Jurnal Presipitasi Effectiveness of Lead and Cadmium Reduction with Adsorption Method using a Combination of Chitosan and Coffee Grounds (Case Study of Industrial Wastewater PT.X Indonesia)

PT. X Indonesia (PXI) is a company engaged in laboratory services in Bekasi Regency. Based on a preliminary study, the concentration of cadmium and lead in wastewater shows that it exceeds the quality standard of PerMenLHK No. P12 of 2020. The presence of cadmium and lead in PXI's wastewater must be resolved immediately to avoid dangerous human activities and polluting the environment. The research was initiated by taking wastewater samples and synthesizing the adsorbent from the combination of chitosan and activated carbon from coffee grounds. The method used in this study is an experimental approach with quantitative descriptive methods based on laboratory data using FT-IR, SEM EDX and AAS instruments. The results showed that chitosan biosorbent and 1.4-gram coffee grounds activated carbon resulted in the highest cadmium metal reduction efficiency of 94.35% and led to a metal reduction efficiency of 90.86%. The results concluded that the adsorbent of chitosan-activated carbon coffee grounds is very effective in reducing cadmium and lead metals in the wastewater of PXI. This research needs to follow up by increasing the mass of activated carbon of coffee grounds to meet quality standards.


Introduction
Heavy metal pollution in water as a result of human activities or industrial activities in the form of heavy metal cations such as Zn2+, Pb2+, Cd2+, Ni2+ and As3+. Ketika logam berat seperti arsen, kadmium, kobalt, tembaga, timbal, nikel atau seng terkandung dalam limbah cair dan masuk ke lingkungan tanpa pengolahan maka akan menghasilkan dampak negatif bagi lingkungan dan makhluk hidup (Panighari & Santhoskumar, 2020). When heavy metals such as arsenic, cadmium, cobalt, copper, lead, nickel or zinc are contained in wastewater and enter the environment without treatment, it will harm the environment and living things (Velusamy et al., 2021). Therefore, removing heavy metal contaminants in drinking and industrial water is an urgent and essential task. Wastewater treatment is a significant problem many countries face (Mosivand et al., 2019).
Removing heavy metals in wastewater has been conducted using several methods, including electrochemistry, chemical oxidation, chemical stabilization, coagulation, precipitation, adsorption, ion exchange, membrane filtration, phytoremediation, etc. These methods have their respective advantages and disadvantages. Adsorption is a physical and chemical process in which the liquid pollutant molecules touch and stick to the surface of the solid/adsorbent (Pratiwi & Prinajati, 2018). Adsorption is an appropriate technique for removing heavy metals in low concentrations from wastewater. The adsorption efficiency depends on the type of adsorbent and the deposition method (Obaid et al., 2018;Prathna et al., 2018). In general, adsorption is proven efficient, cost-effective, and easy to do. The abundance of natural adsorbents in nature is quite a lot. Efficiency and selectivity are high and do not pollute the environment (Naushad et al., 2017;Botahala, 2019).
Coffee is consumed by many populations worldwide and is considered one of the most popular drinks after tea in the world (Ahsan et al., 2021). In Indonesia, coffee is one of the plantation commodity products with high economic potential. It has an essential role as a source of foreign exchange for the country. In addition, coffee is also a source of income for 1.5 million coffee farmers in Indonesia (Rahardjo, 2012). In 2007, coffee production in Indonesia experienced a relatively rapid increase in production, reaching 676.5 thousand tons/year and increased production in 2013 as much as 691.16 thousand tons/year (Badan Pusat Statistik, 2015). Public interest in coffee consumption is high in Indonesia, resulting in extensive waste of coffee grounds. Coffee grounds that are disposed of directly into the environment can be toxic because of the presence of tannin, caffeine and polyphenol compounds (Iqbal et al., 2018).
