DOCSLIB.ORG

Flocculation of Oxides Using Polyethylene Oxide

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Flocculation of Oxides Using Polyethylene Oxide Powder Technology, 62 (1990) 253 - 259 253 Flocculation of Oxides using Polyethylene Oxide E. KOKSAL, R. RAMACHANDRAN*, P. SOMASUNDARAN** and C. MALTESH Langmuir Center for Colloid. and lnterfacu, Henry Krumb School of Mines, Columbia University, New York, NY 10027 (U.S.A.) (Received November 1,1989) SUMMARY to H-bonding forces, physical hydrophobic interactions and chemical mechanisms.Tadros Flocculation of oxides using polyethylene [41 examined the adsorption and flocculation oxide was investigated. Polyethylene oxide properties of silica gel with polyvinyl alcohol adsorbedstrongly on and flocculated sodium and found that maximum flocculation kaolinite...H-bonding is considered to be the occurred at the point of zero charge of the driving force for polyethylene oxide adsorp- oxide and also observedan increasein adsorp- tion on kaolinite. The mechanismof adsorp- tion of PVA upon heat treating the solid up tion of polyethylene oxide on kaolinite was to 700 °c. Tadros examined the mechanism examined by studying the adsorption/ of adsorption basedon the degreeof hydra- flocculation characteristicsof different oxide tion of the substrate. Evidently, other than minerals using the same polymer. Poly- H-bonding, no generic mechanismcould be ethylene oxide flocculated silica gel but did utilized to explain polyethylene oxide adsorp- not adsorb on or flocculate hematite and tion. The U.S. Bureau of Mines has found that alumina. Quartz was flocculated only below polyethylene oxide is an excellent flocculant pH 3. Results are examined in terms of the for clays and red mud [5) and correlated the type of surface groups and the degree of adsorption of the polymer with the electro- hydration of the solids. It is proposed that negativity index. Polyethylene oxide itself adsorption of polyethylene oxide on solids has been a widely used polymer in several requires some optimum hydroxylation of the systemsand its characteristicshave been the surface with displaceablewater species. subject of severalreviews [6,7). The present work focuses on the adsorption of poly- ethylene oxide on clay and the constituent INTRODUCTION minerals of clay. It was the aim to study the adsorption/flocculation behavior of poly- Polyethylene oxide (PEO) has servedas an ethylene oxide on a variety of oxide minerals effective flocculant in severalsystems [1,2]. such as silica gel, quartz, hematite, alumina However, the exact nature of the mechanism and kaolinite and utilize the behavior of of polyethylene oxide adsorption remains polyethylene oxide on each mineral to unexplained. Rubio [3] found that poly- explain its overall flocculation characteristics. ethylene oxide was an effective flocculant The oxides studied vary significantly in their on substancesrecognized to be hydrophobic interfacial properties such as point of zero but the polymer was ineffective on hydro- charge(pzc) and degreeof hydration. philic substratessuch as rutile, quartz and copper carbonate. Rubio attributed the specificity of polyethylene oxide flocculation MATERIALS AND METHODS .Present address: Union Carbide Corporation Na-kaolinite Limited, Technical Center, Bound Brook, New Jersey A homoionic sample of sodium kaolinite 08805. was preparedfrom a well-crystallized sample ..To whom correspondence should be addressed. of Georgiakaolinite which was obtained from 0032-59101901$3.50 @ Elsevier Sequoia/Printed in The Netherlands 254 the clay repository at the University of The top half of the suspensionwas sucked out Missouri. The surfacearea of the samplewas using a suction device. About 20 cm3 of the determined by BET to be 9.4 m2/g. The supernatant from the unsettled portion was methodology used for clay preparation has centrifuged for determination of residual beendiscussed earlier [8]. polymer concentration. Both 100-cm3settled and unsettled portions were filtered sepa- SUicagel rately using filter papers and the residue on Silica gel was purchasedfrom Alfa Products the filter paper was dried and weighed. The Inc. The surface area of silica gel was 300 per cent solid secttledwas determined from m2/g, particle size 70 p.m and pore volume the dry weight of the solid in the settled and 1.6 cm3/g. The characteristics of silica gel unsettled portions. were provided by the manufacturer. 