Indonesian Journal of Chemical Research http://ojs3.unpatti.ac.id/index.php/ijcr Indo. J. Chem. Res., 9(2), 69-79, 2021 DOI: 10.30598//ijcr.2021.9.raf 69 Magnetite-Activated Carbon Composite to Reduce Pollutant:Review Muhammad Rafli1, Reza Mega Wahyuni2, Nilna Muna Zahiro3, I Wayan Dasna4* Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jln. Semarang 5, Malang 65145, Indonesia *Corresponding Author: idasna@um.ac.id Received: March 2021 Received in revised: May 2021 Accepted: August 2021 Available online: September 2021 Abstract Pollution is a serious environmental problem. One of the causes of pollution is the presence of heavy metals. Besides heavy metals, there are plastics that cause serious problems in the environment because they are difficult to decompose. These two problems appear an idea about synthesizing activated carbon- magnetite (Fe3O4) composite based on polyethylene that can absorb heavy metals. The method used literature review of relevant articles. This study examines the properties of magnetite both physical and chemical along with the applications and benefits of magnetite in daily life. This study can become a new perspective effort to reduce heavy metals pollution using plastic waste as a composite with Fe3O4. Keywords: Plastic, pollution, magnetite composites, Fe2O3. INTRODUCTION Dependence on the use of fossil fuels in the transportation, industry, and energy sectors which reached 80% (EIA data for 2018) has an effect on increasing air pollution and decreasing human health. (Kumar et al., 2019). One of the characteristics of air pollution is the increased of heavy metals content such as Zn, Cd, Pb, and Hg (Wan et al., 2019). Small concentrations of heavy metals play a major role in metabolism and growth of plants and animals, but increasing concentrations can cause some toxic effects in humans (Purushotham et al., 2013). Apart from entering the environment naturally, heavy metals can enter through anthropogenic activities, such as mining, smelting, waste disposal, use of pesticides or inorganic fertilizers, and atmosphere deposition. (Haiyan & Stuanes, 2003). The most pollutants from the atmosphere are particulates measuring 2.5 μm (PM2.5) which are easily inhaled, causing several diseases such as damage to respiratory organs and nerve damage (Ma, Liu, Liu, & Bi, 2019; Sankhla, Sharma, & Kumar, 2017). Research on the prevention of air pollution which causes many diseases is needed by applying science and technology. One of the effective ways to reduce pollutants in the air is to adsorb pollutants using adsorbents. The adsorption process has the advantage of being easy to use, economical, simple design, and high efficiency in absorbing pollutants (Al-Ghouti, Da’ana, Abu-Dieyeh, & Khraisheh, 2019; Maddah, Yavaripour, Ramedani, Hosseni, & Hasanzadeh, 2020). Activated carbon is one of the most widely used adsorbents for adsorption, so it can be used to absorb heavy metals in the air. Activated carbon is an adsorbent that is widely used to remove various kinds of organic and inorganic pollutants, polar and non- polar compounds in the liquid and gas phases(Ao et al., 2018). Activated carbon was first reported as a gas adsorbent in 1793 by Dr. D.M. Kehl used wood charcoal to reduce odors and in 1872 as a gas mask with a carbon filter was used in the chemical industry to prevent mercury vapor inhalation (González-García, 2018). Commercial activated carbon is usually made from wood, coal and lignite (S. Wong, Ngadi, Inuwa, & Hassan, 2018). The disadvantages of using these sources include: (1) these materials are not environmentally friendly, (2) require high production cost, and (3) if the carbon source comes from wood, it can cause damage ecosystem although it can still be used as an absorben. In this paper, in addition to a review, a new problem solving is also carried out, namely the manufacture of activated carbon using plastic waste as raw material which is a pollutant in soil and water. The solutions presented have advantages including: (1) Reducing production costs due to available raw materials, (2) being an effort to overcome environmental problems due to plastic waste which is difficult to degrade, and (3) overcoming air pollution with pollutants so that it is very effective in solving Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr.2021.9.raf 70 water, soil and air pollution. As a heavy metal adsorbent, carbon has an active surface that is rich in functional groups that will interact chemically/ physically with heavy metals, the functional groups can be improved by modifying the surface of the carbon (X. Yang et al., 2019). To increase the negative charge on the surface of the activated carbon, a modification was made using magnetite nanoparticles. Magnetite nanoparticles were chosen because they have the