Search

Methylene blue pollutants can be treated by photocatalytic methods using metal oxide-based semiconductor materials and metal organic framework (MOF). These two materials are often coupled into a composite to improve their physicochemical properties and catalytic activity. This research focuses on the synthesis of composites based on Cr-PTC MOF, ZnO, and Fe3O4 by the sonochemical method. The obtained composites were characterized and tested for catalytic activity in methylene blue pollutant degradation in an aqueous system under acidic conditions (pH = 5). Our investigation shows that the Cr-PTC@Fe3O4 composite possesses the lowest band gap energy of 1.86 eV and achieves the highest photocatalytic activity in methylene blue degradation at solution pH = 5, with a percent degradation of 84.36%. The sonochemical incorporation of Fe3O4 and Cr-PTC MOF is able to fabricate materials in a short time with better photocatalytic activity in degrading methylene blue than the single materials. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Free-living N2-fixing bacteria are essential in the soil because they provide a source of nitrogen in the form of ammonium needed by plants to be used in building protein blocks. The fixation of free N2 needs to be increased by adding nanomaterials such as magnetite (Fe3O4), which has an active group and can be a source of nitrogenase enzyme cofactor. In this study, increased N2 fixation used N2-fixing bacteria in Burks medium. This increase was determined by measuring NH3 levels using the Phenate method formed after Burks medium was treated with Fe3O4 and chitosan-magnetite (CS-Fe3O4). The study found that the number of bacteria can be well decreased. This research showed that using Fe3O4 and CS-Fe3O4 increased NH3-N levels in cultures of free-living nitrogen-fixing bacteria by 15.40% and 75.54%. For future development, it can be in the form of optimization, the effect of adding the same material to plant secondary metabolites, and the mechanism of bacteria in using the material.

Abstract: Spirulina platensis Residue (SPR) is obtained from the solid residue of Spirulina platensis extraction, which has high carbohydrate and protein content. Pyrolysis technology will convert SPR into a bio-oil, water phase, char, and gas (CO, CO2, H2, CH4) product with the potential as an environmentally friendly and sustainable fuel. This study aims to obtain data on the optimum conditions and product yield composition of SPR catalytic pyrolysis using the in-situ method. Pyrolysis occurs in a fixed-bed reactor with SPR 50 g feed and Fe3O4 catalyst (2.5 g and 5 g) at temperature variations of 300-600 °C with an average heating rate of 14.07 °C/min. The higher the pyrolysis temperature, the more bio-oil yield, the optimum at a temperature of 500 ⁰C. The use of 2.5 and 5-gram catalysts obtained bio-oil yields of 25.01 and 17.67 %. The yield of biochar will be lower with increasing pyrolysis temperature. The optimum condition for the gas production was achieved at 300 °C, using a catalyst of 2.5 and 5 grams, the yield of gas was 23.59, and 19.74 %. Moreover, the smaller the specific gravity and the higher the bio-oils pH, the better it is as a vehicle fuel. Abstrak: Spirulina platensis Residu (SPR) diperoleh dari residu padat ekstraksi Spirulina platensis yang memiliki kandungan karbohidrat dan protein tinggi. Teknologi pirolisis akan mengubah SPR menjadi produk bio-oil yang berpotensi sebagai bahan bakar ramah lingkungan dan berkelanjutan. Penelitian ini bertujuan untuk mendapatkan data kondisi optimum dan komposisi yield produk dari pirolisis katalitik SPR dengan metode in-situ. Pirolisis SPR akan menghasilkan produk berupa bio-oil, water phase, char dan gas (CO, CO2, H2, CH4). Pirolisis berlangsung dalam reaktor fixed-bed dengan umpan SPR 50 g serta katalis Fe3O4 (2.5 g dan 5 g) pada variasi suhu 300-600°C dengan heating rate rata-rata 14,07 °C/min. Semakin tinggi suhu pirolisis semakin banyak yield bio-oil, optimum pada suhu 500 ⁰C. Pemakaian katalis 2,5 dan 5 gram diperoleh yield bio-oil sebanyak 25,01 dan 17,67 %. Yield biochar akan semakin rendah dengan kenaikan suhu pirolisis. Kondisi optimum produk gas dicapai pada 300 °C dengan katalis 2,5 dan 5 gram diperoleh yield gas sebesar 23,59, dan 19,74 %. Hal tersebut mengakibatkan, semakin kecil berat jenis dan semakin tinggi pH bio-oil maka semakin baik sebagai bahan bakar kendaraan.

