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All Journal Jurnal Matematika & Sains Bulletin of Chemical Reaction Engineering & Catalysis Journal of Mathematical and Fundamental Sciences Indonesian Journal of Biotechnology

Veinardi Suendo

Departemen Kimia, Institut Teknologi Bandung

Author-ID : 444793

Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Earth & Planetary Sciences Immunology & microbiology Materials Science & Nanotechnology Mathematics Physics

Published : 8 Documents Claim Missing Document

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Articles

Pengaruh Media Perendam Terhadap Permeabilitas Membran Polisulfon Cynthia L. Radiman; Yuliany Yuliany; Veinardi Suendo
Jurnal Matematika & Sains Vol 7, No 2 (2002)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar

The performance of membrane separation processes can be generally expressed by membrane permeability and permselectivity. One of the important factors affecting membrane permeability in the filtration process of aqueous solution is membrane hydrophilicity. In this experiment, the effects of various soaking mediums, i.e. ethanol, isopropanol and butanol on the permeability of polysulfone membrane were studied. The results showed that soaking in ethanol gave the greatest effect proved by the drastic increase in permeability for membrane before and after soaking, i.e. from 263.57 L/m2.h to 645.49 L/m2.h. On the other hand, the membrane rejection against dextran T-500 before and after soaking in ethanol only showed a slight decrease from 96 % to 95 %. In addition, the contact angle between water and soaked-in-ethanol membrane gave the smallest value, i.e. 19.8Â°. The interaction between alcohol and soaked membrane is then considered as a reversible physical adsorption since the permeability reached its initial value after being soaked again in water for a long period. The experimental data showed that ethanol could enhance the permeability of polysulfone membrane by increasing the membrane hydrophilicity without giving any significant decrease in the membrane permselectivity.

Isolation of chlorophyll a from spinach leaves and modification of center ion with Zn2+: Study on its optical stability Nurhayati Nurhayati; Veinardi Suendo
Jurnal Matematika & Sains Vol 16, No 2 (2011)
Publisher : Institut Teknologi Bandung

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It is well-known that the pure chlorophyll a, which has a magnesium central ion, is not stable against high intensity light exposure. It was observed that it degrades with a lifetime of 12.8 seconds based on the evolution of fluorescence signal intensity under the irradiation of 60 mW diode laser at 405 nm that resonates with its Soret band. In order to be applied as an optical material, the stability of chlorophyll a needs to be improved. One way to enhance the photostability of chlorophyll a is by changing the center ion, where in this study Mg2+ in chlorophyll a is replaced by Zn2+ to form Zn-pheophytin a. The results show a significant increase in the decay lifetime from 12.8 to 49.5 seconds by introducing the Zn2+ ion into porphyrin ring. It was observed that the absorption maximum of Soret band is red shifted from 413 nm to 424 nm after the introduction of Zn2+ into porphyrin ring, while the Q band maximum is blue shifted from 667 nm to 658 nm. The mass spectroscopy result confirmed that Mg2+ ions have been replaced by Zn2+. The results show the presence of m/z 933.5 and m/z 971.5 species, which are typical for Zn-pheophytin a and Zn-pheophytin a dihydrate, respectively. Keywords: Chlorophyll a, Photodegradation, Optical materials, Optical stability, Porphyrin, Zn-pheophytin a. Â Isolasi Klorofil a dari Daun Bayam dan dan Modifikasi Pusat Ion dengan Zn2+: Studi Stabilitas Optik Abstrak Telah diketahui secara umum bahwa klorofil a murni, dengan ion pusat magnesium, bersifat tidak stabil terhadap penyinaran berintensitas tinggi. Telah diamati pada penelitian ini bahwa klorofil a mengalami degradasi dengan waktu hidup 12,8 detik yang diperoleh dari evolusi intensitas sinyal fluoresensi pada penyinaran dengan laser dioda berdaya 60 mW pada 405 nm yang beresonansi dengan pita Soret. Agar dapat diaplikasikan sebagai material optik, kestabilan klorofil a perlu ditingkatkan. Salah satu cara untuk meningkatkan kestabilan klorofil a adalah mengganti ion pusatnya. Dalam penelitian ini kation yang digunakan adalah Zn2+ yang akan membentuk Zn-pheophytin a. Hasil penelitian menunjukkan peningkatan nilai waktu hidup yang signifikan dari 12,8 detik menjadi 49,5 detik dengan masuknya ion Zn2+ ke dalam cincin porfirin pada klorofil a. Diamati bahwa penyerapan maksimum pita Soret mengalami pergeseran merah dari 413 nm ke 424 nm setelah pergantian ion pusat dengan Zn2+, sedangkan pita Q maksimum mengalami pergeseran Â biru dari 667 nm menjadi 658 nm. Hasil spektroskopi massa memastikan bahwa ion Mg2+ telah tergantikan oleh ion Zn2+. Ditemukan keberadaan spesi dengan m/z 933,5 dan m/z 971,5 yang merupakan m/z spesifik untuk Zn-pheophytin a dan Zn-pheophytin a dihidrat. Kata kunci: Kestabilan optik, Klorofil a, Fotodegradasi, Material optik, Porfirin, Zn-pheophytin a.

