Gunda Gundo orange fruits are cultivated in abundance in the northern region of Ethiopia. Their peels are rich in carotenoid content and could seve as a potential feedstock for natural dye extraction. The aim of this study is to valorize Gunda Gundo orange (Citrus sinensis) peels (GGOP) for dye synthesis followed by its application on dyeing cotton fabric. The natural dye extracted from this renewable biomass feedstock, could reduce environmental contamination, contribute to energy saving and in addition, improvise the livelihood of the farmers cultivating this variety of oranges. The dye extraction was performed using the soxhlet extraction method, in which the effect of extraction temperature (65°C, 72.5°C, 80°C), extraction time (1.5h, 3.25h, 5h) and GGOP to ethanol ratio (0.05g/mL, 0.075g/mL, 0.1g/mL) was studied and optimized by a three-variable, three-level Box–Behnken design using Response Surface Methodology (Design experiment software version 11). A maximum yield of natural dye (40.11%) was achieved at 0.066g/mL GGOP to ethanol ratio at 4.995 h and 79.97°C with a high combined desirability. The high-performance liquid chromatography analysis showed a peak for Gunda Gundo orange peel powder based carotenoid (GGC) dye at R_t value of 2.005 with 3.423 mg/mL dye concentration. Further characterization using Fourier-transform infrared spectroscopy showed the presence of phenols, alkanes and amines. The GGC dye produced were applied onto cotton fabric, using Na₂CO₃ as fixative. Color dyeing and testing were carried out with data color tool analysis (L*, a*, b*) and fastness properties were investigated according to the American Association of Textile Chemists and Colorists (AATCC-61) and the International Organization for Standardization crocking ISO 105 X12 methods. The washing fastness and rubbing fastness for 4% GGC dyed fabric was higher than that of 1% and 2% GGC dyed fabric. The dyed cotton sample from 4% GGC concentration was red, as shown by the International Commission on Illumination CIELAB color space (CIE L^*a^* b^*). The value of a^* (redness) obtained in dyed cotton fabric was as well higher than 1% and 2% GGC. The dye exhibited a good color strength and this suffices the valorization of locally available Gunda Gundo orange peels for natural dye synthesis.

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