Treatment of Dye Wastewater Containing Chromium from Batik Industry using Coconut Shell Activated Carbon Adsorption

Diterima 05 Desember 2020 Disetujui 30 April 2021 Batik is a characteristic Indonesian textile product that use dyes. Various types of batik dyes, one of which is remazol dyes. This is what underlies the process of production of the household batik industry in the village of Purwosekar, District of Tajinan, Malang Regency, with remazol coloring will produce liquid waste that is difficult to be deciphered naturally. This study aims to provide a water treatment solution using the coconut shell activated carbon adsorption method to adsorb remazol dyes. Adsorption experiments were carried out in batches with a mesh size of 8 with coconut shell carbon activated with 1 M HCl solution for 24 hours. The absorption of remazol dyes by coconut shell activated charcoal is carried out with a stirring speed variation (30, 60, and 90 rpm) for 60 minutes and the mass of activated charcoal (200 and 300 g) to find the optimum adsorption conditions. The highest efficiency of coconut shell activated charcoal in reducing chromium (Cr) content in batik waste was the treatment of variations in stirring speed of 90 rpm and mass of 300 g per 1 L of waste. The Cr concentration which was initially 0.8154 mg/L then decreased by 0.2825 mg/L to 0.5329 mg/L, so that an efficiency of 34.6456% was obtained. Thus, the efficiency of the coconut shell activated carbon is proportional to the stirring speed and mass of the coconut shell activated carbon used. Key word: Batik wastewater Remazol Adsorption Coconut Shell Activated Charcoal *e-mail: auliaqisti00@gmail.com Introduction The development of modern industry has dramatically changed the progress of human civilization. Meanwhile, we also suffer from the dangers of environmental pollution while enjoying the beneficial achievements created by industrial civilization [1]. The textile industry holds a big responsibility for one of the environmental problems, namely water pollution by waste generated from industrial processes [2]. In Indonesia, one of the textile industries is batik. Batik is a piece of cloth applied with a dyeresistant technique using “batik-wax” media as the holding medium [3]. Synthetic dyes have been used extensively by the industry to produce colorful batik for many years. Naphthol, Soluble, Direct, Remazol, and Reactive Tilapia are dyes commonly used for the batik coloring process [4]. However, Soebaryo reported that there is a skin disorder found in batik factory workers, namely contact dermatitis, and this skin disorder has a strong correlation with the use of synthetic dyes [5]. Most of the batik produced is in the form of Small and Medium Enterprises (UKM) and usually does not have a wastewater treatment plant. Therefore, generally these industries dispose of wastewater directly into the soil or rivers, which has caused pollution [6,7]. These dyes and chemicals, in addition to their unacceptable appearance and toxic effects once damaged, can contaminate nearby soil, sediment, and surface water, posing a major challenge to global environmental pollution. Colored water is unacceptable because it shows changes in the physical properties of water and indicates that water cannot be consumed [8]. Qisti, A., Pribadi, R. A., Ali, H. F., Utomo, Y., Rokhim, D. A., 2021 8 Metal contamination in textile waste occurs due to the presence of dyes and additives used (for example, caustic soda, sodium carbonate, and salt) during the textile manufacturing stage. The main metals that pose environmental challenges are chromium, zinc, iron, mercury, and lead [9]. However, Adinew reports that the main metals found in chromophore dyes in textile waste are cobalt, copper, and chromium [10]. Chromium compounds, especially in the form of chromium (III) or chromium (VI), are widely used in electroplating, metal finishing, tanning, wood protection, and the manufacture of dyes and catalysts [11]. Cr (VI) has the potential to be a human carcinogen, and its biological toxicity is 1000 times higher than that of Cr (III) [12]. High Cr (VI) intake can lead to cancer and mutagenicity in humans [11]. Activated carbon is a well-known adsorbent for wastewater treatment due to its large specific surface area and porous structure [13]. In addition, activated carbon tends to absorb various kinds of pollutants from water media [14]. Adsorption on activated carbon is superior to other physical and chemical methods for the removal of organic and inorganic waste from water and wastewater due to its high adsorption efficiency, fast adsorption kinetics, and simple design [15]. Whereas DobrowolskiOtto stated that adsorption of heavy metals to activated carbon was found to be the most effective for separation and enrichment of residual metals from aqueous solutions due to their extended surface area, micropore structure, high adsorption capacity, and high level of surface reactivity [16]. In recent years, there has been interest in using