Analysis of ethylene biosynthesis gene expression profile during titanium dioxide (TiO2) treatment to develop a new banana postharvest technology Fenny M Dwivany; Rizkita R Esyanti; Veinardi Suendo; Aksarani ‘Sa Pratiwi; Annisa A Putri
Indonesian Journal of Biotechnology Vol 24, No 2 (2019)
Publisher : Universitas Gadjah Mada

Banana is an important crop that demands proper methods in postharvest handling. As a climacteric fruit, thebanana fruit ripening process is aﬀected by ethylene. Several methods have been developed to extend the shelf life of a banana, such as using ethylene scrubbers. In this study, ttanium dioxide (TiO2), a photocatalyst, was used as an alternatve method to delay the fruit ripening process. The eﬀect of TiO2 on the ripening‐related gene MaACS1 was investgated. Banana fruits were placed in a TiO2‐coated glass chamber and observed for ten days. Fruit ripening in the treated chamber was delayed for eight days compared to the control. Total RNA was extracted from control and TiO2‐treated fruit pulp and synthesized into cDNA. Reverse transcripton PCR was performed to investgate the gene expression, which showed that MaACS1 expression was relatvely lower than treated control. The fnding of these studies suggested that the TiO2 chamber has the potental to extend the shelf life of banana by delaying its ripening process and decreasing the expression of MaACS1. To the best of our knowledge, no previous study has investgated the eﬀect of TiO2 on the expression of genes related to banana fruit ripening.

Synthesis of Spherical Nanostructured g-Al2O3 Particles using Cetyltrimethylammonium Bromide (CTAB) Reverse Micelle Templating Didi Prasetyo Benu; Veinardi Suendo; Rino Rakhmata Mukti; Erna Febriyanti; Fry Voni Steky; Damar Rastri Adhika; Viny Veronika Tanuwijaya; Ashari Budi Nugraha
Bulletin of Chemical Reaction Engineering & Catalysis 2019: BCREC Volume 14 Issue 3 Year 2019 (December 2019)
Publisher : Department of Chemical Engineering - Diponegoro University

We demonstrated the synthesis of spherical nanostructured g-Al2O3 using reverse micelle templating to enhance the surface area and reactant accessibility. Three different surfactants were used in this study: benzalkonium chloride (BZK), sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). We obtained spherical nanostructured particles only using CTAB that form a reverse micelle emulsion. The particles have wide size distribution with an average size of 2.54 mm. The spherical particles consist of nanoplate crystallites with size 20-40 nm randomly arranged forming intercrystallite spaces. The crystalline phase of as-synthesized and calcined particles was boehmite and g-Al2O3, respectively as determined by XRD analysis. Here, the preserved particle morphology during boehmite to g-Al2O3 transformation opens a facile route to synthesize g-Al2O3 particles with complex morphology. The specific surface area of synthesized particles is 201 m2/g, which is around five times higher than the conventional g-Al2O3 (Aldrich 544833). Spherical nanostructured g-Al2O3 provides wide potential applications in catalysis due to its high density closed packed structure, large surface area, and high accessibility.

