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Titre : Chemical treatment Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2020 Article en page(s) : p. 40-44 Langues : Anglais (eng) Catégories : Coagulation
Déchets industriels -- Elimination
Eaux usées -- Epuration
Eaux usées -- Recyclage
Floculation
pH
Précipitation (chimie)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The removal of pollutants from a tannery wastewater is an elementary requirement. Whether it is in the tanner's owen effluent treatment plant (ETP), a communal/common effluent treatment plant (CETP), or a municipal effluent plant will use a combination of methods in the treatment process to achieve this. The three broad categories of these treatments are physical, biological and chemical. These could also be hybridised into treatment systems that use more than one type of treatment. Physical removal methods like one type of tratment. Physical removal methods like screens, brushes, flow velocity fluctuations, pipe pressures or membrane filtration, can force pollutants out of a strem. Physico-chemical methods like electrolysis or reverse osmosis add a physico-chemical attribute to the separation.
Biological systems that are plentiful in tanneries where the weather permits rapid growth of bacteria, algae and other micro-organisms, play a role in removal of pollutants through the action of their enzymes or through bioaccumulation of the effluent chemistry into their biomass. A chemical method that is not going to be detailed in this article is the chemical inclusion of oxygen into the effluent ; a method known as aeration. Other chemical methods are detailed below.Note de contenu : - pH modification
- Coagulation
- Flocculation
- Precipitation (clarification) or flotation
- Fig. 1 : A soluble chemical is often a charged molecule that can electrostatically interact with the polar solvent
- Fig. 2 : By changing the pH or by adding a counterion, the solubility is decreased, and the solute will precipitate or float
- Fig. 3 : When a solute has one charge, it generally repels similar molecules and remains in solution and with a low particle size
- Fig. 4 : If a polymer is added to a solution of a specific charge, the polymer could cause the solute to precipitate and floc together to form very large particle sized aggregates (easili removed)
- Fig. 5 : In a flotation system instead of precipitating and allowing thesludge to sink, dissolved air flotation precipitates the floc and the air bubbles carry the aggregate upwards - to be skimmed offEn ligne : https://drive.google.com/file/d/1e4N2UD9XyhXfrFAOjW4rtqoZB65Ot6zy/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33708
in INTERNATIONAL LEATHER MAKER (ILM) > N° 40 (03-04/2020) . - p. 40-44[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21606 - Périodique Bibliothèque principale Documentaires Disponible
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Titre : Chlorinated pollutants Type de document : texte imprimé Auteurs : Karl Flowers, Auteur ; Abigail Clare, Auteur Année de publication : 2021 Article en page(s) : p. 48-49 Langues : Anglais (eng) Catégories : Alcanes
Chlore -- Composés organiques
Cuirs et peaux -- Industrie -- Aspect de l'environnement
Ecotoxicologie
Environnement -- Etudes d'impact
Perchloréthylène
Phénols
Produits chimiques -- ToxicologieIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Chlorinated compounds have been used for a range of applications in the tanning industry. These compounds are useful due to the excellent sanitation properties of the chlorine element and consist of a hydrocarbon chain with at least one covalently bonded chlorine atom.
Since the 1990s, environmental standards adopted by many countries globally have reduced and restricted the use of harmful chemicals during leather production. According to the European Environment Agency, chlorinated hydrocarbons are categorised as one of the most persistent environmental pollutants due to the highly stable C-Cl bond (which can be resistant to degradation). Therefore, many chlorinated compounds are restricted globally; however, their high environmental persistence means will remain detectable in the environment for years to come.Note de contenu : - Chlorinated phenols
- Chlorinated paraffins
- Other chlorinated solvents
- Fig. 1 : The ecotoxic effect of chlorophenols in the environment
- Fig. 2 : Chlorinated paraffin structure
- Fig. 3 : Perchloroethylene structureEn ligne : https://drive.google.com/file/d/1mVE9-sqSeU7JOG_PPmo3vXvY64Dr26Ft/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37074
in INTERNATIONAL LEATHER MAKER (ILM) > N° 50 (11-12/2021) . - p. 48-49[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23237 - Périodique Bibliothèque principale Documentaires Disponible
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Titre : Chrome-free intermediate Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2023 Article en page(s) : p. 58-60 Langues : Anglais (eng) Catégories : Tannage chrome free Index. décimale : 675.2 Préparation du cuir naturel. Tannage Note de contenu : - Tannage versus leather
- El goat or kip versatility
- Chrome-free breakthroughs
- Transport and storage challengesEn ligne : https://drive.google.com/file/d/1FZj7BUFggBNQf-KehWnxyCCmFYJnJwOy/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39549
in INTERNATIONAL LEATHER MAKER (ILM) > N° 60 (07-08/2023) . - p. 58-60[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 24083 - Périodique Bibliothèque principale Documentaires Disponible
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Titre : Chromium recovery or reuse Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 52-56 Langues : Anglais (eng) Catégories : Chrome -- Recyclage
Récupération (Déchets, etc.)