Coffee grounds waste contains carbon atoms to be processed into activated carbon used as an absorbent or adsorbent (Irmanto, 2009). Activated carbon is a porous solid produced from carboncontaining materials activated by heating at high temperatures. The increased surface area of activated carbon will further expand its adsorption power (Sembiring dan Sinaga, 2003;Rengganis et al., 2017). Utilization of coffee residue/dregs that is processed into activated carbon as a biosorbent can help clean contaminated wastewater and reduce coffee grounds waste in the environment (Ahsan et al., 2021).
In recent years, chitosan has been widely used as a metal adsorbent. Chitosan can be used as a coagulant to reduce the colour content of sasirangan wastewater at a dose of 600 mg/L with an efficiency of 50.5% (Arifin et al., 2017). Chitosan can adsorb chromium (III) metal as much as 138 mg/g at pH 3.5 and a temperature of 20 0 C (Pietrelli et al., 2020), nickel (II) metal as much as 49.9 mg/g at a temperature of 60 0 C (Liao et al., 2016 ), zinc metal (II) 196.1 mg/g at pH 5 and 25 0 C (Seyedmohammadi et al., 2016), lead (II) 843.9 mg/g at pH 4 and 25 0 C (Rodrigues et al., 2019 ). Chitosan can bind lead metal ions 5-6 times greater than chitin (Supriyantini, 2018). The use of chitosan and activated carbon from coffee grounds as adsorbents can reduce metal levels of cadmium by 74.54% and nickel by 73.43% (Sari, 2019) and can minimise micropollutant compounds in pharmaceutical wastewater such as acetaminophen, metamizole, acetylsalicylic acid and caffeine (Lessa et al., 2018).
PT. X Indonesia (PXI) is one of the companies in Bekasi Regency engaged in laboratory services ranging from inspection, testing, certification and training for l0Cal and multi-national companies/industries in Indonesia. PXI operates ISO 17025 accredited state-of-the-art laboratories for food, pharmaceutical, cosmetic and textile testing. PXI generates hazardous and toxic waste, handed over to third parties. Based on the test results of wastewater samples from PXI, the metal concentration of cadmium (Cd) was 1.15 mg/L, and lead (Pb) was 1.02 mg/L. Based on these data, the concentration of cadmium and lead metals produced by PT PXI exceeded the quality standards of the Minister of Environment Regulation No. P12 of 2020 in Appendix III regarding wastewater quality standards in the water holding ponds in B3 waste storage facilities in the form of piles. Waste pile and impoundment are 0.1 mg/L (Menteri LHK, 2020). Therefore, there is a need for research that can contribute to helping PXI solve the problem of heavy metals in its wastewater.
On this occasion, the researchers tried to solve the research gap by utilizing adsorbents from chitosan by varying the mass of coffee grounds activated carbon added to reduce cadmium and lead metals in PXI industrial wastewater treatment, which exceeds the quality standard. The control variables controlled in this study were a pressure of 1 atm and a temperature of 25 0 C with a contact time of 60 minutes. In addition, the use of chitosan and coffee grounds expect to reduce the negative impact of environmental pollution due to the use of chemical adsorbents and the presence of coffee grounds waste.

Research Time and Place
This research was carried out at PXI while sample testing at the PT. TÜV NORD Indonesia l0Cated at Jl. Science Timur 1 bl0Ck B3-F1 Industrial area Jababeka 5 Cibatu Cikarang, Bekasi 17530 starting from the sample preparation stage to testing. This research was conducted for seven months, from February 2021 to September 2021.

Research Tools and Materials
The tools that used in this study consisted of a beaker, analytical balance, filter paper, volume pipette, funnel, porcelain dish, universal indicator, oven, spatula, acrylic plate, hot plate, sieve, furnace, desiccator, rubber bulb, aluminium foil, ball mill, magnetic stirrer, vacuum, atomic absorption spectrophotometer (SSA/AAS) with specifications Agilent Technologies 200 Series AA with Graphite Tube Atomizer (GTA) 120, Fourier Transform-Infra Red (FT-IR) and Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX). The operating conditions of the AAS instrument used are as follows Table 1 as follows:

Argon
The materials used in this study were 12 grams of chitosan (Sigma Aldrich brand) and 100 grams of coffee grounds waste from a coffee shop in Cikarang. And the mother standard solution used was Pb 2+ 1000 mg/L main solution (p.a. Merck) and Cd 2+ 1000 mg/L (p.a. Merck) main solution.

