CS239180B1 - Method of hide and fur chrome tanning - Google Patents
Method of hide and fur chrome tanning Download PDFInfo
- Publication number
- CS239180B1 CS239180B1 CS8310097A CS1009783A CS239180B1 CS 239180 B1 CS239180 B1 CS 239180B1 CS 8310097 A CS8310097 A CS 8310097A CS 1009783 A CS1009783 A CS 1009783A CS 239180 B1 CS239180 B1 CS 239180B1
- Authority
- CS
- Czechoslovakia
- Prior art keywords
- chromium
- tanning
- pickling
- fur
- descaling
- Prior art date
Links
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 title claims description 16
- 238000005554 pickling Methods 0.000 claims abstract description 14
- 239000011651 chromium Substances 0.000 claims abstract description 13
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 12
- PXIPVTKHYLBLMZ-UHFFFAOYSA-N Sodium azide Chemical compound [Na+].[N-]=[N+]=[N-] PXIPVTKHYLBLMZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 8
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 6
- 150000001845 chromium compounds Chemical class 0.000 claims abstract description 6
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 5
- 239000011701 zinc Substances 0.000 claims abstract description 5
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 3
- 230000007935 neutral effect Effects 0.000 claims abstract description 3
- 239000000126 substance Substances 0.000 claims abstract 2
- 230000008569 process Effects 0.000 claims description 11
- 239000002253 acid Substances 0.000 claims description 2
- 239000007800 oxidant agent Substances 0.000 claims 1
- 239000010985 leather Substances 0.000 abstract description 7
- 238000007254 oxidation reaction Methods 0.000 abstract description 5
- 230000003647 oxidation Effects 0.000 abstract description 4
- 230000002378 acidificating effect Effects 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 13
- 238000009792 diffusion process Methods 0.000 description 6
- 241000283707 Capra Species 0.000 description 4
- 102000008186 Collagen Human genes 0.000 description 4
- 108010035532 Collagen Proteins 0.000 description 4
- 150000001844 chromium Chemical class 0.000 description 4
- 229920001436 collagen Polymers 0.000 description 4
- 239000003446 ligand Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 108090000623 proteins and genes Proteins 0.000 description 2
- 102000004169 proteins and genes Human genes 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 241000283690 Bos taurus Species 0.000 description 1
- 101700012268 Holin Proteins 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000012736 aqueous medium Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- GRWVQDDAKZFPFI-UHFFFAOYSA-H chromium(III) sulfate Chemical compound [Cr+3].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRWVQDDAKZFPFI-UHFFFAOYSA-H 0.000 description 1
- 235000015217 chromium(III) sulphate Nutrition 0.000 description 1
- 239000011696 chromium(III) sulphate Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 230000000155 isotopic effect Effects 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 235000018553 tannin Nutrition 0.000 description 1
- 229920001864 tannin Polymers 0.000 description 1
- 239000001648 tannin Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Treatment And Processing Of Natural Fur Or Leather (AREA)
Abstract
Vynález spadajúci do kožiarskeho odboru rieši sposob chromočinenia koží a kožušín. Podstata sposobu podta vynálezu spočívá v tom, že na holinu sa po odvápnení, moření a piklovaní posobí po dobu 4 až 18 hodin bazickými chromitými zlúčeninami s obsahom 0,01 až 2 % hmotnostně redukujúcicii látok, ktorých štandardný redukčnooxidačný potenciál v kyslom alebo neutrálnom prostředí je zápornější ako — 0,65 V. Ako redukujúce látky slúžia kovový hořčík, hliník, zinok alebo azid sodný.The invention of the leather industry resolves the way chromium and fur fur. The essence of the present invention resides in that the shaving is after descaling, pickling and plotting for 4 to 18 hours basic chromium compounds with content 0.01 to 2% by weight reducing substances whose standard redox oxidation potential in acidic or neutral the environment is more negative than - 0.65 V. How reducing agents serve magnesium metal, aluminum, zinc or sodium azide.
Description
Vynález sa týká sposobu chromočinenia kozí a kožušín.The invention relates to a method of chrominating goats and fur.
