Wet process Engineering

Jute is popularly known as perishable, reusable and ecological friendly fiber having golden & silky shine appearance; therefore termed as the Golden fibre in Bangladesh. Jute is budget friendly vegetable fiber procure from the bast or skin of the plant's stem and most important fiber after cellulosic cotton fibre in terms of variation in usage, universal consumption generation & availability. Natural dyestuffs are popular now days for sustainable issues in textiles industries. This research was focused on environment friendly natural dyeing technique on jute fabric with natural dye sources through cold pad batch (CPB) dyeing technique. Java plum fruit, kadamba flower & malbar spinach vegetable were selected as natural dye sources and extracted dye liquors using methanol solvent. Evaluated dyed samples by color coordinate values by spectrophotometer where lighter to darker shades were achieved on dyed jute samples with the dye extracts and K/S value was analysis to assess color strength among dyed samples. Different Color fastness test was done to find better dyeing performance on jute where sample dyed with malbar spinach vegetable extract showed better performance compared to other dye extracts. Moreover, the research was intended to observe dyeing possibilities of jute fabric with natural sources without focusing on mordant for opening a new export area of sustainable dyed jute goods maintaining sustainable textile processing.

Today's environmental concern about the harmful effects of synthetic dyestuffs has arisen in our discourse on the use of natural dyes. Plant dyes are more favorable due to their non-toxicity, non-carcinogenic, non-allergic, and biodegradability over synthetic dyes to human beings. This work is intended to investigate the effects of three different natural yellow shaded dyes on the 100% cotton knit fabric using four kinds of synthetic mordant. A series of experiments were conducted to analyze and compare the results of these three sources of natural yellow dyes. Simultaneous extraction and dyeing methods were found to yield the best hues of yellow dye, as decided by colorimetric tests and visual analysis. The final samples were tested for fastness to light, wash, rubbing and perspiration by following the ISO standards. A significant change was observed in fastness properties and colorimetric analysis on copper sulphate treated turmeric dyed sample.

This paper focuses on the effect of different concentration of hydrogen peroxide (an oxidizing bleaching agent) on 100% single jersey cotton knit fabric. Five different concentrations (25%, 30%, 35%, 40% and 45%) of hydrogen peroxide solution (5% stock solution) were adopted for this experiment. For each individual concentration, bleaching was performed in three different quantities (6gm/L, 8gm/L and 10gm/L) at the same temperature (100˚C) and same time (60 minute) cycle. 5gm samples were taken where 1:10 material and liquor ratio was maintained in each operation. Spectrophotometer (data color 650) was used to test the reflectance of all bleached samples, and their bursting strengths were measured by an Auto burst instrument following ISO 13938-1 method. The effects of hydrogen peroxide concentration on various physical properties such as weight loss, absorbency, GSM, bursting strength, and whiteness was studied to minimize the cost of bleaching process by optimizing the concentration of hydrogen peroxide. As majority of industries have concerned to alineate the production cost with maximum quality assurance which has been obtained through bleaching at 30% concentration.

This paper focuses on the effect of different concentration of hydrogen peroxide (an oxidizing bleaching agent) on 100% single jersey cotton knit fabric. Five different concentrations (25%, 30%, 35%, 40% and 45%) of hydrogen peroxide solution (5% stock solution) were adopted for this experiment. For each individual concentration, bleaching was performed in three different quantities (6gm/L, 8gm/L and 10gm/L) at the same temperature (100˚C) and same time (60 minute) cycle. 5gm samples were taken where 1:10 material and liquor ratio was maintained in each operation. Spectrophotometer (data color 650) was used to test the reflectance of all bleached samples, and their bursting strengths were measured by an Auto burst instrument following ISO 13938-1 method. The effects of hydrogen peroxide concentration on various physical properties such as weight loss, absorbency, GSM, bursting strength, and whiteness was studied to minimize the cost of bleaching process by optimizing the concentration of hydrogen peroxide. As majority of industries have concerned to alineate the production cost with maximum quality assurance which has been obtained through bleaching at 30% concentration.

The present research work was conducted on developing sustainable production of mulberry filament silk fabric dyed with different extracted dye solutions based on extraction ratios of 1:4,
1:6, 1:8, and 1:10 from neem (Azadirachta indica) leaves. The research work focused on evaluating the
antimicrobial and mosquito repellent properties of dyed silk fabric. In the experiment, the samples
were dyed using the exhaust method at different dye bath concentrations i.e., 15 g/L, 20 g/L, and
25 g/L in the presence and absence of mordant at 80 ◦C maintaining 1:60 dyeing liquor ratio. The
absorbance of the extracted dye solutions was determined with a UV/VIS spectrophotometer, which
detected the highest absorbance of 7.73 at the peak 490 nm of λmax of 1:4 extracted dye solution.
Fourier transform infrared (FTIR) spectroscopy was used to investigate the chemical structure of
dyed fabrics; however, no chemical changes or bond formation occurred; instead, dye particles were
deposited on the fabric layer, indicating the presence of bioactive components. Allergy test was also
performed to confirm allergic reactions of neem extract on human skin. The antimicrobial activity
of extracted dye solutions and dyed samples was estimated against Gram-positive (Staphylococcus
aureus) and Gram-negative (Escherichia coli) bacteria using the agar diffusion method and mosquito
repellency of fabrics were examined by the cage method. The results emphasized that dyed fabric
with the highest concentrated dye solution, 1:4 extraction, and highest dye bath concentration, 25 g/L
along with mango bark mordant solution, possesses the highest antimicrobial activity in terms of
an inhibition zone of 0.67 mm against Gram-negative bacteria and 0.53 mm against Gram-positive
bacteria obtained after incubation, and the highest mosquito repellent of 75% due to the absorption
of active bio constituents. The experimental results also determined that the dyed fabric with 1:4
extracted dye solution exhibited good antimicrobial (inhibition zone, 0.65 mm against E. coli and
0.52 mm against S. aureus) and mosquito repellent property (66.67%). The experimental study also
revealed that Potassium dichromate mordant reduced the antimicrobial (inhibition zone, 0.05 mm
against E. coli and no inhibition against S. aureus) and mosquito repellent action (33.33%). In conclusion, the data revealed that the increase in the extraction ratio of dye solution and dye bath
concentration has no impact on the silk fibroin; it only impacts what is deposited on the fabric layer
that improves its antimicrobial and mosquito repellency. The current research showed that neem
leaves were found to have a beneficial effect in controlling microorganisms and mosquitoes through
a sustainable approach.