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Production of Dialdehyde Cellulose and Periodate Regeneration: Towards feasible oxidation processes / Produktion av dialdehydcellulosa och återgenerering av perjodat: Mot möjliga oxidationsprocesserHöglund, Elisabeth January 2015 (has links)
Cellulose is an attractive raw material that has lately become more interesting thanks to its degradability and renewability and the environmental awareness of our society. With the intention to find new material properties and applications, studies on cellulose derivatization have increased. Dialdehyde cellulose (DAC) is a derivative that is produced by selective cleavage of the C2-C3 bond in an anhydroglucose unit in the cellulose chain, utilizing sodium periodate (NaIO4) that works as a strong oxidant. At a fixed temperature, the reaction time as well as the amount of added periodate affect the resulting aldehyde content. DAC has shown to have promising properties, and by disintegrating the dialdehyde fibers into fibrils, thin films with extraordinary oxygen barrier at high humidity can be achieved. Normally, barrier properties of polysccharide films deteriorate at higher humidity due to their hygroscopic character. This DAC barrier could therefore be a potential environmentally-friendly replacement for aluminum which is utilized in many food packages today. The aim of this study was to investigate the possibilities to produce dialdehyde cellulose at an industrial level, where the regeneration of consumed periodate plays a significant role to obtain a feasible process. A screening of the periodate oxidation of cellulose containing seven experiments was conducted by employing the program MODDE for experimental design. The reaction time was varied between 2-8 hours and the ratio NaIO4 to fiber in was between 1-2 (w/w) for small-scale experiments (1 g fiber), which resulted in an aldehyde content between 14-80 %. An oxidation degree around 30 % was set as a goal, and the optimal point at a fixed temperature of 50°C was assessed to be a ratio of 1.5 and a reaction time of 2.5 h, including 30 min of cooling. Furthermore, the MODDE evaluation suggested that the time and quantity of added periodate equally effected the reaction. An up-scaling of the system with 22.5 g of NaIO4 and 15 g of cellulose fibers and a total reaction time of 3h, resulted in 39 % oxidation degree and a yield of 92 %. For the regeneration of periodate, Oxone® was tested, but too low yields were obtained. More studies are needed in order to understand and optimize this process. Better results where gained when utilizing a 10 % hypochlorite solution (NaOCl) that was refluxed with the filtrate from the periodate oxidation of cellulose. A spectrophotometric method was developed to be able to quantify the amount of periodate and thereby the amount of residual iodate (IO3-), i.e. the byproduct to oxidize back to IO4-. An optimization study was performed with eleven experiments with the time varying between 1-4 hours and the molar ratio of NaOCl to IO3- between 1-4. However, it was found that the residual periodate also consumed the hypochlorite, so the real molar ratio of NaOCl to IO3- and IO4- was only 0.38-1.52. The highest ratio of 1.52 with a reaction time of 4 h generated the highest regeneration of 81 %. From the MODDE evaluation it was suggested that the reaction time does not have as significant effect upon the process as the amount of added NaOCl has. By optimizing this reaction further, it should be possible to reach even more satisfying results. However, it was proved that the precipitated product was sodium paraperiodate, Na3H2IO6, and this regenerated product was successfully used to oxidize cellulose fibers to DAC. Surprisingly, the oxidation degree became much higher, 43 %, despite that the same condition was employed as before, but the reason for this can be the lower pH that was utilized. Even though there still are questions to be answered, this study has contributed to knowledge that could be utilized to take the oxidation process closer to industrialization. / Cellulosa är en attraktiv råvara som blivit alltmer intressant tack vare dess nedbrytbarhet och förnybarhet samt samhällets miljömedvetenhet. Med avsikt att hitta nya materialegenskaper och applikationer har studier på derivatiseringen av cellulosa ökat. Dialdehydcellulosa (DAC) är ett derivat som framställs genom selektiv klyvning av C2-C3-bindningen i en vattenfri glukosenhet i cellulosakedjan där natriumperjodat (NaIO4) fungerar som ett starkt oxidationsmedel. Vid en konstant temperatur påverkar reaktionstiden liksom mängden