Chromočinenie patří k najrozšírenejším spósobom činenia pri výrobě usní a kožušín. Podstatou procesu je sieťovacia reakcia, pri ktorej chromité komplexy vytvárajú poměrně pevné vazby koordinačnej povahy a stabilizujú tak hlavnú biellkovinu koze — — kolagen.Chromo-tanning is one of the most widespread tanning processes in leather and fur production. The essence of the process is a cross-linking reaction in which the chromite complexes form relatively strong bonds of a coordinating nature and thus stabilize the main biellum of the skin - collagen.
Z kinematického híadiska sa jedná o heterogénnu reakciu, pozostávajúcu zo súčasne prebiehajúcich procesov difúzie a chemickej reakcie v kožnej bielkovine. Rýchlosť chromočinenia je určovaná najpomalším procesom. Existuje určitá nejednodnosť v názorech na povahu limitujúcich faktorov pri chromočinení.From a kinematic point of view, it is a heterogeneous reaction, consisting of simultaneous processes of diffusion and chemical reaction in the skin protein. The chromination rate is determined by the slowest process. There is some inconsistency in the views on the nature of the limiting factors in chrominating.
V minulosti vedeckí pracovníci, například Mc Langhlin v J. Amer. Chem. ASS 35, 684 (1940) a Briggs v J. Soc. Leather Trade Chem. 29, '123 (1945), 30, 189 (1946), 31, 86 (1947), 50, 139 (196i6) usudzovali, že proces limituje chemická reakcia.In the past, scientists such as Mc Langhlin in J. Amer. Chem. ASS 35, 684 (1940) and Briggs in J. Soc. Leather Trade Chem. 29, 123 (1945), 30, 189 (1946), 31, 86 (1947), 50, 139 (196-16) concluded that the process was limited by a chemical reaction.
Odlišné stanovisko zaujal nedávno Komanovsky a spol. v J. Amer. Leather Chem. ASS 68, 48 (1973), podlá ktorého je proces chromočinenia limitovaný rýchlosťou difúzie, tieto experimenty sa však nezhodujú s teoretickými distribučnými křivkami. Difúzna rýchlosť chromitých činiacich zlúčenín v bielkovine koze je len o trochu menšia ako volná difúzia v roztoku, ako ukazujú experimenty so zlúčeninami označenými 51Cr3+ autorov Blažej, Válko, Kriván, Tolgyessy, Veda a výskům v kožiarenskom priemysle VII, 119 (1963).Recently, Komanovsky et al. in J. Amer. Leather Chem. ASS 68, 48 (1973), according to which the chromination process is limited by the diffusion rate, but these experiments do not coincide with the theoretical distribution curves. The diffusion rate of chromium tanning compounds in the skin protein is only slightly less than the free diffusion in solution, as shown by experiments with compounds labeled 51 Cr 3+ by Blažej, Válko, Kriván, Tolgyessy, Science and Jigs in the Leather Industry VII, 119 (1963) .
Výsledky získané pomocou novej analytickej metódy, umožňujúcej stanovil počet novovytvorených priečnych vazieb v kolagene koze pri chromočinení ukázali, že reakčná rýchlosť je o niekoiko rádov menšia než difúzia. Ak je však chromočinenie limitované reakčným krokom, sú možné niektoré sposoby urýchlenia procesu, ktoré by u difúzneho mechanizmu boli neúčinné.The results obtained using a new analytical method allowing to determine the number of newly formed cross-links in goat collagen during chrominating showed that the reaction rate is several orders of magnitude less than diffusion. However, if the chromination is limited by the reaction step, some ways of accelerating the process are possible which would be ineffective in the diffusion mechanism.
Malá rýchlosť reakcie chromitých zlúčenín pri výměně ligandu je známa. Výměnné reakcie prebiehajú malou rýchlosťou aj v tých prípadoch, ked je reakčná rovnováha prakticky úplné posunutá na stranu vstupujúceho ligandu, například keď sa konstanty komplexity líšia o štyri i viac rádov.The low rate of reaction of chromium compounds in ligand exchange is known. Exchange reactions proceed at a low rate even in those cases where the reaction equilibrium is virtually completely shifted to the side of the incoming ligand, for example when the complexity constants differ by four or more orders.
