Sugarcane bagasse represents a promising lignocellulosic feedstock for second-generation bioethanol production. This study evaluated the performance of immobilized Simultaneous Saccharification and Fermentation (SSF) systems using Saccharomyces cerevisiae and Zymomonas mobilis for ethanol production from alkali-pretreated sugarcane bagasse. Delignification using 10% NaOH enhanced cellulose accessibility for enzymatic hydrolysis by immobilized Aspergillus niger. SSF was conducted under anaerobic conditions at 30°C for 80 h. Reducing sugar dynamics, physicochemical properties, FTIR spectra, and GC analysis were used to evaluate ethanol formation and quality. The SSF system employing S. cerevisiae produced a higher ethanol concentration (2.83% v/v) and purity (99.77%) compared to Z. mobilis (2.20% v/v; 89.92%). Although higher residual reducing sugars were observed in the Z. mobilis system, ethanol conversion efficiency remained lower, indicating metabolic limitations under SSF conditions. FTIR and GC analyses confirmed ethanol formation with high water content in both distillates. These results demonstrate that microbial robustness plays a critical role in immobilized SSF performance, with S. cerevisiae exhibiting superior fermentative stability and ethanol yield compared to Z. mobilis.

North Sumatera Province, known for its jackfruit production, presents an opportunity to explore jackfruit seeds as a viable bioethanol feedstock. The province’s diverse agricultural commodities generate substantial agricultural waste, currently primarily used as fertilizer. This research aims to diversify waste utilization by focusing on jackfruit, a prominent commodity in North Sumatera, and its potential as a bioethanol feedstock. Given the scarcity of fossil fuels, exploring renewable energy sources, such as bioethanol derived from agricultural waste, is crucial. Identifying accessible sources within regions is vital. Converting jackfruit seed starch into bioethanol requires hydrolysis. This paper compares hydrochloric and sulfuric acid for bioethanol production. Qualitative testing confirmed the presence of bioethanol from both acids. The density of bioethanol produced using hydrochloric acid was 0.825 g/mL, 3.4% higher than the Indonesian standard value. Similarly, the density of bioethanol produced using sulfuric acid was 0.894 g/mL, 12% higher than the standard value. The viscosity of bioethanol produced using hydrochloric acid was 1.02 cp, 12% lower than the standard value. In contrast, bioethanol produced using sulfuric acid had a viscosity of 1.04 cp, 11% lower than the standard value. FTIR spectra of bioethanol treated with hydrochloric acid showed five prominent peaks: 3339.88 cm-1 (OH), 2953.35 cm-1 (-CH), 1643.79 cm-1 (-C-C), 1450.75 cm-1 (-CH3), and 1014.17 cm-1 (-CO). FTIR spectra of bioethanol treated with sulfuric acid showed only two major peaks at 3339.46 cm-1 and 1635.42 cm-1, both corresponding to -OH and -CH. The NMR spectra show three distinct peaks. In ethanol’s proton NMR spectrum, the first doublet at 1.71 and 1.61 ppm is the methyl group protons. The second peak at 2.02 ppm is the hydroxyl group proton. The third doublet at 3.59–3.62 ppm is the methylene group protons. All methods indicate that hydrochloric acid is a more effective hydrolytic agent than sulfuric acid.

Oil fuels derived from fossils are non-renewable, so over time, they will run out and have a negative impact on air pollution. To overcome this, there is a need for environmentally friendly alternative fuels from renewable sources such as biodiesel. This research used microwave heating with a CaO catalyst. NaOH-impregnated snail shells and active carbon support. This research aims to determine the effect of power on the conversion of candlenut seed oil into biodiesel using the NaOH/CaO/CA catalyst both in terms of compliance with the SNI 7182-2015 standard and analysis using GC-MS (Gas Chromatography-Mass Spectrometry). The synthesis of the NaOH/CaO/CA catalyst was carried out through wet impregnation and calcination at a temperature of 500°C and analyzed using gas sorption analysis (GSA). Then proceed to the transesterification process, where the power for microwave heating was varied to 300, 450, and 600 watts with a mole ratio of esterified oil and methanol, namely 1:10 for 3 minutes. The analysis results of the NaOH/CaO/CA catalyst using the GSA instrument have a surface area of 9.306 m2/g, pore volume of 0.033 cc/g, and pore diameter of 14.043 nm. Meanwhile, the results of the biodiesel analysis showed that the optimum biodiesel yield was 85.625% at 600 watts of power and had a kinematic density and viscosity that met the SNI 7182-2015 biodiesel standards. Analysis of biodiesel characteristics using GC-MS showed that the three most optimum biodiesel components were hexadecanoic acid, methyl ester (22.664%), 9,12-Octadedecadienoic acid (Z,Z)-, methyl ester (30.176%) and 9-Octadecenoic acid (Z)-, methyl ester (38.656%).