advantages of having a high surface area ratio and can be modified, good magnetic properties, reusable, economical, non-toxic, and have an active side spreaded on the surface so it is very potential if it is combined with activated carbon as an absorbent for heavy metals (Alfe, Ammendola, Gargiulo, Raganati, & Chirone, 2015; Giraldo, Erto, & Moreno-Piraján, 2013a; Jain et al., 2018). There are no studies that have made activated carbon composites from plastics-magnetite nanoparticles with applications as an absorber of heavy metals in air. Research on pollutant adsorbents using magnetite nanoparticles has been widely carried out to adsorb pollutants in water such as Pb(II), Cu(II), Zn(II), and Mn(II). Although composites have never been applied to absorb heavy metals in the air, they have the ability to absorb heavy metals. Beside on the structure, magnetite nanoparticles can be used as adsorbents because they have an active side in the form of O atoms on the surface so they can interact with molecules using Lewis acid-base interactions (Alfe et al., 2015).Therefore, in this paper we will review activated carbon from plastic-magnetite nanoparticles and their suitability as an adsorbent of heavy metals in air. ACTIVATED CARBON AS AN ADSORBENT The carbon material is mainly composed of carbon atoms which have several allotropes including diamond, graphite, and fullerenes with various derivatives such as nanotubes and nanofibers (Menéndez-Díaz & I. Martín-Gullón, 2006). Sources of carbon material can be obtained, including from plants, vegetable oils, and waste. In several previous studies, most of the carbon sources were taken from plants and vegetable oils, including from papaya peel waste (Abbaszadeh, 2016), oak nut shells (Esra Altıntıg, Altundag, Tuzen, & Sarı, 2017), olive fruit waste Palm oil (Cazetta, 2016), harmala peganum seeds (Fazlzadeh, 2017), guava seed (Pezoti, 2016), spruce sawdust (Kazemi, 2016), cocoa shells (Saucier, 2015), bagasse (Sharma, 2019), Moringa Oleifera seeds (Reck, 2018), Babassu Coconut (Reck, 2018), Pine tree waste (Tonucci, 2015), Parthenium plant (Kamaraj, 2020), Rice husk charcoal (Li, 2019), Cucumber skin (Mahmoodi, 2019), and orange peel (Lam, 2017). Plants can be used as carbon sources because they consist of compounds that contain many carbon atoms, one of which is cellulose (Suhas, 2016). In addition, other studies also use non-plant waste such as rubber tire waste (Saleh, 2017), fabric waste (Taís L. Silva et al., 2018), and coal (C. Yang, 2020). Carbon material has the ability as an adsorbent because it has layers and pores that allow a molecule or particulate to be adsorbed on the surface or insertion between layers and pores (Figure 1). Figure 1. Carbon Structure. (a) Layer (Housecroft dan Sharpe, 2012) dan (b) Pore (Menéndez-Díaz dan I. Martín-Gullón, 2006) To increase the adsorption capacity, carbon activation can be carried out both thermally (for example, pyrolysis is then oxidized) and chemically (for example using phosphoric acid) (Menéndez-Díaz dan I. Martín-Gullón, 2006). The activated carbon surface will have a functional group as shown in Figure 1(Moseley, Rand, Davidson, & Monahov, 2018) so that it can attract polar molecules (dipole-ion force) and nonpolar (induced dipole-dipole force) (Reucroft, Simpson, & Jonas, 1971). The carbon with the different sources and material morphology will produce activated carbon with different surface areas and pore specifications. As a result, the capacity of activated carbon will vary when adsorbing certain species (Asuquo, Martin, Nzerem, Siperstein, & Fan, 2017; Lam, 2017; Li, 2019). The weakness of carbon adsorbent is its limited capacity so it is necessary to combine with other materials to increase its adsorption capacity. Research conducted by (Esra Altıntıg, Altundag, Tuzen, & Sarı, 2017b) shows that using activated carbon only, the adsorption capacity is 303.0 mg/g. Whereas after being composite with magnetite the adsorption capacity becomes 357.1 mg/g. MAGNETITE NANOPARTICLES AND THEIR MODIFICATIONS Magnetite nanoparticles are magnetite materials which have the compound formula Fe3O4. Magnetite (a) (b) Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr.2021.9.raf 71 nanoparticles have an active side in the form of O and metal atoms on the surface so they can interact with molecules using Lewis acid-base interactions (Alfe et al., 2015), so that it can be used to absorb heavy metal particles in the air which are positively and neutral. Magnetite nanoparticles which have a magnetic field are often used as adsorbents because they have the advantage of being easily separated by external magnetic fields (Hadi Baseri & Tizro, 2017), The high specific surface area of the nanoparticles also leads to a high adsorption capacity (Bao, Fu, & Bao, 2013), and