tillsatt perjodat det resulterande aldehydinnehållet. DAC har visat sig ha lovande egenskaper och genom att lösa upp dialdehydfibrerna till fibriller kan tunna filmer med en utomordentlig syrebarriär vid hög fuktighet erhållas. Normalt sett blir den fina barriären gjord av polysackaridfilmer försämrad vid högre luftfuktighet på grund av den hygroskopiska karaktären. Denna DAC barriär kan därför vara en potentiell och miljövänlig ersättare till det aluminium som används i många livsmedelsförpackningar idag. Syftet med denna studie var att undersöka möjligheterna att kunna producera dialdehydcellulosa på en industriell nivå, där regenerering av förbrukad perjodat spelar en viktig roll för att erhålla en genomförbar process. En screening av perjodatoxidering av cellulosa innehållande sju experiment utfördes genom att använda programmet MODDE för experimentell design. Reaktionstiden varierade mellan 2-8 timmar och förhållandet NaIO4 till fibrer i gram mellan 1-2 för småskaliga experiment (1 g fiber), vilket resulterade i en aldehydhalt mellan 14-80 %. En oxidationsgrad omkring 30 % sattes som ett mål och den optimala punkten vid en konstant temperatur av 50° C bedömdes vara ett förhållande på 1,5 och en reaktionstid om 2,5 timmar inklusive 30 min avsvalning. Vidare föreslog MODDE-utvärderingen att tiden och mängden tillsatt perjodat påverkade reaktionen likvärdigt. En uppskalning av systemet med 22,5 g NaIO4 och 15 g cellulosafibrer och en total reaktionstid om 3 timmar resulterade i en oxidationsgrad på 39 % och ett utbyte på 92 %. För att återgenerera perjodat testades Oxone® men alltför låga utbyten erhölls. Fler studier behövs för att förstå och optimera denna process. Bättre resultat erhölls när en 10 % hypokloritlösning (NaOCl) användes, vilken återloppskokades med filtratet från perjodatoxideringen av cellulosa. En spektrofotometrisk metod utvecklades för att kunna kvantifiera mängden perjodat och därmed mängden kvarvarande jodat (IO3-), dvs. biprodukten att oxidera tillbaka till IO4-. En optimeringsstudie utfördes med elva experiment där tiden varierade mellan 1-4 timmar och det molära förhållandet av NaOCl till IO3- mellan 1-4. Efter detta visade det sig att den kvarvarande perjodaten också konsumerade hypoklorit, så det verkliga molförhållandet mellan NaOCl till IO3- och IO4- var endast 0,38-1,52. Det högsta förhållandet 1,52 med en reaktionstid om 4 timmar genererade den högsta återgenereringen på 81 %. Från MODDE-utvärderingen föreslogs att reaktionstiden inte har lika stor inverkan på processen som mängden tillsatt NaOCl har. Genom att optimera denna reaktion ytterligare bör det vara möjligt att nå än mer tillfredsställande resultat. Hur som helst bevisades det att den utfällda produkten var natriumparaperjodat, Na3H2IO6 och denna regenererade produkt användes framgångsrikt för att oxidera cellulosafibrer till DAC. Överraskande nog blev oxidationsgraden mycket högre, 43 %, trots applicering av samma betingelser som tidigare, men orsaken till detta kan vara att ett lägre pH användes. Även om det fortfarande finns frågor kvar att besvara så har denna studie bidragit till kunskap som kan användas för att ta denna oxidationsprocess närmre industrialisering.
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Electrochemical oxidation of the iodate ionMc Ardle, Siobhan January 1994 (has links)
No description available.
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Determination of the Degree of Oxidation in Dialdehyde Cellulose Using Near Infrared Spectroscopy / Bestämning av oxidationsgraden i dialdehydcellulosa med nära infraröd spektroskopiBrandén, Carl-Magnus January 2017 (has links)
The purpose of this thesis work was to investigate possible in-, on- or at-line methods to determine the degree of oxidation in dialdehyde cellulose. Several technologies were reviewed which led to a feasibility study into a possible on-line or at-line method using near infrared spectroscopy for determining the degree of oxidation in wet dialdehyde cellulose. A calibration model was built using the near infrared spectra of 19 samples created from kraft pulp with a degree of oxidation between 0 and 52.1 %. The obtained model uses five significant principal components and has a goodness of fit (R2) of 0.998 and a goodness ofprediction (Q2) of 0.991. The first principal component describes the degree of oxidation and the second the water content. A validation set of six samples was used to test the model and the predicted values resulted in a root mean square error of prediction of 0.85 in comparison with the reference method which had a pooled standard deviation of 0.69.