bcl Morphology Formation Strategy on Nanostructured Titania via Alkaline Hydrothermal Treatment Fry Voni Steky; Veinardi Suendo; Rino Rakhmata Mukti; Didi Prasetyo Benu; Muhammad Reza; Damar Rastri Adhika; Viny Veronika Tanuwijaya; Ashari Budi Nugraha
Bulletin of Chemical Reaction Engineering & Catalysis 2019: BCREC Volume 14 Issue 3 Year 2019 (December 2019)
Publisher : Department of Chemical Engineering - Diponegoro University

Titanium dioxide (TiO2) is a semiconductor material that plays an important role in photocatalysis. Bicontinuous concentric lamellar (bcl) is an interesting morphology with an open channel pore structure that has been successfully synthesized on silica-based materials. If bcl morphology can be applied in TiO2 system, then many surface properties of TiO2 can be enhanced, i.e. photocatalytic activity. A simple and effective strategy has been demonstrated to transform aggregated and spherical TiO2 particles to bcl morphology via alkaline hydrothermal route. Alkaline hydrothermal treatment successfully transforms TiO2 particle surface to have bcl morphology through swelling with ammonia then followed by phase segregation process. We proposed this strategy as a general pathway to transform the particle surface with any shape to have bcl morphology.

Investigation of Chlorophyl-a Derived Compounds as Photosensitizer for Photodynamic Inactivation Listiana Oktavia; Irma Mulyani; Veinardi Suendo
Bulletin of Chemical Reaction Engineering & Catalysis 2021: BCREC Volume 16 Issue 1 Year 2021 (March 2021)
Publisher : Department of Chemical Engineering - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.16.1.10314.161-169

Chlorophyll has unique physicochemical properties which makes them good as photosensitizer of Photodynamic Inactivation (PDI). The physicochemical properties of chlorophyll as photosensitizer can be optimized through several routes. One of the possible route is by replacing the metal ion center of chlorophyll with other ions. In this research, the effect of coordinated metal ion in the natural chlorophyll-a was studied for bacterial growth (S. aureus) inhibition. The replacement of metal in the center of chlorophyll hopefully can improve the intensity of Intersystem Crossing Mechanism (ISC) lead to the formation of singlet oxygen species. The chlorophyll a and b were isolated from spinach via precipitation technique using 1,4 dioxane and water. The chlorophyll a and b were separated using sucrose column chromatography. The thin layer chromatography result showed that chlorophyll a (Rf: 0.57) had been well separated with chlorophyll b (Rf: 0.408). The absorption spectra of chlorophyll a and b showed that the Soret band was observed at 411 and 425 nm, while the Q band appeared at 663 and 659 nm. Replacement of metal ion center shifted the Soret band of chlorophyll- a derivatives to lower energy region, while Q-band was slightly shifted to the higher energy region. The absorption and the fluorescence intensity were also observed decreasing after ion replacement. The Inhibition activity investigation over S. aureus showed the highest inhibition activity was exhibited by Zn-pheophytin-a (66.8%) followed by chlorophyll a (30.1 %) and Cu-pheophytin-a (0%). The inhibition activity is correlated with decreasing fluorescence intensity. The formation of singlet oxygen by ISC mechanism is hypothesized to deactivate the excitation state of Cu-pheophytin-a. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Preparation of Polyaniline Emeraldine Salt for Conducting-Polymer-Activated Counter Electrode in Dye Sensitized Solar Cell (DSSC) using Rapid-Mixing Polymerization at Various Temperature Auliya Nur Amalina; Veinardi Suendo; Muhammad Reza; Phutri Milana; Risa Rahmawati Sunarya; Damar Rastri Adhika; Viny Veronika Tanuwijaya
Bulletin of Chemical Reaction Engineering & Catalysis 2019: BCREC Volume 14 Issue 3 Year 2019 (December 2019)
Publisher : Department of Chemical Engineering - Diponegoro University

