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Purpose Furthermore, the purpose of this study is to compare the student engagement and the learning outcomes in offline and online PBL in the aforementioned course. The COVID-19 pandemic has caused disruption in various sectors, including education. Since it was first announced in mid-March 2020 in Indonesia, teaching and learning activities have been carried out online. In this study, a comparison of the offline (Spring 2019, prior to the pandemic) and online (Spring 2021, during the pandemic) problem-based learning (PBL) method in the sustainable chemical industry course is investigated. Design/methodology/approach A quantitative analysis was conducted by measuring the students’ engagement, course-learning outcomes (CLOs) and student learning outcomes (SLOs). Difference tests of engagement score, CLOs and SLOs were investigated by using the t-test or Mann–Whitney U-test. Furthermore, the perceived students’ stressors were measured. Findings It is found that the students’ engagement in offline and online PBL gives similar scores with no significant difference. This is possible because of the PBL structure that demands students to be actively engaged in gaining knowledge, collaboratively working in teams and interacting with other students and lecturers. Although similarly engaged, the CLOs and SLOs of online PBL are significantly lower than offline PBL, except for SLO related to oral and written communication skills and affective aspect. The decrease in CLOs and SLOs could be influenced by students’ academic, psychological and health-related stressors during the COVID-19 pandemic time. Originality/value This study provides a recommendation to apply online PBL during the COVID-19 pandemic time and beyond, although some efforts to improve CLOs and SLOs are needed.

Lithium-ion capacitors are considered highly promising as a hybrid-type energy storage system and are suitable for large-scale energy storage applications because of their superior power and energy density as well as prolonged cycle life. In this study, we developed an activated carbon (AC)-based electrode with excellent capacitive performance using salacca peel, a native Indonesian fruit, as the carbon precursor. The AC was synthesized via hydrothermal treatment of salacca peel with cerium (III) chloride (CeCl3) as the catalyst, followed by microwave-assisted chemical activation; the obtained sample was denoted as AC–S–CE. The addition of CeCl3 during the hydrothermal carbonization facilitated the formation of micropores in the AC; this resulted in a considerably greater surface area (1264.4 m2 g–1) and a more defective graphitic structure than that of AC synthesized in the absence of CeCl3 (AC–S, 988.9 m2 g–1) and of commercially available AC (742.8 m2 g–1). In terms of being an LIC cathode, all the ACs exhibited a non-faradaic charge–discharge mechanism. AC–S–CE exhibited a higher capacitance of 90.6 F g–1 at 0.05 A g–1 and improved cycling performance compared with those of AC–S and commercially available AC.

Utilisation of natural coagulants in water and wastewater treatment has gained a considerable amount of interest in recent years. This is possible due to its advantages such as being renewable, bei...

Coagulation is a water and wastewater treatment technology that has been widely used due to its high efficiency and effectiveness. Various inorganic salts are commonly used as coagulant; however, there are some negative impacts of utilization of these chemical coagulants, such as high costs, large sludge volume, and also potential negative impact to human health. To overcome these problems, natural-based coagulants have been explored to reduce and substitute chemical coagulants. In this study we investigated utilization of Leucaena leucocephala seed protein, extracted using 0.5 M MgCl2 solution as natural coagulant to treat synthetic Congo red wastewater. From the protein solubility profile at various pH, it could be observed that leucaena protein’s isoelectric point was around pH 4. The optimization of coagulation condition was done by using Response Surface Method (RSM)—Central Composite Design (CCD) with variations of pH (2.93–4.12), coagulant dose (183.52–496.58 mg eq BSA/L), and dye concentration (44.1–56 mg/L). This experimental design was used to obtain the optimum condition that gave maximum dye removal percentage and minimum sludge volume. It was found that pH, coagulant dose, and dye concentration were significant for dye removal and sludge volume. Furthermore, it became evident that charge neutralization was the coagulation mechanism in this study. Based on the obtained model, 88.61% dye removal with 16.93 mL/L sludge volume was obtained at the optimum condition. The predicted optimum condition was in a good agreement with experimental data with relatively low error value. The obtained result implies good potency of leucaena as natural coagulant.

