⁺, and ⁵⁷Co²⁺ were used to study the absorption of their respective stable metal ions Cu²⁺, Cd²⁺, and Co²⁺ into and from the silk sorbents. The total amount of each metal ion absorbed and time taken to reach equilibrium occurred in the following order: Cu²⁺ > Cd²⁺ > Co²⁺. In all cases the silk powders absorbed metal ions faster than their respective silk fibers. Intensive degumming of the fibers and powders significantly reduced the time to absorb respective metal ions and the time to reach equilibrium was reduced from hours to 5–15 min at pH 8. Once bound, 45–100% of the metal ions were released from the sorbents after exposure to pH 3 buffer for 30 min. The transition metal ion loading capacity for the silk sorbents was considerably higher than that found for commercial ion exchange resins (AG MP‐50 and AG 50W‐X2) under similar conditions. Interestingly, total Cu²⁺ bound was found to be higher than theoretically predicted values based on known specific Cu²⁺ binding sites (AHGGYSGY), suggesting that additional (new) sites for transition metal ion binding sites are present in silk fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Metal ion binding properties of poly(N-vinylimidazole) hydrogels

The ability of poly(N-vinylimidazole) hydrogels to bind Cu(II), Co(II), Ni(II), Zn(II), Cd(II), Pb(II), Hg(II), Na(I) and Ca(II) cations, as well as uranyl, vanadium, rhenium, and molybdenum complexes, was studied by a batch equilibrium procedure using atomic absorption spectroscopy and UV-Vis spectrophotometry. The optimum pH for ion adsorption was determined in any case. The influence of the crosslinking degree of the hydrogel on the sorption kinetics and the sorption capacity at equilibrium were also studied. Sorption from the binary mixture Cu(II) + U(VI) was also analyzed at the optimum pH. Elution of the ions adsorbed from single and binary solutions was achieved in all cases. A selective desorption of loaded hydrogels with two types of ions was attained. The general conclusion is that poly(N-vinylimidazole) hydrogels are excellent materials for retention of all the ions studied here [except for Pb(II), Na(I), and Ca(II)]. The elution, which can be selective, allows regeneration of the hydrogel. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1109–1118, 1998     

Adsorption of heavy metal cations from aqueous solutions by wool fibers

Adsorption of metal cations by kivircik wool from aqueous NiCl₂, CuCl₂, ZnCl₂, CdCl₂, HgCl₂ and Pb(NO₃)₂ solutions at 25°C and 50°C was investigated using atomic absorption spectroscopy. A fiber diffusion controlled adsorption rate model was used to predict the effective diffusion coefficients of metal ions in wool. It has been shown that wool is a potential adsorbent for removing toxic metal ions from contaminated water.     

Reaction moulding of metal and ceramic powders

A processing route for fabrication of products from hard metal and ceramic powders is described in which a reactive monomer such as ethylcyanoacrylate is used as carrier and binder with the opportunity of recovery through thermal depolymerization. A feasibility study has examined some of the main technical points including monomer–powder reactivity and rheology, debinding rates and compact green density. The stability of ethylcyanoacrylate with various powder volume fractions of silicon nitride and 316L stainless steel has been examined, with p-toluenesulphonic acid used as polymerization inhibitor, and it was found that mixes with higher powder volume fractions required higher levels of inhibitor. Assessment of the flow behaviour of several of the compositions showed them to be significantly non-Newtonian and the high viscosity of blends with a high loading of stainless steel suggests some premature polymerization. Measurement of green density of polymerized compacts demonstrated that high packing efficiency could be achieved. Thermogravimetry showed that rates of binder loss depended upon sample size and powder thermal conductivity.     

