Magnesium in nature can be found in the form of minerals and seawater. Bittern is a sea-salt industry by-product that contains magnesium and potassium salts. Usually, bittern is discharged back to the sea, even though bittern can be further processed to obtain magnesium contained in it. Magnesium oxide (MgO) nanoparticles can be used in a variety of applications because of their good surface recreation properties. In this study, precipitation of Mg2 + ions from bitterns was carried out using sodium hydroxide to produce magnesium hydroxide. Then, it was calcined and went through sonochemical process to produce nano magnesium oxide. Sonication time and amplitude were used as variables. Sample with sonication time of 16 minutes and amplitude of 30% has the smallest particles with an average diameter of 195.7 nanometers.
Proses dekomposisi dolomit menjadi MgO dan CaO merupakan proses penting mengingat kedua oksida tersebut banyak digunakan dalam berbagai aplikasi. Untuk melihat pengaruh suhu proses kalsinasi terhadap dekomposisi dolomit menjadi MgO dan CaO, maka dilakukan kalsinasi. Proses kalsinasi menggunakan tungku Muffle furnace dengan suhu sebesar 500 o C, 600 o C, 700 o C, 800 dan 900 o C. Sebanyak kurang lebih 100 gram/sampel dolomit dimasukkan dalam tungku dan dipanaskan dengan laju pemanasan 10 o C/menit pada berbagai suhu yang kemudian ditahan masing-masing selama 1 jam, 2 jam, 3 jam, 4 dan 5 jam. Produk kalsinasi kemudian ditimbang dan dikarakterisasi dengan X-Ray Diffraction (XRD) dan Scanning Electron Microscope (SEM). Hasil percobaan menunjukkan kalsinasi dolomit semakin meningkat seiring dengan kenaikkan suhu kalsinasi. Proses kalsinasi dolomit optimum tercapai pada suhu 900 o C selama 4 jam dengan pengurang berat mencapai 46,74 %. Berdasarkan perhitungan stoikiometri pengurangan berat 46,74 % menunjukkan bahwa 97,78 % dolomit terdekomposisi menjadi MgO dan CaO. Pembentukan fasa MgO dan CaO dari dolomit melalui dua tahapan yaitu tahapan pembentukan fasa MgO-CaCO 3 pada suhu 700 o C dan tahapan pembentukan CaO pada suhu 800 o C-900 o C. Kesimpulan yang didapatkan dari proses kalsinasi dolomit ini adalah peningkatan suhu kalsinasi dapat meningkatkan proses dekomposisi dolomit menjadi fasa MgO dan CaO.
Graphene oxide and reduced graphene oxide attract a lot of attention due to graphene provides some properties that suitable for wider application. Properties of graphene are unique since it can be tuned regarding to its controlled synthesis method and several treatments. This work, graphene oxide was synthesized from used graphite electrode by modified Hummer’s method in which oxidation process controlled. Zinc was used to produce reduced graphene oxide. Graphene oxide and reduced graphene oxide were characterized by SEM, EDS, FT-IR, UV-vis, and XRD. Effective strategy was studied to produce graphene oxide and reduced graphene oxide by controlling its oxidation process. These results prove that chemical and structural properties of graphene oxide and reduced graphene oxide depend on oxidation duration. Furthermore, carbon/oxygen ratio was studied to evaluate effective oxidation process.
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