This paper aims to evaluate the economic feasibility of Fe 3 O 4 nanoparticle production from a laboratory scale to an industrial scale feasibility. The evaluation was conducted using 2 models of feasibility studies, namely: technical analysis and economic evaluation. Technical analysis provides information on the potential for large-scale production and the results of this process can be applied using commercially available and inexpensive equipment. Economic evaluation is based on a comparison of the Cumulative Net Present Value graph in an ideal condition and the graph when parameters changing are made (such as changes in the dollar exchange rate, the quantity of sales products, and the value of employee salaries). From the evaluation results, all parameter changes give a positive value indicating that the project is feasible to run commercially and on a large scale. This is because the evaluation results provide a stable index of profit for some changes in parameter values. This study shows that Fe 3 O 4 fabrication can provide promising profits in developing countries and can attract foreign investors to work together on Fe 3 O 4 fabrication.

Telah dilakukan penambahan SiO2 pada bahan nanokatalis bermagnet Fe3O4/TiO2 menggunakan larutan Tetraethyl Orthosilicate (TEOS) membentuk Fe3O4/SiO2/ TiO2 dengan tujuan untuk meningkatkan efektivitas katalitik bahan nano komposit Fe3O4/TiO2. Pembuatan Fe3O4/SiO2/TiO2 dilakukan dengan metode kombinasi yaitu presipitasi dan sol-gel. Metode presipitasi digunakan pada pembuatan superparamagnetik Fe3O4, sedangkan “sol-gel” digunakan pada pelapisan Fe3O4 dengan SiO2 menggunakan larutan TEOS untuk membentuk Fe3O4/SiO2, dan pelapisan Fe3O4/SiO2 oleh TiO2 dengan Tetrabutyl Orthotitanate (TBOT) membentuk komposit Fe3O4/SiO2/TiO2. Karakterisasi hasil sintesis menggunakan alat X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Vibration Scanning Microscope (VSM), Surface Area Analyzer (SAA), dan UV-Visible Diffuse Reflectance Spectroscopic (UV-Vis DRS). Uji kinerja fotokatalitik dilakukan terhadap senyawa methylene blue. Hasil karakterisasi menunjukkan bahwa dengan adanya penambahan SiO2 pada bahan katalis bermagnet Fe3O4/TiO2 tidak mempengaruhi fase maupun ukuran partikel, akan tetapi menurunkan nilai energi band gap. Dengan berkurang nilai energi band gap, efektivitas fotokatalitik menjadi meningkat. Dari hasil uji kinerja fotokatalitik terhadap methylene blue menunjukkan bahwa dengan penambahan SiO2 pada katalis Fe3O4/TiO2 terjadi kenaikkan efisiensi degradasi dari 85% hingga mendekati 100%.

Synthesis and characteristics of the black, red and yellow pigment made from iron sand have been done. The purpose of this research is performing the synthesis and characterization of pigments using raw materials of iron sands using calcination methods. The manufacture of black pigment was done by mixing iron sand with a solution of NaOH and NH4OH then heating them at a temperature of 800 °C. The red pigment was made by dissolving iron sand in a solution of H2SO4 and it was heated at a temperature of 650 °C. While the yellow pigment was made of red pigment powder dissolved into a solution of HCl and heated at a temperature of 250 °C. Pigment powders were characterized by using XRD, SEM-EDX and PSA and Crommameter. The results showed that the black, red and yellow powder pigment have a cubic crystal structure with the form of the surface morphology and grain size as follows: the particles of the black pigment is uniform spherical granules with a grain size of 926.4 nm, the red pigment granules have a spherical shape with grain size of 72.2 nm and yellow pigments have a spherical shape with grain size of 349 nm. The main elements of black, red and yellow pigment are iron (Fe) and oxygen (O). From the result of pigment powder test using Crommameter it was found that L * a * b * and DE coordinat of black pigment were 23.76, 1.35, 1.43, 2.339, red pigment are 43.23, 16 , 17.3 and 9.893, and yellow pigment are 66.76, 14.84, 49.95 and 4.862. The pigment colors produced are in accordance with standards.