This study investigated the potential of porous silica material extracted from volcanic ash of Mount Sinabung, Indonesia, as a corrosion inhibitor. The new material was subjected to comprehensive analysis using the X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Search Engine Marketing (SEM), and Atomic Absorption Spectrophotometry (AAS). Corrosion test was conducted by coating the metal surface with synthesized silica. XRD data showed the presence of amorphous silica, while SEM indicated a rough and irregular pore cavity. Based on AAS characterization, the concentration of silica in the Mount Sinabung volcanic ash was 79.23 % (v/v) with a yield of 29.73 %(w/w). Furthermore, coated and uncoated iron plates, with grit variations of 800, 1200, 1500, and 2000, were tested against HCl 15 % (v/v) and NaCl 3.5 % (w/v) as model corrosive solutions. The SEM results showed that coated plates had fewer holes and cracks formation while the XRD analysis of the same samples presented a slight decrease in the intensity of iron phase. Among silica-coated iron plates, the 1500 grit variation had the lowest corrosion rate and the highest corrosion inhibitor efficiency in both HCl 15 % (v/v) and NaCl 3.5 % (w/v) corrosive solutions, recording efficiencies of 26.3 and 91.8 %, respectively.

Silica oxide (SiO2) is a chemical compound that can be obtained from the extraction of volcanic ash from Mount Sinabung. Silicon dioxide has the properties of high porosity, high mechanical strength, high thermal stability, large pore surface area, stable surface in acidic media so that it can be applied in the chemical coating field.This research aims to measurement of performance natural silica from volcanic ash of mount Sinabung Indonesia as additives to the paint to inhibit corrosion rate in metal surface. The addition of silica additives to the paint was carried out by dispersing (0; 0.5; 0.75; and 1) g with 10 mL of paint with each composition carried out for 60 minutes. Iron plate in sandpaper with 1500 grid and polished with bludru cloth using autosol metal polish, then coated with paint and a combination of silica-paint through the dipcoating method. The corrosion test was carried out on a corrosive solution of HCl 15% (v/v) and NaCl 3.5% (w/v). The corrosion rate using HCl 15% (v/v) showed C (0,286) mpy, SC1 (0,123) mpy, SC2 (0,149) mpy, SC3 (0,120) mpy. While at 3.5% (w/v) NaCl, namely C (0,282) mpy, SC1 (0,120) mpy, SC2 (0,142) mpy, SC3 (0,098) mpy. Inhibitor efficiency for various variations of silica composition in corrosive HCl 15%(v/v) solution, e.g., SC1 (56,9%), SC2 (47,9%), and SC3 (58,04%). The inhibitor efficiency at various compositions of silica in NaCl 3.5% (w/v) are SC1 (57,44%), SC2 (49%) dan SC3 (65,24%).

Biodiesel is a biofuel made from vegetable oil through an esterification-transesterification process. The process of making biodiesel is carried out by conventional heating methods and microwave heating. The reaction process was carried out according to the specified variables, with a concentration of 0.1% of the volume of methanol and a variable microwave power of 135, 225 and 315 watts with time variations of 5, 3 and 1 minute, as well as conventional heating at 60°C for 1 hour. The best result is the one using microwave heating with a power of 315 watts for 1 minute. The best biodiesel yield is 88.879%, with water content of 0.01%, an acid number of 0.56 Kg-KOH/g, a density of 0.892 g/mL and a viscosity of 2.617 cSt. The best result of biodiesel oil in comparison of is using the microwave heating method.