88% = ms. ?'!'~~"'~ Quartz ms + mus Natural Brazilian quartz prepared by wet SS% = solid settled per cent grinding and leaching was used. The surface ms = weight of solid in 100 cm3 of settled areaof quartz as measuredby BET was 0.5 portion m2/g. mus = weight of solid in 100 cm3 of unsettled Hematite portion Synthetic hematite was obtained from Polymer concentration was determined Alfa Products Inc. The surface area of using the method of Attia and Rubio [9]. hematite as measuredby BET was 7.5 m2/g. Alumina RESULTS Alumina of 0.3 /lm size was purchased from Alfa Products. Effect of conditioning time The role of conditioning time in determin- Polymer ing flocculation was investigatedinitially at a Polyox coagulant obtained from Union concentration of 0.5 ppm of polyethylene Carbide Corporati9n was used as a flocculant. oxide. The polymer was added dropwise for Polyethylene oxide used in the experiments 55 s at a steady flow rate of 0.1 cm3fs.Con- had an approximate molecular weight of ditioning time here refers to the time for 5 million as determined by the manufacturer. which the suspensionwas further stirred after Polyethylene glycol (PEG), molecular weight addition of the polymer. Figure 1 showsthat 8000, was also used in some experiments. maximum flocculation occurs when the All experiments were conducted in solution made up with triply distilled water. 100 ~ Adsorption and flocculation experiments Five grams of the solid were equilibrated v. 80 E with 195 cm3 of triply distilled water or solu- :70 tion of appropriate ionic strength and pH in a :! 250-cm3glass beaker using a magnetic stirrer ."eo-0 at bar for about 2 h. The pH of the suspension ~ was measuredafter equilibration and taken as PEO 5.106 MW/No-kOOIINte in Water the final pH. The beaker was fitted with pH .6.8 baffle plates and the suspensionstirred using Polymer Concentration' O.5j1pm a propeller for 3 min. Five cubic centimetres of the polymer solution at the desired concen- tration was added dropwise while the suspen- 0 1 2 3 4 5 6 7 8 9 10 sion was being stirred. As soon as all the Conditioning Time, min. polymer was added, the stirring was stopped Fig. 1. Flocculation of sodium kaolinite as a function and the suspensionallowed to settle for 15 s. of conditioning time. 255 stirring is stopped as soon as polymer addition Polymer solutions and suspensionswere pre- is complete. Per cent solid settled dropped pared at the same ionic strength in these from 78% to 65% in 1 min and did not change experiments. It is clear that maximum floc- significantly beyond that time period. It was culation occurs in triply distilled water both also possible to visually observe the floc in the presence and in the absence of breakageduring conditioning after polymer polymer. Addition of salt led to reduction in addition was complete. All flocculation flocculation and reached a constant value at results reported in this work were obtained about 0.1 kmol/m3 NaCI. Figure 4 showsthe at zero conditioning time after polymer effect of pH on flocculation of kaolinite. addition. Clearly, flocculation is enhancedat acidic pH conditions. The molecular weight of poly- Effect of polymer concentration ethylene oxide also had a significant role in Figure 2 shows per cent solid settled of determining flocculation. Literature data have sodium kaolinite as a function of initial shown the importance of molecular weight in polymer concentration. It is clear that flocculation of colloidal dispersions. In this kaolinite is flocculated by polyethylene oxide study, polyethylene glycol (MW 8000) and even at very low concentrations (1 ppm). polyethylene oxide (MW 5 million) were used. Over the concentration range studied, no As shown in Fig. 5, the higher molecular restabilization occurred. The effect of ionic 100 strength on flocculation is shown in Fig. 3. ~ 90 ~ 80 ~ ~ 10 '".. ~"~ ~ :! 