The purpose of this work was to understand
the effect of the acoustic
cavitation on the alkaline hydrolysis of wool and compare it with
a conventional method of steam based alkaline hydrolysis. In acoustic
cavitation assisted alkaline hydrolysis, the effect of concentration
of solid (wool) and alkali on the properties of wool were also investigated.
In conventional alkaline hydrolysis, the experiments were carried
in a laboratory scale autoclave at temperature of 120 °C and
pressure of 2 bar for 15 min. While acoustic cavitation assisted hydrolysis
was carried out using the untreated and treated wool, hydrolyzed samples
were characterized using FTIR, TGA and DSC to find out the extent
of structural degradation occurring as a result of the treatment.
It was observed that both the processes resulted in to a cleavage
of disulfide bonds in wool, which cross-link the protein chains and
are responsible for the higher stability and lower solubility of wool.
However, the acoustic assisted alkaline hydrolysis is an environmentally
friendly and less energy intensive process as it was performed at
room temperature. The wool hydrolysates produced using acoustic assisted
alkaline hydrolysis could find a potential application in agricultural
fields such as fertilizer, soil improvement additive, etc.
The purpose of this work is to understand the impact of superheated water hydrolysis treatment on the chemical properties of wool, and compare it with a conventional method of alkaline hydrolysis. The effects of hydrolysis temperature and concentration of alkali on the properties of wool were investigated. Superheated water hydrolysis was carried out at the temperatures of 140℃ and 170℃, with a material to liquor ratio of 1:3 for 1 hour. In conventional alkaline hydrolysis, the experiments were carried out in the same conditions using potassium hydroxide (KOH) and calcium oxide (CaO) with a concentration in the range of 5%–15% on the fiber weight (o.w.f.). The effects of hydrolysis temperature and alkali concentrations on wool properties were checked using optical and scanning electron microscopy. It was observed that the hydrolyzates obtained in both cases contained low molecular weight proteins and amino acids. Both the hydrolysis processes resulted in degradation of the wool fibers. However, superheated steam hydrolysis is an environmentally friendly and less expensive process, as it is performed using water as a solvent. The wool hydrolyzates produced using superheated water hydrolysis could find a potential application in agriculture, such as fertilization, soil improvement and suchlike.
A large amount of coarse wool, practically
unserviceable for textile use, is generated in Europe from sheep shearing
and butchery. Such a byproduct is either dumped, burned, or sent to
landfill. Following the European Commission regulations on animal
byproduct control, unserviceable raw wool is classified as a category
3 special waste materials. The collection, storage, transport, treatment,
use, and disposal of such unserviceable raw wool are subject to European
Union regulations because of a potential risk to human and animal
health. This study aims at converting the waste wool into nitrogen
fertilizers at a commercial scale for grassland management and cultivation
purposes. The chemical transformation of waste wool in to fertilizer
is based on a green economically sustainable hydrolysis treatment
using superheated water. The experiments were carried out in a semi-industrial
reactor feeding superheated water. The wool/superheated water system
was maintained for different reaction times. The optimal conditions
for this treatment were as follows: 170 °C for 60 min with a
solid to liquor ratio (MLR) close to 1. The hydrolyzed product was
analyzed using amino acid analysis and molecular weight distribution.
Both the amino acid and molecular weight distribution analysis revealed
that the wool was completely degraded and the hydrolyzed product contains
a low molecular weight proteins and amino acids. Several hydrolyzed
product obtained at different conditions were tested for germination
which showed a germination index higher than 100% without collateral
phytotoxicity. The presence of amino acids, primary nutrients, and
micronutrients in wool hydrolyzates, along with a concentration of
heavy metals below the standard limit, confirm the possibility of
using wool hydrolyzates as a nitrogen based ecologically sound fertilizer.
A large
amount of wool produced in the EU region is coarse and of low quality.
The limited or nonutilization of such coarse wool leads to landfilling
causing environmental pollution. In this paper, we studied the properties
of keratin hydrolyzate, produced by a sustainable hydrolysis process,
to be used as a foaming agent in foam dyeing of cotton and wool fabrics.
This is a preliminary step on the way to find possible applications
which overcome the environmental problem of wool waste and byproducts.
We report for the first time the use of keratin hydrolyzate as a foaming
auxiliary in the textile dyeing process. The surface tension, molecular
weight, foam stability, blow ratio, and bubble size of keratin hydrolyzate
in aqueous solutions with and without dyeing auxiliaries were determined.
The dyeing influential parameter such as wet pickup was studied to
identify their effect on dye fixation and color strength. The foam
dyeing was compared with conventional cold-pad batch and pad-steam
processes for cotton and wool, respectively. In the investigated variant,
keratin hydrolyzate shows a reduction in surface tension, good foam
stability along with dyeing auxiliaries, a blow ratio of about 10:1,
and 0.02–0.1 mm diameter bubble sizes. These results make possible
its application as a foaming agent. Cotton and wool fabrics were dyed
using reactive and acid dyes respectively, on a horizontal padding
mangle. In both cases, hydrolyzed keratin acts as a carrier for dye
molecules and the mechanism of dyeing depends on the respective pH
of the dye solution, keratin, and fiber. Foam dyeing of cotton resulted
in comparable color strength, while wool shows higher color strength
when compared with conventional dyeing processes. Washing and rubbing
fastness of cotton and wool foam dyed fabrics are similar to the respective
conventional dyed fabrics. The combinations of sustainable keratin
hydrolyzate production and its use as an eco-friendly, biodegradable
foaming agent in less add on foam dyeing technology resulted not only
in saving of large amounts of water and energy but also will be helpful
in minimizing a load on effluent and the environment.
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