In recent years, lithium-sulfur (LiS) battery has emerged as promising energy storage systems to replace the conventional lithium ion battery. This battery system uses elemental sulfur as cathodes and Li metal as anodes and possess a higher specific capacity (1,675 mAh/g) compared to that of lithium ion battery. However, some technical problems such as the low conductivity of sulfur, huge volume expansion during cycling and the shuttle effect of polysulfide have prevented this kind of battery system to be commercialized. One method to solve those problems is by using carbon materials as cathode component together with sulfur to form Carbon-sulfur composite cathodes. Carbon materials could improve the electrochemical performance of LiS battery due to the electrical conductivity and highly porous structure. Biomass derived conductive carbon materials have attracted increasing attention on account of their abundance, sustainability, and easy accessibility. Here, onion peel waste has been utilized to synthesize amorphous porous carbon (OPWC) as cathode component for LiS battery. Porous carbons were prepared by using hydrothermal carbonization followed by the chemical activation process using KOH. The carbon-sulfur composites were then obtained after sulfur loading using the melt diffusion method. As obtained OPWC/S composite demonstrates stable cycle performance and a reversible specific capacity of 630 mAh/g after 100 cycles at current density of 0.1 C when used for LiS battery.

This study focused on utilization of Leucaena leucocephala seeds’ extract and iron oxide nanoparticles (IONPs) under magnetic field to provide effective coagulation process. Leucaena seeds’ extract was obtained using 3 M NaCl solution as solvent at feed-to-solvent mass ratio of 1:20. IONPs were synthesized using co-precipitation method. The obtained IONPs were analyzed using scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Based on analysis results, the obtained IONPs were the agglomerate of Fe3O4 phase with average particle diameter of 14.6 nm. The extract and IONPs were used as natural coagulant at various pHs (3–12), coagulant dosages (4–40 mL extract/L), and IONPs concentrations (0.5–3 mg/mL extract) under external magnetic field. It was obtained that pH 3 was the best pH because positively charged Leucaena protein at pH 3 acts to neutralize negatively charged Congo red molecules. The highest removal was obtained at coagulant dosage of 20 mL/L, and further increase in dosage was decreasing the removal due to colloid re-stabilization effect. The variation of IONPs concentration did not give any effect on the %removal and sludge volume. However, further investigation using pseudo-second-order kinetic model showed that the increase in IONPs concentration gave increase to the kinetic constant, signifying faster settling kinetics. The best condition was obtained at pH 3, coagulant dosage 20 mL/L, and IONPs concentration of 3 mg/mL extract that gave 90% Congo red removal, 30 mL/L sludge volume, and 30 min settling time.

Lithium sulfur battery has become one of the promising rechargeable battery systems to replace the conventional lithium ion battery. Commonly, it uses carbon–sulfur composites as cathode materials. Biomass based carbons has an important role in enhancing its electrochemical characteristics due to the high conductivity and porous structures. Here, potato peel wastes have been utilized to prepare porous carbon lithium sulfur battery through hydrothermal carbonization followed by the chemical activation method using KOH. After sulfur loading, as prepared carbon–sulfur composite shows stable coulombic efficiencies of above 98% and a reversible specific capacity of 804 mAh g−1 after 100 cycles at current density of 100 mA g−1. These excellent electrochemical properties can be attributed to the unique structure of PPWC showing mesoporous structure with large specific surface areas. These results show the potential application of potato peel waste based porous carbon as electrode’s materials for lithium sulfur battery.