60 '" " ~ ""I ~~::::::::::~.. ~50 PEO 5.10. MWINa-Kaolinlte In Wat... Pafrmer Concentratian . 0 0 0.5,pm , I I I . I I I I I 234557.9101112 pH Fig. 4. Effect of pH on the flocculation of sodium - kaolinite. .. ~ 80 .! ; 70 go ~ go080 ~ 50 40 IonicStre",th(MI pH (Noturol) 0 -2 6.89 3.10 4.95 0.5 4.71 1 4.94 I I I I I I I . I 0 0;1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 to Ionic Strength, kmole/m3 NoCI Fig. 3. Effect of ionic strength on the flocculation of sodium kaolinite. 256 * I:~ 1 eo~ # 10 40 PEO5.10. _'&".'.a .. Wato, 0" . ..8 (Nat.all 0 2 4 6 . 10 12 14 .. 16 20 22 25 1.."101 POI,.. COftCM'ro'i..., pp" Fig. 9. Flocculation of alumina as a function of polymer concentration. weight polyethylene oxide is a much better flocculant than polyethylene glycol. This is probably due to the bigger molecule being more amenableto the formation of tails and loops that are favorable for bridging floccula- tion to occur. In order to identify the key solid proper- ties responsible for polyethylene oxide adsorption, flocculation of a seriesof oxide minerals of varying hydration and surface charge characteristicswere studied. Figures 6 - 9 show the flocculation of silica, quartz, hematite and alumina along with adsorption densitiesas a function of polymer concentra- tion. Figures 10 - 12 show the flocculation of these oxide minerals as a function of pH. Silica gel was strongly flocculated by poly- DISCUSSION ethylene oxide at natural pH (around 6.9) but the polymer had little effect on the settling The kinetics of flocculation monitored by behavior of alumina and hematite over a wide stirring the suspensionafter addition of the pH range. Quartz in contrast to silica gel was polymer show the importance of hydro- flocculated only at pH 2.5.
Load more

Recommended publications
  • Sustainable Oxygen: a Low Power Approach for Providing Emergency Medical Oxygen for Spacecraft and Hospitals in Developing Countries
    Portland State University PDXScholar Mechanical and Materials Engineering Faculty Publications and Presentations Mechanical and Materials Engineering 7-1-2011 Sustainable Oxygen: A low power approach for providing emergency medical oxygen for spacecraft and hospitals in developing countries Anndee L. Huff Evan Rhead Zdenek Zumr Evan A. Thomas Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/mengin_fac Part of the Systems Engineering Commons Let us know how access to this document benefits ou.y Citation Details Huff, A., Rhead, E., Zumr, Z., Thomas, E., Sustainable Oxygen: A low power approach for providing emergency medical oxygen for spacecraft and hospitals in developing countries, International Conference on Environmental Systems, Portland, Oregon, 2011 This Article is brought to you for free and open access. It has been accepted for inclusion in Mechanical and Materials Engineering Faculty Publications and Presentations by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Sustainable Oxygen: A low power approach for providing emergency medical oxygen for spacecraft and hospitals in developing countries Anndee L. Huff 1, Evan Rhead2, Zdenek Zumr, BSME3, Evan A. Thomas, Ph.D., P.E.4 Portland State University, Portland, Oregon, 97201 An oxygen concentrator targeting an 80% reduction in power demand over commercial systems is being developed using a pressure swing adsorption process. This system is targeted for a service interval five times longer than commercial systems, and is tolerant to high humidity environments—the leading cause of device failure in developing countries. This system could provide emergency medical oxygen in a spacecraft without increasing oxygen concentration in the vehicle.