low toxicity (Z. F. Akl, El-Saeed, & Atta, 2016). Previous studies conducted the synthesis of magnetite nanoparticles using several methods, including coprecipitation and solvothermal. In the last 10 years, the majority of research on magnetite has been carried out by compositing it with other compounds to produce different characteristics, thereby increasing the adsorption capacity as research has been done by (Hadi Baseri & Tizro, 2017) and (Tanhaei, 2015). The disadvantage of magnetite nanoparticles when used as an adsorbent is that they tend to form aggregates, so it is necessary to modify them with other compounds (El- Dib, Mohamed, El-Shamy, & Mishrif, 2020). CHARACTERIZATION STUDY OF ACTIVATED CARBON AND MAGNETITE- ACTIVATED CARBON NANOPARTICLE COMPOSITES Activated carbon and activated carbon-magnetite nanoparticle composites that have been synthesized must be characterized using several instruments. To determine the success of activating carbon and activated carbon-nanoparticle magnetite composites, tests were carried out using the XRD technique. Activated carbon that was successfully activated was then compared with JCPDS XRD data no. 7440- 44-0, while the magnetite-activated carbon nanoparticle composite was compared with JPCDS 98- 008-2450 (Figure 2c). One of the XRD results of the activated carbon is shown in Figure 3a above with a peak at 2ϴ about 25° dan 43° (Shamsuddin, Yusoff, & Sulaiman, 2016). These results show a peak at 2θ which is almost the same when compared to the results of our characterization of activated carbon that we have synthesized, namely the peaks of 25° and 44° (Figure 2a). The characterization results of the activated carbon-magnetite nanoparticle composites that we have synthesized compared to JPCDS 98-008-2450 also showed a peak at the same 2 which is at 31.73°; 35.19°; 43.01°; 53.56°; 57.02°; dan 62.56° (Figure 2c). Figure 2. (a) Activated carbon XRD pattern (Shamsuddin et al., 2016), (b) SEM results of activated carbon (Yuliusman, Puspitasari, & Nafisah, 2019b), (c) XRD pattern of composite activated carbon-magnetite nanoparticles experimental results, (d) SEM results of activated carbon-magnetite nanoparticles composites (K. T. Wong et al., 2016). (a) (b) (c) (d) Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr.2021.9.raf 72 Characterization techniques to determine the microsutructure and surface morphology of activated carbon and magnetite-activated carbon-nanoparticle composites can be done using SEM. Research using a source of activated carbon from plastics was carried out by (Yuliusman, Puspitasari, & Nafisah, 2019), with SEM results shown in Figure 2b which shows a porous surface of activated carbon. The characterization of the activated carbon-magnetite nanoparticle composite is shown in Figure 2d. To test the specific surface area and pore character, the Brunaur, Emmett and Teller (BET) test was performed. Characterization using FTIR is used to determine the presence of functional groups on activated carbon and magnetite such as carboxyl, hydroxyl, and carbonyl which have specific wave numbers. The adsorption capacity of activated carbon and magnetite can be carried out using Freundlich and Langmuir isotherm models. The results of the characterization of activated carbon, magnetite, and their modification in several previous studies are shown in Tables 1 and 2. COMPOSITE ACTIVATED CARBON- MAGNETITE NANOPARTICLES AS ADSORBENT OF HEAVY METALS IN AIR Adsorption on activated carbon occurs in the presence of dipole ion interactions if the one bound is positively charged or induced dipole-dipole if the nonpolar compound is attached (Reucroft et al., 1971). The intermolecular forces that exist on adsorption using activated carbon are quite weak when compared to ion- ion interactions. Therefore, other useful compounds are needed to cause the surface of activated carbon to have a negative charge so that the electrostatic force becomes stronger, such as the addition of magnetite nanoparticles. Previous research on activated carbon composites-adsorbent magnetite nanoparticles has been carried out with different activated carbon sources such as oak nut shells (E. Altıntıg, 2017), Palm shells (Cazetta, 2016), and commercial activated carbon (Juang, 2018). Polyethylene plastic waste which has many C atoms can be used as a carbon source. The advantage of activated carbon from polyethylene plastic is that in addition to being able to carry out adsorption, it can also reduce plastic waste which is difficult to degrade. So, it can be used for reduce water and soil pollution. The resulting polyethylene plastic activated carbon is then composited with magnetite nanoparticles. The adsorption mechanism of heavy metal pollutants on the adsorbent and testing mechanism shown in Figure 3. (a) (b) Figure 3. (a) The