In this paper we described preparation of new sustainability course that used problem based learning in its teaching learning activities. The new course was deemed necessary to prepare our future chemical engineers that could apply their knowledge in sustainability frameworks. This course is taught at 8th semester of curriculum thus it should accommodate the depth learning materials that integrate basic knowledge of chemical engineering and apply it in the context of sustainability. Problem based learning is considered appropriate to accommodate these needs. Furthermore, we measured the difference of students’ learning approach before and after participating 1 semester problem based learning session, using Study Process Questionnaires (SPQ). It was found that there was increase of deep approach with decrease of surface approach values. Positive feedbacks were also given by the students, as they could explore learning materials, team works, and other personal soft skills.

In this work, waste tea-based porous carbons were prepared by hydrothermal carbonization and then followed by the chemical activation using KOH and ZnCl2. As-prepared porous carbons were then used to host sulfur as composite cathodes for lithium–sulfur (LiS) battery system. The porous carbon–sulfur composite electrodes with optimized sulfur loading of 60 wt% exhibited the best electrochemical performance by delivering initial specific capacity of 1048 mAh g−1 at 0.05 C and maintained specific capacity of 627 mAh g−1 after 100 cycles. Moreover, it showed good capacity retention of 428 mAh g−1 at 0.5 C even after 100 cycles, which demonstrates its promising roles as host material for sulfur cathodes in LiS batteries.

Activated carbon (AC) has been utilized for various applications including as an electrode for supercapacitor, i.e., electric double-layer capacitor (EDLC) as well as hybrid capacitor such as lithium ion capacitor. In this research, salacca peel was used as a raw material for AC. It was chosen among other biomass wastes because it is abundant and is still considered as a waste. The hydrothermal carbonization was conducted at 5 MPa, temperature of 200–250 °C, and 5 h in subcritical water, which is a green dehydrating agent. The effect of parameters (temperature and addition of citric acid as a catalyst) on the hydrochar and AC product was investigated. The hydrochar from hydrothermal carbonization was activated by chemical activation using potassium hydroxide (KOH) as an activated agent to enhance the surface area and porosity. The morphology of both hydrochar and AC was measured by scanning electron microscopy (SEM), its chemical transformation was measured by Fourier transform infrared spectroscopy (FTIR) while the surface area and pore size distribution were measured by nitrogen adsorption at 77.35 K. The electrochemical performance of activated carbon from salacca peel as well as commercial activated carbon using a coin cell in a Li half-cell system was evaluated by CV, GCD, and EIS. The results show that the presence of citric acid contributes to higher specific capacitance in the rate performance test of LIC at different current density as well as in long rate stability test.

Hard carbons are one of the most promising carbon anode materials for sodium ion batteries (SIBs) due to the high specific capacity and excellent cycle properties. Among the precursors used to synthesize hard carbon, natural starches are of great interest due to their unique morphologies. In this paper, ganyong starch based hard carbons (GSHC) were prepared by direct carbonization at various temperatures (700–1100) °C. The obtained hard carbons exhibit high reversible capacities of sodium-ion batteries of about 239 mAh g–1 at current density of 0.1 C. after 100 cycles. The excellent cycle profiles are attributed to the unique morphology and defect carbon structures.

In this study we compared utilization of FeCl3 extracted leucaena protein and FeCl3 to treat synthetic Congo red wastewater. The extraction was done at leucaena seeds kernel to 0.5 M FeCl3 solution ratio 1:20 with various initial extraction pH (2 to 9). It was observed that pH 2 gave the highest protein concentration of 1.7 mg eq BSA/mL, compared to other pH. The extract obtained at this condition was further used in the coagulation study. At various initial coagulation pH (2 to 10), the highest Congo red removal was observed at initial coagulation pH 6. This result indicated that FeCl3 was the active coagulating agent despite of the presence of leucaena extract, with charge neutralization coagulation mechanism. Variation of coagulant dosage was done from 4 to 44 mL/L. At dosage 4 to 12 mL/L, low color removal was observed due to insufficient coagulant to neutralize Congo red molecules. Over addition of coagulant also lowered the coagulation efficient, and increased the sludge volume due to colloid re-stabilization phenomenon. The best Congo red removal was observed at coagulant dosage 20mL/L FeCl3 – leucaena extract combination with color removal of 95% with 9 mL/L sludge volume, slightly higher compared to FeCl3 only. Based on this result, it could be concluded that FeCl3 could act effectively as coagulant without the presence of leucaena extract.