    [Show full text]
  • Contamination Control by Use of Ethylene Oxide
    / CONTAMINATION CONTROL BY USE OF ETHYLENE OXIDE TECHNOLOGY SUMMARY (Task 12) Contract NASw-2062 National Aeronautics and Space Ad .. t t' minIS ra Ion Planetary Quarantine Office Washington, D. C. 20546 :NASA-CR-126034) CONTAMINATION CONTROL BY JSE OF ETHYLENE OXIDE R.H. Stroud, et al ;Exotech, Inc.) Apr. 1972 42 P CSCL 06" EXOTECH SYSTEMS, INC. 525 School Street, S.W. Washington, D. C. 20024 Roproduced by NATIONAl TECHNICAL INFO~~V,,\ r:c~~ SeRVICE TR72-11 US Deportment of Commerce Springfield VA 22151 FOREWORD This document is a state-of-the-art summary prepared by Exotech Systems Inc. in partial fulfillment of contract NASW-2062, under the cognizance of the NASA Planetary Quarantine office. The initial purpose of the report had been to summarize the technological advances in the application of ethylene oxide, which had been developed under the NASA Planetary Quarantine program. After a review of a preliminary draft, the scope of this paper was expanded to include the technological advances developed for non-space applica­ tions. This state-of-the-art report should, therefore, be useful in evaluating the potential for new and further uses of ethylene oxide as a decontaminant for Planetary Quarantine related applications. i TABLE OF CONTENTS FOREWORD 0 • • 0 • • • •••0••••0•• i INTRODUCT10N. .••• • 0 • •• 1 I. APPLICATIONS AND LIMITATIONS. •• 2 IT. CHEMICAL AND PHYSICAL PROPERTIES • •• 6 lIT. GERMICIDAL ACTIVITY. •••••.••.. 8 A. INDEPENDENT VARIABLES. • 0 8 1. Sterilant Concentration. .. 0 0 0 •• 8 2 • Exposure Time. .••..••• 0 •• 9 3. Temperature. •.......• 0 • • • 0 12 4. Humidity. .•. 0••••••0••• •• 12 5. Microorganism Age •••.•...• •• 16 B. STERILANT MIXTURES.
    [Show full text]
  • Oxygen Concentrator Filter Re-Design & Testing
    OXYGEN CONCENTRATOR FILTER RE-DESIGN & TESTING Michael Madea Biomedical Engineering Wyatt Albert Eleventh Annual School of Science, Engineering, and Health Symposium May 2, 2014 CLIENT f Macha Mission Hospital f Dr. John Spurrier f Mr. Melvin Mabeta f DeVilbiss Healthcare- partnering organization OXYGEN CONCENTRATORS f Purpose: Delivering concentrated oxygen for patients f Elderly with respiratory issues f Infants and children with bronchiolitis PROJECT IDENTIFICATION f Problem: Premature concentrator failure f Average life is 43% lower than expected f Non-ideal conditions- humidity and dust f Irregular maintenance f Goal: To sustain oxygen concentrator function f Increase longevity of machine f Maintain adequate oxygen output f Simplify maintenance procedures WHAT ARE OXYGEN CONCENTRATORS? f Oxygen concentrators vs. oxygen tanks f Access f Sieve beds-filter out Nitrogen f Mode of failure 21% Oxygen 95% Oxygen 78% Nitrogen 5% Other gases 1% Other gases HOW IT WORKS To the Patient Natural Air Depressurizes Oxygen Gas Nitrogen Purge Pressurizes Photo: Devilbiss Healthcare WHAT IS ZEOLITE? f Zeolite f Separates gasses f Crystal structure f Cage-like resemblance f Molecular exclusion Photo: molecularsive.org WHY IS PRESSURE IMPORTANT? f Adsorption vs. Absorption f Adsorption = Physical bond High Temperature (weak) f Absorption = Chemical Bond (strong) f Pressure Swing Adsorption f High pressure = High adsorption Adsorption Low Temperature f Low pressure = Low adsorption Increasing FIRST SOLUTION f Desiccant based filter f Removes humidity f Preserves zeolite functionality f Chose Silica Gel as desiccant PAST WORK f Designed Dehumidifying Filter f Desiccant based f Site team trip May 2013 f Evaluated prototype on site f Provided aid with repairs George Mono and Steven Bandstra 2013 RESEARCH f Desiccant vs.