Dyeing of wool with antibiotics to develop novel infection resistance materials for extracorporeal end use

Two antibiotics, doxycycline (Doxy) and ciprofloxacin (Cipro), were applied under a variety of conditions to wool and to hydrolyzed wool at 40°C. Nylon was used as a synthetic control. Sorption of Doxy was much higher in wool than in nylon, whereas sorption of Cipro was similar in both fibers. FTIR spectroscopy confirmed that a drastic increase in sorption of antibiotics by hydrolyzed wool was attributed to an increase in polar functional groups by peptide scission and in oxidized sulfur groups by cystine oxidation. Both sorption and zone of inhibition (ZOI) values were improved by hydrolysis of wool. Wool hydrolyzed for 20 or 40 min at 40°C and dyed with Doxy at 45°C for 3.5 h maintained around 30 mm of ZOI after 24 h of challenge by a simulated flow of blood. Wool hydrolyzed for 60 min at 40°C and dyed with Cipro at 45°C for 3.5 h also maintained its antibiotic activity for an extended time. For the most part, ZOI values for nylon dyed by both antibiotics were zero within 24 h. This technique produced infection‐resistant biomaterials of potential use in extra‐corporeal biomedical and biological applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3343–3354, 2004     

Preparation and properties of AlON powders

Aluminum oxynitride (AlON) powders were synthesized using the raw materials of γ-Al₂O₃ and carbon black through the carbothermal reduction and nitridation process. The carbon content in the γ-Al₂O₃/C mixture and heating temperature were investigated. The AlON powders were synthesized by calcination for 2 h at 1750 °C when the carbon content in the γ-Al₂O₃/C mixture was 5.8 wt%. The particle size of powder is important to the transparency of ceramics, but the size of the synthesized powder was large. Therefore, a few methods, such as freeze-drying, ultrasonic dispersion, and liquid nitrogen ball milling, were used to reduce the particle size of powders. Among the three methods, liquid nitrogen milling had the best results.     

玻璃棉及其制品的应用

玻璃棉及其制品是理想的吸声材料,同时也是高效的节能材料。本文通过玻璃棉的化学成分、主要性能指标等的论述,指出了玻璃及其制品的性能特点及应用,同时也指出了建筑绝热保温材料是建筑节能的物质基础。     

Microstructures,dielectric response and microwave absorption properties of polycarbosilane derived SiC powders

Carbon-rich SiC powders with high dielectric loss were prepared via pyrolysis of polycarbosilane (PCS). The effects of pyrolysis temperature on microstructures, dielectric response and microwave absorption properties in X-band (8.2–12.4 GHz) of PCS-derived SiC powders were investigated. The PCS-derived SiC powders are mainly composed of SiC nanocrystal, turbostratic carbon and amorphous phase (SiC and/or C). The size of SiC nanocrystals and the graphitization degree of carbon both increase with the elevation of pyrolysis temperature. Furthermore, the residual carbon is transformed from amorphous into turbostratic structure with a phenomenon of regional enrichment. Moreover, the relative complex permittivity increases notably with the higher pyrolysis temperature. Meanwhile, the dielectric loss tangent increases from 0.19 to 0.57, while the microwave impedance decreases from 73.20 to 53.58. The optimal reflection loss of ?35 dB for PCS-derived SiC powders is obtained when the pyrolysis temperature is 1500 °C, which exhibits a great application prospect in microwave absorbing materials.     

Determination of wool wax in raw wool by raman spectroscopy

A Raman spectroscopic method for the determination of wool wax content in raw wool has been developed. The analyses were performed on 250-mg wool samples by using a spectral component band resolution method. The method has a moderate sample throughput rate, is non-destructive and does not require the use of solvents. Samples ranging between 0.5 and 31% (w/w) wool wax were analyzed. The results obtained were compared with those obtained by a solvent extraction method. If the nonextractable lipid content of the wool is considered, the results of the Raman spectral and extraction methods were in excellent agreement. From a practical standpoint, the minimum detection limit of the method is 3% wax. In general, the precision of the Raman spectroscopic method was better than that obtained for the extraction method.     

