جستجوی مقالات مرتبط با کلیدواژه « ماده رنگزای گیاهی » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Nowadays, despite the presence of synthetic dyes, due to the environmental damage caused by these substances, the approach of returning to natural sources has been revived. Meanwhile, the indigo plant is one of the best plant sources to achieve blue color. Much research has been conducted to extract dyes from indigo and woad since long ago. The purpose of this research is to collect the studies done in this field and, secondly, to use the results of previous research by researchers to improve the extraction methods. The results of the research showed that several methods, such as traditional, hot water, microbial, enzyme, microwave, etc., could be applied. It was also found that variables such as oxidation speed, oxidation time, alkaline environment of fermentation, type of alkaline material, resting time of fermentation, etc. influence the extraction process of indigo and woad dyes, the effect of pH is much important.</em>.</em>

Reseda luteola is a plant species in the genus Reseda. The common name is weld. The plant is rich in luteolin, a flavonoid that produces a bright yellow dye. This dye is more important and noticeable than other natural yellow dyes due to its high transparency and color strength, and better general fastness. Cellulose and waste tissue in natural dyes reduce the efficiency and quality of natural dyeing, occupy a large volume of dyeing equipment with dye plant pulp and complex dye matching. To make maximum use of the dye in the plant, applying the extraction methods is inevitable. Much research has been done in the field of dye extraction from this plant. Extraction of natural dyes from weld with the help of traditional methods such as boiling, soaking and steaming and modern techniques such as Soxhlet, microwave, ultrasound, plasma, membrane, critical liquid and the effect of various solvents such as water, methanol, ethanol, water-ethanol, and water Methanol as well as auxiliaries during dyeing and extraction have been considered by researchers. The results show the effectiveness of some extraction methods compared to the conventional method, different solvents, and the effects of extraction bath pH. The results of dye extraction from weld using filtration methods and wool dyeing led to the superiority of deposition of dyes by alum mordant and then ultrafiltration. Compared to Soxhlet extraction methods with the ultrasonic technique, extraction efficiency was superior and less time and energy was spent in the ultrasound method showed excellent extraction efficiency. In general, research has been demonstrated that dye powder extracted from weld can be used instead of the plant. In addition, use in the pharmaceutical and health industries increases the efficiency and quality of dyeing and can be an excellent alternative to synthetic dyes. In this study, the researches related to different dye extraction methods from the weld, the effect of solvents and auxiliaries on the extraction efficiency, and dyeing quality are reviewed and introduced.

The purpose of this study is investigation of the colourfastness of saffron according to the instructions of dyeing in Persian historical treatises, and identifying the advantages and disadvantages of applying it in the restoration of manuscripts. Three types of selected papers (I, II and III) were dyed with saffron via different instructions. Ageing was done based on the ISIRI 20283 in Xenon container. Then, the color changes, fiber morphology and degree of cellulose degradation were compared before and after ageing. The experiments had shown that paper III, which was not dyed, had more stability than the other two types of paper after ageing. Comparing three types of dyeing methods, saffron had not been caused the oxidation of papers and the direct dyeing method was more appropriate for dyeing among three types of papers. Colourfastness in meta-mordanting method was more stable than pre-mordanting method. However, in the pre-mordanting method, comparing the total color difference (∆E) show that paper II was more stable than paper I. So, the type of paper can affect on the colourfastness of dye and this should be considered as an important issue in dyeing.