The Effect of The Utilization of Gambier Processing Wastewater for Tannery with Variations of Alum and Tunjung on Physical Properties Test

The study involved variations in the percentage of alum and tunjung added as mordants, with percentages of 0%, 2%, 4%, and 6% used during the processing of wastewater from gambier. To evaluate the physical properties of tanned leather, the researchers followed the SNI 06-0463-1989-A. The findings indicated that using alum (aluminium sulfate) and tunjung (ferrous sulfate) as mordants affected the physical properties of tanned leather. Alum yielded better physical properties compared to tunjung, as evidenced by the higher tensile strength and flexural strength/elongation in the tanned leather treated with alum. The physical properties of tanned leather were found to be significantly influenced by the percentage of alum used, with higher percentages resulting in increased tensile strength and decreased flexural strength. The most effective treatment involved adding 2% alum, which suggests that combining gambier processing wastewater with alum can be a viable method for tanning leather. These findings demonstrate the potential for using alternative chemicals in leather tanning, which may offer benefits in terms of cost and environmental impact.


Introduction
The leather tanning industry usually uses synthetic tanning materials.This synthetic tanner uses a chrome process which produces liquid waste containing chromium metal.The chrome produced is chromium with trivalent (3 + ) valence which is obtained from the leather tanning process.This liquid waste can harm the environment because trivalent can change its valence to hexavalent (6 + ) chromium in alkaline conditions, which is a type of hazardous and toxic waste (B3) that can endanger [1,2].
As an alternative to reduce and replace this chrome tanner, environmentally friendly substitute tanneries have been used using combination tanning.In general, combination tanning uses vegetable tanners such as mimosa, acacia wood, mangrove wood, and tingi wood [3].However, the use of mimosa also eventually became a problem, because mimosa is an imported item that is quite expensive.Meanwhile, vegetable tanning using acacia wood and mangrove can also have a negative impact on environmental sustainability, because these two types of trees are protected and preserved.Continuous removal of bark can cause growth disturbances in trees and can even cause trees to die.Recently, it has been reported that alternative environmentally friendly tannery materials have been reported to replace chromium, acacia, and mangrove tanneries with cultivated plants such as Gambier [4].
In West Sumatra, gambier is widely cultivated and the province is currently the largest producer of gambier, accounting for around 90% of national production and exporting more than 80% of the world's gambier [5].However, the leather tanning industry in the region has yet to utilize gambier for tanning leather, despite its availability in relatively large quantities.Gambier (Uncaria gambir (Hunter) Roxb ) has the potential to be used as a substitute for imported materials such as mimosa, mangrove, and acacia [4].Several studies have explored the utilize of gambier as a substitute for vegetable tanning in combination tanning, including studies on gambier for combination tanners cube [4,5,6] black gambier for tanners [7].
Gambier is a natural dye source that is utilized in the textile industry.The industrial wastewater generated during the textile dyeing process using Gambier can originate from various sources [8].Gambier is a member of the Rubiaceae family of plants and is considered a smallholder plantation commodity.The extract from the plant is primarily composed of catechins, along with other components such as kateku tannic acid, kuesertin, red cateku, fluorescent gambier, fat, and wax.Gambier is commonly used as a mixture of ingredients for chewing betel, as it adds a delicious taste to the bitter mixture and can provide nourishment to teeth, gums, and throat [9].In line with the development of the industry that puts forward the concept of returning to nature (back to nature), gambier is starting to be widely needed as an ingredient in medicines, cosmetics, batik, and insecticides.
The leaves and twigs of gambier plant are extracted to produce raw gambier.This product is further refined into a versatile finished product [10].The production process of gambier generates wastewater, commonly known as gambier waste.In West Sumatra, the total gambier production in 2016 was approximately 14,220 tons, resulting in the production of around 5,688,000 liters of wastewater per year.Despite its high tannin content, gambier liquid waste has not been widely utilized.Tannins make up about 9-11% of the wastewater, as they are easily soluble in hot water and remain in the boiling water or are separated during the boiling process of gambier plant leaves and twigs [5].This high tannin content makes the liquid waste a potential agent for leather tanning.
Gambier wastewater is reddish brown to blackish brown with a viscosity of 7-8 Poise and pH of 4.5-5 [5].In research on the use of gambier wastewater for dyeing silk fabrics.It has been reported that, so that the color of gambier waste can be used for fabric dyes and the color has good color strength, it is necessary to provide a color generator in the mordanting process.Commonly used color generators are alum, tunjung, and lime.The color obtained from tanning with mordants can vary depending on the type of mordant used.Lime, alum (aluminum sulfate), and tunjung (ferrous sulfate) mordants can produce different colors, such as reddish-brown, bright yellow, and moss green [9,10].
In research on the use of Gambier wastewater for leather tanning using combination tanning, researchers utilized mordants for color generation, namely alum (aluminum sulfate) with the formula Al 2 (SO 4 ) 3 and tunjung (ferrous sulfate) with the formula FeSO4.These two materials can provide sharp color compared to other mordant substances, easy to obtain, and the price is relatively cheap, does not contain poison, besides that alum and tunjung are substances that are safe for the environment because they easily decompose in water, even alum and tunjung are coagulants that can work well in waste Industrial liquid.
2.1.2.Tools.The equipment used in this research is a tanning drum with a capacity of 10 kg.Physical testingequipment such as tensile strength, elongation, and tear strength using Zwick/Roell 2020.Equipment for thickness testing uses SG 300.Equipment for the degree of tanning test.Equipment for testing the wrinkle temperature using an engineered tool.Other equipment used are scissors, knife, stove, basin, oven, desiccator, Erlenmeyer, porcelain dish, electric oven, furnace, 100 ml volumetric flask, pipette, 100 ml erlenmeyer, analytical balance, beaker, stirring rod, measuring cup, goiter pipette, so let flask, spray flask, funnel, water bath, filter paper, and Kjeldahl flask.

