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All Journal Makara Journal of Science
Riwandi Sihombing, Riwandi
Department of Chemistry, FMIPA, Universitas Indonesia, Depok

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Adsorption of Phosphate Ion in Water with Lithium-Intercalated Gibbsite Sihombing, Riwandi; Krisnandi, Yuni Krisyuningsih; Widya, Rahma; Luthfiyah, Siti Zahrotul; Yunarti, Rika Tri
Makara Journal of Science Vol. 19, No. 4
Publisher : UI Scholars Hub

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In order to enhance adsorption capacity of gibbsite (Al(OH)3 as an adsorbent for the adsorption of phosphate in water, gibbsite was modified through lithium-intercalation. The purification method of Tributh and Lagaly was applied prior to intercalation. The Li-Intercalation was prepared by the dispersion of gibbsite into LiCl solution for 24 hours. This intercalation formed an cationic clay with the structure of [LiAl2(OH)6]+ and exchangeable Cl- anions in the gibbsite interlayer. A phosphate adsorption test using Lithium-intercalated gibbsite (LIG) resulted in optimum adsorption occurring at pH 4.5 with an adsorption capacity of 11.198 mg phosphate/g LIG which is equivalent with 1.04 wt% LIG. The adsorption capacity decreased with decreasing amounts of H2PO4-/HPO4- species in the solution. This study showed that LIG has potential as an adsorbent for phosphate in an aqueous solution with pH 4.5–9.5.
Fe(III) Oxide-modified Indonesian Bentonite for Catalytic Photodegradation of Phenol in Water Pradisty, Novia Arinda; Sihombing, Riwandi; Howe, Russell Francis; Krisnandi, Yuni Krisyuningsih
Makara Journal of Science Vol. 21, No. 1
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Phenol, which is a major organic pollutant, is usually detected in industrial wastewater, and thus the wastewater should be processed further before discharged into water bodies. Application of heterogeneous catalysis using natural-basedmaterials is known to be effective and environmentallyfriendlyinremoving hazardous substances in water. In this study, local natural bentonite from the Tapanuli region in Indonesia was modified to eliminate dissolved phenol. Elimination by photodegradation reaction was conductedinaphoto-Fenton system utilizing Fe(III) oxide-modifiedbentonite (Fe-B) as catalyst. Fe-B was prepared byacation exchanging process using mixture solutions of NaOH and FeCl3 with OH/Femolar ratio of 2:1 and calcined at 300 °C. Material characterization was performed by X-ray diffraction (XRD), low-angle XRD, Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The reaction components consisted of ultraviolet Clight, H2O2, and Fe-B, and they were processed in a batch reactor. The role of each component was analyzed by a series of reaction conditions (i.e., adsorption, photolysis, H2O2effect, Fenton, and homogeneous photo-Fenton). The heterogeneous photo-Fenton system was found to be essential for phenol degradation, as none of the reaction conditions caused total phenol removal in the 180 min reaction time. To conclude, heterogeneous photo-Fenton gave the highest photodegradation activity, and the best experimental condition for 1.10 mM phenol removal was 5 g L-1 catalyst, 78.35 mM H2O2, and 90 minreaction time.
The Effect of Alkaline Treatment to the Structure of ZSM5 Zeolites Octaviani, Savitri; Krisnandi, Yuni K.; Abdullah, Iman; Sihombing, Riwandi
Makara Journal of Science Vol. 16, No. 3
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Self-Assembly and Hydrogelation of Peptide Amphiphiles Irwansyah, Irwansyah; Sihombing, Riwandi; Suwarso, Wahyudi Wahyudi
Makara Journal of Science Vol. 16, No. 1
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Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometer (MALDI-TOF MS). Atomic force microscopy (AFM) study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG). Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC) lower than 1% (w/v).
Co-Authors Iman Abdullah Irwansyah Irwansyah Luthfiyah, Siti Zahrotul Octaviani, Savitri Pradisty, Novia Arinda Russell Francis Howe, Russell Francis Suwarso, Wahyudi Wahyudi Widya, Rahma Yunarti, Rika Tri Yuni K. Krisnandi Yuni Krisyuningsih Krisnandi, Yuni Krisyuningsih