The poultry industry produces a great amount of waste feathers
each year, e.g. 1.8 million tons in US [1], which causes an environmentally
difficult disposal problem. Therefore, from both an
economic and environmental point of view, it is quite desirable
to develop effective and profitable process to use these resources.
However, feathers are mainly used as low nutritional value animal
feed. Currently, researchers have been searching for new applications
of feathers and many publications and patents proposing
applications of feathers have been issued. Polyethylene-based composites
can be prepared using keratin fibers obtained from chicken
feathers [2]. Keratin fibers from chicken feathers were used as a
short-fiber reinforcement for a poly(methyl methacrylate) matrix
[3]. Feather keratin and polyurethane were combined to synthesize
hybrid synthetic-natural membranes which could be applied
to separation process [4].
Keratin is the major component of feathers, which is a structural
protein characterized by a high cystine content and a significant
amount of hydroxyl amino acids, especially serine (about 15%) [5,6].
It contains a range of noncovalent interactions (electrostatic forces,
hydrogen bonds, hydrophobic forces) and covalent interactions
(disulfide bonds), which must be destroyed in terms of dissolution
of feathers. Keratin is insoluble in polar solvents like water,
weak acids and bases, as well as in apolar solvents while it is active
because cystine can be reduced, oxidized and hydrolyzed [7–11].
However, one of the most serious shortcomings concerning these
methods for extracting keratin is that a large quantity of reagents
such as acids or reductants is consumed and cannot be recycled.
Thus, researchers have focused on finding simple and eco-friendly
processing methods to dissolve feather keratin.
Recently, ionic liquids (ILs) have received recognition as green
and promising materials for potential applications in various fields
because they are typically non-volatile, non-flammable, chemical
and thermal stability and remarkable solubility [12–16]. They
have also been termed as ‘designer solvents’ as their properties
can be manipulated by a careful choice of cation/anion
according to the requirements. Ionic liquids exhibit excellent
solubility characteristics because of their special structures compared
to the traditional molecular solvents. Some recent works
have been reported regarding the dissolution and regeneration
of keratin fibers in ionic liquids. Xie et al. [17] reported the
dissolution and regeneration of wool keratin fibers in 1-butyl-3-
methylimidazolium chloride (BMIMCl) ionic liquid. Hameed et al.
[18] prepared natural wool/cellulose blends in BMIMCl and the
films were formed subsequently from the coagulated solutions. In
fact, the costs of ionic liquids are obviously higher than that of inorganic
reagents, but they can be reused and improve the efficiency of
whole process, leading to lower the overall cost. Separation of keratin
from hydrophilic ionic liquids after reaction is an inconvenient
and troublesome problem.
In this study, a hydrophobic ionic liquid ([HOEMIm][NTf2])
was used to dissolve chicken feathers to obtain keratin. The aim
of our research work was to extract keratin with hydrophobic
ionic liquids instead of acids and bases. The effects of mass ratio
of feathers and ionic liquid, mass ratio of feathers and NaHSO3,
reaction temperature and time on the extraction yield of keratin
were investigated and the reusability of ionic liquid was also studied.
Furthermore, the extracted keratin was analyzed by infrared
spectrometry (IR) to confirm its structure and determined by gel
permeation chromatography (GPC) to get its molecular weight
The poultry industry produces a great amount of waste featherseach year, e.g. 1.8 million tons in US [1], which causes an environmentallydifficult disposal problem. Therefore, from both aneconomic and environmental point of view, it is quite desirableto develop effective and profitable process to use these resources.However, feathers are mainly used as low nutritional value animalfeed. Currently, researchers have been searching for new applicationsof feathers and many publications and patents proposingapplications of feathers have been issued. Polyethylene-based compositescan be prepared using keratin fibers obtained from chickenfeathers [2]. Keratin fibers from chicken feathers were used as ashort-fiber reinforcement for a poly(methyl methacrylate) matrix[3]. Feather keratin and polyurethane were combined to synthesizehybrid synthetic-natural membranes which could be appliedto separation process [4].Keratin is the major component of feathers, which is a structuralprotein characterized by a high cystine content and a significantamount of hydroxyl amino acids, especially serine (about 15%) [5,6].It contains a range of noncovalent interactions (electrostatic forces,hydrogen bonds, hydrophobic forces) and covalent interactions(disulfide bonds), which must be destroyed in terms of dissolutionof feathers. Keratin is insoluble in polar solvents like water,weak acids and bases, as well as in apolar solvents while it is activeเนื่องจากสามารถลด cystine ออกซิไดซ์ และ hydrolyzed [7-11]อย่างไรก็ตาม แสดงรุนแรงส่วนใหญ่เรื่องเหล่านี้อย่างใดอย่างหนึ่งวิธีสำหรับการดึงข้อมูล keratin เป็นที่ reagents จำนวนมากเช่นกรดหรือ reductants มีการบริโภค และไม่สามารถรีไซเคิลดังนั้น นักวิจัยได้มุ่งเน้นในการค้นหาง่าย และเป็น มิตรกับสิ่งแวดล้อมวิธีการประมวลผลเพื่อละลาย keratin ขนล่าสุด ของเหลว ionic (ILs) ได้รับรู้เป็นสีเขียวและสัญญาวัสดุสำหรับโปรแกรมประยุกต์ที่เป็นไปได้ในฟิลด์ต่าง ๆเนื่องจากโดยทั่วไปไม่ใช่ระเหย ไม่ติดไฟ สารเคมีและความมั่นคงความร้อนแล้วละลายน่าทึ่ง [12-16] พวกเขานอกจากนี้ยังถูกเรียกว่าเป็น 'นักออกแบบหรือสารทำละลาย' เป็นคุณสมบัติของพวกเขาสามารถจัดการ โดยมาย cation/anion ระมัดระวังตามความต้องการ ของเหลว Ionic แสดงดีลักษณะการละลายเนื่องจากโครงสร้างพิเศษของพวกเขาที่เปรียบเทียบต้องการแบบโมเลกุลหรือสารทำละลาย ผลงานล่าสุดบางมีการรายงานเกี่ยวกับการยุบและการฟื้นฟูของเส้นใย keratin ในของเหลว ionic เจีย et al. [17] รายงานการยุบและฟื้นฟูของขนสัตว์เส้นใย keratin ใน 1-ด...-3 -คลอไรด์ (BMIMCl) ของเหลว methylimidazolium ionic Hameed et al[18] เตรียมเซลลูโลสธรรมชาติผ้าขนสัตว์ผสมใน BMIMCl และฟิล์มเกิดขึ้นมาจากโซลูชั่น coagulated ในความจริง ต้นทุนของของเหลว ionic จะชัดมากกว่าของอนินทรีย์reagents แต่พวกเขาสามารถนำกลับมาใช้ และปรับปรุงประสิทธิภาพของwhole process, leading to lower the overall cost. Separation of keratinfrom hydrophilic ionic liquids after reaction is an inconvenientand troublesome problem.In this study, a hydrophobic ionic liquid ([HOEMIm][NTf2])was used to dissolve chicken feathers to obtain keratin. The aimof our research work was to extract keratin with hydrophobicionic liquids instead of acids and bases. The effects of mass ratioof feathers and ionic liquid, mass ratio of feathers and NaHSO3,reaction temperature and time on the extraction yield of keratinwere investigated and the reusability of ionic liquid was also studied.Furthermore, the extracted keratin was analyzed by infraredspectrometry (IR) to confirm its structure and determined by gelpermeation chromatography (GPC) to get its molecular weight
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