    [Show full text]
  • Alkali-Silica Reactivity: an Overview of Research
    SHRP-C-342 Alkali-Silica Reactivity: An Overview of Research Richard Helmuth Construction Technology Laboratories, Inc. With contributions by: David Stark Construction Technology Laboratories, Inc. Sidney Diamond Purdue University Micheline Moranville-Regourd Ecole Normale Superieure de Cachan Strategic Highway Research Program National Research Council Washington, DC 1993 Publication No. SHRP-C-342 ISBN 0-30cL05602-0 Contract C-202 Product No. 2010 Program Manager: Don M. Harriott Project Maxtager: Inam Jawed Program AIea Secretary: Carina Hreib Copyeditor: Katharyn L. Bine Brosseau May 1993 key words: additives aggregate alkali-silica reaction cracking expansion portland cement concrete standards Strategic Highway Research Program 2101 Consti!ution Avenue N.W. Washington, DC 20418 (202) 334-3774 The publicat:Lon of this report does not necessarily indicate approval or endorsement by the National Academy of Sciences, the United States Government, or the American Association of State Highway and Transportation Officials or its member states of the findings, opinions, conclusions, or recommendations either inferred or specifically expressed herein. ©1993 National Academy of Sciences 1.5M/NAP/593 Acknowledgments The research described herein was supported by the Strategic Highway Research Program (SHRP). SHRP is a unit of the National Research Council that was authorized by section 128 of the Surface Transportation and Uniform Relocation Assistance Act of 1987. This document has been written as a product of Strategic Highway Research Program (SHRP) Contract SHRP-87-C-202, "Eliminating or Minimizing Alkali-Silica Reactivity." The prime contractor for this project is Construction Technology Laboratories, with Purdue University, and Ecole Normale Superieure de Cachan, as subcontractors. Fundamental studies were initiated in Task A.
    [Show full text]
  • Mechanical Properties and Brittle Behavior of Silica Aerogels
    Gels 2015, 1, 256-275; doi:10.3390/gels1020256 OPEN ACCESS gels ISSN 2310-2861 www.mdpi.com/journal/gels Review Mechanical Properties and Brittle Behavior of Silica Aerogels Thierry Woignier 1,2,* Juan Primera 3,4, Adil Alaoui 5, Pascal Etienne 6, Florence Despestis 6 and Sylvie Calas-Etienne 6 1 Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, UMR CNRS 7263, 13397 Marseille, France 2 IRD UMR 237-Campus Agro Environnemental Caraïbes-B.P. 214 Petit Morne, 97232 Le Lamentin, Martinique, France 3 Departamento de Fisica, FEC, LUZ, 4011 Maracaibo, Venezuela; E-Mail: [email protected] 4 Escuela Superior Politécnica del Litoral (ESPOL) Facultad de Ciencias Naturales y Matemáticas, Departamento de Física, Campus Gustavo Galindo Km 30.5 Vía Perimetral, P.O. Box 09-01-5863, 090150 Guayaquil, Ecuador 5 Faculté des Sciences et Techniques de Tanger, B.P. 416, 90000 Tanger, Marroco; E-Mail: [email protected] 6 Laboratoire Charles Coulomb, Université Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 5, France; E-Mails: [email protected] (P.E.); [email protected] (F.D.); [email protected] (S.C.-E.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +33-596-42-30-34. Academic Editor: Francoise Quignard Received: 15 October 2015 / Accepted: 30 November 2015 / Published: 10 December 2015 Abstract: Sets of silica gels: aerogels, xerogels and sintered aerogels, have been studied in the objective to understand the mechanical behavior of these highly porous solids. The mechanical behaviour of gels is described in terms of elastic and brittle materials, like glasses or ceramics.
