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All Journal EKSAKTA: Journal of Sciences and Data Analysis IJCR (Indonesian Journal of Chemical Research)
winata, wahyu fajar
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Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Earth & Planetary Sciences Materials Science & Nanotechnology

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Studi Kinetika Adsorpsi Cu(II) Dan Pb(II) dengan Menggunakan Biosorben dari Polimer Ekstrak Kulit Buah Rambutan Winata, Wahyu Fajar; Yanti, Ika
INDONESIAN JOURNAL OF CHEMICAL RESEARCH Volume 5, ISSUE 1, 2020
Publisher : Chemistry Department, Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (35.093 KB) | DOI: 10.20885/ijcr.vol5.iss1.art1

Abstract

RecoveryCu(II) dan Pb(II) yang sebagian besar terkandung dalam limbah cair industri, baik industri besar maupun rumah tangga telah dilakukan, salah satunya adalah dengan proses adsorpsi. Penelitian ini dilakukan studi kinetika adsorpsi Cu(II) dan Pb(II) dalam limbah cair untuk mengetahui efektivitas biosorben dari ekstrak kulit buah rambutan terhadap limbah cair yang mengandung Cu(II) dan Pb(II).Penentuan kinetika adsorpsi Cu(II) dan Pb(II) dengan menggunakan biosorben dari ekstrak kulit buah rambutan dilakukan melalui beberapa model kinetika yaitu model kinetika Langmuir-Hinshelwood,Santosa, Lagergreen dan Ho. Kinetika adsorpsi Cu(II) dan Pb(II) semuanya mengikuti model kinetika Ho, yang merupakan mekanisme kinetika orde dua semu.
Effect of Phenol–Formaldehyde Molar Ratio on the Physicochemical Properties of Phenolic Synthetic Tanning Agent (Syntan) Winata, Wahyu Fajar; Hermawan, Prasetyo; Nurbalia, Elis
EKSAKTA: Journal of Sciences and Data Analysis VOLUME 7, ISSUE 1, April 2026
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/EKSAKTA.vol7.iss1.art10

Abstract

Phenolic synthetic tanning agents (syntans) are widely used in the leather industry due to their controllable properties and consistent performance. This study aims to investigate the effect of phenol– formaldehyde molar ratio on the physicochemical properties of syntans synthesized via sulfonation. The syntans were prepared using various molar ratios (0:1, 0.5:1, 1:1, 1.5:1, 1:0.5, and 1:0) throughcondensation followed by sulfonation. The products were characterized in terms of pH, specific gravity, viscosity, degree of sulfonation (DS), and functional groups using FTIR spectroscopy. The results show that increasing phenol or formaldehyde concentration led to higher specific gravity and viscosity, indicating increased polymerization. The pH values ranged around ~4, confirming suitability for leather processing. The DS decreased with increasing phenol or formaldehyde concentration, suggesting competition between polymerization and sulfonation reactions. The optimal molar ratio (1:1) produced the most homogeneous and stable syntan system. The pH values of all syntans were consistently around ~4, indicating suitability for leather processing. Increasing phenol or formaldehyde concentration resulted in higher viscosity and specific gravity, while the degree of sulfonation decreased significantly, confirming the trade-off between polymerization and sulfonation reactions. In conclusion, the phenol–formaldehyde molar ratio significantly influences syntan properties by controlling the balance between polymerization and sulfonation. These findings provide a scientific basis for optimizing syntan formulation and improving efficiency in sustainable leather processing.
Binder Engineering of Leather Shaving Waste–Based Collagen Composite for Shoe Insole Application: Mechanical–Moisture Trade-Off Analysis Winata, Wahyu Fajar; Nurbalia, Elis; Rahmayani, Elyka; Dewi, Zahra Saadiya; Tiyastuti, Rini
INDONESIAN JOURNAL OF CHEMICAL RESEARCH Vol. 11 No. 1 (2026): Volume 11, ISSUE 1, 2026
Publisher : Chemistry Department, Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/ijcr.vol11.iss1.art6

Abstract

Leather shaving waste (LSW) generated from the tannery industry contains chromium-stabilized collagen fibers that are environmentally persistent and difficult to manage. This study investigates the valorization of LSW into leather board for shoe insole applications through binder system engineering. LSW was neutralized using alkaline treatment and compounded with polyester resin and polyvinyl acetate (PVAc), followed by press molding. Mechanical properties and water absorption were evaluated according to SNI 1294-2009 standards. The results show that binder composition significantly influences interfacial adhesion, mechanical strength, and moisture sensitivity. Formulation F3 exhibited superior tensile and tear strength due to enhanced fiber–matrix bonding, while formulation F4 demonstrated improved water resistance. An Engineering Performance Index (EPI) was introduced to integrate mechanical strength and moisture stability, revealing a clear trade-off between maximum mechanical performance and durability against water absorption. Formulation F6 presented a more balanced mechanical–moisture profile suitable for practical insole applications. These findings confirm that binder engineering governs the structure–property relationship of collagen-based composites and provides a sustainable pathway for circular utilization of tannery solid waste.
Co-Authors Dewi, Zahra Saadiya Ika Yanti, Ika Nurbalia, Elis Prasetyo Hermawan Rahmayani, Elyka Tiyastuti, Rini