Natural colorant from the bark of Macaranga peltata: kinetic and adsorption studies on silk

Abstract

The colour component from the bark of Macaranga peltata has been extracted and, using spectral techniques, the main colouring ingredient has been identified as ellagic acid. The dyeing properties of the extract on silk have been studied. The colour coordinates of the dyed samples were found to be in the yellow-red quadrant of the colour space diagram and the dyed samples exhibited acceptable fastness properties. The effect of temperature and dye concentration on the rate of dyeing has been studied. Adsorption studies revealed that the process fits well with the Langmuir isotherm model. The thermodynamic parameters of the dyeing process have been evaluated using an Arrhenius plot. The experimental results revealed that the adsorption was exothermic and spontaneous in nature, and exhibited first-order kinetics. Further, the effect of electrolyte on rate of dyeing has also been recorded. The rate of adsorption increases as the disrupting effect of the added electrolyte cation increases and follows the order: Al 3+ > Ca 2+ > Na + . ª

Mechanistic Investigations of Ruthenium(III) Catalyzed Oxidation of L-Tryptophan by Diperiodatocuprate(III) in Aqueous Alkaline Media (Stopped Flow Technique): A Kinetic Study

“…However, the Michaelis-Menten plot also proved the complex formation between catalyst and reductant, which explains the less than unit order dependence on [L-trp]. Such type of complex between a substrate and a catalyst has been observed in other studies [27]. 2-]) of denominator of equation 8can be neglected as compared with higher values of other terms in the denominator in the view of low concentrations of Ltryptophan and periodate used in the study.…”

Metal mordanting in dyeing with natural colourants

“…The changes in colour depth vs light fastness grades in dyeings mordanted with aluminium (), tin (), iron (), chromium (), and copper () salts . Quadrants are indicated by Roman numerals in part (a) of the figure.…”

“…Mordants are agents applied onto substrates before, during, or after the coloration step (termed pre‐, meta‐, and post‐mordanting respectively). Plant polyphenols such as tannins and tannic acid function as mordants , but metal salts are by far most commonly used.…”

Mechanistic Aspect of Iridium(III) Catalyzed Oxidation of Ethylene Glycol by Chloramine-T in Aqueous Acidic Medium: A Kinetic Model

“…The versatile nature of N-haloamines is attributed to the presence of halonium cations and nitrogen anions in their structure, which can act as both a base and a nucleophile [1][2][3][4][5]. As a result, these compounds can react with a wide range of functional groups to cause numerous kinds of molecular changes.…”