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Dea Dwi Ananda
Department of Chemistry, The Republic of Indonesia Defense University, Kawasan IPSC Sentul, Bogor 16810, Indonesia

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Radar Absorber Composite Graphene Oxide/Magnetite/Zinc Oxide in Polypyrole Matrix Allodya Nadra Xaviera; Vania Agatha Nareswari; Dea Dwi Ananda; Hazzha Azzahra; Thessa Ocatvia Joyetta Tarigan; Tiara Rizki Yulita; Nugroho Adi Sasongko; Rahmat Basuki
Sorption Studies Vol. 1 No. 1 (2025): Sorption Studies, Vol. 1 No. 1 June 2025
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ss.v1i1.80

Abstract

The development of stealth technology in modern defense systems demands superior radar absorbing material (RAM) innovation. This study aims to synthesize and characterize Fe₃O₄/ZnO modified carbon-based RAM composites in a polypyrrole (PPy) matrix using graphite oxide (GiO). The composites were synthesized via a modified Hummer method as well as a one-pot technique, and characterized using FTIR, XRD, SEM-EDX, and VNA. The FTIR characterization results showed that the C=C peak decreased in intensity after the oxidation process, indicating the breaking of the aromatic double bond and the formation of new functional groups such as C–O and C=O. This change was detected in both pGiO and kGiO samples. XRD data showed a shift in the main peaks to 2θ = 11.25° and 42.20° for pGiO and 2θ = 11.56° and 42.40° for GiO-k, respectively. This shift indicates the formation of a more amorphous graphite oxide structure compared to the original graphite.The results show that GiO/Fe₃O₄/ZnO has the highest reflection loss value of -9.20 dB at 10.91 GHz (GiO-p/Fe₃O₄/ZnO 66%-PPy) with an absorption value of 88.03% and rGO/Fe₃O₄/ZnO/PPy the highest RL value reached -7.51 dB at 11.57 GHz (rGO-k/Fe₃O₄/ZnO 66%-PPy) with an absorption value of 82.21%. This research proves that Fe3O4/ZnO modified carbon-based composites in a polypyrrole matrix have high potential as an efficient radar absorbing material and can support the needs of domestic defense technology.
Effect of Different Temperatures in Magnetite Synthesis on Methylene Blue Adsorption Dea Dwi Ananda; Sultan Napoleon; Thessa Octavia Joyetta Tarigan; Tiara Rizki Yulita; Latisa Stefi Alivia; Bagas Kusuma; M. Rizki Fajri; Kayla Sophia Putri; Nayantaka Virsa Artdero; Nurwanto; Rudi Hartono; Rahmat Basuki
Sorption Studies Vol. 1 No. 2 (2025): Sorption Studies, December 2025
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ss.v1i2.84

Abstract

This study aims to synthesize magnetite (Fe₃O₄) particles using the coprecipitation method, with variations in temperature (70°C and 90°C) and reaction system (open and closed) to evaluate their effects on product quality. Characterization was conducted using FTIR, XRD, and organoleptic observation to confirm the formation of Fe₃O₄. Additional tests included magnetic attraction measurements through mass response and adsorption capacity (Q) analysis using methylene blue. FTIR analysis showed absorption bands at 3417.00 cm⁻¹, 1627 cm⁻¹, 1404 cm⁻¹, and 578 cm⁻¹, indicating the presence of O–H, C=O, and Fe–O functional groups. XRD patterns revealed diffraction peaks at 2θ values of 30.27°, 35.23°, 43.22°, 53.71°, 57.43°, and 62.11°, confirming the spinel crystal structure of Fe₃O₄. The sample synthesized at 90°C under closed conditions exhibited a darker black color and higher mass yield, suggesting improved crystallinity and phase purity. The closed system also showed higher adsorption capacities of 0.0008 mmol·g⁻¹ at 70°C and 0.0018 mmol·g⁻¹ at 90°C, along with stronger magnetic response. The open system produced a black precipitate with lower yield and weaker magnetic response, suggesting oxidation of Fe²⁺ to Fe³⁺ due to direct contact with oxygen, leading to the formation of compounds such as hematite or maghemite with lower magnetic properties. These results confirm that higher reaction temperatures and closed conditions optimally enhance the quality and stability of magnetite.
Recent Advances in Nickel Ferrite-Polymer Nanocomposites for Radar Absorbing Material Applications Thesalonika Br Panjaitan; Alya Hijrianisa; Yusuf Bramastya Apriliyanto; Dea Dwi Ananda; Rahmat Basuki; Hotma Renta
Sorption Studies Vol. 1 No. 2 (2025): Sorption Studies, December 2025
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ss.v1i2.125

