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Endang Tri Wahyuni
Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara, Yogyakarta 55281, Indonesia
Chemical Engineering, Chemistry & Bioengineering Chemistry

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Modified Silica Adsorbent from Volcanic Ash for Cr(VI) Anionic Removal Endang Tri Wahyuni; Roto Roto; Firda Ainun Nissa; Mudasir Mudasir; Nurul Hidayat Aprilita
Indonesian Journal of Chemistry Vol 18, No 3 (2018)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (337.464 KB) | DOI: 10.22146/ijc.26905

Abstract

In the present research, cetyltrymethyl ammonium bromide (CTAB)-modified silica from Kelud’s volcanic ash has been prepared and examined as adsorbent for removal of the hazardous Cr(VI) anion. The research was initiated with purification of SiO2 from the volcanic ash that was carried out by reacting the volcanic ash with NaOH powder at 900 °C for 2 h, followed by dissolving the ash to water at 100 °C, and then was acidified with HCl 1 M to form hydrogel. By calcination of the hydrogel, silica (SiO2) gel was obtained. The next step was modification of the silica with CTAB, that was performed by interacting the CTAB solution with the gel, in which the concentration of the CTAB was varied. Then the CTAB-modified silica samples were characterized by using FTIR, XRD, and SEM machines. The activity of the adsorbent was examined for adsorption of CrO4= in the solution. The results of the research demonstrate that the amorphous silica gel and the amorphous CTAB-modified silica have been obtained. The CTAB-modified silica was found to possess much higher ability in the adsorption of CrO4= anion, that was 48.90 mg/g, compared to that of the unmodified silica gel, as much 5.68 mg/g. These findings strongly prove that the negative surface of the CTAB-modified silica adsorbent has been successfully formed. Furthermore, it is also observed that increasing concentration of CTAB in SiO2-CTA can promote more effective adsorption of the CrO4= from the solution, but the further enlargement of the CTAB concentration leads to the adsorption decreased, and the highest adsorption was shown by CTAB-modified silica prepared with 0.10 mole of CTAB/1 mole SiO2.
Adsorption and Photodegradation of Cationic and Anionic Dyes by TiO2-Chitosan Nanocomposite Imelda Fajriati; Mudasir Mudasir; Endang Tri Wahyuni
Indonesian Journal of Chemistry Vol 19, No 2 (2019)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (598.191 KB) | DOI: 10.22146/ijc.38278

Abstract

The adsorption and photodegradation of cationic and anionic dyes by TiO2-chitosan nanocomposites have been studied. This study investigated the specific surface area, pores volume, pores size of TiO2-Chitosan nanocomposite, and determination kinetics of the reaction on the adsorption and photodegradation process. The methods were carried out by mixing TiO2-nanocomposite into cationic and anionic dyes in various contact times and initial dye concentrations. The results showed that nanocomposite adsorption capacity increased with an increase in the amount of chitosan (TiO2/Chit 0.13) even though the specific surface area (SBET) was reduced. The results indicated that the adsorption on nanocomposite was influenced by the amount of -NH2 and -OH on the chitosan surface. The maximum adsorption capacity (qm) and the observed reaction constant (kObs) for MO were also known to be higher than MB, which means that the TiO2-chitosan nanocomposites could remove anionic dye more than cationic one.
Antifungal Activity of TiO2/Ag Nanoparticles under Visible Light Irradiation Nahzim Rahmat; Endang Tri Wahyuni; Adhitasari Suratman
Indonesian Journal of Chemistry Vol 21, No 1 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.49150

Abstract

The doping of TiO2 by Ag(I) from [Ag(S2O3)2]3– contained in radiophotography wastewater by photoreduction method has been performed. TiO2/AgNPs photocatalyst was examined for its activity as an antifungal material for the inhibition of C. albicans in water under visible light irradiation. In the doping process, the weight of TiO2 was varied to obtain TiO2/AgNPs with different amounts of Ag. The TiO2/AgNPs samples were characterized by using FTIR, SRUV, TEM, SEM-EDX, and XRD methods. The antifungal test was carried out by disc diffusion method under visible light irradiation, wherein the amount of Ag-doped on TiO2, the dose of TiO2/AgNPs, and the irradiation time were optimized. The research results indicated that the antifungal activity of TiO2/AgNPs in inhibiting C. albicans has been successfully prepared. The highest inhibition was achieved by using 0.5 g/L of TiO2/AgNPs (I), at 5 h of irradiation time.
Performance Improvement of Tetraethylorthosilicate Consolidated Andesite Rock by Adding Titanium Tetraisopropoxyde and Silica Particles Nahar Cahyandaru; Endang Tri Wahyuni; Nuryono Nuryono
Indonesian Journal of Chemistry Vol 21, No 1 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.49786

Abstract

A study to improve the performance of andesite mortar and rock consolidated with tetraethylorthosilicate (TEOS) sol and a solvent of ethanol in the presence of titanium tetraisopropoxyde (TTIP) and silica particles has been conducted. The improvements include minimizing the shrinkage using silica particles from rice husk ash, rheological property suitability of the consolidant, and mechanical properties of the consolidated mortar and rock. The effect of TTIP concentration, ethanol volume, and addition of the silica particles on rheological properties of TEOS-based consolidant, and also mechanical properties of the consolidated mortar and rock were evaluated. The results showed that the increase of TTIP content in the consolidant shortens the gelling time, and the weight percentage ratio of TTIP:TEOS:ethanol of 5%:55%:40% was the optimum composition for the consolidation. Consolidation of andesite block using that composition significantly increased the compressive strength up to 57.61% (0.58 kgf/mm2). The addition of 2% of silica particles into the consolidant decreased the gel shrinkage and increased the Young modulus of the mortar. The presence of water in the andesite matrix reduced the consolidation performance, and 0.5% was the maximum percentage of water content acceptable for the consolidation.
Advanced Oxidation Processes of Amoxicillin Based on Visible Light Active Nitrogen-Doped TiO2 Photocatalyst Kusuma Putri Suwondo; Nurul Hidayat Aprilita; Endang Tri Wahyuni
Indonesian Journal of Chemistry Vol 23, No 2 (2023)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.81387

Abstract

Environmental consequences during the COVID-19 pandemic have attracted attention due to the excessive use of antibiotics which lead to the release of the drug's residue, such as amoxicillin (AMX), into the environment. In this work, an advanced oxidation process based on a visible, active N-doped TiO2 photocatalyst was carried out to eliminate AMX. Nitrogen with different initial doping concentrations (15, 30, 45% w/w) was doped into TiO2 by the sol-gel method. The characterization technique such as XRD, FTIR, UV-SRS, and SEM-EDX revealed that nitrogen with 30% doping concentration improved the TiO2 response in the visible region, attributed to the lower band gap energy (2.97 eV). In the photodegradation processes, the TiO2-N (30%) photocatalyst possessed higher AMX degradation than undoped TiO2 for both UV and visible light irradiation. In an aqueous solution, the degradation percentage of AMX by TiO2-N (30%) was 68.5 and 84.12%, while the degradation percentage of AMX by TiO2 was 38.7 and 78.01% under visible and UV light, respectively.
Co-Authors Adhitasari Suratman Firda Ainun Nissa Imelda Fajriati Kusuma Putri Suwondo Mudasir Mudasir Nahar Cahyandaru Nahzim Rahmat Nurul Hidayat Aprilita Nuryono Nuryono Roto Roto