46 ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version) Fibers and Polymers 2015, Vol.16, No.1, 46-53 Response Surface Methodology Optimized Dyeing of Wool with Cumin Seeds Extract Improved with Plasma Treatment Aminoddin Haji* and Sayyed Sadroddin Qavamnia Textile Engineering Department, Birjand Branch, Islamic Azad University, Birjand 9717711111, Iran (Received April 11, 2014; Revised August 3, 2014; Accepted August 27, 2014) Abstract: In this study, the aqueous extract of Cuminum Ciminum L. seed was applied on wool as a novel natural colorant. Gas chromatography coupled with mass spectrometry was conducted to identify the composition of the extract. Response surface methodology and D-optimal design were employed to investigate and optimize the effects of three independent factors including mordant concentration, dyeing pH and temperature on the color strength of dyed samples. A statistical model was obtained to correlate between the amounts of three independent factors and color strength of dyed samples as the response. Low pressure plasma treatment using oxygen, argon, and their mixture was employed to improve the dyeability of wool fibers. The effect of different plasma treatments on the surface chemistry and morphology of wool fibers were studied using attenuated total reflectance-Fourier transform infrared spectroscopy and field emission scanning electron microscopy, respectively. The fastness properties of dyed samples were also investigated. Keywords: Plasma, Wool, Natural dye, Response surface methodology, Gas chromatography-mass spectrometer Introduction After the discovery of Mauveine by Perkin in 1856, synthetic dyes quickly replaced the traditional natural dyes. They cost less, offer a vast range of new colors, and impart better properties to the dyed materials. However, synthetic dyes are known to be a major source of environmental pollution and their excessive use has led to serious health hazards and disturbances in the eco-balance of nature [1,2]. Due to the toxic nature and harmful effects associated with synthetic dyes, today there is a great tendency to revive the tradition of using natural dyes as these dyes are safe, eco- friendly and produce beautiful attractive shades. The use of biodegradable natural dyes can replace and significantly minimize the volume of toxic effluent resulting from the conventional dyeing process [3,4]. They have the potential to be included for sustainable development of materials related to textiles if the harvesting of such dyes is done sensibly without posing threats to the environment. However, natural dyes are presently replaced by synthetic dyes chiefly due to their poor color fastness properties and low color yield [5]. The majority of studies on natural dye sources and dyestuff extraction are focused on collecting plant materials from the wild and exploring the coloring properties of extracts from different plant parts. However, direct commercial use of native plants in dyestuff production without investigating sustainability issues may lead to overexploitation of natural resources. Studies focusing on agronomic potential and related environmental consequences related to the harvesting of natural dye yielding crops are rare [6]. Research on new natural dye sources along with eco- friendly, robust, and cost-effective technologies for their processing and application has a great effect of widening the scope of natural dyes in various traditional and advanced applications [6]. Low color yield of source natural dyes necessitates the use of more dyestuffs, higher dyeing time, and excess cost for mordants and mordanting. Almost all of the natural dyes show poor exhaustion and usually a pretreatment or a suitable fixing agent under the dyeing process is needed [7]. Plasma technology is used to impart functional finishes to textile materials without the use of harmful chemicals or water [8,9]. Plasma treatment removes the lipid layer and the surface cuticle of wool without affecting its bulk properties. The treatment can improve the wetting ability and increase dye uptake, leading to an enhancement in the depth of shade and evenness [10,11]. Cumin (Cuminum cyminum L.) is an aromatic plant included in the Apiaceae family and is used to flavor foods, added to fragrances, and for medical preparations [12]. It is a wild grassy plant, growing in various parts of Iran. It is also widely implanted in several places in Iran. In Iranian folk medicine, cumin seeds have been used to treat diarrhea, toothache, and epilepsy. Cumin has been found to possess antioxidant, anticancer, stimulant, and carminative phar- macological properties [13,14]. The chemical composition of the cumin seed extract has been extensively studied [13]. It contains several aromatic compounds which are capable of being used as a source of natural dye for wool dyeing. Tayade and Adivarekar have studied the adsorption kinetic of cumin seeds dye on silk fabric in terms of enthalpy, entropy changes, and activation energy of adsorption and found that the kinetics of cumin dye on silk fabric follows the pseudo second order model [15]. Optimization of the dyeing process is important in gaining the best conditions of the dyeing procedure and amounts of reagents while the exhaustion remains at the highest level *Corresponding author: Ahaji@iaubir.ac.ir DOI 10.1007/s12221-015-0046-5