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Structure and tanning properties of dialdehyde carboxymethyl cellulose: Effect of degree of substitutionYi, Yudan, Ding, Wei, Jiang, Zhicheng, Wang, Ya-nan, Bi 26 June 2019 (has links)
Content:
Developing novel tanning agents from renewable biomass is regarded as an effective strategy for sustainable leather industry. In this study, a series of dialdehyde carboxymethyl cellulose (DCMC) were
prepared by periodate oxidation of carboxymethyl cellulose (CMC) with varying degrees of substitution (DS: 0.7, 0.9 and 1.2). The structural properties of DCMC were characterized. Size Exclusive
Chromatography measurements showed that CMC underwent severe degradation during periodate oxidation, resulting in the decline of weight-average molecular weight from 250,000 g/mol to around
13,000 g/mol. FT-IR analysis illustrated that aldehyde group was successfully introduced into DCMC. The aldehyde group content of DCMC decreased from 8.38 mmol/g to 2.95 mmol/g as the DS rose from 0.7 to 1.2. Interestingly, formaldehyde was found to be produced in DCMC, and its content was 159.4, 151.7 and 38.4 mg/L, respectively when the DS of CMC was 0.7, 0.9 and 1.2, respectively. Further analysis by HPLC found that fructose was formed during oxidative degradation, and was subsequently oxidized to generate formaldehyde. This was in accordance with the fact that higher DS resulted in lower formaldehyde content in DCMC. The whole reaction mechanism is still under investigation at the moment. Tanning trials showed that the shrinkage temperature and thickening rate of DCMC tanned leather decreased as the DS increased. This should be due to the difference in aldehyde content of DCMC. Leather tanned by DCMC-0.7 (DS of CMC was 0.7) had the highest shrinkage temperature of 81°C and thickening rate of 76%. It was noteworthy that the formaldehyde content in DCMC tanned leather was only 0.11-0.40 mg/kg even though DCMC contained a small amount of formaldehyde. In general, we hope the work on dialdehyde tanning agent derived from CMC could provide some essential data for the development of sustainable tanning material and process.
Take-Away:
1. Higher degree of substitution (DS) of CMC resulted in lower aldehyde group content of DCMC.
2. The formaldehyde content of DCMC was negatively correlated with DS.
3. The tanning performance of DCMC with lower DS was better.
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Striding towards self sustainability using Aluminium from Tanzanian kaolin for combination Tanning systemChina, Cecilia, Jayakumar, G. C., Hilonga, A., Kanth, S. V., Njau, K. N. 28 June 2019 (has links)
Content:
Sustainability is a key factor which control future leather manufacture. Developing several new technologies is one of the primary agenda for sustainability. However, developing countries are facing
several challenges which not only limited to best practice technologies but also finding self sustainability in maximizing the available resources. In the present study, an attempt has been made to explore the
potential resource of aluminium from kaolin of Pugu hills, Tanzania for combination tanning. Though, extraction of aluminium from several resources are available, there is limited literature pertaining to
Tanzania resources. Moreover, the extracted aluminium is basified and studied for its tanning efficiency.
Diffraction and vibrational spectroscopic studies were carried out to assess the confirmation of extracted aluminium. Combination tanning has been carried out with vegetable tannins and dialdehyde starch
tanning chemicals, which are from natural resources. Leathers tanned with aluminum and wattle resulted with a shrinkage temperature of 118ºC as compared to Al-Dialdehyde starch leathers showed around
90-100ºC. Physical strength characteristics such as tensile, tear and grain crack strength met the standard norms. Grain surface of leathers are found to be smooth which has been confirmed through microscopic studies. The study provides a new insight on accomplishing self sustainability through available resources and manufacture of eco-friendly system.
Take-Away:
1. Tanzania is endowed with massive kaolin rich in aluminium, which is potential for application in leather industry for sustainable development of leather industry
2. The combination tanning system using aluminium from Tanzania kaolin with wattle tannins or Dialdehyde starch imparts leather with both physical and organoleptic properties that meet the stipulated norms
3. This new tanning system provides new insight on ecofriendly tanning system for the sustainability of leather industry.