Natural coagulants from plants resources have gained a lot of attention as it is renewable, biodegradable, non-hazardous, lower cost, and less sludge generated compared to chemical coagulants. However there are still some drawbacks, namely long settling time and possible increase of dissolved organic carbon in the treated water. In this paper we tried to address these drawbacks by utilizing citrate modified Fe3O4 to adsorb protein from Leucaena leucocephala as the active coagulating agent. The effect of trisodium citrate concentration and protein adsorption pH to the adsorbed protein was investigated. It was found that the trisodium citrate concentration of 0.5 M and pH 4.0 gave the highest protein adsorption. The obtained magnetic coagulant was furthermore characterized using Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, and Transmission Electron Microscopy to observe the characteristics before and after protein adsorption. Furthermore, the effect of pH (2 to 10) and coagulant dosage (60 to 600 mg L-1) to the removal of synthetic Congo red wastewater and sludge volume formation was investigated. It was found that pH 3 was the best pH for coagulation due to charge neutralization mechanism of leucaena protein. Furthermore the highest removal was obtained at dosage 420 mg L-1 with 80% removal. This result was comparable with crude extract of leucaena with half settling time (20 min) and lower increase of permanganate value, indicating lower increase of dissolved organics in the treated water.

Salacca peel-based porous carbon (SPPC) with high surface area (1945 m(2) g(-1)) and large specific pore volume (1.68 cm(3) g(-1)) was prepared by pre-carbonization and K2CO3 activation method. Based on the TGA results, it can be estimated that up to 70 wt% of sulfur-active materials could be infiltrated into the pores of SPPC to form SPPC/S composite cathode for LiS battery. The porous structure of SPPC could act as a buffer layer against volume expansion and minimize the shuttle effect due to the penetration of intermediate polysulfides during cycle tests. Optimization on sulfur loading (50, 60 and 70 wt%) in SPPCC/S composite was also investigated. It was found that the SPPC/S composites with 60 wt% of sulfur loading had the best electrochemical performances. With 60 wt% of sulfur loading, SPPC/S composite electrodes showed excellent electrochemical performances in terms of high initial specific discharge capacity of 1006 mAh g(-1) at 0.5 C and capacity retention of 71% until the 100th cycle. For both cases of low and high sulfur loading, they caused much worse electrochemical performances. Based on the experimental results, it can be concluded that porous carbons derived from the salacca peel were promising materials for sulfur loading in LiS battery.

Activated carbon is a highly porous material that has been used as electrodes for batteries, symmetric, and asymmetric supercapacitors. In this study we utilize salacca peel as a precursor to synthesis activated carbon (AC) using hydrothermal carbonization (HTC) and microwave assisted chemical activation method. The HTC was done at 225°C, 50 bar for 5 h using citric acid as a catalyst. The obtained hydrochar (HC) was furthermore impregnated using KOH as activating agent at various HC to KOH mass ratio (1:2, 1:3, and 1:4). The activation was done under microwave radiation of 700 Watt for 8 min. The obtained AC samples were characterized using scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and methylene blue adsorption. The best AC with ratio 1:4 was furthermore tested as nickel ion's capacitor electrode. The electrochemical characteristics (cyclic voltammetry) were measured by using half-cell test pouch with nickel oxide as a reference electrode and 6 M KOH as electrolyte. The results obtained showed that AC from salacca peel gave better performance compared to commercial AC.