Research Pr0cedure 2.3.1 Wastewater Collection
The required sample was taken by grab sampling with the required volume and put into a container that has been washed thoroughly and rinsed using HNO3 1:1 and rinsed again using aquabidest. Then the sample is put into a filter with filter paper with a pore size of 0.45 µm and then accommodated into a container for analysis (SNI 6989.59: 2008).

Preliminary Test
This wastewater quality test is used to determine wastewater's initial content before going through a reduction treatment pr0Cess using an adsorbent by the Minister of Environment and Forestry Regulation No. P12 of 2020 concerning Wastewater Quality Standards in Water Storage Ponds in Hazardous Waste Storage Facilities in the form of Waste Piles and Waste Impoundment.
The material used is PT. X as much as 100 mL. The preliminary study used Atomic Absorption Spectroscopy (AAS) with specifications Agilent Technologies 200 Series AA with Graphite Tube Atomizer (GTA) 120. After initial research, the results calculate based on equation 1 as follows (APHA 3113 B, 2017): Metal Grade (mg/L) = C x fp…………………………………(1) Description: C = The concentration obtained from the measurement results fp = Final volume of the test sample (mL)

Wastewater Sample Preparation
The homogenized test sample was pipetted 100 mL and put into a 250 mL beaker. Then 10 mL of concentrated HNO 3 was added and covered with a watch glass. It is heated on a hot plate until the remaining volume is 15-20 mL, then 5 mL of concentrated HNO 3 is added if the destruction is not complete (not apparent). The watch glass was rinsed using aquabidest. After that, the test sample was filtered and transferred into a 100 mL volumetric flask, then added aquabidest to the mark and homogenized (APHA 3113 B, 2017).

Synthesis Activated Carbon From Coffee Ground
The coffee grounds were dried in an oven at 100 0C for 24 hours to remove the moisture content. The tea dregs are put into a porcelain cup and burned with an electric stove until the temperature is ± 950 0C for 15 minutes for the carbonation pr0Cess. After that, it was removed from the electric stove and cooled to room temperature. Then for the activation pr0Cess, the carbon is immersed in a 30% ZnCl2 solution for 24 hours. Then washed with warm water at 80 0C for 20 minutes and washed with 0.1 N HCl for 20 minutes, washed again using warm water until there are no air bubbles (Nurhidayanti, 2020). Then calculate the moisture, ash, volatile matter, and bound carbon content (Sari, 2019).

Synthesis and Characterization Adsorbent
Activated carbon from coffee grounds was conducted by determining the moisture, ash, volatile, and bound carbon content. Characterization of physical and chemical properties in the form of surface morphology of the adsorbent and components of coffee grounds activated carbon and coffee grounds chitosan-activated carbon was carried out using SEM EDX instrument, while chemical characterization to determine the functional groups of the adsorbent was carried out using FTIR methods (Sharma and Bhardwaj, 2019;Yurdakal et al., 2019) at the UPT laboratory Integrated Diponegoro University. 1.2 grams of chitosan was weighed, then dissolved in 60 mL of 3% acetic acid, added 0.6 grams of coffee grounds carbon, stirred until homogeneous. Poured into an acrylic glass, dried in an oven at 60°C for 24 hours. The resulting product was immerged with 1 M NaOH for 24 hours. Then, removed from the acrylic glass and washed with distilled water until neutral. It was dried at room temperature stored in a desiccator. The same thing was complete with variations by weight of the addition of carbon as much as 0.8; 1; 1.2, and 1.4 grams (Sari, 2019). Chitosan-activated carbon adsorbent of coffee grounds with a weight variation of 0.6 g; 0.8 g; 1g; 1.2 g; and 1.4 g introduce into the column. Pipette 50 mL of prepared wastewater into the queue. Then the wastewater is passed through the column with a vacuum pump and collected for analysis, and the wastewater is ready to be measured using AAS (Sari, 2019).