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Chemical modification of starch in order to get thermoplastic propertiesHallbert, Emma, Wadman, Elsa January 2023 (has links)
There are numerous advantages of replacing traditional non-biodegradable synthetic plastics with bio-based plastics. Starch is globally available, cheap, renewable, and biodegradable. However, starch has a poor product performance and is relatively difficult to process, as conventional melt processing techniques cannot be used. By introducing thermoplastic properties to starch, the mechanical properties and processability can be enhanced. The aim of the project was to modify starch and give it thermoplastic properties. The implementation of this included various experiments, where aromatic, cyclic and aliphatic side groups were added to the biopolymer. The effect of the different side groups provided valuable insight into how the material properties changed. Subsequently, the thermoplastic properties of the modified starch were analyzed by different analytical methods, including Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). In conclusion, the TGA showed lower thermal stability in the functionalized starch compared to native starch. Some indications of thermoplastic behavior were observed from the DSC. Trade-off between functionality and thermostability needs to be overlooked when aiming to increase thermoplastic behavior and future work should explore TEMPO oxidation, to obtain better results from the TGA. / Det finns många fördelar med att ersätta traditionella, icke-biologiskt nedbrytbara syntetiska plaster med biobaserade plaster. Stärkelse är globalt tillgängligt, billigt, förnybart och nedbrytbart. I nuläget har stärkelse dock en bristande produktprestanda och är relativt svår att bearbeta eftersom konventionella smält bearbetningstekniker inte kan användas. Genom att ge stärkelse termoplastiska egenskaper kan man förbättra de mekaniska egenskaperna och bearbetbarheten. Syftet med projektet var därför att modifiera stärkelse och introducera termoplastiska egenskaper. Genomförandet av detta innefattade flera olika experiment där aromatiska, cykliska och alifatiska sidogrupper tillsattes till stärkelsen. Effekten av de olika sidogrupperna gav värdefull insikt i hur materialegenskaperna förändrades. Därefter analyserades de termoplastiska egenskaperna hos den modifierade stärkelsen med olika analytiska metoder, inklusive Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) och Differential Scanning Calorimetry (DSC). Slutsatsen var att TGA visade en lägre termisk stabilitet hos den funktionaliserade stärkelsen jämfört med i den naturliga stärkelsen samt att vissa indikationer på termoplastiskt beteende observerades med hjälp av DSC analysen. En avvägning mellan funktionalitet och termisk stabilitet bör tas i beaktande i strävandet efter att öka termoplastiskt beteende. Framtida arbete inom ämnet rekommenderas att utforska TEMPO-oxidation för att uppnå bättre resultat från TGA.
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Functionalized nanocelluloses in wastewater treatment applicationsSuopajärvi, T. (Terhi) 31 March 2015 (has links)
Abstract
The chemicals currently used for wastewater treatment are mainly based on synthetic inorganic or organic compounds. Oil-derived polyelectrolytes are used for the removal of colloidal solids from wastewater by flocculation and coagulation, for example, while activated carbon adsorbents are typically used to remove soluble impurities such as heavy metals and recalcitrance organic matter. Many of these chemicals have associated negative health impacts, and use of activated carbon has proved to be expensive. Moreover, the present synthetic chemicals are not readily biodegradable or renewable. Thus there is a high demand for “green” water chemicals which could offer a sustainable solution for achieving high-performance, cheap water purification.
Water chemicals of a new type based on nano-scale particles (nanofibrils) derived from cellulose, i.e. nanocelluloses, are examined as possible bio-based chemicals for wastewater treatment. Two anionic nanocelluloses (dicarboxylic acid, DCC, and sulphonated ADAC) were tested as flocculants in the coagulation-flocculation treatment of municipal wastewater, while the flocculation performance of cationic nanocellulose (CDAC) was studied with model kaolin clay suspensions, and nanocelluloses produced from sulphonated wheat straw pulp fines (WADAC) were tested for the adsorption of lead (Pb(II)).
The anionic nanocelluloses (DCC and ADAC) showed good performance in treating municipal wastewater in a combined coagulation-flocculation process with a ferric coagulant. In the case of both anionic nanocelluloses the combined treatment resulted in a lower residual turbidity and COD in a settled suspension with highly reduced total chemical consumption relative to coagulation with ferric sulphite alone. Likewise, the CDACs resulted in powerful aggregation of kaolin colloids and maintained effective flocculation performance over wide pH and temperature ranges. The capacity of the nanofibrillated and sulphonated fines cellulosics (WADAC) for the adsorption of Pb(II) was 1.2 mmol/g at pH 5, which is comparable to the capacities of commercial adsorbents. / Tiivistelmä
Jätevesien kemiallinen käsittely pohjautuu pääsääntöisesti synteettisten epäorgaanisten ja orgaanisten kemikaalien käyttöön. Öljypohjaisia polyelektrolyytteja käytetään kolloidisten partikkeleiden poistamiseen jätevesistä koaguloimalla ja flokkuloimalla, kun taas liuenneita epäpuhtauksia, kuten raskasmetalleja, poistetaan useimmiten adsorboimalla ne aktiivihiileen. Synteettiset vesikemikaalit valmistetaan uusiutumattomista luonnonvaroista ja niiden hajoaminen luonnossa voi olla hidasta, minkä lisäksi monet näistä käytetyistä synteettisistä vesikemikaaleista ovat terveydelle haitallisia. Aktiivihiilen käyttö puolestaan on kallista, johtuen sen korkeista valmistus- ja käyttökustannuksista. Uusille ”vihreille vesikemikaaleille, jotka tarjoavat ympäristöystävällisempiä, halpoja sekä tehokkaita ratkaisuja vedenpudistukseen, onkin suuri kysyntä.