Research Method 2.2.1. Initial tanning preparation process.
The working procedure of goat leather tanning is carried out based on the modified method of the leather tanning procedure of the Leather Technology Academy Yogyakarta (2009), the percentage of the material used is based on the weight of the leather after being weighed for the soaking and liming process.The Initial tanning preparation process includes soaking, limming until pH=12, weighing: to look for Bloten (weight after the fur is gone), deliming (remove lime) unyil pH =7, bating (protein scraping), and pikle (acidification) with pH = 3.

2.2.2.
Tanning process.This research was carried out through two stages of tanning, namely tanning stage I with the use of chrome and tanning stage II with the treatment of mixing gambier wastewater with alum and tunjung respectively 0%, 2%, 4%, and 6%.Tanning stage I: using chrome.Add 6% pickle leather and then rotate it, add 1.5% sodium carbonate, dissolve, add Na2CO3 solution each 30 minutes rotation, rotate again for 60 minutes, check until pH = 4.Then, boiled at temperature of 100 o C for 2 minutes.The next process is neutralization with 100% water, plus 1% sodium bicarbonate dissolved 1:10.Add the solution each 30 minutes, then check pH = 7.The final step is washing process.Tanning stage II: using gambier waste was varied with alum and tunjung respectively 0%, 2%, 4%, 6%.Each treatment was repeated 3 times.Added 1% formic acid 3 times each 15 minutes.Washed with running water.Remove the remaining tannery substance that is still attached.Drying is done by stretching in the open air and avoiding direct heat.

Tanned leather test.
Observations of the physical observations were made, based on SNI.06.0994-1989 on the tanned leather.Physical observations by testing tensile strength and flexural strength/elongation.