Data Analysis Method
The data pr0Cessing pr0Cess in this study was calculated the effectiveness of reducing the concentration of PT. X with the adsorption method using chitosan-activated carbon from coffee grounds as the adsorbent. Comparisons were made for each parameter by comparing the initial concentration

Preliminary Test
The waste used is the textile industry wastewater of PT. X. This wastewater quality test is used to determine wastewater's initial content before going through the reduction treatment pr0Cess using an adsorbent by PerMenLHK No. P12 of 2020 concerning Wastewater Quality Standards in Water Storage Ponds at Hazardous Waste Storage Facilities in the Form of Waste Pile and Waste Impoundment. The results of the preliminary test can be seen in Table 2 as follows:

Characterization of Coffee Ground Activated Carbon and Chitosan-Activated Carbon 3.2.1 Characterization of Coffee Ground Activated Carbon
The characterization of activated carbon aims to determine the ability of activated carbon to absorb wastewater containing heavy metals. The results of the description of the coffee grounds triggered carbon obtained are presented in Table 3 as follows: Based on the results of testing the water content, ash content, volatile matter content and bound carbon content in the activated carbon of coffee grounds, it has met the carbon quality requirements of SNI No. 06-3730-1995. The water content that meets SNI indicates that there are still activated carbon pores that can be occupied by the adsorbate so that the adsorption takes place optimally (Ghafarunnisa et al., 2017). Ash content with SNI indicates the number of metal oxides or inorganic materials in coffee grounds' activated carbon (Solihat et al., 2021). The level of volatile substances shows the decomposition results of the substances that make up charcoal due to the heating pr0Cess during the preparation of coffee grounds, resulting from the interaction between carbon and water vapour (Wardani, 2018). The bound carbon content obtained was 75.08%, indicating the large fraction of carbon bound in the charcoal in addition to the fraction of water, volatile matter, and ash after the carbonation and activation pr0Cess (Erawati et al., 2018).

Biosorbent Characterization Using FT-IR and SEM-EDX
The results of the characterization of the chitosan-activated carbon biosorbent functional group of coffee grounds using FT-IR are presented in Figure 1  Based on Figure 1 above, it can be determined several functional groups contained in the bioadsorbent combination of chitosan-activated carbon coffee grounds based on the reference according to Table 4 as follows: Tabel 4. FT-IR data analysis of coffee grounds activated carbon and chitosan-activated carbon of coffee grounds Based on table 4 above shows that the results of the FT-IR spectrum analysis on coffee grounds activated carbon there are several absorption peaks, including indicating the presence of functional groups CH (as alkanes), NH (possibly as secondary/primary amines and amides), CO (possibly as alcohols). / ether/ ester/ carboxylic acid/anhydride), CN (amine) and C-Cl (chloride). While the results of the FT-IR spectrum analysis on chitosan-activated carbon of coffee grounds, there were several absorption peaks, including indicating the presence of functional groups CH (as alkanes), NH (possibly as secondary/primary amines and amides), N=O (nitro), CO (possibly as alcohol/ ether/ ester/ carboxylic acid/ anhydride), CN (amine) and C-Cl (chloride) (Mohamed et al., 2017). Based on the results of the FT-IR analysis, it shows that there is an addition of a functional group N=O on the adsorbent of chitosan -coffee grounds activated carbon compared to coffee grounds activated carbon. It shows that the interaction that 0Ccurs between the activated carbon of coffee grounds and chitosan is a physical interaction (Sari, 2019) and a chemical interaction in the form of a nitrogen oxidation reaction that causes the formation of a nitro group (NO2) in the chitosan bio adsorbent -coffee grounds activated carbon. The addition of a nitro group to the adsorbent of chitosan-activated carbon coffee grounds increases the adsorption ability due to the electrostatic interaction between the nitro functional group and the metal cations of cadmium and lead. The results of the characterization of chitosan biosorbent and activated carbon of tea pulp using SEM EDX are presented in Table 5, and Figure 2 is as follows:   Table 2, the dominant element in the biosorbent of chitosan and activated carbon of coffee grounds is the C atom. Chitosan is a polysaccharide polymer, while coffee grounds are polymers in cellulose chains. The table shows an increase in the carbon element (C) of coffee grounds activated carbon by 69.26% to 74.30% after combining with chitosan. The cellulose-based coffee grounds polymer structure indicates a relatively strong chemical adsorption ability on metal ions and organic bases. The increase in % the mass of carbon atoms in chitosan-coffee grounds suggests an increase in the adsorbent's performance (Suwazan et al., 2022). Figure 2a shows the surface of the coffee grounds activated carbon, and Figure 3b shows the character of the chitosan-activated carbon coffee grounds biosorbent. Figures 3a and 3b show that the pores of the chitosan-activated carbon of coffee grounds are irregular with more significant and more profound cavities.
In contrast, the pores of the activated carbon of coffee grounds have an almost flat surface with several round holes with large pore sizes. Smaller than coffee grounds started carbon chitosan. It shows that adding coffee grounds activated carbon to chitosan can enlarge the surface pores and increase the biosorbent active site to increase the absorption of cadmium and lead metals in PXI industrial wastewater (Sari, 2019;Sahu et al., 2021). The increase in pore size and quality of the adsorbent causes the combination of chitosan-coffee grounds activated carbon to be more effectively used as an adsorbent compared to chitosan adsorbent or coffee grounds activated carbon. The larger the surface area of the adsorbent, the higher the adsorption ability (Pranoto et al., 2020).

