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All Journal Sorption Studies
Hazzha Azzahra
Department of Chemistry, The Republic of Indonesia Defense University, Kawasan IPSC Sentul, Bogor 16810, Indonesia
Chemical Engineering, Chemistry & Bioengineering Chemistry Materials Science & Nanotechnology

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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.
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.
Co-Authors Akhmad Rifai Allodya Nadra Xaviera Almanda Naura Candra Putri Dea Dwi Ananda Gunaryo Gunaryo Kayla Sophia Putri Mayang Fauziah Putri Kuntjahjono Muhammad Afif Aji Patria Nugroho Adi Sasongko Nugroho Adi Sasongko Nugroho Adi Sasongko Nuha Nuha Patricya Inggrid Wilhelmina Bolilanga Rahmat Basuki Rahmat Basuki Robith Alzamzani Sultan Napoleon Thessa Ocatvia Joyetta Tarigan Thessa Octavia Joyetta Tarigan Tiara Rizki Yulita Tiara Rizki Yulita Vania Agatha Nareswari Yusuf Bramastya Apriliyanto