Rýchlosť výměny molekúl vody v aquochromitom komplexe má počas izotopovej výměny 54 hodin. Podobná reakcia u aquohlinitého komplexu má velkost 10_2 s. Podobné údaje platia pre vačšinu ostatných kovov. Malú rýchlosť výměny ligandov u chrómu možno vysvětlit vysokými nárokmi na aktivačnú energiu pri vzniku přechodových, sedem alebo pat koordinovaných komplex ov.The rate of exchange of water molecules in the aquochromite complex is 54 hours during isotopic exchange. A similar reaction with aquohlinitého complex has a size of 10 to _2. Similar data applies to most other metals. The low exchange rate of chromium ligands can be explained by the high demands on activation energy to produce transient, seven or fifth coordinated complexes.
Podstata spósobu podlá vynálezu spočívá v tom, že na holinu sa po odvápnení, moření a piklování působí po dobu 4 až 18 hodin bázickými chromitými zlúčeninami s obsahom 0,01 až 2 % hmot. redukujúcich látok, ktorých štandardný redukčno-oxidačný potenciál v kyslom alebo neutrálnom prostředí je zápornější ako —0,65 V. Ako redukujúca látka slúži kovový hořčík, hliník, zinok alebo azid sodný.The method according to the invention is characterized in that, after descaling, pickling and pickling, the wort is treated for 4 to 18 hours with basic chromium compounds containing 0.01 to 2% by weight. reducing agents whose standard reduction-oxidation potential in acid or neutral media is more negative than -0.65 V. Metallic magnesium, aluminum, zinc or sodium azide serves as reducing agent.
Katalytický účinok si vysvětlujeme 'přechodným znížením oxidačného stupňa chromitých komplexov, kedy je rýchlosť výměny ligandov značné vyššia a opatovným na stálejší vyšší oxidačný stupeň účinkom vzdušného kyslíka. Tento názor vychádza z analogie používanej například v komplexometrickej analýze, kde zníženie oxidačného stupňa chromitých zlúčenín v přítomnosti etyléndiaminotetraacetátu (EDTA) pomocou zinku značné zrýchli vznik kvantitativného komplexu. Dóvodom rýchlej reakcie je nízká aktivačná energia přechodných pat alebo sedem koordinovaných chromitých komplexov.We explain the catalytic effect by temporarily reducing the oxidation degree of chromium complexes, where the rate of exchange of ligands is considerably higher and by providing for an increasingly higher oxidation degree by the action of air oxygen. This view is based on an analogy used, for example, in complexometric analysis, where the reduction of the oxidation degree of chromium compounds in the presence of ethylenediaminotetraacetate (EDTA) by zinc significantly accelerates the formation of the quantitative complex. The reason for the rapid reaction is the low activation energy of the intermediate heels or the seven coordinated chromium complexes.
Katalytické zrýchlenie sieťujúcej reakcie chromočinenia je výhodné, pretože ovplyvňuje najpomalejší a teda limitujúci proces. Výhodné je ekonomicky, pretože lačným a na energiu nenáročným spósobom ovplyvňuje najdůležitejšiu reakciu prebiehajúcu pri chromočinení, ktorá patří k najpomalejším technologickým procesom pri výrobě usni a kožušín.Catalytic acceleration of the crosslinking reaction of chromium tinning is advantageous because it affects the slowest and thus limiting process. It is economically advantageous because it affects the most important chromo-tanning reaction, which is one of the slowest technological processes in the production of leather and fur, by fasting and energy-saving methods.
Katalytický účinok sa výrazné prejavuje zrýchlením vzostupu tzv. teploty zmrštenia kolagenu behom činenia. Menej sa prejavuje. na celkovom obsahu viazaného chrómu, sieťujúci (dvojbodove viazaný) chróm tvoří len asi 10 % z celkového množstva chrómu viazaného pri činění.The catalytic effect manifests itself significantly in the acceleration of the rise of the so-called. collagen shrinkage temperatures during tanning. Less manifested. on the total bound chromium content, the crosslinked (point-bound) chromium constitutes only about 10% of the total amount of chromium bound in tanning.
Účinok spósobu chromočinenia podlá vynálezu vidno z přiložených obrézkov ako i z nasledujúcich príkladov prevedenia. Na obr. 1 je znázorněný priebeh sietovania pri různých teplotách bez přítomnosti katalyzujúcich látoik v závislosti počtu priečnych vazieb (N/mol) od doby činenia vyjadrenej v hodinách.The effect of the chromo-tanning method according to the invention can be seen from the enclosed figures as well as from the following examples. In FIG. 1 shows the course of crosslinking at various temperatures in the absence of catalysts as a function of the number of cross-links (N / mol) depending on the tanning time in hours.
