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Natural dyes are mostly used for dyeing of natural fibre textiles to improve their eco-friendly features. For successful commercial use of natural dyes, the appropriate and standardized dyeing techniques need to be adopted. Appropriate scientific techniques or procedures need to be derived from scientific studies on dyeing methods, dyeing process variables, dyeing kinetics and compatibility of selective natural dyes with minimal use of hazardous chemicals.

In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the study are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept.

Experiments showed that enzymatic treatment can give good colour strength to silk fabric using Rubia as a dye source and has good potential for commercial dyeing. It is a non-toxic dye. Use of enzymes were a deliberate attempt to avoid metal mordanting in silk dyeing, as it would make textile dyeing eco-friendlier. The order of reactivity of enzymes in one-step process was found to be protease > phytase > xylanase > amylase > pectinase. Similarly, for two-step dyeing process, the order of reactivity of enzymes observed was protease > amylase > xylanase = pectinase > phytase. Protease enzyme was the best option in both the cases. Overall, it can be concluded that in the case of enzymatic treatment, the two-step process was better in terms of larger K/S values, colour coordinate values and dye adherence.

A new domain of room temperature dyeing technique has been introduced.

In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the research are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept. Overall, the ease of use for industrial application. Rubia dye from Sri Lanka has been used in conjunction with different enzymes to show that metal mordanting can be easily replaced by the use of eco-friendly and biodegradable enzymes. The most attractive feature of this study is the low-temperature dyeing at 30-40°C. For any dyeing house, this process can be easily adapted on jigger, winch or even in continuous padding machine. Good fastness properties and dye adherence have been the other highlights of this study.

It is recognised that environmental air pollution is one of the global problems and is a common problem for both developing as well as developed countries. In the era of globalisation, it is the most important global environmental issue. In general, urban air quality is becoming vulnerable especially in the developing countries due to adopting various developmental schemes. Air pollution problem in Kolkata, capital city of West Bengal, is under serious for a long day. As per guidelines of World Health Organization, for residential areas, air pollution level in Kolkata is considerably higher than the standard enumerated. There are several types of air pollutants which are continuously exposing the air of Kolkata. West Bengal pollution control board (WBPCB) has been monitoring ambient air quality (AAQ) for the parameters viz. suspected particulate matters (SPM), respiratory particulate matters (RPM), sulphur dioxide (SO₂), nitrogen dioxide (NO₂) and lead (Pb) in Kolkata throughout the years. Present study has been designed to determine the vertical floor-wise air quality status of the city of Kolkata and the seasonal variation of the pollutants over the consecutive years from 2011 to 2017. It is demonstrated that the air pollution is the highest in the winter due to dry weather, second is festive season followed by winter due to heavy movement of vehicles and pedestrians for festival shoppings as well as pandel hoppings and then next is summer. But coming to the point of rainy season, this is the lowest due to wetted air or wind of monsoon. This chapter attempts to understand the long-run trend of air pollution as the periodical average value suggests.