This study aims to determine the bioethanol yield and characteristics from pineapple peel with two methods such as Simultaneous Saccharification and Fermentation (SSF) and Separate Hydrolysis and Fermentation (SHF). The percent yield of bioethanol produced from the fermentation of pineapple peel (Ananas comosus) with the Simultaneous Saccharification and Fermentation method was 63.50%, while the yield of bioethanol from the Separate Hydrolysis and Fermentation method was 58.75%. The physical characteristics of bioethanol pineapple peel waste using Simultaneous Saccharification and Fermentation method has a density of 0.8237 w/v whilst with Separate Hydrolysis and Fermentation is 0.8858 w/v. Furthermore, viscosity of bioethanol using Simultaneous Saccharification and Fermentation is 1.05 Cp whereas using Separate Hydrolysis and Fermentation is 1.02 Cp. Pineapple peel bioethanol method of Simultaneous Saccharification and Fermentation has concentration of 13% while Separate Hydrolysis and Fermentation method has concentration of 7.92%. FTIR spectra from SHF bioethanol missing the peak correlated with CH, CH3, and CO. These missing peaks is due to the high percentage of water. Furthermore, bioethanol from SSF method showed peaks corresponding to CH, CH3, and CO functional groups. It can be concluded that SSF method give bioethanol with optimum result.

The quality of an education always refers to the results or academic achievements achieved by students. Chemistry can be a place or means for students to practice critical thinking skills, be creative and be able to solve problems where students relate them to everyday phenomena. Certainly, there are many factors that influence the success of students in learning chemistry. This study aims to determine the relationship between self-efficacy and creative thinking skills with student chemistry learning outcomes. The sample of this study was 50 students of class XI taken by random sampling technique. Data were collected using a self-efficacy questionnaire as well as creative thinking ability tests and chemistry learning outcomes tests. Data analysis using multiple linear regression test. The results showed that there was a positive and significant relationship between self-efficacy and student chemistry learning outcomes, there was a positive and significant relationship between creative thinking skills and student chemistry learning outcomes; there is a significant and simultaneous relationship between self-efficacy and creative thinking skills with student chemistry learning outcomes with a coefficient of determination of 36.2%.Kualitas suatu pendidikan selalu mengacu pada hasil atau prestasi akademik yang dicapai oleh peserta didik. Ilmu kimia dapat menjadi wadah atau sarana bagi siswa untuk melatih kemampuan berpikit kritis, kreatif dan mampu memecahkan masalah dimana siswa mengaitkannya dengan fenomena sehari-hari. Tentunya ada banyak faktor yang mempengaruhi keberhasilan siswa dalam belajar kimia. Penelitian ini bertujuan untuk mengetahui hubungan self-efficacy dan kemampuan berpikir kreatif dengan hasil belajar kimia siswa. Sampel penelitian ini adalah siswa kelas XI sebanyak 50 orang yang diambil dengan teknik random sampling. Data dikumpulkan menggunakan angket self-efficacy serta tes kemampuan berpikir kreatif dan tes hasil belajar kimia. Analisis data menggunakan uji regresi linier berganda. Hasil penelitian menunjukkan bahwa terdapat hubungan yang positif dan signifikan antara self-efficacy dengan hasil belajar kimia siswa, terdapat hubungan yang positif dan signifikan antara kemampuan berpikir kreatif dengan hasil belajar kimia siswa; terdapat hubungan yang signifikan dan simultan antara self-efficacy dan kemampuan berpikir kreatif dengan hasil belajar kimia siswa dengan koefisien determinasi sebesar 36,2%.

Ceria has unique abilities that makes it possible to be used as catalyst supports. The abilities of ceria are to store and release oxygen and easy transformation of Ce+4 to Ce+3 and vice versa Ceria as a catalyst support, showed a disadvantage over high temperature. The purpose of the paper is finding the right recipe for growing Mn-ceria mixed oxide. STM, XPS and LEED were used to acquire fundamental information. LEED experiments from Mn doped ceria mixed oxide specified that the films is well ordered. The LEED results is showing six spots that indicated the well ordered film and follow the (111) plane. Furthermore, for Mn doped ceria mixed oxide, there is no disctinct difference between higher stoichiometry and lower stoichiometry mixed oxide. But between higher and lower percentage of Mn, it has different structure. The triangle islands from higher Mn mixed oxide is MnO follow (111) plane. For both lower and higher Mn, oxygen vacancies can be recognized in reduced films.

