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Digitale Medien

In situ methane enrichment in anaerobic digestion (1990)

Hayes, T. D. ; Isaacson, H. R. ; Pfeffer, J. T. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 35 (1990), S. 73-86

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ISSN: 0006-3592

Schlagwort(e): Chemistry ; Biochemistry and Biotechnology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: A major cost consideration in the use of anaerobic digestion to convert biomass and waste to utility-grade gas is the expense of separating CO2 from the product gas. Anaerobic digestion has a number of inherent properties that can be exploited to increase the methane content of the gas directly produced by the digester, the most important of which is the high solubility of CO2(40-60 times that of methane) in water under digestion conditions. The methane enrichment concept examined in this study involved the recirculation of a liquid stream from the digester through a CO2 desorption process and the return of the liquid stream back to the digester for absorption of additional CO2 produced by the conversion of organic materials. A steady-state equilibrium model predicted that a digester gas methane content exceeding 94% could be achieved with this scheme using modest recirculation rates provided a desorption process could be designed to achieve a 60+% CO2 removal efficiency in the degassing of the liquid recycle stream. Using fixed-film laboratory digesters operated on synthetic feedstocks, the technique of methane enrichment was tested under pressurized and unpressurized conditions. A 93 + 2% methane gas stream was produced from a volatile-acid-fed bench-scale digester simulating the methanogenic stage of two-phase digestion under conditions of (1) a pH swing achieved without caustic addition that allowed digestion at pH 7. 5 and air stripping at pH 6. 5-7. 0, (2) digester pressurization to 30 psig, and (3) a recycle rate of 0. 33 L/L reactor/day. Significant but lower levels of methane enrichment were achieved with the single-stage digester at the low experimental recycle rate. However, the narrow range among all experiments of CO2 desorption efficiencies achieved in air stripping the recycle stream (35-60% CO2 removal) suggests that comparable methane enrichment-may be achieved with unpressurized single-stage digestion using greater recycle rates. A materials balance analysis of data from an unpressurized, single-stage digester employing no chemical addition and using laboratory degassing efficiencies indicated that 94% methane could be produced at recycle rates of less than 1. 4 L/L reactor/day with a methane loss of less than 2%.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bit.260350111

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Digitale Medien

Potentiometric anion selectivities of polymer membranes doped with indium(III)-porphyrins (1991)

Park, S. B. ; Matuszewski, W. ; Meyerhoff, M. E. ; [weitere]

Weinheim : Wiley-Blackwell

Electroanalysis 3 (1991), S. 909-916

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ISSN: 1040-0397

Schlagwort(e): Indium ; potentiometry ; membrane ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The potentiometric anion responses of polymeric membranes doped with various indium (III)-porphyrin structures are examined. The appropriate membranes are prepared by incorporating 1.0 wt % of the In(III)-porphyrins in plasticized poly(vinyl chloride) films. When such membranes are incorporated within standard ion selective electrode bodies, the resulting electrodes display non-Hofmeister anion selectivity, with a particularly enhanced and super-Nernstian response to chloride. Among those porphyrins investigated, membranes doped with chloro(octaethylporphyrinato)indium(III) yield the largest and most reproducible potentiometric anion responses. These same membrane electrodes exhibit negligible response to protons (or hydroxide) in the range of pH 4.5-9.0. When utilized as a flow-injection detector in conjunction with a protein diluent/buffer stream, the In(III)-porphyrin based electrodes may be used to determine chloride levels in human serum samples.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/elan.1140030906

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Digitale Medien

Structure/permeability relationships of polyimides with branched or extended diamine moieties (1993)

Stern, S. A. ; Liu, Y. ; Feld, W. A.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 939-951

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ISSN: 0887-6266

Schlagwort(e): permeability of gases in 6FDA polyimides ; polyimides, 6FDA, permeation of gases in ; selectivity of 6FDA polyimides for gas separations ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Mean permeability coefficients for CO2, O2, N2, and CH4 in seven types of 6FDA polyimides with branched or extended diamine moieties were determined at 35.0°C (95.0°F) and at pressures up to 10.5 atm (155 psia). In addition, solubility coefficients for CO2, O2, N2, and CH4 in six of these polyimides were determined at 35.0°C and at 6.8 atm (100 psia). Mean diffusion coefficients for the six gas/polyimide systems were calculated from the permeability and solubility data. The relationships between the chemical structure of the polyimides, some of their physical properties (glass transition temperature, mean interchain spacing, specific free volume), and their gas permeability, diffusivity, and solubility behavior are discussed. The 6FDA polyimides studied here exhibit a considerably lower selectivity for the CO2/CH4 and O2/N2 gas pairs than 6FDA polyimides with short and stiff aromatic diamines with comparable CO2 and O2 permeabilities. © 1993 John Wiley & Sons, Inc.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1993.090310804

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Digitale Medien

Bone-particle-impregnated bone cement: An in vivo weight-bearing study (1991)

Dai, K. R. ; Liu, Y. K. ; Park, J. B. ; [weitere]

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 25 (1991), S. 141-156

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ISSN: 0021-9304

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Medizin , Technik allgemein

Notizen: To evaluate an experimental inorganicbone-particle-impregnated bone cement, canine hip prostheses were implanted in dogs using a regular bone cement on one side and the experimental bone cement on the other. In a preliminary feasibility study, bone ingrowth into the resorbed bone-particle spaces was established 3 months after implantation in three dogs. In a more detailed study, twenty-eight (28) dogs were divided in four groups to delineate the effects of time on the phenomena of bony ingrowth. One month after implantation, active bone ingrowth into the bone cement was obvious. By 3 months postimplantation, the ingrowth appeared to have traversed the thickness of the bone-particle-impregnated cement. By the fifth month, most of the interconnected inorganic bone particles were replaced by new bone. At the end of a year, the ingrown bone was mature and negligible new bone activity was present. Biomechanical pushout tests closely corroborated the histologic observations. The maximum shear strength of the cement/bone interface of the experimental side reached 3.6 times that of the control side at 5 months postimplantation. No further improvements were seen at 12 months postimplantation. A viable bone/cement interface may result in a better orthopedic implant fixation system by combining the advantages of both cement for immediate rigidity and biological ingrowth for longterm stability.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jbm.820250202

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Inorganic bone and demineralized bone matrix impregnated bone cement: A preliminary in vivo study (1993)

Henrich, D. E. ; Cram, A. E. ; Park, J. B. ; [weitere]

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 27 (1993), S. 277-280

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ISSN: 0021-9304

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Medizin , Technik allgemein

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jbm.820270218

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