The effect of pH and temperature on the dye sorption of wool powders

The sorption behavior of wool powders for three acid dyes (C. I. Acid Red 88, C. I. Acid Red 13 and C. I. Acid Red 18) and a basic dye (methylene blue) was investigated as a function of pH and temperature. The sorption capacity of wool powders depends on the pH of dye solution. The maximum uptake of acid dyes and methylene blue by wool powders occurred at pH 2.5 and pH 7.5, respectively. The effect of pH on the sorption of the hydrophilic dyes (C. I. Acid Red 13 and C. I. Acid Red 18) was more significant than that of the uptake of the hydrophobic dye (C. I. Acid Red 88). Increasing temperature enhanced the dye sorption ability of coarse wool powders, but did not impact that of fine wool powders. The dye‐absorption models of wool powders agree with the Langmuir isotherm. Comparison to activated charcoal and other sorbents indicates that fine wool powders have excellent dye sorption capacity even at room temperature, and may be used as a potential sorbent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of composite mineral powders

Mineral powders such as ground calcium carbonate (GCC) and wollastonite are widely used as fillers in plastics, rubber, paper, paints and other fields. The interface compatibility between the polymer matrix and the mineral particles is relatively weak, both because of the smooth cleavage surface and the sharp particle edges formed during pulverizing. It is beneficial therefore to modify the surface properties of mineral powders before they are used in a polymer composite. In this paper, we report the successful preparation of composite mineral particles, coated by nanoparticles of calcium carbonate of 20-100 nm particle size, by chemical reaction using the Ca(OH)₂-H₂O-CO₂ system. The degree of nanoparticle coverage can reach 100% if the operating parameters are effectively controlled, and the specific surface area can be increased to three times the value before modification. Mechanical testing of polypropylene containing composite wollastonite powder as a filler shows an increase in the impact strength of 65% compared to similar samples prepared using conventional filler powder.     

Binding of metal cations to chemically modified wool and antimicrobial properties of the wool–metal complexes

Wool was modified by treatment with tannic acid (TA) or by acylation with ethylenediaminetetraacetic (EDTA) dianhydride. Kinetics of modification with TA and acylation with EDTA–dianhydride was investigated as a function of the reaction time. Wool displayed a higher breaking load and lower elongation at break as the degree of acylation increased. The absorption of metal cations (Ag⁺, Cu²⁺) by untreated and chemically modified wool was studied as a function of the kind of modifying agent, weight gain, and pH of the metal solution. Absorption of Ag⁺ and Cu²⁺ at alkaline pH increased with increasing weight gain of both TA and EDTA–dianhydride. The absorption of metal cations by untreated and TA‐treated wool below pH 7 was negligible. Acylation with EDTA–dianhydride enabled wool to absorb and bind significant amounts of metal cations at acidic and neutral pHs. The wool–Ag complexes exhibited low levels of metal desorption at acidic pH, irrespective of chemical modification. Higher levels of metal desorption were shown by wool–Cu and wool–EDTA–Cu complexes. Wool–Ag complexes exhibited prominent antimicrobial activity against Cornebacterium and E. coli. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3513–3519, 2001     

Metal ion permeation properties of silk fibroin/chitosan blend membranes

Silk fibroin/chitosan (SF/CS) blend membranes were prepared and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy. It was found that SF and CS were compatible in the blend membranes and that the membranes were dense without microscopic phase separation. Swelling experiments showed that the swelling ratio of the blend membranes increased with CS content and reached the highest value when CS content was 70 wt%. Experiments indicated that the permeability coefficient of K⁺ through the blend membrane was 2–4 times higher than that of pure CS membrane, and 10 times higher than that of pure SF membrane. The permeation rate of K⁺ increased linearly with CS content in the blend membrane for the lower concentration feeding solution. For different metal ions, the permeability through SF/CS blend membranes was in the sequence K⁺ > Ca²⁺ > Cd²⁺ > Pb²⁺ > Cu²⁺ > Ni²⁺. Copyright © 2006 Society of Chemical Industry     

Metal ion effect on dyeing of wool fabric with catechu

Wool fabric was dyed with catechu by two different process sequences using various metal sulphates as mordant. The dyeing behaviour has been assessed by measuring K/S values and different fastness properties. The effect of different metal ions have been studied with respect to their influence on colour and fastness properties. The mechanism of mordant interaction with the fibre has been briefly considered.     