Abstract

Nickel ferrite (NiFe₂O₄) and its polymer-based composites have emerged as promising candidates for radar absorbing materials (RAMs) due to their unique combination of magnetic and dielectric loss mechanisms. This review highlights recent advances in synthesis strategies, including sol–gel, hydrothermal, co-precipitation, and microwave-assisted methods, which enable precise control of particle size, morphology, and crystallographic defects. Such control supports flexible structural design of nickel ferrite spinel structures, allowing dopant incorporation to tailor magnetic anisotropy and saturation magnetization. These structural features directly affect electromagnetic performance. Magnetic loss is mainly governed by natural resonance and, to a lesser extent, eddy current effects, while dielectric loss arises from dipole polarization, interfacial polarization, and conduction loss. The synergistic balance of magnetic and dielectric losses makes nickel ferrite–polymer nanocomposites promising broadband radar absorbing materials. The discussion emphasizes the role of cation substitution, polymer matrices, and hybridization with carbon-based materials in enhancing microwave absorption bandwidth and impedance matching. Various synthesis approaches, including sol–gel, hydrothermal, and in-situ polymerization, are compared with respect to their influence on particle size, morphology, and absorption efficiency. Challenges such as limited bandwidth, thermal and mechanical stability, and scalability are highlighted, along with potential solutions through advanced nanostructuring, multifunctional design, and sustainable synthesis. Future research directions are also outlined to support the development of next-generation stealth and electromagnetic interference shielding technologies.
Recent Advances in Neodymium as a Magnetic Nanoparticle Material Candidate for Microwave Absorption Dea Dwi Ananda; Thessa Octavia Joyetta Tarigan; Tiara Rizki Yulita; Kayla Sophia Putri; Hazzha Azzahra; Sultan Napoleon; Mayang Fauziah Putri Kuntjahjono; Almanda Naura Candra Putri; Muhammad Afif Aji Patria; Yusuf Bramastya Apriliyanto; Rahmat Basuki; Nugroho Adi Sasongko; Akhmad Rifai; Nuha Nuha
Sorption Studies Vol. 2 No. 1 (2026): Sorption Studies, Vol. 2 No. 1, June 2026
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ss.v2i1.145

Abstract

Magnets are materials that can attract or repel other objects due to the magnetic field generated by the arrangement of electron spin moments in atoms. One important magnetic material is magnetite (Fe₃O₄), which has been widely used and continues to be developed to meet the needs of modern technology. Innovation in material development is achieved through ion-substitution strategies, such as the use of the trivalent metal neodymium to replace Fe³⁺ in the ferrite structure. This strategy allows regulation of the microstructure and ion distribution in the crystal lattice, thereby significantly influencing the material's magnetic performance. Neodymium nanoparticles are known to exhibit superparamagnetic properties due to their tiny dimensions, so that each particle behaves as a single magnetic domain. These particles possess significant magnetic moments; however, their magnetization disappears once the external magnetic field is removed due to thermal fluctuations. The magnetic behavior of neodymium-based nanoparticles is strongly influenced by particle size, crystal structure, composition, and synthesis conditions. Based on theoretical calculations, neodymium exhibits a high magnetic moment due to its unpaired 4f electrons and strong spin–orbit coupling, with a magnetic spin moment of approximately 2.85 × 10⁻²² JT⁻¹. The characteristics of 4f electrons that are localized and protected by the outer shell produce strong spin-orbit coupling, contributing to a significant total magnetic moment and high crystal magnetic anisotropy. This phenomenon strongly aligns the magnetization along specific crystallographic directions, thereby stabilizing the magnetic orientation. This unique property makes neodymium a potential candidate for high-performance magnetic materials, including in high-frequency electromagnetic wave absorption technology. Nd-based magnetic materials exhibit enhanced microwave absorption performance through improved dielectric/magnetic losses and impedance matching, achieving reflection loss values below −40 dB with broad absorption bandwidths for electromagnetic shielding and radar absorbing applications.
Adsorption of Malachite Green using Coconut Shell–Graphite Oxide (CS-GiO): Kinetic and Isotherm Studies Hazzha Azzahra; Sultan Napoleon; Patricya Inggrid Wilhelmina Bolilanga; Rahmat Basuki; Gunaryo Gunaryo; Dea Dwi Ananda; Mayang Fauziah Putri Kuntjahjono; Robith Alzamzani; Nugroho Adi Sasongko; Akhmad Rifai; Nuha Nuha
Sorption Studies Vol. 2 No. 1 (2026): Sorption Studies, Vol. 2 No. 1, June 2026
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ss.v2i1.160

Abstract

Malachite green (MG) is a toxic cationic dye commonly found in textile wastewater and poses serious environmental and health risks. In this study, coconut shell–derived graphene oxide (CS-GiO) was synthesized and evaluated as an adsorbent for the removal of MG from aqueous solutions. The material was prepared through carbonization of coconut shells followed by a modified Hummers method to oxidize coconut shell graphite (CS-Gi) into graphene oxide. Prior to oxidation, the carbonized material was purified using HF treatment. Structural characterization using FTIR confirmed the presence of oxygen-containing functional groups, indicating successful oxidation of CS-Gi into CS-GiO. Meanwhile, XRD analysis revealed the characteristic (002) diffraction plane and showed that CS-GiO exhibited lower crystallinity compared to CS-Gi due to the incorporation of oxygen functional groups that disrupted the original crystalline structure. Adsorption behavior was evaluated through isotherm and kinetic studies. The adsorption equilibrium was better described by the Langmuir isotherm model (R² = 0.9957) than the Freundlich model (R² = 0.9617), indicating monolayer adsorption on relatively homogeneous active sites. The maximum adsorption capacity (qm) was 35.95 mg g⁻¹, with a Langmuir constant (KL) of 37873.42 L mol⁻¹ and a separation factor (RL = 0.000995), confirming that the adsorption process is highly favorable. Kinetic analysis revealed that the adsorption follows the pseudo-second-order (PSO) model (R² = 0.99818), with a rate constant (k₂) of 813.63 g mol⁻¹ min⁻¹ and an equilibrium adsorption capacity of 0.000349 mol g⁻¹, suggesting a relatively rapid adsorption process. The adsorption mechanism is likely dominated by chemisorption, involving interactions between oxygen-containing functional groups on the CS-GiO surface and cationic MG molecules through electrostatic attraction, coordination interactions, and possible electron transfer. These findings demonstrate that CS-GiO derived from coconut shells is a promising adsorbent for the efficient removal of malachite green from aqueous systems.