low-cost and abundantly available agricultural waste materials, such as bagasse [17], orange peels [18], rice husks [19], pistachio shells [20], etc., as precursors for the preparation of carbon materials. Coconut shells are also a potential precursor for low-cost activated carbon production due to their excellent natural structure and low ash content and provide a potentially cheap alternative to existing commercial carbon [21]. Coconut shell activated carbon was found to be an effective adsorbent to remove Cr (VI) and Ni (II) metal ions from water solution [22]. Therefore, the authors tried to do research to reduce levels of chromium (Cr) in batik industrial wastewater by using an adsorbent in the form of activated carbon. This study was intended to determine the ability of activated carbon to reduce levels of chromium (Cr) in wastewater. From the results of this study, we hope it can provide information to the public, especially batik industry, about wastewater treatment using activated carbon as an adsorbent or adsorbent. Material and Methods The stages in this research are divided into three stages, including the preparation stage, the literature study stage, and the implementation stage. The preparation stage is to identify the problem of the object of research, namely batik waste. In this case, a survey was carried out to the home-scale batik industry around Purwosekar Village, District of Tajinan, Malang Regency. The next stage is to conduct literature studies, compile and submit research proposals, and prepare tools and materials for research such as making artificial waste (figure 1). The third stage is the implementation stage. Materials and reagents Coconut shell charcoal and batik materials such as cloth, wax, remazol dye, and waterglass, are purchased from market in Malang. The chemical reagents and materials such as HCl and filter paper are collected from Chemistry Laboratory in Department of Chemistry, Faculty of Mathematics and Sciences, Universitas Negeri Malang. Making artificial batik wastewater In this research, we create artificial waste, which can be assumed to be the same as the waste in the field. The tools used include a set of batik-making tools, namely a frying pan, stove, and canting; bucket, used as a place for dyeing and washing; and pans, used to boil water. Meanwhile, the materials needed are cloth for batik media, wax, remazol-type dye, and water glass. Making batik waste is done by making batik then the waste is used as a sample. Before making batik, the cloth must first be measured and torn according to its length. It is sometimes boiled and dried to soften the fibers Qisti, A., Pribadi, R. A., Ali, H. F., Utomo, Y., Rokhim, D. A., 2021 9 and allow the material to absorb the wax. The next process is to draw motifs on the cloth using a pencil and outline the motifs and small ornaments made for the first time using a tool called canting. This step is the first staining by soaking the cloth as often as necessary to obtain the desired shade. After drying, the fabric is batik again. The process of beating the fabric and coloring is done in turns. After the last staining, the cloth is boiled to remove the wax, then washed and dried. The water that is discharged in the process is sampled. The sample was taken as much as 1 L and put in a closed glass bottle. Wastewater preliminary testing (before treatment) Initial characteristics test using waste samples from the batik-making process. Chromium levels in the waste samples were tested by AAS (Atomic Absorption Spectrophotometry) [23]. From these measurements obtained data on the concentration of chromium in units of mg/L. Wastewater treatment Mass measurement of coconut shell charcoal Total coconut shell charcoal to be used as adsorbent is weighed using an analytical balance to determine its mass. The charcoal used is 100 g. Activation of coconut shell charcoal 100 g coconut shell charcoal is activated with activator solution. Making the activator solution using concentrated HCl [24] which is diluted to a concentration of 1 M. Then the weighed coconut charcoal is soaked in 500 mL HCl 1 M solution for 24 hours. The activated charcoal is then filtered using filter paper and then rinsed using distilled water to remove the activator solution [25]. Furthermore, to remove moisture content, activated charcoal is heated for a certain time [26]. In this experiment, heating in an oven at a temperature of 150-175°C for 60 minutes. Wastewater treatment with coconut shell activated charcoal absorbent First, weigh the activated charcoal to be used, namely 10 g and 15 g three times, respectively. Next, measure the volume of each of the six waste samples that will be treated using a measuring cup. The volume required is as much as 50 mL per sample. Each sample was inserted into a different beaker glass (table 1). Activated charcoal was added to the sample and then stirred for 60 minutes using a magnetic stirrer with the following conditions: Table 1. The sample to be processed by adsorption