Polyaniline Emeraldine Salt (PANI ES) as a conductive polymer has been used as a Pt-free counter electrode materials in DSSC. In this study, polymerization temperature was varied at relatively high temperature from 308 to 348 K with respect to the standard low polymerization temperature at 273 K. The synthesis held in varied high-temperature to study the effect of synthesis condition resulted to the performance as counter electrode in DSSC. The effect of high-temperature synthesis condition gives interesting results, the FTIR-ATR spectra show the presence of vibrational modes of phenazine structure obtained at high polymerization temperature, indicate the changing in the chain geometry. Raman Spectroscopy shows the decrease of the I1194/I1623 intensity ratio that can be interpreted that the degree-of-freedom of C-H bond bending mode decreases in the benzenoid ring, while the stretching mode degree-of-freedom along the chain is preserved or increased. The electrical conductivity profile has changed from metal-like at low-temperature into a semiconductor-like profile at high-temperature. Scanning Electron Microscope images reveals that a change in the morphology of PANI ES with temperature. At low-temperature (273 K) the morphology has a globular shape, while at high-temperature it tends to form nanorod structure. DSSC device with highest efficiency is attained for PANI ES polymerized at 273 K (1.91%) due to its high conductivity. The lowest efficiency is observed in device using PANI ES synthesized at 328 K (1.15%) due to its low conductivity due to the formation of phenazine structure.

Ab Initio Calculation of UV-Vis Absorption Spectra of a Single Chlorophyll a Molecule: Comparison Study between RHF/CIS, TDDFT, and Semi-Empirical Methods Veinardi Suendo; Sparisoma Viridi
Journal of Mathematical and Fundamental Sciences Vol. 44 No. 2 (2012)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2012.44.2.1

Chlorophyll a is the most abundant pigment on Earth responsible for trapping light energy to perform photosynthesis in green plants. This molecule has been studied for many years from different points of interest with both experimental and theoretical methods. In this study, the Restricted Hartree-Fock/Configuration Interaction Single (RHF/CIS), Time-Dependent Density Functional Theory (TDDFT), and several semi-empirical methods (CNDO/S and ZINDO) calculations were carried out to reconstruct the UV-Vis absorption spectra of chlorophyll a. To some extent, the calculation results based on the single-molecule approach succeeded to reconstruct the absorption spectra, but they required to be rescaled to fit the experimental results. In general, the semiempirical methods provide a better energy scaling factor. However, they lack vertical transition fine features with respect to the spectrum obtained experimentally. In this case, the ab initio calculations provided more complete features, especially the TDDFT with high-level basis sets, which also has a good accuracy with regards to the transition energies. The contribution of the ground state and excited state orbitals in the main vertical transitions is discussed based on the delocalized nature of the wave functions and the presence of solvents using the polarizable continuum model (PCM).

Co-Authors Aksarani ‘Sa Pratiwi Annisa A Putri Ashari Budi Nugraha Ashari Budi Nugraha Auliya Nur Amalina Benu, Didi Prasetyo Cynthia L. Radiman Damar Rastri Adhika Damar Rastri Adhika Erna Febriyanti Fenny M Dwivany Fry Voni Steky Irma Mulyani Listiana Oktavia Muhammad Reza Phutri Milana Rino Rakhmata Mukti Risa Rahmawati Sunarya Rizkita R Esyanti Sparisoma Viridi Viny Veronika Tanuwijaya Viny Veronika Tanuwijaya Yuliany Yuliany

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