Ceria has attracted great attention in recent years in the catalysis community. Metal catalysts supported on ceria exhibit a promising catalytic activity due to the ceria’s unique redox properties and oxygen storage capacity. The purpose of this paper is to look at the fundamental aspect of CeO x (111) thin films on Ru(0001). The investigation presented in this paper utilizes the surface science method to understand the properties of CeO x (111). In one component, through a series of XPS studies, it is shown that the deposition of Ce in the presence of oxygen on Ru(0001) can produce ceria thin films. Fully oxidized CeO 2 can be obtained with an oxygen pressure of 2 x 10 −7 Torr. With the decrease in the oxygen pressure, partially reduced CeO x films can be prepared. Moreover, STM images are collected from the CeO 2 growth in the presence of 2×10 −7 Torr of oxygen and partially reduced ceria with oxygen pressures of 8×10 −8 Torr. These films can completely cover the Ru(0001) substrate. The measured step height is about 0.3 nm, which is consistent with the 0.313 nm spacing of O-Ce-O tri-layers in the CeO 2 (111) fluorite bulk structure.

Low coverage of Ni was deposited onto well-ordered Ti-doped CeOx (111) (1.5 < x < 2) thin films at 300 K under ultrahigh vacuum conditions. The morphology and interaction of Ni with Ti-ceria interfaces were investigated with X-ray photoelectron spectroscopy and scanning tunneling microscopy. Ti doped-CeOx (111) mixed oxide interfaces can be prepared by physical vapor deposition of submonolayer coverages of Ti onto both fully oxidized CeO2 (111) and partially reduced thin films (e.g. CeO1.92) at room temperature followed by heating to 700 K. Ti is oxidized to Ti4+ at the cost of ceria reduction. Titania features are uniformly distributed on CeOx with an average height of 0.31 nm. Upon Ni deposition over both Ti-CeO2 (111) and Ti-CeO1.92 surfaces at 300 K, oxidation of Ni to NiO occurs and thus both metallic Ni and Ni2+ species are present in the particles formed over Ti-CeOx surfaces. The extent of Ni oxidation depends on the nature of Ti-CeOx. 28% of deposited Ni is in the +2 state over Ti-CeO2. With heating to 700 K, the percent of the Ni2+ species increases to 37% over Ti-CeO2. However, metallic Ni is the predominant species over Ti-CeO1.92. The difference in the Ni species present in the particles results in a different particle sintering behavior with heating. Compared to pure ceria, modifications of ceria with addition of Ti metal dopants can significantly stabilize Ni as smaller nanoparticles upon heating.

Well-ordered CeO2(1 1 1) thin films were prepared on a Ru(0001) single crystal substrate in an oxygen environment. Co-deposition of Ce and Mn during the CeO2(1 1 1) thin film growth can produce well-ordered Ce1-xMnxO2-d(1 1 1) mixed oxide films with a low Mn composition of similar to 6%. The incorporated Mn atoms in the ceria film exhibit the +2 oxidation state. Segregation of Mn to the ceria surface and formation of MnO islands occur upon heating with the increase of the Mn metal composition above 9%. Addition of Mn into the ceria lattice causes the reduction of ceria. Mn-doped ceria was also prepared by depositing submonolayer coverage of Mn over CeO2(1 1 1) thin films at room temperature followed by heating to 700 K, which forms two dimensional triangular structures of MnO at the CeO2-delta surface. Mn is oxidized to Mn2+ at the cost of Ce4+ reduction. Effects of Mn dopants in ceria were investigated for deposited Ni. Both metallic Ni and Ni2+ species are present in the particles upon Ni deposition over both types of Mn-doped ceria surfaces. Compared to pure ceria, addition of Mn dopants can provide different anchoring sites for Ni that can affect the size, thermal stability and interaction between deposited Ni and modified ceria.

The growth and structure of Mn on reducible ceria were investigated under ultrahigh vacuum conditions with X-ray photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy techniques. Submonolayer coverage of Mn was deposited on well-ordered CeOx(111) (1.5<x<2) thin films by physical vapor deposition method at room temperature. Mn is oxidized and formally in the +2 oxidation state on both fully oxidized and partially reduced ceria. Oxidation of Mn is accompanied with the reduction of ceria. STM results show the presence of atomic-layer high islands of Mn forming Mn-O-Ce linkages uniformly distributed on the ceria surface. With heating to higher temperatures, these Mn0 features can coalesce to form slightly larger two-dimensional structures. Our combined spectroscopy and microscopy studies demonstrate a strong interaction between Mn and ceria supports. Introduction of Mn can form mixed Mn-Ce oxides at the interface which can represent model metal-doped ceria surfaces for further examination of the chemical behavior. (C) 2016 Elsevier B.V. All rights reserved.