adsorption mechanism of heavy metal pollutants on the adsorbent, (b) Testing mechanism Compared with activated carbon adsorbent only, the polyethylene-magnetite plastic activated carbon composite will increase the adsorption capacity of heavy metals in positively charged air because it has a more negative adsorbent surface in the presence of magnetite which has a negative charge on its surface. When a heavy metal is positively charged, it will be attracted to the composite due to the electrostatic force as shown in Figure 3a. Testing can be done by inserting a heavy metal sample into a device that has been fitted with an adsorbent with a certain thickness as shown in Figure 3b so that adsorption occurs. The metal that is not adsorbed will come out into the acid solution, then the metal that is not adsorbed will be tested using AAS. Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr. 73 Table 1. Characterization of activated carbon and its modification Source Modification Adsorbed compound Surface Area (m2 g-1) Total Pore Volume (cm3 g-1) Micropore Volume (cm3 g-1) Mesopore Volume (cm3 g-1) Average Pore Diameter (nm) Adsorption Capacity (mg g-1) Reference Papaya skin waste - Lead (II) 15.26 0.0469 - - - 38.31 (Abbaszadeh, 2016) Commercial Modification with metal oxides Acetaldehide - - - - - Increase 20% with La2O3 (Baur, 2015) Oak shell seeds - Methylene blue 870.356 - 0.27 - - 330.0 (E. Altıntıg, 2017) Oak shell seeds Magnetite Methylene blue 940.132 - 0.23 - - 357.1 (E. Altıntıg, 2017) Olive fruit waste - Copper (II) 1194 0.56 0.552 0.009 2.072 8.832 (Bohli, 2015) Olive fruit waste - Cadmium (II) 1194 0.56 0.552 0.009 2.072 34.173 (Bohli, 2015) Olive fruit waste - Lead (II) 1194 0.56 0.552 0.009 2.072 84.33 (Bohli, 2015) Palm shells Magnetite Sunset yellow dye 1:1 = 372 2:1 = 337 3:1 = 238 1:1 = 0.210 2:1 = 0.172 3:1 = 0.118 1:1 = 0.156 2:1 = 0.141 3:1 = 0.101 1:1 = 0.054 2:1 = 0.031 3:1 = 0.017 1:1 = 2.26 2:1 = 2.04 3:1 = 1.98 22.31 (Cazetta, 2016) Harmala peganum seeds Coated with ZnO nanoparticles Chromium (VI) 442 0.233 - - 2 74.67 (Fazlzadeh, 2017) Guava seeds - Amoxicillin 2573.6 - - - Mesopore :4.42 Micropore :1.96 570.48 (Pezoti, 2016) Orange peel - Malachite green dye 1350 0.60 0.38 0.22 23 28.5 (Lam, 2017) A mixture of plastic, paper and palm oil waste - Malathion 115.17 - - - - 32.1 (Habila, 2015) Waste paper - Methylene blue 1670 1.14 0.06 - 29.8 350 (Novais, 2018) Cocoa shell - Sodium diclofenac 619 0.315 - - 4.8 DFC = 63.47 NM = 74.81 (Saucier, 2015) Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr.2021.9-raf 74 Continued (DFC) and nimesulide (NM) Rubber tire Composite with magnetite, modified with polyethylenei mine Uranium (VI) ion 303 - - - 62 115.31 (Saleh, 2017) Moringa Oleifera seeds - Tartrazine 18.93 0.026 0.003 0.023 2.571 91.27 (Reck, 2018) Babassu Coconut - Tartrazine 624.30 0.351 0.304 0.028 1.400 31.10 (Reck, 2018) Fabric waste - Remazol Brilliant Blue R 1582 1.005 0.17 0.39 3.6 292 (T.L. Silva, 2018) Table 2. Characterization of magnetite and its modification Composites Methode Diameter (nm) Adsorbed substance Capacity (mg/g) Reference Hidroxyapatite Coprecipitation - Pb(II) 598.8 (Dong, Zhu, Qiu, & Zhao, 2010) Graphene Oxide Solvothermal 9 Rhodamine B Malachite Green 13.15 22 (Sun, Cao, & Lu, 2011) Dodecylbenzene sulfonate Coprecipitation 53 - - (Eskandari & Shariati, 2011) Montmorillonite (MMT) Polyethylenimine (PEI) Coprecipitation 40 Cr (VI) PEI 800 g/mol = 8.77 PEI 25000 g/mol = 7.69 (Larraza, López-Gónzalez, Corrales, & Marcelo, 2012) Graphene Oxide two-step reaction 13 Hg (II) 289.9 (Fu, 2013) Zeolit Precipitation 17 (Yamaura & Fungaro, 2013) Graphene Oxide - - SDZ STZ SDD 10 8 6 (Shi & Ye, 2014) Chitosan 36, 30, dan 29 Methyl orange 417 (Tanhaei, 2015) Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, 2021 DOI: 10.30598//ijcr.2021.9-raf 75 Continued Al2O3 Maize tassel Coprecipitation Cd(II) 52.05 (Guyo, 2015) Carbon Coprecipitation CO2 20 (Alfe, 2015) Acrylamido- amineamidoxime-co-2- acrylamido-2-methylpropane sulfonic acid (AO/AMPS) - - U(VI) 476.190 (Z. Akl, 2016) - Coprecipitation As(V) Cu (II) - (Iconaru, 2016) Graphene Oxide Solvothermal 10 dan 30 Methylene blue (Sharif, 2017) - Coprecipitation 60±10 Ni (II) 46.513 (H. Baseri, 2017) Graphene Coprecipitation (Musa, 2018) cetyltrimethylammonium bromide (CTAB) Coprecipitation 10-20 Congo red 93.46 (Saksornchai, 2018) naturalbentonite - 2-50 Cu (II) 46.94 (Mohammed, 2018) Potential Development of Magnetite-Activated Carbon Nanoparticle Composites In the future, the resulting composites can be added in factory chimneys and in the exhaust of motorized vehicles where the air is prone to containing heavy metals. The polyethylene-magnetite nanoparticle composite can be printed in the form of a plate and then arranged like an electric mosquito repellent