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All Journal Tekno - Pedagogi : Jurnal Teknologi Pendidikan MUSTEK ANIM HA Walisongo Journal of Chemistry Fullerene Journal of Chemistry
Rettob, Abraham Laurens
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Chemistry Electrical & Electronics Engineering Engineering Mechanical Engineering Other

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PENGARUH KONSENTRASI LARUTAN HF PADA PROSES PREPARASI TERHADAP KADAR UNSUR BAHAN MAGNETIK PASIR BESI Rettob, Abraham Laurens; Karbeka, Martasiana
Walisongo Journal of Chemistry Vol 2, No 1 (2019): Walisongo Journal of Chemistry
Publisher : Department of Chemistry Faculty of Science and Technology Walisongo

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1694.899 KB) | DOI: 10.21580/wjc.v3i1.3877

Abstract

Bahan magnetik (BM) pasir besi alam merupakan salah satu sumber adsorben magnetik. Selain BM, pasir besi alam juga mengandung bahan non-magnetik . Preparasi BM pasir besi dilakukan pada penelitian ini dengan tujuan untuk meningkatkan kadar unsur magnetik di dalamnya. Pasir besi alam yang digunakan berasal dari pesisir pantai Lansilowo. Preparasi dilakukan dengan pencucian menggunakan larutan HF dengan konsentrasi 0, 2, 5 dan 10%. Hasil analisis kadar unsur dengan XRF menunjukkan bahwa unsur dominan pada pasir besi Lansilowo adalah Fe dan Cr, yang merupakan unsur penyumbang sifat kemagnetan pada BM. Pencucian dengan larutan HF berbagai konsentrasi menyebabkan terjadinya perubahan kadar unsur pada BM. Semakin tinggi konsentrasi larutan HF mengakibatkan terjadinya peningkatan kadar Fe dan Cr total (89,56%) serta penurunan kadar Si (2,60%).  Hasil penelitian menunjukkan bahwa konsentrasi larutan HF optimum yang digunakan adalah 10%. 
KARAKTERISASI LEMPUNG ASAL DISTRIK TANAH MIRING KABUPATEN MERAUKE BERDASARKAN ANALISIS SEM DAN XRD Parlindungan, John Yoro; Rettob, Abraham Laurens
MUSTEK ANIM HA Vol 10 No 01 (2021): MUSTEK ANIM HA
Publisher : Faculty of Engineering, Musamus University, Merauke, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35724/mustek.v10i01.3574

Abstract

Kabupaten Merauke memiliki kekayaan dan potensi alam yang sangat banyak, salah satunya adalah lempung. Karakterisasi lempung asal Merauke terutama distrik tanah miring telah dilakukan menggunakan SEM dan XRD. Berdasarkan kedua analisis tersebut didapatkan hasil mineral lempung didominasi oleh Quartz dan Illite.
The Effect of the POE Learning Model on Students' Cognitive Learning Outcome Noviyanti, Mila Anggita; Rettob, Abraham Laurens; Parlindungan, John Yoro; Siregar, Lamtiar Ferawaty; Sumanik, Novike Bela; Asmaningrum, Henie Poerwandar
Tekno - Pedagogi : Jurnal Teknologi Pendidikan Vol. 15 No. 1 (2025): Tekno-Pedagogi
Publisher : Program Magister Teknologi Pendidikan Universitas Jambi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22437/teknopedagogi.v15i1.47925

Abstract

This study investigates the effectiveness of the POE learning model in enhancing cognitive learning outcomes of chemistry education students, with particular emphasis on redox reaction concepts in the Basic Chemistry 2 course. The research is motivated by the persistent challenge that chemistry is perceived as abstract and calculation-intensive, which hinders students’ conceptual understanding and reduces academic achievement. Employing a pre-experimental one-group pre-test – post-test design, data were collected from 12 second-semester students at Musamus University. Validated essay-based instruments were used to measure learning outcomes, and data analysis included N-Gain testing, Shapiro–Wilk normality testing, and paired sample t-tests. Results revealed a significant improvement in students’ performance, with mean scores rising from 19.4 (pre-test) to 74.6 (post-test), an N-Gain score of 0.67 categorized as moderate, and a t-count of 9.360 exceeding the t-table value of 2.22. The novelty of this research lies in the contextual application of the POE model under pandemic-induced learning constraints, demonstrating that active learning strategies integrating prediction, observation, and explanation are effective even within limited instructional settings. The contribution of this study is twofold: theoretically, it reinforces constructivist approaches in chemistry education by providing empirical evidence of POE’s impact on cognitive outcomes; practically, it offers lecturers a viable pedagogical alternative to foster motivation, engagement, and deeper understanding of abstract chemical concepts. These findings underscore the potential of POE as a scalable instructional strategy to address learning challenges in higher education science contexts.
Characterization of Clay from Merauke Regency and Its Utilization as an Adsorbent of Free Fatty Acids in the Purification of Waste Cooking Oil Maulana, Muhammad Rasyiid; Parlindungan, John Yoro; Rettob, Abraham Laurens; Siregar, Lamtiar Ferawaty; Hitijahubessy, Hendro
Jurnal Kimia Fullerene Vol 10 No 2 (2025): Fullerene Journal Of Chemistry
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37033/fjc.v10i2.747

Abstract

This study investigates the characterization and application of natural clay from Merauke as an adsorbent for the purification of waste cooking oil. The clay was characterized using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) before and after acid activation. XRD analysis revealed quartz as the dominant mineral, while acid activation caused partial dissolution of layered silicates, leading to structural modifications without affecting quartz stability. SEM images confirmed morphological changes from compact aggregates with limited pores to rougher surfaces with larger and more interconnected pores, indicating increased surface area and porosity. Adsorption experiments demonstrated that both natural and acid-activated clays reduced free fatty acids (FFA) in waste cooking oil, with the acid-activated clay consistently showing higher efficiency. Prolonged stirring times (1, 3, and 5 hours) further enhanced adsorption, though the reduction rate decreased over time as adsorption sites approached saturation. In addition to lowering FFA levels, the treatment improved the visual quality of the oil by reducing discoloration. These findings highlight that acid-activated clay from Merauke possesses promising potential as a low-cost and effective adsorbent for oil purification and broader environmental remediation applications.
Co-Authors Hendro Hitijahubessy Henie Poerwandar Asmaningrum, Henie Poerwandar John Yoro Parlindungan Martasiana Karbeka Maulana, Muhammad Rasyiid Novike Bela Sumanik Noviyanti, Mila Anggita Siregar, Lamtiar Ferawaty