Effect of microwave irradiation on the physical properties and structures of wool fabric

Microwaves are high frequency radio waves which are capable of penetrating many materials and causing heat to be generated in the process. To investigate the effect of microwave irradiation on the physical property, chemical structure, surface morphological structure, and fine structure of wool fabric, wool fabric was treated with microwave irradiation under variety of conditions in terms of the power and the time of microwave treatment. The breaking strength, breaking elongation, and whiteness of the treated wool fabric in different humid state were investigated. The structures of the untreated and treated wool were investigated with Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Laser Raman spectroscopy (LRS). The results show that the physical properties of the treated wool fabrics were changed with microwave irradiation time and power. The chemical structure had not significant change. The surface morphological structure, the concentration of cystine S S bonds and crystallinity of the treated wool were changed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

阻燃羊毛纤维的热性能研究

用氟锆酸钾、有机二酸处理羊毛线、用热分析、剩碳率及氧指数等分析方法对其阻燃性进行了研究,并用Kissinger方程计算热降解反应活化能。实验证明：经过阻燃处理的羊毛毛线比未经阻燃处理的羊毛毛线的剩碳率、氧指数均有所提高,热降解反应活化能和热分解温度降低。     

Effect of chemical modification of wool on metal ion binding

The effect of specific functional group modification of wool on the binding of a number of metal ions (individually) from aqueous solutions was studied. The metal ion uptake profiles for the different modified keratin polymers show that a degree of specificity of binding is imparted by the various modifications in terms of changes in capacities or rates of metal ion uptakes. The changes of uptake depend on both the particular ion and the particular protein modification involved. The results show the potential usefulness of the keratin derivatives for removal of toxic and industrial metal ions from water and contribute to interpretation of metal ions interactions with native wool and proteins in general. Treatments of woven wool with aqueous solutions of certain metal salts impart flame and insect resistance to the fabric.     

硝化和磺化泥炭对重金属离子的吸附性能的研究

泥炭经硝化或磺化处理后对重金属离子Pb2 + 、Cu2 + 的单组分溶液进行吸附试验 ,讨论了影响吸附的因素。结果表明 ,硝化泥炭、磺化泥碳对Pb2 + 、Cu2 + 重金属离子有很好的吸附性 ,以磺化泥炭吸附效果较好 ,其吸附规律基本符合Langmuir方程     

Metal ion retention properties of water‐insoluble polymers containing carboxylic acid groups

Crosslinked poly(acrylic acid), PAA, and poly(2‐acrylamidoglycolic acid), PAAG, were synthesized by radical polymerization. Both resins contain carboxylic acid groups. PAA at basic pH exists basically as an acrylate anion and PAAG shows three atoms or groups, carboxylic acid, hydroxyl, and amide groups, that can act as ion exchanger or chelating groups. Both resins are studied as adsorbents to trace metal ions from saline aqueous solutions and natural sea water and their properties by Batch equilibrium procedure are compared. The metal ions studied under competitive and noncompetitive conditions were Cu(II), Pb(II), Cd(II), and Ni(II). The effects of pH, time of contact, amount of resin, temperature, and salinity were studied. Resin PAA shows a high affinity (>80%) for Cu(II) and Cd(II) and resin PAAG shows also a high affinity for Ni(II), Pb(II), and Cd(II). By treatment of the metal ion‐loaded resin with 4M HNO₃ it is possible to recover completely the Cu(II) ions from resin PAA and Ni(II) and Pb(II) from resin PAAG. The metal ion retention properties were studied with natural sea water. For those natural sea waters containing Cu(II) and Cd(II), the resins showed a high affinity for Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 697–705, 2006     

磁记录用金属磁粉的发展与应用

金属磁粉颗粒细小,具有较高的矫顽力和剩磁,是较为理想的高密度磁记录材料。金属磁粉自从1978年开始制作盒式磁带以来,其颗粒不断向细微化方向发展,磁性能不断提高,制作了多种磁记录品。本文介绍了金属磁粉的特性、发展和应用。详细介绍了纳米金属磁粉优异的磁性能和制备方法。