Na obr. 2 je taká istá závislost za přítomnosti hliníkového prášku a na obr. 3 za přítomnosti zinkového prachu. Vo všetkých prípadoch bol zisťovaný prírastok priečnych vazieb v kolagéne, ktoré vznikajú pri činění v 0,5 M roztoku síranu chromitého o bázicite 33,33 % vo vodnom prostředí obsahujúcom 10 % NaCl.In FIG. 2 is the same dependence in the presence of aluminum powder; and FIG. 3 in the presence of zinc dust. In all cases, an increase in cross-links in collagen was observed, which was formed in a 0.5 M solution of chromium (III) sulphate with a basicity of 33.33% in an aqueous medium containing 10% NaCl.
Množstvo přidaného· práškového hliníka bolo 1 g na 1 000 ml činiaceho roztoku a v případe zinku 0,5 g na 1 000 ml činiaceho roztoku. Zvýšenie rýchlosti sietovania je zvlášť viditelné pri vyšších teplotách i keď za obyčajnej teploty je tiež značné — přibližné 80 %-né.The amount of aluminum powder added was 1 g per 1000 ml tanning solution and in the case of zinc 0.5 g per 1000 ml tanning solution. The increase in sieving speed is particularly noticeable at higher temperatures, although at ordinary temperatures it is also considerable - approximately 80%.
Příklad 1Example 1
Holina po odvápnení, moření a piklování sa činí v 100 % piklujúcej lázně pomocou bázických chromitých zlúčenín v· množstve odpovedajúcom 2,2 % CržCú na holinovú váhu v přítomnosti 1 g hliníkového prachu na 1 1 činiaceho roztoku po dobu 4 až 8 hodin. Behom činenia sa robí otupovanie prídavkom NaHCO3 alebo inými otupovacími látkami tak, aby pH ku konců činenia bolo v rozmedzí 3,8 až 4,2.The descaling, pickling and pickling was carried out in a 100% pickling bath using basic chromium compounds in an amount corresponding to 2.2% Cr2C4 per holin weight in the presence of 1 g of aluminum dust per liter of tanning solution for 4 to 8 hours. During the tanning, blunting is performed by adding NaHCO3 or other blunting agents such that the pH to the ends of the tanning is in the range of 3.8 to 4.2.
Přiklad 2Example 2
Hovadzia koza po luhovaní, odvápňo-vaní, moření a piklovaní s 1,2 % kyseliny sír-ovej sa činí v 60 -% lázně pomocou bazických chromitých solí v množstve 2 % na holinovú váhu. Na začiatku činenia sa přidá 0,25 gramov ZN/1 a 0,5 % kaustického magnezitu pre otupovanie. Činenie je ukončené za 3 až 6 hodin pohybu.The bovine goat after leaching, descaling, pickling and pickling with 1.2% sulfuric acid is made in a 60% bath using basic chromium salts in an amount of 2% by weight to the tannin weight. At the start of tanning, 0.25 grams of ZN / L and 0.5% caustic magnesite are added for blunting. The tanning is completed in 3 to 6 hours of movement.
Usne sa vyťahujú a ďalej spracovávajmLeather is pulled out and further processed
Příklad 3Example 3
Holina 1'ubovol'ného druhu koze po odvápnení, moření a piklovaní sa činí s 10 % sam-ootupujúceho chromitého materiálu, například Chromzaz SB, obsahujúceho 24 až % CrzCb a 2 -o/o hliníkového prachu na váhu činiaceho- prostriedku. Doba činenia za pohybu je 4 hodiny.A leg of any kind of goat after descaling, pickling and pickling is made with 10% self-extinguishing chromium material, for example Chromzaz SB, containing 24 to% CrzCb and 2o / o aluminum dust per tanning agent weight. Tanning time on the move is 4 hours.
Příklad 4Example 4
Holina ťažších váhových -tried sa po odvápne-ní, moření a piklovaní činí chromitými soíami v množstve 2 % CrzCte na holinovú váhu v přítomnosti 0,5 g azidu sodného na liter. Otupovanie sa robí kausti-ckým magnezitom. Cineníe sa ukončí za 3 až 6 h-odín pohybu.The heavier weight grades after descaling, pickling and pickling are made with chromium salts in an amount of 2% Cr 2 Cte per holium weight in the presence of 0.5 g sodium azide per liter. The blunting is done by caustic magnesite. Tinning is terminated after 3 to 6 hours of movement.