    [Show full text]
  • How to Choose the Right Plate for Thin- Layer Chromatography?'
    HOW TO CHOOSE THE RIGHT PLATE FOR THIN- LAYER CHROMATOGRAPHY?' O. Kaynar* and Y. Berktas Department of Biochemistry, Faculty of Veterinary Medicine, Atatiirk University, Erzurum 25240, Turkey SUMMARY Thin-layer chromatography (TLC) is the simplest and most widely used chromatographic method for qualitative and quantitative analysis. But choice of the correct plate for TLC is the first and also the most critical step for the efficacy of the separation and accuracy of the analysis. This review article discusses selection appropriate plate for TLC. INTRODUCTION Thin-layer chromatography (TLC) is a chromatographic separation process in which the stationary phase consists of a thin layer applied to a solid support /1,2/. Thin-layer chromatography (TLC) is without doubt the most widely used chromatographic methods in the chromatographic techniques for qualitative and quantitative analysis of organic or inorganic compounds /3,4,5/. In this method a chromatography tank or a suitable jar containing suitable solvent or solvent mixture and a plate coated with suitable porous sorbent layer are required to perform chromatography ß,61. A small aliquot of sample is applied to 1-1,5 cm away from one edge of the plate to form the 'This work was partially presented in Vth National Congress of Analytical Chemistry, June 21-25, 2010, Erzurum, Turkey. Corresponding author: Ozgur Kaynar, DVM, PhD, Asst. Prof. Department of Biochemistry, Faculty of Veterinary Medicine. Atatürk University, Erzurum 25240, Turkey. Phone: +90-442- 231 5529, Fax: +90^142-236-0881 5511, E-mail: [email protected] 129 Vol. 29, Nos. 3-4, 2010 Right Plate for TLC starting point /3,6/.
    [Show full text]
  • A Review on Silica Aerogel-Based Materials for Acoustic Applications
    Journal of Non-Crystalline Solids 562 (2021) 120770 Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol A review on silica aerogel-based materials for acoustic applications Zahra Mazrouei-Sebdani 1,*, Hasina Begum 2, Stefan Schoenwald 3, Kirill V. Horoshenkov 2, Wim J. Malfait 1 1 Laboratory for Building Energy Materials & Components, Empa Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland 2 Department of Mechanical Engineering, University of Sheffield, Sheffield, S1 3JD, England, United Kingdom 3 Laboratory Acoustics/Noise Control, Empa Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland ARTICLE INFO ABSTRACT Keywords: Silica aerogels are popular in terms of production volume and real-world applications. Although the current Silica aerogel market growth rate is driven exclusively by thermal insulation, aerogels may also be attractive for acoustic Composite-aerogels applications with the potential in aiding sound absorption/insulation. This paper is a summary of the acoustics Acoustic application related studies of silica aerogel-based products. It introduces silica aerogels, some acoustic characterization Insulation properties methods, and reviews systematically the available data on sound absorption/insulation of silica aerogels, Review polymer-silica aerogel composites, nonwoven-silica aerogel blankets, and aerogel renders/glazing. The work identifiesareas where further research is required, including experimental and theoretical work on the physics of sound absorption in mesoporous materials, and more systematic and standardized evaluations of the acoustic properties of aerogel and aerogel-composites. Aside from this call to action, the opportunities and barriers for the commercialization of silica aerogel products for acoustic applications are presented.