Tässä työssä selluloosasta valmistettuja nanokokoisia partikkeleita, eli nanoselluloosia, on tutkittu yhtenä varteenotettavana biovaihtoehtona uusiksi kemikaaleiksi jätevesien puhdistukseen. Kahden anionisen nanoselluloosan (dikarboksyyli, DCC, ja sulfonoitu, ADAC) flokkauskykyä testattiin koagulointi-flokkulointi reaktioissa kunnallisen jäteveden puhdistuksessa. Kationisen nanosellun (CDAC) flokkauskykyä tutkittiin puolestaan kaoliinisaven malliliuoksilla ja vehnän korsisellun hienoaineista nanofibrilloimalla sekä sulfonoimalla valmistetuilla (WADAC) nanoselluloosamateriaaleilla testattiin lyijyn (Pb(II)) adsorptiota vesiliuoksista.
Anioniset nanoselluloosat (DCC ja ADAC) toimivat tehokkaasti kunnallisen jäteveden flokkauksessa ferri-sulfaatin kanssa yhdistetyissä koagulointiflokkulointi reaktioissa. Yhdistetyissä reaktioissa molemmat anioniset nanoselluloosat vähensivät sameutta sekä COD pitoisuutta laskeutetuissa jätevesinäytteissä huomattavasti pienemmillä kemikaalikulutuksilla paremmin kuin pelkästään ferri-sulfaatilla koaguloitaessa. Myös CDAC:t toimivat tehokkaasti flokkauksessa keräten tehokkaasti kaoliinin kolloidipartikkeleita yhteen laajalla pH- ja lämpötila-alueella. Nanofibrilloidun ja sulfonoidun vehnäsellun hienoaineen (WADAC) adsorptiokapasiteetti lyijylle Pb(II) oli 1.2 mmol/g pH:ssa 5, mikä on verrannollinen kaupallisten adsorptiomateriaalien kapasiteettiin.
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Vers des thermodurcissables bio-sourcés : polybenzoxazines à partir de cardanol et composites à base de dialdéhyde cellulose / Towards greener thermosets : cardanol-based polybenzoxazines and dialdehyde cellulose based compositesGanfoud, Rime 10 December 2018 (has links)
L’utilisation et la valorisation de ressources renouvelables dans le domaine de la chimie connait un intérêt grandissant pour remplacer les ressources fossiles. Le travail présenté dans ce manuscrit de thèse est axé sur deux ressources bio-sourcées utilisées pour la préparation de thermodurcissables bio-sourcés : huile végétale et biomasse lignocellulosique. La première partie concerne les polybenzoxazines. A partir d’un monomère à base de phénol, le caractère bio-sourcé est progressivement augmenté par substitution du phenol par du cardanol. Le cardanol est un dérivé phénolique bio-sourcé extrait de l’huile de coque de noix de cajou. Une première étude se concentre sur les effets apportés par cette chaine alkyle sur la réactivité et les propriétés finales du matériau. Par la suite, la réaction de polymérisation du composé de référence est évaluée par des études cinétiques, corrélées aux analyses thermo-mécaniques pour une meilleure compréhension de la réaction de polymérisation. La seconde partie de cette thèse se concentre sur la préparation de composites totalement bio-sourcés, avec des microfibrilles de cellulose (MFC) modifiées pour obtenir des dialdehyde cellulose (DAC). Le poly(alcool furfruylique) (PFA) est une matrice bio-sourcée polymérisée à partir d’alcool furfurylique (FA) et d’anhydride maléique, tous deux obtenus à partir du HMF. Les propriétés du PFA peuvent être modifiées en y incorporant un renfort, tel que la cellulose. La modification de MFC par oxydation génère des fonctions aldéhydes réactives qui améliorent la compatibilité avec la matrice. Cette étude compare différents composites préparés à partir de MFC oxydée à différents DO pour déterminer quel DO entraine une meilleure compatibilité. Pour finir, des matériaux préparés à partir d’une unique source de cellulose, les « all cellulose composites », ont fait l’objet de la dernière étude. Deux différents renforts furaniques ont été utilisés pour contrer les problèmes de sensibilité à l’humidité de la cellulose, et donc augmenter l’hydrophobicité. / To reduce the use of finite petroleum-based resources, interest has grown regarding the valorization of renewable resources in chemistry. The work presented in this thesis focused on two bio-based resources: plant oil and lignocellulosic biomass, for the preparation of greener thermoset materials. The first part discussed about polybenzoxazine thermosets. The bio-based content was gradually increased through substitution of petro-based phenol by bio-based cardanol. Cardanol is a natural phenolic derivative