Iron oxide nanoparticles, such as Fe3O4, are commonly used in various applications, such as drug delivery, magnetic fluid, water purification, and enzyme immobilization. These applications require protein to be adsorbed on the surface of iron oxide nanoparticles. However direct utilization of iron oxide nanoparticles has several drawbacks, thus modification of iron oxide nanoparticles is usually done. In this study, we reported surface modification of Fe3O4 using tannic acid to adsorb bovine serum albumin (BSA). The effect of modification and the BSA adsorption on the Fe3O4 was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy, and Transmission Electron Microscopy. Furthermore the adsorption performance of modified and unmodified Fe3O4 was investigated at various initial pH, BSA concentration, and adsorption temperature. Several kinetic and isotherm adsorption models were used to describe the adsorption in this study. It was found that highest BSA adsorption was obtained at pH 4.8, near BSA’s isoelectric point. The adsorption kinetics followed the pseudo 2nd order model and reached equilibrium after 210 min adsorption. Based on Langmuir monolayer adsorption capacity, it was found that tannic acid modified Fe3O4 had 5 times higher adsorption capacity (222 mg/g), compared to unmodified Fe3O4 (46 mg/g). Furthermore, from the thermodynamic study, it was suggested that the BSA adsorption was endothermic, spontaneous, and random in nature.

Perubahan metode pembelajaran yang sebelumnya berpusat pada pengajar (teacher-centered learning) menjadi berpusat pada siswa (student-centered learning), menuntut penggunaan berbagai model pembelajaran yang inovatif. Dalam penelitian ini dipaparkan penerapan model pembelajaran berbasis masalah (problem based learning; PBL) dalam mata kuliah Manajemen Limbah Bahan Beracun dan Berbahaya (B3) di Program Studi Teknik Kimia UNPAR pada semester genap 2016/2017, dengan tujuan mengamati perubahan gaya belajar mahasiswa sebelum dan setelah pembelajaran dengan model PBL dengan menggunakan kuesioner Grasha. Selain itu mahasiswa diminta untuk mengisi kuesioner evaluasi pelaksanaan kegiatan pembelajaran. Teramati perubahan gaya belajar mahasiswa, yaitu pada menurunnya gaya belajar avoidant, kenaikan pada gaya belajar competitive dan collaborative. Sekalipun terlihat perubahan, hasil tersebut belum signifikan secara statistik. Hasil umpan balik dari mahasiswa peserta kuliah pun cukup positif, karena mahasiswa merasa lebih aktif, belajar bekerja dalam tim, dan berkomunikasi. Hasil-hasil positif yang ditunjukkan dalam penerapan model PBL pada mata kuliah ini membuka peluang untuk menerapkan model pembelajaran serupa pada berbagai mata kuliah lain.

Hydrochar from the hydrothermal treatment of biomass is considered as a potential precursor for activated carbons (AC) which has been widely utilized not only for adsorbents but also for energy storage application. The advantages of hydrochar from hydrothermal treatment include its high Oxygenated Functional Group (OFG) and high porosity. The authors have been working on the biomass conversion for energy storage application. In our study, salacca peel was used as a biomass source. In previous research for the preparation of AC, conventional carbonization and activation methods were used, resulting in a high surface area of AC. In the current research, the authors investigated the biomass conversion in hydrothermal conditions. Water at a subcritical condition (with temperatures of 200, 225 and 250 °C and at a pressure of 50 MPa) and carbonization time of 4, 5 or 6 hours, with or without delignification, were critical in the research to investigate the conversion of salacca peel into hydrochar. The produced hydrochar from 225 °C, 5 h was chemically activated and compared to commercially-AC. The hydrochar and AC were then used as electrodes for the supercapacitor, and capacitance was measured by cyclic voltammetry (CV). The results showed that the capacitance of hydrochar was higher than that of AC while ACs from salacca peel exhibited much higher levels of capacitance compared to commercially-AC.