    [Show full text]
  • A Protective Packaging Evaluation Involving a High Barrier Film Lamiation, Desiccants and Oxygen Absorbers
    Rochester Institute of Technology RIT Scholar Works Theses 1996 A Protective packaging evaluation involving a high barrier film lamiation, desiccants and oxygen absorbers Philip Rollo Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Rollo, Philip, "A Protective packaging evaluation involving a high barrier film lamiation, desiccants and oxygen absorbers" (1996). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. A PROTECTIVE PACKAGING EVALUATION INVOLVING A HIGH BARRIER FILM LAMINATION, DESICCANTS AND OXYGEN ABSORBERS BY PHILIP J. ROLLO A thesis submitted to the Department of Packaging Science in the College of Applied Science and Technology of Rochester Institute of Technology in partial fulfillment of the requirements of MASTERS OF SCIENCE in PACKAGING SCIENCE Rochester, New York 1996 A PROTECTIVE PACKAGING EVALUATION INVOLVING A HIGH BARRIER FILM LAMINATION, DESICCANTS AND OXYGEN ABSORBERS I, Philip J. Rollo, hereby grant permission to the Wallace Library of the Rochester Institute of Technology to reproduce my thesis in whole or in part. Any reproduction will not be for commercial use or profit. Signature of Author: _ Department of Packaging Science College of Applied Science and Technology Rochester Institute of Technology Rochester, New York CERTIFICATE OF APPROVAL M.S. Degree The M.S. Degree thesis of Philip J. Rollo has been examined and approved by the thesis committee as satisfactory for the thesis requirements for the Master of Science Degree Dr.
    [Show full text]
  • Effects of the Heat Treatment in the Properties of Fibrous Aerogel Thermal Insulation
    Article Effects of the Heat Treatment in the Properties of Fibrous Aerogel Thermal Insulation Ákos Lakatos 1,*, Attila Csík 2, Anton Trník 3,4 and István Budai 5 1 Department of Building Services and Building Engineering, Faculty of Engineering, University of Debrecen, Ótemető str 2-4 1, 4028 Debrecen, Hungary 2 Institute for Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/c, 4026 Debrecen, Hungary; [email protected] 3 Department of Physics, Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Tr. A Hlinku 1, 94974 Nitra, Slovakia; [email protected] 4 Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 16629 Prague, Czech Republic 5 Department of Engineering Management and Enterprise, Faculty of Engineering, University of Debrecen, Ótemető str 2-4, 4028 Debrecen, Hungary; [email protected] * Correspondence: [email protected]; Tel.: +36-3033-468-61 Received: 29 April 2019; Accepted: 22 May 2019; Published: 25 May 2019 Abstract: Nowadays, besides the use of conventional insulations (plastic foams and wool materials), aerogels are one of the most promising thermal insulation materials. As one of the lightest solid materials available today, aerogels are manufactured through the combination of a polymer with a solvent, forming a gel. For buildings, the fiber-reinforced types are mainly used. In this paper, the changes both in the thermal performance and the material structure of the aerogel blanket are followed after thermal annealing. The samples are put under isothermal heat treatments at 70 °C for weeks, as well as at higher temperatures (up to 210 °C) for one day.