Tannage au chromeIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Chromium tanning is a highly inefficient chemical process if allowed. For the last 130 years, tanners have learnt progressively how to make this process more efficient. There are a few significant methods that allow the process to go from a low yield process into a more efficient method :
- Effective chromium and collagen masking allowing deeper penetration.
- Lower float use, increases the concentration of chromium and this drives penetration.
- pH at the higher end of basifying range.
- Temperature at the end of basifying.
- Masking agents that help with chromium binding (chrome savers).
- Chase pickle type tannages.
Many of these have driven the process towards efficiencies that are in the 80-90% range. Some tannages have even claimed 95-99% efficiencies. For those levels of efficiencies, the residual levels of chromium may be too insignificant to financially motivate for the reuse or recycling of the chromium salts.
For a tannery that has a 65% uptake of the chromium salts, the amount of remaining chromium salts will be in the order of 35% (350 g/L) chromium that could be used in the next iteration of the process. A tannery having 5% (50 g/L) chromium could use the liquor remaining from the tannage (after pH correction) and could directly apply it into the pickle, the sait and residual chromium (and water of course) would mean significant reductions in chemicals and water used at this processing step.Note de contenu : - Waste hierarchy
- Chromium efficiency
- Recycling/reuse
- Recovery
- Circularity
- Fig. 1 : The waste hierarchy
- Fig. 2 : The chromium recycle system
- Fig. 3 : The chromium recovery systemEn ligne : https://drive.google.com/file/d/1QCSUQSP7K8PMiZbsw8Deh4eDFqHdspoC/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33141
in INTERNATIONAL LEATHER MAKER (ILM) > N° 38 (11-12/2019) . - p. 52-56[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21284 - Périodique Bibliothèque principale Documentaires Disponible Chromium species and testing (part 1) / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 36 (07-08/2019)
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Titre : Chromium species and testing (part 1) Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 40-46 Langues : Anglais (eng) Catégories : Chromatographie
Colorimétrie
Cuir -- Teneur en chrome hexavalent
Cuir -- Teneur en chrome trivalent
Diphénylcarbazide
Essais (technologie)
Extraction (chimie)
Maroquinerie
Matériaux -- Détérioration
Spectroscopie d'absorption atomiqueIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : In this two-part paper the first will look of the basics of chromium and how the different types of chromium are tested. In the second part, more detailed chemistry will be covered to allow greater understanding of this complex subject.
Hexavalent chromium, Cr(VI), is not intentionally added to leather during its manufacture. Cr(VI) is formed during poor chromium management (or design) of the process and treatment of the leather articles made of chromium tanned material.
A European Union (EU) Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Annex XV dossier was submitted to the European Chemical Agency (ECHA) on January 19 2012, by Denmark providing evidence that exposure to Cr(VI) through die skin from leather articles posed a risk to human health by inducing an allergic response. Restrictive measures in Europe were requested and die ars Risk Assessment Committee (RAC) and the Committee for Socio-Economic Analysis (SEAC) considered it.
The RAC concluded (on November 28 ,2012) that a content in leather of 3 mg/kg (3 parts per million or 0,0003%, by dry weight) of Cr(VI) is expected to be 80% effective in reducing Cr(VI)-related allergic dermatitis. The SEAC agreed (on March 6, 2013) that an EU-wide restriction was appropriate to address the identified risks relative to the socio-economic balance of an enforcement.
In March 2014 the new restriction was introduced into REACH Annex XVII and from May 2015 leather articles touching the skin should not be placed on die market when they contain Cr(VI) in concentrations equal in excess of 3 parts per million (ppm). The restriction excludes second-hand articles placed on die market before May 1, 2015.
Cr(VI) has been listed on the Californian Safe Drinking Water and Toxic Enforcement Act of 1986 (also known as Proposition 65) since 1988 due to Prop 65's concern over links to cancer, and reproduction/ developmental toxicity.Note de contenu : - Basics of chromium (III)
- Trivalent vs. hexavalent
- Leathermaking and chromium
- Basics of testing
- The principle of detection
- Titration
- Colorimetry with 1-5-diphenylcarbazide
- Chromatography
- Atomic absorption spectroscopy and inductively couple plasma
- Extraction and ageing
- Table 1 : Table outlining chromium species
- Table 2 : Table outlining chromium test methodsEn ligne : https://drive.google.com/file/d/11exWkAs3w0VhXb9lrZlkzNM1o55-LFUT/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33442
in INTERNATIONAL LEATHER MAKER (ILM) > N° 36 (07-08/2019) . - p. 40-46[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21385 - Périodique Bibliothèque principale Documentaires Disponible PermalinkPermalinkPermalinkPermalinkPermalinkPermalinkCutting by-products from car leathers / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 53 (05-06/2022)
PermalinkDetanning chromium leather waste / Abigail Clare in INTERNATIONAL LEATHER MAKER (ILM), N° 54 (07-08/2022)
PermalinkPermalinkDNA and compound barcoding of raw materials / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 51 (01-02/2022)
PermalinkPermalinkEnvironmental credentials of vehicles / Abigail Clare in INTERNATIONAL LEATHER MAKER (ILM), N° 53 (05-06/2022)
PermalinkFinishing developments 2022 / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 54 (07-08/2022)
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