Lead Metal Reduction Effectiveness
The results of measuring the concentration of lead metal in PT PXI wastewater samples after the adsorption pr0Cess can be seen in Table 6 below: The table above shows that the maximum absorption of lead metal in the combination of chitosan with the addition of 1.4 grams of activated carbon is 0.93 mg/L, while the lowest absorption is in the variety of chitosan with the addition of 0.6 grams of activated carbon which is only capable of absorbs the concentration of Pb metal to 0.76 mg/L. That shows that the higher the dose of activated carbon added will increase the absorption of lead metal in the biosorbent. Chitosan has active amino and hydroxyl groups and can chelate several metals, including lead. The active site of chitosan with the addition of coffee grounds activated carbon either in the form of NH2 or in a protonated state NH3+ can increase the absorption of lead metal through chemical interactions by forming chelates electrostatic interactions in the presence of ion-exchange or the formation of electron pairs. Increase the adsorption ability of the adsorbent (Sari, 2019). The graph of the effectiveness of the preparation of lead metal concentrations is presented in Figure 3 as follows: The graph shows that the effectiveness of reducing the lowest concentration of lead metal in the use of chitosan activated carbon coffee grounds is 0.6 grams, which is 74.24%. It has an increase in the use of chitosan activated carbon coffee grounds as much as 0.8 grams, which is 78.31%, then experienced a continuous increase in the addition of 1.0-gram coffee grounds activated carbon; 1.2 grams and 1.4 grams, the effectiveness of reducing the maximum metal concentration of lead on the use of 1.4 grams of activated carbon coffee grounds chitosan is 90.86%. This shows that the energy of lowering the lead concentration increases with the increase in the mass of activated carbon added to coffee grounds (Lessa et al., 2018). Previous research stated that chitosan-coated with activated carbon could increase the percentage of lead and other heavy metals absorption. Activated carbon is a very effective adsorbent to absorb metals in wastewater due to the high number of micropores and mesopores, large surface area, and functional groups on the activated carbon surface that interact with heavy metal ions (Rodriguez et al., 2017). Lead metal ions will be attracted to the surface of the activated carbon pores and are trapped in these pores. The more activated carbon, the more metal is absorbed in the carbon pores so that the decrease in metal content in chitosan with the addition of carbon is higher (Sari, 2019). The addition of coffee shell waste with a concentration of 10% in chitosan for 120 minutes can reduce the concentration of lead metal with an efficiency of 92.26 (Ayunda et al., 2019). Based on the results of the study showed that the use of a combination of chitosan-activated carbon from 1.4 grams of coffee grounds could reduce the concentration of lead metal with an efficiency of 90.86% to 0.09 mg/L so that it could meet the quality standard of the Minister of Environment and Forestry Regulation No. P12 of 2020.

