Chemical Structure of Mangrove Species Rhizophora stylosa as Natural Dyes

Textile dyes are divided into two types, natural dyes and synthetic dyes. Natural dyes commonly made from extraction. Extraction is a process in which one or more components are separated selectively from a liquid or solid mixture, the feed, by means of a liquid immiscible solvent. Extraction can be classified into two group, liquid extraction and solid-liquid extraction. Solvents that are usually used in the extraction of natural dyes are aquades and ethanol. The purpose of this research was to determine the chemical structure, especially tannin in natural dyes from mangrove species Rhizophora stylosa through several samples testing natural dyes. Rhizophora stylosa that have been extracted and evaporated will conducted several tests to obtain chemical structures in natural dyes and yield of tannin in natural dyes. Tests carried out include testing FT-IR, and HPLC. Based on FT-IR analysis, the extraction of Rhizophora stylosa containing tannin indicated by the presence of hydroxyl (O-H) in the area of 3385.36 cm -1 , aromatic (C-H) in the area of 1365.53 cm -1 , carbonyl (C=O) in the area 1646.36 cm -1 , esters (C-O) in the area 1217.30 cm -1 . While tannin content obtained from the analysis of HPLC were 6.087 ppm .


INTRODUCTION
Batik in Indonesia has a comparative advantage in the economic field (Setiawati et al., 2015). The high demand for batik both domestically and abroad, the more dyes are used. Textile dyes are divided into two types, natural dyes and synthetic dyes. Synthetic dyes can be derived from coal or crude oil which are the product of aromatic hidrocarbon such as benzene, naphthalene, and anthracene. The use of synthetic dyes has been proven to be cheaper but have a negative impact because they are carcinogenic, due to the heavy metal content of synthetic dyes (Paryanto, et al., 2012). Compared to natural dyes, synthetic dyes have the advantage in the resulting color, color variations, price, availability, to stability (Lee, et al., 2005). However, judging from its constituent components, the use of dyes that contain chemicals to the use of wax that is insoluble in water causes problems in the surrounding environment (Manurung, 2012). Natural dyes are biodegradable and less toxic and allergenic than synthetic dyes, they are considered to be environmentally friendly (Punrattanasin et al., 2013). Natural dyes can be obtained from various plant, one of which is mangrove tannin content in mangroves can be used as a natural coloring agent (Purnaningtyas, 2014).
Natural dyes are known for their use in coloring of food, leather, wood, as well as natural fibers like wool, silk, cotton and flax since ancient times (Punrattanasin et al., 2013). Subsequent developments in the use of natural dyes were displaced by synthetic dyes found, because of their superior color resistance properties, they are not easy to fade, are easily produced, the color direction is more varied, and the price is cheaper than natural dyes (Kasmudjiastuti, 2017).
Natural dyes comprise of colorants that are obtained from animal or vegetable matter without any chemical processing (Umbreen et al., 2008). Chemical Structure of Mangrove Species Rhizophora stylosa….. (Paryanto et al.) Natural dyes have been used for many purposes especially in textile sector such as the colouring of natural fibres, cosmetic, to produce ink, watercolour and artist's paints (Baha et al., 2011). Most dyes are obtained from plants because plants have a variety of color pigments unlike in animals. Pigments contained in plants depend on the chemical structure contained in these plants. Tannin is a natural coloring pigment in the form of a brown coloring agent (Rahim et al., 2007). The purpose of this research was to determine the chemical structure, especially tannin in natural dyes from mangrove species Rhizophora stylosa through several samples testing natural dyes.