plate as shown in Figure 4. In addition, the activated carbon-nanoparticle magnetite composite can also be used as an antimicrobial when combined with other species such as Ag (Furlan et al., 2017) so it is necessary to be installed in central air conditioning. Based on this explanation, it is known that the polyethylene-magnetite nanoparticle composite is very potential to be researched and developed. Figure 4. Application and arrangement of adsorbents in factory chimneys and motor vehicle exhausts Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, year DOI: 10.30598//ijcr.2021.9-raf 76 CONCLUSIONS Activated carbon can be synthesized from polyethylene plastic waste which has many carbon atoms. To increase the adsorption capacity of the material, compost is carried out using magnetite which has a negative charge on its surface. The composites formed can adsorb heavy metals in the air by interacting with ions so that they can reduce air pollution. REFERENCES Abbaszadeh, S. (2016). Treatment of Lead- Contaminated Water Using Activated Carbon Adsorbent from Locally Available Papaya Peel Biowaste. Journal of Cleaner Production, 118, 210–222. https://doi.org/10.1016/j.jclepro.2016. 01.054 Akl, Z. F., El-Saeed, S. M., & Atta, A. M. (2016). In- Situ Synthesis of Magnetite Acrylamide Amino- Amidoxime Nanocomposite Adsorbent for Highly Efficient Sorption of U(VI) ions. Journal of Industrial and Engineering Chemistry, 34, 105–116. https://doi.org/10.1016/j.jiec.2015.10. 042 Alfe, M., Ammendola, P., Gargiulo, V., Raganati, F., & Chirone, R. (2015). Magnetite Loaded Carbon Fine Particles as Low-Cost CO2 Adsorbent in A Sound Assisted Fluidized Bed. Proceedings of the Combustion Institute, 35(3), 2801–2809. https://doi.org/10.1016/j.proci.2014.06.037 Al-Ghouti, M. A., Da’ana, D., Abu-Dieyeh, M., & Khraisheh, M. (2019). Adsorptive Removal of Mercury from Water by Adsorbents Derived from Date Pits. Scientific Reports, 9(1), 15327. https://doi.org/10.1038/s41598-019-51594-y Alkhatib, A. J. (2015). Medical and Environmental Applications of Activated Charcoal: Review Article. European Scientific Journal, 11, 3. Altıntıg, E. (2017). Effective Removal of Methylene Blue from Aqueous Solutions Using Magnetic Loaded Activated Carbon as Novel Adsorbent. Chemical Engineering Research and Design, 122, 151–163. https://doi.org/10.1016/j.cherd.2017. 03.035 Ao, W., Fu, J., Mao, X., Kang, Q., Ran, C., Liu, Y., … Dai, J. (2018). Microwave assisted preparation of activated carbon from biomass: A review. Renewable and Sustainable Energy Reviews, 92, 958–979. https://doi.org/10.1016/j.rser.2018.04. 051 Asuquo, E., Martin, A., Nzerem, P., Siperstein, F., & Fan, X. (2017). Adsorption of Cd (II) and Pb (II) Ions from Aqueous Solutions Using Mesoporous Activated Carbon Adsorbent: Equilibrium, Kinetics and Characterization Studies. Journal of Environmental Chemical Engineering, 5(1), 679- 698. https://doi.org/10.1016/j.jece.2016.12.043 Bao, J., Fu, Y., & Bao, Z. (2013). Thiol-Functionalized Magnetite/Graphene Oxide Hybrid as a Reusable Adsorbent for Hg2+ Removal. Nanoscale Research Letters, 8(1), 486. https://doi.org/ 10.1186/1556-276X-8-486 Baseri, Hadi, & Tizro, S. (2017). Treatment of Nickel Ions from Contaminated Water by Magnetite Based Nanocomposite Adsorbents: Effects of Thermodynamic and Kinetic Parameters and Modeling with Langmuir and Freundlich Isotherms. Process Safety and Environmental Protection, 109, 465–477. https://doi.org/ 10.1016/j.psep.2017.04.022 Baur, G. (2015). Activated Carbon Fibers Modified by Metal Oxide as Effective Structured Adsorbents for Acetaldehyde. Catalysis Today, 249, 252–258. https://doi.org/10.1016/j.cattod.2014.11.021 Benhouria, A. (2015). Calcium Alginate-Bentonite- Activated Carbon Composite Beads as Highly Effective Adsorbent for Methylene Blue. Chemical Engineering Journal, 270, 621–630. https://doi.org/10.1016/j.cej.2015.02.030 Bohli, T. (2015). Evaluation of an Activated Carbon from Olive Stones Used as An Adsorbent for Heavy Metal Removal from Aqueous Phases. Comptes Rendus Chimie, 18(1), 88–99. https://doi.org/10.1016/j.crci.2014.05.009 Cazetta, A. (2016). Magnetic Activated Carbon Derived from Biomass Waste by Concurrent Synthesis: Efficient Adsorbent for Toxic Dyes. ACS Sustainable Chemistry and Engineering, 4(3), 1058–1068. https://doi.org/10.1021/ acssuschemeng.5b01141 Dong, L., Zhu, Z., Qiu, Y., & Zhao, J. (2010). Removal of Lead from Aqueous Solution by Hydroxyapatite/Magnetite Composite Adsorbent. Chemical Engineering Journal, 165(3), 827-834. https://doi.org/10.1016/j.cej.2010.10.027 El-Dib, F. I., Mohamed, D. E., El-Shamy, O. A. A., & Mishrif, M. R. (2020). Study the Adsorption Properties of Magnetite Nanoparticles in the Presence of Different Synthesized Surfactants for Heavy Metal Ions Removal. Egyptian Journal of Petroleum, 29(1), 1–7. https://doi.org/10.1016/ j.ejpe.2019.08.004 Eskandari, H., & Shariati, M. R. (2011). Dodecylbenzene Sulfonate-Coated Magnetite Nanoparticles as a New Adsorbent for Solid Phase Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, year DOI: 10.30598//ijcr.2021.9-raf 77 Extraction-Spectrophotometric Determination of Ultra Trace Amounts of Ammonium in Water Samples. Analytica Chimica Acta, 704(1–2), 146– 153. https://doi.org/10.1016/j.aca.2011.07. 