The simultaneous oxidation of cyanide and reduction of cadmium from electroplating wastewater using UV/TiO2 photocatalysis was investigated in this study. The investigation was performed using a batch-wise 3 L bubble-column photoreactor equipped with a 64-Watt low-pressure ultraviolet (UV) amalgam lamp (20 W at 254 nm). Preliminary experiments were conducted to identify the optimum aeration rate for ensuring the mixing of the catalyst and the wastewater. More specifically, this study focused on the two main factors that influence the effectiveness of oxidative and reductive processes, namely the TiO2 concentration (0.5–2 g/L) and the solution’s pH (11–13), at cyanide and cadmium ion concentrations of 50 and 100 ppm, respectively. A sample was taken every 30 minutes for 3 hours, and the cyanide and cadmium ion concentrations were determined using an ion-selective electrode and atomic absorption spectroscopy (AAS), respectively. It was determined that 3 L/min aeration was optimum, resulting in the removal of approximately 80% of the pollutants. A further increase in the aeration rate resulted in a decrease in the %removal rate due to competition between the oxygen and cadmium ions in terms of reacting with the electrons produced by the photocatalyst. An increase in the pH resulted in an increase in both the removal rate and the kinetics due to the high availability of the hydroxide ions needed to form the radical hydroxide that effectively oxidized the cyanide ions. It was observed that an increase in the TiO2 concentration increased both the removal rate and the kinetics until the optimum point, after which the performance of the photocatalyst decreased due to the shielding effect of the UV resulting from the excessive level of TiO2 present in the mixture. Within the experimental range, the best (most effective) condition was chosen based on the pseudo first-order rate constants. The best condition for cyanide oxidation was identified at pH 13 and 1 g/L TiO2 with kCN- 0.033 min-1, while the reduction of cadmium was found to be optimum at pH 13 and 2 g/L TiO2 with kCd2+ 0.039 min-1.

Indonesia is a tropical country which is known for its high variety of natural resources. However, there is limited access to clean water, thus forcing people in rural areas to use turbid water. Furthermore, some of water sources in Indonesia are already polluted by heavy metals with high biological oxygen demand (BOD) and chemical oxygen demand (COD) value. Simple and easy water purification methods are needed to overcome this situation. Coagulation and flocculation are widely used method to treat water. However, chemical coagulants (alum, ferrum, PAC, etc.) are not easily obtained and could cause some health problems if treated water is consumed. Natural coagulants have a good potential to solve these problems. Various possible plant-based natural coagulants which are abundant in Indonesia are highlighted in this paper. Fruit wastes and inedible legumes are suggested to be used as natural coagulant as there are no food competition presents. Further research is needed especially to scale up laboratory scale research that has been done in these years; thus, it can be applied to solve clean water scarcity problem.