METHODOLOGY
Extraction of natural dyes was carried out at the Chemical Engineering Laboratory, Faculty of Engineering, Sebelas Maret University. Extraction is carried out for ±1 hour and evaporation is carried out ±45 minutes 4 times. The following materials and tools will be used for the extraction of natural dyes Rhizopora stylosa mangroves and water. The tools used in this study were extractor-evaporator, HPLC (High pressure liquid chromatography), and FT-IR spectrophotometer.
The preparation stage is by chopping and drying the mangrove Rhizophora stylosa in an oven at 100ºC for 3 hours. The extraction stage is carried out by inserting dried mangrove stylosa into the extractor-evaporator tube and adding water with a ratio between mangrove: water, that is 1:10 (Paryanto et al., 2016). Arranging the extractorevaporator then igniting the stove and the stirring motor. The extraction process lasts for 1 hour at a temperature of 96ºC. The evaporation stage is carried out by opening the evaporator faucet for 45-60 minutes. Equation by Crisholithus (2008).

RESULTS AND DISCUSSION
In the process of taking pigments of natural dyes required a comparison between ingredients and solvents is 1:10. Dried mangroves used as much as 250 grams and as much as 2.5 liters of water solvent. The extraction process lasts for 1 hour at a temperature of 96ºC followed by an evaporation process for ± 45 minutes. From the extraction and evaporation process a volume of concentrate of 1.8 L. was obtained.
The test results with FT-IR obtained FT-IR spectrum data of mangrove fruit species Rhizophora stylosa shown in   Marais et al. (2006) revealed that flavonone is a building unit of proanthocyanidin compounds which are condensed tannins. Parubak (2013) who found that the flavonoid compounds from the flavonone group had a OH OH functional group, CH aliphatic, C = O, C = C Aromatic, C-O and C -H aromatic. So it can be said that the research we have done is right.
Test results with High-Performance Liquid Chromatography (HPLC) with the following operating conditions: 1. Flowrate: 1 mL / min; 2. The mobile phase: MeOH: H20 (50:50); 3. λ (long gel): 271 nm; 4. Column: C18, 250 mm. From the results of three replicas of the tannin standard ( Figure 4) using a chromatogram, the following data are obtained (Table2). From the results of two replicas of the mangrove Rhizophora stylosa natural dyes ( Figure 5), the following data were obtained Table  2.   From the results of two replicas of the mangrove Rhizophora stylosa natural dyes (Figure 4), the following data were obtained Table 3. With the data that has been obtained from the replica results, it can be calculated the concentration of tannins in natural dyes from mangrove species Rhizophora stylosa. The initial sample is diluted 10 times then taken 1 mL and diluted again 10 times.  So, tannin content in the Rhizophora stylosa sample were 609 ppm.

Figure 2. Rhizophora stylosa FT-IR Spectrum
In the research of Hardoko et al. (2015) mangrove fruit species Rhizopora Mucronata has a tannin content of 819 ppm. The tannin content in the mangrove fruit species Rhizophora stylosa is smaller than the mangrove type Rhizopora Mucronata species, this is because the size of the mangrove fruit species Rhizophora stylosa is smaller than the size of the mangrove fruit species Rhizopora Mucronata. This was confirmed by the study of Sudarmadji (2004) mangrove Rhizopora Mucronata type which has a fruit shaped like a guava, size 2-2.3 cm, yellowish green color, hypocotyl cylindrical diameter of 2-2.5 cm, length can reach 90 cm, while mangrove Rhizophora stylosa species have fruit similar to the shape of water guava, brown color, size 1.5-2 cm, hypocotyl 2-2.5 cm in diameter, smooth surface, length can reach 30 cm.
The strength of our research is that it is the first research on the chemical structure of tannins in mangrove fruit species of Rhizophora stylosa, so that they can be used as a reference and this research can also optimize the use of natural dyes from Rhizophora stylosa mangrove fruits for batik cloth dyes in Indonesia so as to reduce the use of synthetic dyes that are harmful to humans and the environment.

CONCLUSION
Based on FT-IR analysis, the extraction of Rhizophora stylosa mangroves containing tannin was indicated by the presence of hydroxyl (O-H) in the area of 3385.36 cm -1 , aromatic (C-H) in the area of 1365.53 cm -1 , carbonyl (C=O) in the area of 1646.36 cm -1 , esters (C-O) in the area of 1217.30 cm -1 . While tannin content obtained from the analysis of HPLC were 608.712 ppm.