extracted from the cashew nutshell liquid. A first study focused on the effect of this aliphatic side chain and how it can tune the reactivity and the final thermo-mechanical properties of the materials. In the following study the reactivity of polymerization of di-phenol monomer was investigated using advanced isoconversional analyses and thermo-mechanical analyses for a better understanding of the polymerization reaction. The second part discussed about the preparation of fully bio-based composites using modified cellulose microfibrils (MFC). Poly(furfuryl alcohol) (PFA) is a bio-based matrix obtained after polymerization of furfruyl alcohol (FA) with maleic anhydride, both obtained from HMF. The PFA properties can be modified by the introduction of cellulose as a filler. MFC was modified by oxidation to lead to reactive dialdehyde functions. By varying the degree of oxidation (DO), the properties of different composites were studied to determine the most adequate DO for the better PFA/MFC compatibility and the most adequate PFA/MFC ratio. Finally, the last study of this thesis focused on the concept of “all cellulose composites” (ACC), and particularly how to reduce the moisture sensitivity of these materials. Two different furanic compounds were used as cross-linkers to increase the hydrophobicity: a first compound with one furan ring and a second with two furan rings.
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A Pragmatic Approach Towards the Manufacture of Wet-White Leathers Using a Bio-Polymeric Tanning SystemKariuki, Peter, Yasothai, A., Jayakumar, G. C., Kanth, S. V. 28 June 2019 (has links)
Content:
Different tanning materials endow leather with varying colors observable in undyed leathers. Periodateoxidized starch tanned leathers have a yellow tinge or light brown color and get darker with age. The color change in situ is ascribable to iodate ions that are byproducts of periodate oxidation. Iodate ions undergo reduction to form iodine molecules that are yellow or brown in low or at higher concentrations. This study focuses on the removal of iodate ions from Dialdehyde Tapioca Starch (DTS) using a simple precipitation method. Preparation of DTS is by periodate oxidation and precipitation of iodate ions using an inorganic precipitant. The experiments for manufacturing wet-white leathers used pickled goatskins and DTS (unmodified and modified) tanning agents at various percentages based on pelt weight. Glutaraldehyde (GTA) tanning was the control. The percentage removal of iodate ions in modified DTS was 98%. Both unmodified and modified DTS had an aldehyde content of 70%. FT-IR and 1H-NMR confirmed the aldehyde groups. GTA, unmodified, and modified DTS tanned leathers had shrinkage temperatures of 80, 87, and 89°C, respectively. The physico-mechanical properties of the control and experimental leathers are comparable. GTA tanned leather had the typical brown color associated with GTA tannages. The ‘b’ color value of unmodified DTS tanned leather was high confirming yellowing of leathers upon ageing. Wet-white leather tanned with modified DTS had no discernible color change. Analysis of the spent tan liquor shows a reduction in the BOD, COD, TS, and TDS load when compared to GTA tanning system evincing the biodegradability of DTS. This study has overcome the drawback associated with periodate-oxidized starch tanning agents, viz. leather darkening over time, considering the chemical and physico-mechanical properties of the resultant leathers. The novel iodate free DTS can be scaled-up for commercial availability.
Take-Away:
Removal of iodate ions from periodate-oxidized starch before its use as a tanning agent is imperative to avoid leather color change over time.
This study reports the successful removal of iodate ions from Dialdehyde Tapioca Starch (DTS).
Wet-white leather tanned with the modified DTS had no observable color change upon ageing.
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Discovery and Development of Natural Products from Plant and Microbial Sources: Drimane Sesquiterpenes and Abyssomicins as Mosquito Control and Antimicrobial AgentsManwill, Preston Kim 13 November 2020 (has links)
No description available.
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