Příklad 5Example 5
Kožušiny po namočení a mechanickom miešaní s-a činia v roztoku obsahujúcom 100 gramov Na-C-1/1, 12 g kyseliny mravčej/1, chromité činiace zlúčeniny v množstve odpoved-ajúc-om 15 g Cr2O3/l a 1,5 g hliníkového prachu na liter činiacej lázně. Doba činenia s občasným pohybom je 5 až 12 hodin.The fur after soaking and mechanical agitation is made up in a solution containing 100 grams of Na-C-1/1, 12 g of formic acid / l, chromium tanning compounds in an amount corresponding to 15 g of Cr2O3 / l and 1.5 g of aluminum dust per liter of tanning bath. The tanning time with intermittent movement is 5 to 12 hours.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS8310097A CS239180B1 (en) | 1983-12-29 | 1983-12-29 | Method of hide and fur chrome tanning |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS8310097A CS239180B1 (en) | 1983-12-29 | 1983-12-29 | Method of hide and fur chrome tanning |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CS1009783A1 CS1009783A1 (en) | 1985-05-15 |
| CS239180B1 true CS239180B1 (en) | 1985-12-16 |
Family
ID=5447941
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CS8310097A CS239180B1 (en) | 1983-12-29 | 1983-12-29 | Method of hide and fur chrome tanning |
Country Status (1)
| Country | Link |
|---|---|
| CS (1) | CS239180B1 (en) |
-
1983
- 1983-12-29 CS CS8310097A patent/CS239180B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| CS1009783A1 (en) | 1985-05-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Sundar et al. | Cleaner chrome tanning—emerging options | |
| Sreeram et al. | Sustaining tanning process through conservation, recovery and better utilization of chromium | |
| Dreisinger et al. | The oxidation of ferrous sulphate by molecular oxygen under zinc pressure-leach conditions | |
| US2577887A (en) | Activation of oxalate metal coating compositions | |
| ATE28337T1 (en) | PROCESSES FOR THE PROCESSING OF FERROUS AND ZINC-CONTAINING MORTISAL ACID. | |
| US2739907A (en) | Process for imparting an improved finish to the surface of metals by means of diffusion treatment | |
| Hamm et al. | Complex Ions of Chromium. V. Reactions of Malonate Ion with Chromium (III) 1, 2 | |
| CS239180B1 (en) | Method of hide and fur chrome tanning | |
| Prokein et al. | Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation | |
| Pasquali et al. | Adsorption of Cr (VI) by wet blue leather: Sustainable solution for leather industry effluents | |
| EP0495873B1 (en) | A method of treating hides | |
| Furness et al. | Polarographic determination of ethylenediamine-tetra-acetic acid | |
| Li et al. | Recent research on chemically modifying the surface of Zero-valent iron: a mini review | |
| US3174817A (en) | Chrome-acetate complex tannage | |
| Gaidau | Applicative chemistry of tanning metallic heterocomplexes | |
| US3015594A (en) | Phosphate coating process | |
| US725648A (en) | Process of tanning hides, skins, or other animal tissues. | |
| EP0406234B1 (en) | Process for recovering chromic anhydride from exhausted aqueous chromium plating bath solutions with exploitation of the recovered chromium | |
| US4105402A (en) | Treatment of sulfide-limed pelts in acid baths | |
| JPS582165B2 (en) | Processing method for chromic acid waste liquid | |
| Kolthoff et al. | Characteristics of polarographic catalytic waves observed with bovine-serum albumin: effects of type of buffers, pH, ionic strength, calcium, and tetraalkyl salts | |
| Kuwabara et al. | Successive potentiometric titration of iron (II) and iron (III) with cobalt (II) in the presence of 1, 10-phenanthroline | |
| Janardhanan et al. | Chromium and leather | |
| Burns et al. | Investigation of Commercial Chrome-Tanning Systems: Part VI. Full-Scale Trials of Chrome Liquor Recycling and the Importance of Salt Concentration | |
| SU834131A1 (en) | Method of tanning hides and pelts |