Optimization of dyeing process variables for eco-friendly dyeing of cotton fabric with babul bark extract as a natural dye and gallnut extract as a bio-mordant

ABSTRACT

In the present study, cotton fabric has been dyed with aqueous extract of babul bark (Acacia nilotica) using gallnut (Quercus infectoria) as bio-mordant containing hydrolyzable tannins like gallic acid, elagic acid and polyphenolic gallotannins to produce light yellow color. On the other hand when gallnut bio-mordanted cotton is subsequently dyed with babul bark extract as a natural dye containing similar but non-hydrolyzable tannin-rich color component including small amount of catechin and epi-gallo-catechin, it produces a medium to deep brown color through formation of giant insoluble colored complex of cotton-gallotannins (gallnut)-catechin/epigallocatechin and other color components present in babul bark extract. The process variables for extraction, pre-mordanting and dyeing have been optimized to standardize this dyeing technique. Scattered CDI values for dye-bath pH and dye concentration identified them as the most important dyeing parameters that need to be controlled for obtaining uniform dyeing. High UPF value of upto 35 rendered by application of both gallnut and babul bark through preferential absorption of UV light by the gallotannins in both gallnut and babul bark indicates good UV protection properties of dyed cotton fabrics.

摘要

以五倍子 (Quercus infectoria) 为生物媒染剂, 含没食子酸, 亚麻酸, 多酚没食子酸等可水解单宁, 用巴布树皮水提液 (Acacia nilotica) 对棉织物进行染色, 得到浅黄色。另一方面, 当五倍子生物媒染棉随后用巴布尔树皮提取物作为天然染料染色时, 含有类似但不可水解的富含单宁的颜色成分, 包括少量儿茶素和表没食子酸, 通过形成棉花没食子酸 (五倍子) -儿茶素/表没食子儿茶素和巴布尔树皮提取物中存在的其他颜色成分的巨大不溶性有色复合物, 产生中等至深棕色. 对萃取, 预媒介和染色的工艺参数进行了优化, 使该染色技术标准化. 分散的染色浴pH值和染料浓度的CDI值表明它们是获得均匀染色所需控制的最重要的染色参数. 五倍子和巴布尔树皮通过五倍子和巴布尔树皮中的没食子酸对紫外光的优先吸收而获得高达35的UPF值, 表明染色棉织物具有良好的紫外线防护性能.

KEYWORDS:

• Babul bark
• bio-mordant
• cotton
• dyeing process variables
• gallnut
• upf

关键词:

• 巴布尔树皮
• 生物媒染剂
• 棉花
• 染色工艺变量
• 五倍子

SupplementaryMaterial

Supplemental data for this article can be accessed here.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.