005 Fazlzadeh, M. (2017). Green Synthesis of Zinc Oxide Nanoparticles Using Peganum Harmala Seed Extract, and Loaded on Peganum Harmala Seed Powdered Activated Carbon as New Adsorbent for Removal of Cr (VI) from Aqueous Solution. Ecological Engineering, 103, 180–190. https://doi.org/ 10.1016/j.ecoleng.2017.02.052 Bao, J., Fu, Y., & Bao, Z. (2013). Thiol-Functionalized Magnetite/Graphene Oxide Hybrid as a Reusable Adsorbent for Hg2+ Removal. Nanoscale Research Letters, 8(1), 486. https://doi.org/ 10.1186/1556-276X-8-486 Furlan, P., Fisher, A., Furlan, A., Melcer, M., Shinn, D., & Warren, J. (2017). Magnetically Recoverable and Reusable Antimicrobial Nanocomposite Based on Activated Carbon, Magnetite Nanoparticles, and Silver Nanoparticles for Water Disinfection. Inventions, 2(2), 10. https://doi.org/10.3390/inventions 2020010 Giraldo, L., Erto, A., & Moreno-Piraján, J. C. (2013a). Magnetite Nanoparticles for Removal of Heavy Metals from Aqueous Solutions: Synthesis and Characterization. Adsorption, 19(2–4), 465–474. https://doi.org/10.1007/s10450-012-9468-1 González-García, P. (2018). Activated Carbon from Lignocellulosic Precursors: A Review of the Synthesis Methods, Characterization Techniques and Applications. Renewable and Sustainable Energy Reviews, 82, 1393–1414. https://doi.org/ 10.1016/j.rser.2017.04.117 Gupta, V. K., Ali, I., Saleh, T. A., Siddiqui, M. N., & Agarwal, S. (2013). Chromium Removal from Water by Activated Carbon Developed from Waste Rubber Tires. Environmental Science and Pollution Research, 20(3), 1261–1268. https://doi.org/ 10.1007/s11356-012-0950-9 Guyo, U. (2015). Application of Response Surface Methodology for Cd (II) Adsorption on Maize Tassel-Magnetite Nanohybrid Adsorbent. Journal of Environmental Chemical Engineering, 3(4), 2472–2483. https://doi.org/10.1016/j.jece. 2015.09.006 Habila, M. (2015). Activated Carbon from Waste as an Efficient Adsorbent for Malathion for Detection and Removal Purposes. Journal of Industrial and Engineering Chemistry, 32(Query date: 2020-09- 06 11:34:59), 336–344. https://doi.org/ 10.1016/j.jiec.2015.09.009 Haiyan, W., & Stuanes, A. O. (2003). Heavy Metal Pollution in Air-Water-Soil-Plant System of Zhuzhou City, Hunan Province, China. Water, Air, and Soil Pollution, 147(1), 79–107. https://doi.org/10.1023/A:1024522111341 Housecroft, C. E., & Sharpe, A. G. (2012). Inorganic Chemistry Fourth Edition. London: Pearson Education Limited. Iconaru, S. (2016). Magnetite (Fe3O4) Nanoparticles as Adsorbents for As and Cu removal. Applied Clay Science, 134, 128–135. https://doi.org/10.1016 /j.clay.2016.08.019 Iftikhar, P. M., Ali, F., Faisaluddin, M., Khayyat, A., De Gouvia De Sa, M., & Rao, T. (2019). A Bibliometric Analysis of the Top 30 Most-cited Articles in Gestational Diabetes Mellitus Literature (1946-2019). Cureus. https://doi.org/ 10.7759/cureus.4131 Jain, M., Yadav, M., Kohout, T., Lahtinen, M., Garg, V. K., & Sillanpää, M. (2018). Development of Iron Oxide/Activated Carbon Nanoparticle Composite for The Removal of Cr (VI), Cu (II) and Cd (II) Ions from Aqueous Solution. Water Resources and Industry, 20, 54–74. https://doi.org/10.1016/j.wri.2018.10.001 Juang, R. (2018). Synthesis of Magnetic Fe3O4/Activated Carbon Nanocomposites with High Surface Area as Recoverable Adsorbents. Journal of the Taiwan Institute of Chemical Engineers, 51–60. https://doi.org/10.1016/ j.jtice.2017.12. 005 Kamaraj, M. (2020). Facile Development of Sunlit ZnO Nanoparticles-Activated Carbon Hybrid from Pernicious Weed as an Operative Nano- Adsorbent for Removal of Methylene Blue and Chromium from Aqueous Solution: Extended Application in Tannery Industrial Wastewater. Environmental Technology and Innovation, 17. https://doi.org/10.1016/j.eti. 2019.100540 Kazemi, F. (2016). Thiol-Incorporated Activated Carbon Derived from Fir Wood Sawdust as an Efficient Adsorbent for the Removal of Mercury Ion: Batch and Fixed-Bed Column Studies. Process Safety and Environmental Protection, 100, 22–35. https://doi.org/10.1016/ j.psep.2015.12.006 Kumar, P., Druckman, A., Gallagher, J., Gatersleben, B., Allison, S., Eisenman, T. S., … Morawska, L. (2019). The Nexus Between Air Pollution, Green Infrastructure and Human Health. Environment International, 133, 105181. https://doi.org/ 10.1016/j.envint.2019.105181 Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, year