Coagulation and flocculation are commonly used in water and wastewater treatment. Inorganic coagulant such as alum (Al 2 (SO 4 ) 3 ), ferrous sulphate (FeSO 4 ), and polyaluminium chloride (PAC) are commonly used. These coagulants are known for its effectiveness and simple operation procedure. However, there are some drawbacks such as reduction in pH, potential negative health effect when the treated water is consumed, and large sludge volume. To overcome these problems, utilization of natural coagulants has been proposed. Based on its active coagulating agent, natural coagulant could be divided as polyphenolic, polysaccharides, and protein. Protein from beans and seeds is commonly used as the source of active coagulating agent, due to its effectiveness, availability, and relatively simple pretreatment is needed. Usually the protein is extracted by using 0.5-1 M NaCl solution as globulin is the major protein fraction in beans.The extracted protein could act as cationic polymer to neutralize negatively charged colloids through adsorption-charge neutralization mechanism. Extracted protein could work effectively to treat turbid and waste water with lower cost compared to alum. However, most of existing studies are still focused on small – pilot scale utilization thus further explorations are still needed . A B S T R A K Koagulasi dan flokulasi merupakan proses yang umum digunakan dalam pengolahan air dan limbah cair. Pada umumnya digunakan koagulan seperti alum (Al 2 (SO 4 ) 3 ), ferro sulfat (FeSO 4 ), dan polialuminium klorida (PAC). Selain efektif, koagulasi merupakan proses yang relatif sederhana dan mudah diterapkan. Akan tetapi koagulasi dengan koagulan anorganik memiliki beberapa kekurangan seperti menurunnya pH menjadi asam saat digunakan, potensi gangguan kesehatan jika air hasil pengolahan terkonsumsi, serta volume sludge yang dihasilkan relatif tinggi. Penggunaan koagulan alami menjadi alternatif dalam pengolahan air untuk mengatasi berbagai kekurangan tersebut. Berdasarkan bahan aktif koagulannya, koagulan alami dapat dibagi menjadi polifenol, polisakarida, dan protein. Protein dari kacang-kacangan merupakan salah satu sumber koagulan alami yang umum digunakan, karena selain efektif, kacang-kacangan mudah didapat, serta membutuhkan perlakuan yang relatif sederhana, meliputi pengeringan, pengecilan ukuran, ekstraksi, serta purifikasi. Proses ekstraksi kacang-kacangan pada umumnya menggunakan larutan garam NaCl dengan konsentrasi 0,5-1 M, dikarenakan fraksi protein dominan pada protein kacang-kacangan pada umumnya berupa globulin. Protein yang terekstrak berfungsi sebagai polimer kationik yang cocok digunakan untuk mengolah koloid yang bermuatan negatif melalui mekanisme adsorpsi-netralisasi muatan. Pemanfaatan ekstrak protein dapat bekerja efektif untuk mengolah kekeruhan dan air limbah, dengan biaya yang lebih rendah dibandingkan alum. Akan tetapi pemanfaatannya masih pada skala laboratorium-pilot, sehingga diperlukan pengembangan lebih lanjut untuk isolasi ekstrak serta aplikasinya pada skala industri. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

International audience; Sodium (Na) ion battery (NIBs) are considered as one of the most prospective battery system to substitute lithium ion batteries (LIBs) especially for stationary applications. In this study, rambutan peels were selected as carbon precursors to prepare hard carbons as anode materials for NIBs. Hard carbons were prepared by applying hydrothermal carbonization and then continued by the pyrolysis treatment at different temperatures (800, 1000 and 1200 °C). The electrochemical studies were carried out by cyclic voltammetry (CV) and galvanostatic charge discharge (GCD). The obtained hard carbons at pyrolysis temperature of 1000 exhibited the best electrochemical performance. It showed the highest reversible capacity of 225 mAh g−1 (0.1 C-rate, 1 C = 300 mA g−1) after 100 cycles if tested as the anode materials for NIBs. It is attributed to the disordered carbon structure, low degree of graphitization, large interlayer spacing and flake-like morphology of carbon sample which can provide more space for sodium storage and facilitate sodium ion transfer.

This study describes preliminary study of tamarind seeds kernel powder as natural coagulant for color removal of drimarene dark red (DDR) synthetic wastewater (20 mg/L). The effect pH (2-7), dosage (1-3 g/L), and their interactions were investigated using general factorial design. The seeds powder was also characterized using Fourier Transform Infrared Spectroscopy (FTIR) to observe the possible active coagulating agent in this study. It was found that the seeds powder contained protein that could act as coagulant. Dosage, pH, and their interactions were found to be statistically significant to the removal of DDR. Highest removal of 84.60% was obtained at pH 3 and dosage 3 g/L.

Coagulation is a well-known technology applied in water and wastewater treatment. Inorganic salts, such as alum, ferrous sulfate, and polyaluminum chloride, are usually used. It is widely known that utilization of these inorganic coagulants poses several disadvantages, such as high coagulant cost and high sludge volume that increase water treatment expenses. The use of alum also poses health risk to human as it may cause degenerative diseases. In order to minimize these disadvantages, the use of various coagulants from natural resources has been recently proposed. In this research, study was performed on the extraction and use of a potential natural coagulant (Leucaena leucocephala) seed kernel as natural coagulant. Leucaena seed kernel was extracted at various NaCl concentrations (0–5 mol L−1). Extract with highest protein content obtained at NaCl concentration of 3 mol L−1 was further used to treat a synthetic wastewater model substance (Congo red solution) at various pH (2–10) and dosage (2–40 mL L−1). This natural coagulant successfully removed 99.9% of the color at pH 3 and dosage 10 mL L−1, with only half sludge volume discharged when compared to alum. The result suggests that leucaena is a promising natural coagulant for water and wastewater treatment.

