Preparasi zeolit dari abu laying batu bara PLTU Suralaya secara alkali hidrotermal telah dilakukan. Preparasi dilakukan terhadap abu laying yang telah direfluks dengan HCl 1M dan tanpa refluks. Larutan NaOH dengan konsentrasi tertentu (1, 2 dan 3 M) dicampur dengan abu laying batu bara dengan rasio 10 ml larutan tiap 1 gram abu laying, ke dalam tabung Teflon 100 ml dalam suatu auto clave stainless-steel. Autoclave kemudian dipanaskan pada temperatur 80-16 0C selama 3 hari. Zeolit sintesis yang dihasilkan selanjutnya diuji secara kualitatif dengan menggunakan spektroskopi inframerah., dan Difraksi Sinar-X. Hasil penelitian menunjukkan bahwa aktivasi abu laying dengan proses alkali hidrotermal dapat material yang mempunyai struktur mirip zeolit (zeolit-like). Produk hidrotermal terdiri dari campuran zeolit ( Zeolit P, Zeolit Y) serta Kristal sodalit dan mulit. Pada temperatur 160 0C, diperoleh zeolit dengan kristalinitas lebih tinggi daripada 100 0C, baik melalui refluks atau tanpa refluks. Karakteristik zeolit yang terbentuk sangat ditentukan oleh kondisi proses, yang meliputi konsentrasi NaOH, waktu dan temperatur.Kata kunci : abu layang batu bara, alkali hidrotermal, preparasi, karakterisasi, zeolit
The bio-oil produced from pyrolysis of woody biomass typically shows unfavourable characteristics such as high acidity, hence it becomes highly corrosive. An upgrading process, e.g., esterification, is necessary to improve the bio-oil quality prior to its use as a transportation fuel. In this work, the bio-oil was produced through a fast pyrolysis of Sengon wood in a fixed-bed pyrolyser at various temperatures. The characteristics (density, viscosity, total acid number, relative concentration of acetic acid, etc.) of the bio-oil were evaluated. The bio-oil with the highest acidity underwent an esterification catalysed by Indonesian natural zeolites at 70 oC for 0-180 min with a ratio of bio-oil to methanol of 1:3. The catalytic performance of the Indonesian natural zeolites during the esterification was investigated. A significant decrease in the total acid number in the bio-oil was observed, indicating the zeolite catalyst’s good performance. No significant coke formation (0.002-3.704 wt.%) was obtained during the esterification. An interesting phenomenon was observed; a significant decrease in the total acid number was found in the heating up of the bio-oil in the presence of the catalyst but in the absence of methanol. Possibly, other reactions catalysed by the Brønsted and Lewis acids at the zeolite catalyst surface also occurred during the esterification.
The separation of Ce, La, and Nd elements from rare earth metal (REOH) concentrates from monazite sand processing needs to be done because the uses of La and Nd in the industry are very large. This research was conducted to determine the optimization of leaching in the separation of Ce, La, and Nd. The method used to separate the elements Ce, La, and Nd from the rare earth metal concentrate is through calcination at a temperature of 600°, 800°, 1000°C for 2 hours and without calcination, followed by a leaching process using 0.9 M HCl solvent at a temperature of 75°C. Variations made are the ratio of solid and liquid ratio and variations in time (5, 10, 15, 20, and 25 minutes), and the stirring speed is fixed at 150 rpm. From the results of FT-IR and XRD analysis, it is known that calcination can convert REOH concentrate into REO. Residual analysis of leaching results using XRF showed that the increase in calcination temperature with a solid and liquid ratio and leaching time could affect the leaching efficiency results. The highest leaching efficiency for the element La was obtained at a calcination temperature of 1000°C with a time of 10 minutes, which was 73.20%. Meanwhile, the optimum condition for the best leaching process for Nd is at a calcination temperature of 1000°C with a contact time of 5 minutes with a leaching efficiency of 49.68%.