DOI: 10.30598//ijcr.2021.9-raf 78 Lam, S. S. (2017). Microwave-Assisted Pyrolysis with Chemical Activation, an Innovative Method to Convert Orange Peel into Activated Carbon with Improved Properties as Dye Adsorbent. Journal of Cleaner Production, 162, 1376–1387. https://doi.org/10.1016/j.jclepro.2017.06.131 Larraza, I., López-Gónzalez, M., Corrales, T., & Marcelo, G. (2012). Hybrid Materials: Magnetite– Polyethylenimine–Montmorillonite, as Magnetic Adsorbents for Cr (VI) Water Treatment. Journal of Colloid and Interface Science, 385(1), 24–33. https://doi.org/10.1016/j.jcis.2012.06.050 Li, M. (2019). Preparation of a dual Pore Structure Activated Carbon from Rice Husk Char as an Adsorbent for CO2 Capture. Fuel Processing Technology, 186, 35–39. https://doi.org/10.1016/j.fuproc.2018.12.015 Ma, Z., Liu, R., Liu, Y., & Bi, J. (2019). Effects of Air Pollution Control Policies on PM2.5 Pollution Improvement in China from 2005 to 2017: A Satellite-Based Perspective. Atmospheric Chemistry and Physics, 19(10), 6861–6877. https://doi.org/10.5194/acp-19-6861-2019 Maddah, B., Yavaripour, A., Ramedani, S. H., Hosseni, H., & Hasanzadeh, M. (2020). Electro Spun Pu Nanofiber Composites Based on Carbon Nanotubes Decorated with Nickel-Zinc Ferrite Particles as an Adsorbent for Removal of Hydrogen Sulfide from Air. Environmental Science and Pollution Research, 27(28), 35515– 35525. https://doi.org/10.1007/s11356-020- 09324-9 Mahmoodi, N. (2019). Activated Carbon/Metal- Organic Framework Composite as a Bio-Based Novel Green Adsorbent: Preparation and Mathematical Pollutant Removal Modeling. Journal of Molecular Liquids, 277, 310–322. https://doi.org/10.1016/j.molliq.2018.12.050 Menéndez-Díaz, J. A. & I. Martín-Gullón (Eds.). (2006). Types of carbon adsorbents and their production. Elsevier: Amsterdam. Mohammed, A. (2018). Bentonite Coated with Magnetite Fe3O4 Nanoparticles as a Novel Adsorbent for Copper (ii) Ions Removal from Water/Wastewater. Environmental Technology and Innovation, 10(Query date: 2020-09-05 21:12:03), 162–174. https://doi.org/10.1016/j.eti.2018.02.005 Moseley, P. T., Rand, D. A. J., Davidson, A., & Monahov, B. (2018). Moseley, P. T., Rand, D. A. J., Davidson, A., & Monahov, B. (2018). Understanding the Functions of Carbon in the Negative Active-Mass of the Lead–Acid Battery: A Review of Progress. Journal of Energy Storage, 19, 272–290. https://doi.org/10.1016/ j.est.2018.08.003 Musa, M. (2018). Graphene-Magnetite as Adsorbent for Magnetic Solid Phase Extraction of 4- Hydroxybenzoic Acid and 3,4-Dihydroxybenzoic Acid in Stingless Bee Honey. Food Chemistry, 265, 165–172. https://doi.org/10.1016/ j.foodchem.2018.04.020 Novais, R. (2018). Extremely Fast and Efficient Methylene Blue Adsorption Using Eco-Friendly Cork and Paper Waste-Based Activated Carbon Adsorbents. Journal of Cleaner Production, 197, 1137–1147. https://doi.org/10.1016/j.jclepro. 2018.06.278 Pezoti, O. (2016). Naoh-Activated Carbon of High Surface Area Produced from Guava Seeds as a High-Efficiency Adsorbent for Amoxicillin Removal: Kinetic, Isotherm and Thermodynamic Studies. Chemical Engineering Journal, 288(Query date: 2020-09-06 11:34:59), 778–788. https://doi.org/10.1016/j.cej.2015.12.042 Purushotham, D., Rashid, M., Lone, M. A., Rao, A. N., Ahmed, S., Nagaiah, E., & Dar, F. A. (2013). Environmental Impact Assessment of Air and Heavy Metal Concentration in Groundwater of Maheshwaram Watershed, Ranga Reddy District, Andhra Pradesh. Journal of the Geological Society of India, 81(3), 385–396. https://doi.org/10.1007/s12594-013-0049-z Reck, I. (2018). Removal of Tartrazine from Aqueous Solutions Using Adsorbents Based on Activated Carbon and Moringa Oleifera Seeds. Journal of Cleaner Production, 171, 85–97. https://doi.org/10.1016/j.jclepro.2017.09.237 Reucroft, P. J., Simpson, W. H., & Jonas, L. A. (1971). Sorption Properties of Activated Carbon. The Journal of Physical Chemistry, 75(23), 3526– 3531. https://doi.org/10.1021/j100692a007 Saksornchai, E. (2018). Simple Wet-Chemical Synthesis of Superparamagnetic CTAB-Modified Magnetite Nanoparticles Using as Adsorbents for Anionic Dye Congo Red Removal. Materials Letters, 213, 138–142. https://doi.org/10.1016/ j.matlet.2017.11.015 Saleh, T. (2017). Polyethylenimine Modified Activated Carbon as Novel Magnetic Adsorbent for the Removal of Uranium from Aqueous Solution. Chemical Engineering Research and Design, 117, 218–227. https://doi.org/10.1016/j.cherd.2016.10.030 Sankhla, M. S., Sharma, K., & Kumar, D. R. (2017). Heavy Metal Causing Neurotoxicity in Human Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, year DOI: 10.30598//ijcr.2021.9-raf 79 Health. International Journal of Innovative Research in Science, Engineering and Technology, 6(5). https://doi.org/10.15680 /IJIRSET.2017.0605054 Saucier, C. (2015). Microwave-Assisted Activated Carbon from Cocoa Shell as Adsorbent for Removal of Sodium Diclofenac and Nimesulide from Aqueous Effluents. Journal of Hazardous Materials, 289(Query date: 2020-09-06 11:34:59), 18–27. https://doi.org/10.1016/ j.jhazmat.2015.02.026 Shamsuddin, M. S., Yusoff, N. R. N., & Sulaiman, M. A. (2016). Synthesis and Characterization of Activated Carbon Produced from Kenaf Core Fiber Using H3PO4 Activation. Procedia Chemistry, 19, 558–565. https://doi.org/10.1016/ j.proche.2016.03.053 Sharif, F. (2017). Electrochemical Regeneration of a Reduced Graphene Oxide/Magnetite Composite Adsorbent Loaded with Methylene Blue. Water Research, 114, 237–245. https://doi.org/10.1016/ j.watres.2017. 