    [Show full text]
  • 199 Laboratory Validation and Field Verification of Silica
    Malaysian Journal of Science 31 (2): 199-206 (2012) LABORATORY VALIDATION AND FIELD VERIFICATION OF SILICA GEL SAMPLING TUBE FOR MEASURING ETHYLENE OXIDE IN AIR Chong Kian Wei1, Md. Sani Ibrahim2, Goh Teik Beng3 1Chemistry and Biology Division, School of Arts and Science, Tunku Abdul Rahman College, Jalan Genting Kelang, Setapak, 53300 Kuala Lumpur, Malaysia 2SaniChem Resources Sdn. Bhd., D/A Pusat Inkubator SIRIM, Bandar Baru Salak Tinggi, 43900 Sepang, Selangor 3The Drug Research Centre, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia. ABSTRACT A sampling and analytical method for the measurement of ethylene oxide (EtO) level in air was developed. The procedure was based on the entrapment of ethylene oxide in an activated silica gel adsorbent inside a sampling tube. The ethylene oxide was desorbed by distilled water and the eluent was analyzed by gas chromatography with flame ionization detector. Parameters such as breakthrough volume, method detection limit, desorption efficiency and storage tests for 14 days in ambient temperature and refrigerator were determined. Field samplings were performed at two factories in Kulim and Pulau Pinang respectively, which use ethylene oxide gas as sterilization substance. The desorption efficiency of ethylene oxide from silica gel tube was determined to be 87.8% over concentration range of 0.2 – 4.0 ppm in 3 liters of air sample. The method detection limit was determined to be 1.0 ppm whereas the precision of procedure was 10.7%. All the parameters were shown to be meeting OSHA requirements. ABSTRAK Satu kaedah persampelan dan analisis untuk mengukur tahap etilena oksida dalam udara telah dibangunkan. Prosedur ini berasaskan pemerangkapan etilena oksida dalam penjerap gel silika yang telah diaktifkan dalam suatu tiub persampelan.
    [Show full text]
  • What Happens If I Eat Silica Gel?
    POISON ology SAFETY & FIRST AID TIPS FROM THE ARIZONA POISON AND DRUG INFORMATION CENTER What happens if I eat silica gel? If there's one thing most people know about silica gel, the unseen substance that occupies those little white packets inserted in new shoe boxes, purses, and Asian snack foods, it's that you're not supposed to eat it. Ususally, the scary warning "do not eat" is displayed across the packet. Often it is accompanied by the command, "throw away." In case that's not clear enough, a few varieties have a skull and crossbones. OK, so, what happens if you eat it? Nothing. Silica gel is a form of the naturally occurring mineral silicon dioxide, better known in its granular form as sand or in crystals as quartz. It absorbs up to 40 percent of its weight in water and has been widely used to remove moisture by placing it inside containers to prevent the contents from getting damp. Used in everything from museum display cases to electronic equipment packaging to boxes of seaweed, it is popular in part because—contrary to the warnings—it is essentially harmless. Indigestible, it passes through the body and comes out looking much the same as when it went in. So why all the doom and gloom on the labeling? Because a surprising number of people, especially children, mistake the packets for food. In 2009, some 38,000 people reported swallowing these packets, according to the American Association of Poison Control Centers. Of those, 34,000 were under the age of 6.
    [Show full text]
  • Silicon Dioxide and Silica Gel Fact Sheet
    United States Pesticides And 738-F-91-107 Environmental Protection Toxic Substances September 1991 Agency (7508W) R.E.D. FACTS Silicon Dioxide and Silica Gel Pesticide All pesticides sold or used in the United States must be registered by Reregistration EPA, based on scientific studies showing that they can be used without posing unreasonable risks to people or the environment. Because of advances in scientific knowledge, the law requires that pesticides which were first registered years ago be reregistered to ensure that they meet today's more stringent standards. In evaluating pesticides for reregistration, EPA obtains and reviews a complete set of studies from pesticide producers, showing the human health and environmental effects of each pesticide. The Agency imposes any regulatory controls that are needed to effectively manage each pesticide's risks. EPA then reregisters pesticides that can be used without posing undue hazards to human health or the environment. When a pesticide is eligible for reregistration, EPA announces this and explains why in a Reregistration Eligibility Document, or RED. This fact sheet summarizes the information in the RED for silicon dioxide and silica gel. Use Profile Silicon dioxide and silica gel are insecticides and acaracides, used in controlling insects, mites and ticks in a variety of indoor and outdoor sites. Silicon dioxide dust is applied with a hand-held or power duster to stored grain, other food, feed and ornamentals; in food handling areas; and on pets and their living/sleeping quarters. Silica gel dust or pressurized liquid is applied by hand-held power duster, aerosol can or injection into cracks and crevices.
    [Show full text]