The Effect on The Tensile Strength
The results of physical measurements of the tensile strength of tanned leather at various levels of treatment with concentrations of a tanned combination of gambier waste with 0%, 2%, 4%, and 6% tunjung and alum concentrations are shown in Figure 1.It can be known that the tensile strength ranges from 273.74-330.94kg/cm 2 .Based on the results of physical measurements, it can be observed that the tensile strength of tanned leather increases as the concentration of alum and tunjung increases.At the highest concentration of 6%, the tensile strength reaches 330.94 kg/cm 2 , which is higher compared to the control sample with no addition of gambier waste.This indicates that the combination tanning of gambier waste with alum and tunjung can improve the tensile strength of tanned leather.However, it should be noted that excessive concentrations of tanning agents can have adverse effects on the quality of leather, such as decreased flexibility and increased stiffness.Therefore, it is important to optimize the concentration of the tanning agents to achieve the desired physical properties of the leather.
In tanning using gambier waste without alum and tunjung (0%) gave the lowest tensile strength of the leather, namely 273.74 kg/cm 2 .It is important to note that while higher concentrations of gambier with alum resulted in higher tensile strength, there may be a limit to how much gambier can be added before it starts to have a negative impact on the quality of the leather.Additionally, the stiffness of the leather and its resistance to heat may be important factors to consider depending on the intended use of the leather [11].When compared with the standard results, the minimum of leather tensile strength in all treatments is 75 kg/cm 2 .It indicates that the tanning process using gambier waste with a combination of alum and tunjung can produce leather that meets the quality standard for tanned goat leather in Indonesia, SNI No. 06-994-1989-A.The utilization of gambier waste in leather tanning can also be considered as an eco-friendly and sustainable approach to reduce waste and promote the circular economy.

The Effect on Leather Elongation
The elongation of leather refers to the increase in length of the material when it is pulled to the point of breaking, divided by its original length, and expressed as a percentage.Figure 2 displays the physical properties of elongation in tanned leather, which has been treated with various concentrations of gambier waste combined with alum and tunjung.The elongation of leather ranges between 22.64-25.01kg/cm 2 as shown in the figure 2. The elongation of the tanned leather of gambier-alum waste was higher than that of gambier-tunjung waste.The use of alum in the leather-making process has an inverse relationship with the elongation of the leather, meaning that the higher the use of alum, the lower the elongation of the resulting leather.This suggests that the elongation of leather is closely related to its elasticity.Elastin is a fibrous protein that is known for forming highly elastic fibers due to the presence of amino acid chains that form angles.The elongation of tanned leather refers to the material's ability to stretch before breaking, and the longer the leather size at the point of breakage, the greater the resulting tensile strength value [3,6] There are several factors that can affect the leather elongation, such as the protein composition found in the leather fibers, the initial condition of the leather, and the bating process.It is important to ensure that the tanning agent used does not affect the elongation of the leather.The bad bating process will cause the leather to become hard and easily broken so that the elongation is low.If the leather protein fibers are upright and tight, the leather will have low elongation, but if the leather fibers are vertical and the webbing is not tight, the elongation will be high [12].
Moreover the factors mentioned earlier, other factors that can affect the leather elongation include its thickness, as well as the sex and age of the animal it was sourced from.The thickness of the leather is determined by the animal's species and age, while the animal's sex and age are also factors that can affect the tensile strength of the leather's tissue structure.Animals with tanned leather have less tensile strength than female animals.Likewise, with older animals, the tensile strength of their leather is smaller than that of younger ones.When compared with the standard results of the study, the combination of gambiertunjung waste and gambier-alum waste for all treatments meets the SNI 0253-2009 tanned goat leather with a maximum elongation standard of 70%.

Conclusion
According to the physical property tests, introducing alum in the tanning process results in leather with better tensile strength and elongation compared to using tunjung.The amount of alum used during treatment is an important factor that determines the physical characteristics of the tanned leather, particularly its tensile and flexural strength.As the percentage of alum increases, the tensile strength improves while the flexural strength decreases.The treatment that yielded the best results involved a 2% alum addition.This implies that combining gambier processing wastewater with alum could be

Figure 1 .
Figure 1.The tensile strength of tanned leather with alum-tunjung concentration treatment in gambier processing wastewater

Figure 2 .
Figure 2. The Elongation of tanned leather with alum-tunjung concentration treatment in gambier processing wastewater