The study of Mg(OH)2 from seawater bittern as an adsorbent for Congo red (CR) from an aqueous solution has been performed. This study aimed to determine the effect of pH, contact time, and initial CR concentration on CR adsorption by Mg(OH)2. The adsorption kinetics and isotherms of CR on Mg(OH)2 in an aqueous solution were also studied. The optimum adsorption was obtained at pH 8 within 90 minutes of contact time with an adsorption capacity of 46.3 mg/g for an initial CR concentration of 29 mg/L. The adsorption process followed the Freundlich isotherm model with an n value of 2.579 and the pseudo-second-order kinetic model with a k2 value of 0.0021 g mg−1min−1.
Bittern is a by-product of the manufacture of salt which has a high MgCl2 content. Bittern can produce Mg(OH)2 which is one of the important precursors of MgO. MgO compounds can be used as an antibacterial against E. coli that contaminates food. This research aims to synthesize MgO nanoparticles as well as antibacterial testing against E.coli. Synthesis was performed using the wet precipitation method with bittern reaction and technical NaOH with volume ratio 1: 1 which was then calcined at 5000C, 6000C, and 7000C. Characteristic tests using XRD, FT-IR, and SEM and antibacterial activity testing using disc diffusion method with concentrations of 10 mg/mL, 20 mg/mL, and 30 mg/mL. Inhibition is measured based on the size of the diameter of the bacterial growth inhibition area. Based on the results of the XRD test showed the result of pure MgO with a crystalline size of 6.3 nm; 7.2 nm; and 15.8 nm at each calcination temperature, the FT-IR test produced an absorption at a wave <450 cm-1 indicating the presence of MgO clusters and the SEM test produced a nano-structure that was almost round, dense as a cavity in the grains. The results of testing the antibacterial activity of MgO nanoparticles showed inhibitory activity with a diameter range between 5 mm - 8 mm which was interpreted in the medium category. The best inhibition value is 5000C calcination at a concentration of 30 mg/ml of 7.87 mm.
Ceramic membrane technology plays an essential role in separation fields such as wastewater treatment. Fly ash as a membrane material has proven to be very effective for many separation processes, including water and air purification, as well as industrial and environmental resource recovery. This study aims to develop a microfiltration ceramic membrane based on fly ash with the addition of dolomite. The synthesized ceramic membranes were then characterized using XRD, SEM, and TGA. Ceramic membranes are used to reduce COD and BOD levels in tofu industrial wastewater. The results showed that the value of membrane porosity tends to increase with the addition of dolomite 0% (D0) to 30% (D30). The increase in the porosity value in the membrane was followed by a decrease in the average pore size, namely 1.6994 m at D0 and 1.1730 m at D30. The membrane with 30% dolomite composition has the best mechanical properties with a compressive strength of 35.29 MPa and superior thermal resistance. This is very beneficial for the use of membranes in the long term. Meanwhile, the membrane filtration ability and the ability of the membrane to reduce COD and BOD levels of waste increased with the addition of dolomite from 0% to 30%. However, the decrease in COD and BOD was smaller in the membrane with 45% dolomite. D30 membrane can reduce COD 80% and BOD up to 71.44%. D30 membrane is the most effective fly ash and dolomite composition in forming pores on the membrane with the best COD and BOD reduction performance.
ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI. Penelitian mengenai komposisi unsur, densitas, makrostruktur, dan fasa paduan U-6Zr-xNb pasca uji korosi telah dilakukan. Analisis komposisi paduan dilakukan sebelum uji korosi yang meliputi uji kadar uranium dengan titrasi potensiometri, uji kadar pengotor dengan Atomic Absorption Spectroscopy (AAS) serta uji kadar Zr dan Nb dengan X-Ray Fluorescence (XRF). Analisis komposisi paduan bertujuan untuk memastikan bahwa bahan bakar U-6Zr-xNb memenuhi syarat kualitas bahan bakar nuklir. Uji densitas dilakukan untuk menjadi salah satu parameter dalam menghitung laju korosi, sedangkan pengamatan makrostruktur dan fasa paduan dilakukan untuk mengetahui kerusakan atau produk korosi serta lapisan/fasa yang terbentuk setelah terjadi korosi. Hasil uji komposisi paduan U-6Zr-xNb dengan XRF maupun titrasi potensiometri menunjukkan bahwa kadar uranium sudah mendekati kadar yang syaratkan, sedangkan untuk uji pengotor dengan AAS menunjukkan adanya kadar pengotor melebihi yang disyaratkan untuk bahan bakar nuklir antara lain Al, Fe dan Si. Berdasarkan hasil tersebut, bahan bakar U-6Zr-xNb masih memenuhi persyaratan. Dilihat dari sifat neutroniknya, unsur Al, Fe dan Si memiliki tampang serapan neutron yang rendah. Hasil uji densitas sampel U-6Zr, U-6Zr-1Nb, U-6Zr-4Nb, dan U-6Zr-7Nb masing-masing sebesar 16,9798 g/mL, 16,6115 g/mL, 15,594 g/mL, dan 15,3564 g/mL. Pengamatan makrostruktur paduan pasca korosi menunjukkan adanya bercak hitam yang merupakan hasil oksidasi U (IV) menjadi U (VI). Paduan U-6Zr-xNb mengalami korosi paling besar pada media air bebas mineral. Kerusakan pada permukaan paduan semakin menurun seiring bertambahnya presentase berat Nb dalam paduan. Hasil karakterisasi paduan pasca korosi menggunakan XRD menunjukkan bahwa sampel U-6Zr dan U-6Zr-1Nb terbentuk fasa α, sedangkan untuk sampel U-6Zr-4Nb dan U-6Zr-7Nb terbentuk fasa γ. Lapisan oksida protektif Nb2O5 yang terbentuk sangat kecil, sehingga tidak terdeteksi oleh XRD.Kata kunci: Paduan UZrNb, komposisi, pengotor, korosi, densitas, makrostruktur, pembentukan fasa.
Diclofenac sodium is a non-steroidal anti-inflammatory drug with a relatively short release time. This short release time promotes a more frequent drug consumption and could lead to side effects in the stomach, e.g., gastrointestinal disorders, gastrointestinal bleeding, and gastric ulcers. A drug delivery system with a slow-release activity is one of the promising technologies to control the drug amount released to the stomach. A surfactant-modified natural zeolite as a carrier for diclofenac sodium has been used in this study. This study focused on the preparation, characterization, and slow-release performance of HDTMA-modified natural zeolite as a carrier for diclofenac sodium. The zeolite underwent chemical and physical activation, as well as milling prior to use. It was proven that the zeolite used was dominated by mordenite and clinoptilolite with high stability properties towards acid treatments, as indicated by the XRD patterns. A modification of the zeolite surface using HDTMABr was also successfully performed, indicated by the appearance of peaks at wavenumbers of 2923.05 cm-1 and 2853.39 cm-1 (symmetrical and asymmetrical CH2 strains of HDTMA molecules, respectively) in the FTIR spectra. The synthesized HDTMA-modified natural zeolite also showed an excellent surface property such as surface area, pore-volume, and size, as indicated by the BET-BJH isotherms on the nitrogen adsorption. The slow-release performance of the zeolite-based drug delivery system was studied by investigating the adsorption-desorption behavior of HDTMA-modified zeolite towards diclofenac sodium. The HDTMA-modified zeolite adsorbed the diclofenac sodium of 54.01% at a pH of 7.5, the contact time of 60 min, and the initial concentration of 100 ppm. The adsorbed diclofenac sodium of 73.95% could be released from the HDTMA-modified adsorbent for 8 h, mimicking the time length of drug metabolism in the human body.
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