Activated porous carbons originating from the Indonesian snake skin fruit peel has been prepared by carbonization process followed by the ZnCl2 activation process. This porous carbon was then applied as cathode component along with sulfur in lithium sulfur (Li-S) batteries. The carbon materials possessed a high surface area of 2247m(2)g(-1) and a large pore volume of 1.97cm(3)g(-1) with sulfur loading of 63%. From the x-ray diffraction (XRD) patterns, Raman analysis, and SEM observation of the composites, it was shown that the sulfur was uniformly encapsulated inside the carbon pores, which was beneficial for the optimum utilization of sulfur and the confinement of soluble lithium polysulfides. The fabricated carbon-sulfur composite electrodes demonstrated an initial specific capacity of 945mAhg(-1) and good capacity retention until the 100th cycle at 0.1 C rate. At high C rate (1 and 2 C), the composite electrodes exhibited specific discharge capacity of 538 and 466mAhg(-1) until the 100th cycle, respectively. Those excellent electrochemical performances were attributed to the high surface area, combination of micropore/mesopore structures and low average pore diameter of porous carbons.

Measurement of the outcomes becomes a vital part in OBE system to ensure the attainment of each outcome. In Indonesia, OBE was adopted in 2015 for higher education level. However, the changes were not accompanied with clear method to measure the outcomes, which became the urgency of this research. In this study, a preliminary method to measure student learning outcomes (SLO) and course learning outcomes (CLO) was presented. The measurement of SLO and CLO attainment was started by SLO mapping to courses, which usually had been done at curriculum design. Based on the mapping, formulation of CLO with a set of direct assessment was planned at the start of each course. After the teaching learning activities, a series of calculation was designed to obtain the attainment of SLO and CLO for each student, course, and whole study program. In the same time the final mark for GPA calculation of each student could also be obtained. The designed method could play an essential part in teaching-learning quality assurance and curriculum continuous improvement, which is aligned with both international and national accreditation criteria and standards. Furthermore, this study could provide insight for other study program in SLO and CLO attainment measurement.

Lithium ion capacitor (LIC) is a novel hybrid capacitor technology that possesses a better performance than the conventional supercapacitor, such as EDLC and lithium ion battery. However, the overall performance of LIC is limited by activated carbon’s capacity as its cathode. This work is focused on synthesize of activated carbon from Indonesian local orange peel waste for LIC cathode and its modification to perform a good electrochemical performances. Activated carbon was synthesized by ZnCl2 as impregnant with mass ratio of orange peel to ZnCl2 1:2 for 1 h at 500 °C. The obtained activated carbon possessed large surface area (1200 m2 g −1), higher than commercial activated carbon (Merck-p.a.) with surface area of 775.6 m2 g−1. Modification was done using wet oxidation method by utilizing HNO3 65 %, H2SO4 98 %, and H2O2 30 %, with ratio 1:1 (w/w). Electrochemical properties were studied by using half cell test pouch with Li metal as reference electrode and 1 M LiPF6 (EC:EMC:DMC = 1:1:1) as electrolyte. Modification had successfully increased oxygen atoms in activated carbon samples. Surface-modified cells demonstrated a higher capacitance (almost twice in the galvanostatic test) than that of the unmodifed one due to the pseudocapacitance effect of oxygen functional groups. However, its electrochemical performance was unstable. The unmodified cell showed a stable performance with 56.3 F g−1 at current density of 0.3 mA g−1 and voltage window 2.5–4 V.