02.042 Sharma, M. (2019). ZnO Tetrapod’s and Activated Carbon-Based Hybrid Composite: Adsorbents for Enhanced Decontamination of Hexavalent Chromium from Aqueous Solution. Chemical Engineering Journal, 358, 540–551. https://doi.org/10.1016/ j.cej.2018.10.031 Shi, P., & Ye, N. (2014). Magnetite–Graphene Oxide Composites as a Magnetic Solid-Phase Extraction Adsorbent for the Determination of Trace Sulfonamides in Water Samples. Analytical Methods, 6(24), 9725–9730. https://doi.org/ 10.1039/C4AY02027H Silva, Taís L., Cazetta, A. L., Souza, P. S. C., Zhang, T., Asefa, T., & Almeida, V. C. (2018). Mesoporous Activated Carbon Fibers Synthesized from Denim Fabric Waste: Efficient Adsorbents for Removal of Textile Dye from Aqueous Solutions. Journal of Cleaner Production, 171, 482–490. https://doi.org/10.1016/j.jclepro.2017.10.034 Silva, T.L. (2018). Mesoporous Activated Carbon Fibers Synthesized from Denim Fabric Waste: Efficient Adsorbents for Removal of Textile Dye from Aqueous Solutions. Journal of Cleaner Production, 171, 482–490. https://doi.org/ 10.1016 /j.jclepro.2017.10.034 Suhas. (2016). Cellulose: A Review as Natural, Modified and Activated Carbon Adsorbent. Bioresource Technology, 216, 1066–1076. https://doi.org/ 10.1016/j.biortech.2016.05.106 Sun, H., Cao, L., & Lu, L. (2011). Magnetite/Reduced Graphene Oxide Nanocomposites: One Step Solvothermal Synthesis and Use as a Novel Platform for Removal of Dye Pollutants. Nano Research, 4(6), 550–562. https://doi.org/10.1007/ s12274-011-0111-3 Tanhaei, B. (2015). Preparation and Characterization of a Novel Chitosan/Al2O3/Magnetite Nanoparticles Composite Adsorbent for Kinetic, Thermodynamic and Isotherm Studies of Methyl Orange Adsorption. Chemical Engineering Journal, 259, 1–10. https://doi.org/10.1016/ j.cej.2014.07.109 Tonucci, M. (2015). Activated Carbons from Agricultural Byproducts (Pine Tree and Coconut Shell), Coal, and Carbon Nanotubes as Adsorbents for Removal of Sulfamethoxazole from Spiked Aqueous Solutions: Kinetic and Thermodynamic Studies. Industrial Crops and Products, 74(Query date: 2020-09-06 11:34:59), 111–121. https://doi.org/10.1016/ j.indcrop.2015.05.003 Wan, D., Song, L., Mao, X., Yang, J., Jin, Z., & Yang, H. (2019). One-Century Sediment Records of Heavy Metal Pollution on the Southeast Mongolian Plateau: Implications for Air Pollution Trend in China. Chemosphere, 220, 539–545. https://doi.org/10.1016/j.chemosphere.2018.12.1 51 Wong, K. T., Eu, N. C., Ibrahim, S., Kim, H., Yoon, Y., & Jang, M. (2016). Recyclable Magnetite- Loaded Palm Shell-Waste Based Activated Carbon for the Effective Removal of Methylene Blue from Aqueous Solution. Journal of Cleaner Production, 115, 337–342. https://doi.org/ 10.1016/ j.jclepro.2015.12.063 Wong, S., Ngadi, N., Inuwa, I. M., & Hassan, O. (2018). Recent advances in applications of activated carbon from biowaste for wastewater treatment: A short review. Journal of Cleaner Production, 175, 361–375. https://doi.org/ 10.1016/j.jclepro.2017.12.059 Yamaura, M., & Fungaro, D. A. (2013). Synthesis and Characterization of Magnetic Adsorbent Prepared by Magnetite Nanoparticles and Zeolite from Coal Fly Ash. Journal of Materials Science, 48(14), 5093–5101. https://doi.org/10.1007/s10853-013- 7297-6 Yang, C. (2020). Bifunctional ZnO-MgO/Activated Carbon Adsorbents Boost H2S Room Temperature Adsorption and Catalytic Oxidation. Applied Catalysis B: Environmental, 266, Muhammad Rafli et al. Indo. J. Chem. Res., 9(2), 69-80, year DOI: 10.30598//ijcr.2021.9-raf 80 118674. https://doi.org/10.1016/ j.apcatb. 2020.118674 Yang, X., Wan, Y., Zheng, Y., He, F., Yu, Z., Huang, J., … Gao, B. (2019). Surface Functional Groups of Carbon-Based Adsorbents and Their Roles in the Removal of Heavy Metals from Aqueous Solutions: A Critical Review. Chemical Engineering Journal, 366, 608–621. https://doi.org/10.1016/j.cej. 2019.02.119 Yuliusman, Y., Puspitasari, M., & Nafisah, A. R. (2019a). Preparation of Activated Carbon by Chemical Activation Using KOH and Acetone from Low Density Polyethylene (LDPE) Wastes. AIP Conference Proceedings, 2175(1), 020027. https://doi.org/10.1063/1.5134591