Cadmium Lead Metal Reduction Effectiveness
The results of measuring the concentration of lead metal in PT PXI wastewater samples after the adsorption pr0Cess can be seen in Table 7  The table above shows that the maximum absorption of cadmium metal in the combination of chitosan with the addition of 1.4 grams of activated carbon is 1.08 mg/L, while the lowest absorption is in the variety of chitosan with the addition of 0.6 grams of activated carbon which is only able to absorb the concentration of Pb metal to be 0.86 mg/L. That shows that the higher the dose of activated carbon added will increase the absorption of cadmium metal in the biosorbent. Chitosan combined with coffee grounds activated carbon will increase the pore surface capacity to absorb cadmium metal. The higher the mass of activated carbon added will increase the number of active carbon pore surface active sites. The ability to absorb cadmium and other heavy metals will increase (Ayunda et al., 2019;Cherdcoo et al., 2019). The graph of the effectiveness of reducing the concentration of cadmium metal is presented in Figure 4 as follows: Figure 3. Graph of the effectiveness of cadmium metal concentration reduction during the adsorption pr0cess Figure 3 shows the effectiveness of decreasing the lowest concentration of cadmium metal on the use of coffee grounds activated carbon chitosan as much as 0.6 grams, which is 74.57%. An increase in the use of coffee grounds triggered carbon chitosan by 0.8 grams, which is 81.87%, then there is a continuous increase. On the addition of 1.0 grams of coffee grounds activated carbon, 1. grams of activated carbon coffee grounds chitosan is 94.35%. That shows that reducing the concentration of cadmium metal increases with the increase in the mass of activated carbon added to coffee grounds (Lessa et al., 2018). Previous research states that chitosan-coated with activated carbon can increase the percentage of absorption of cadmium metal and other heavy metals (Park et al., 2019). Activated carbon is a very effective adsorbent to absorb metals in wastewater due to the high number of micropores and mesopores, large surface area, and functional groups on the activated carbon surface that interact with heavy metal ions (Rodriguez et al., 2017;Rodrigues et al., 2019). Cadmium metal ions will be attracted to the surface of the activated carbon pores and are retained in these pores. The more activated carbon, the more heavy metals are absorbed in the carbon pores. The decrease in cadmium metal content in chitosan with the addition of carbon is higher. Adding 0.6 grams of coffee grounds activated carbon in chitosan can reduce cadmium metal levels by 74.54% and nickel-metal by 73.43% (Sari, 2019). Based on the study results, it was shown that the use of a combination of chitosan-activated carbon from 1.4 grams of coffee grounds could reduce the concentration of cadmium metal with an efficiency of 94.35% 0.07 mg/L. P12 in 2020 is 0.05 mg/L. Further research needs to be completed by increasing the mass of coffee grounds activated carbon added to the adsorbent.

Conclusion
Based on the results, it can be concluded that using a combination of chitosan-activated carbon 1.4 grams of coffee grounds result in the absorption of lead metal of 1.08 mg/L with the effectiveness of reducing the concentration of lead metal by 90.86% and the absorption of lead metal of 0.93 mg/L with the effectiveness of reducing the concentration of lead metal is 94.35%. The combination of chitosanactivated carbon coffee grounds effectively reduces cadmium and lead metals. It has complied with the quality standard for metal concentrations of a lead according to PerMenLHK No. P12 in 2020. However, further research needs to be done by increasing the mass of coffee grounds activated carbon used so that cadmium metal can meet the expected quality standards. After pr0Cessing PT, PXI wastewater does not pollute the environment.